The 46^th Annual Meeting of the European Society for Blood and Marrow Transplantation: Physicians Poster Session (P001-P706)

29 August - 1 September, 2020 ● Virtual Meeting

Modified and published with permission from https://www.ebmt.org/annual-meeting

Sponsorship Statement: Publication of this supplement is sponsored by the European Society for Blood and Marrow Transplantation. All content was reviewed and approved by the EBMT Committee, which held full responsibility for the abstract selections.

Acute leukaemia

P001 Allogeneic Stem Cell Transplantation for AML Patients with Runx1 Mutation in First Complete Remission: A Study on behalf of the ALWP of the EBMT

Johanna Waidhauser¹, Myriam Labopin^2,3, Jordi Esteve⁴, Nicolaus Kröger⁵, Jan Cornelissen⁶, Tobias Gedde-Dahl⁷, Gwendolyn Van Gorkom⁸, Jürgen Finke⁹, Montserrat Rovira⁴, Nicolaas Schaap¹⁰, Eefke Petersen¹¹, Dietrich Beelen¹², Donald Bunjes¹³, Christoph Schmid¹, Arnon Nagler¹⁴, Mohamad Mohty^2,3

¹Universitiy Medical Center Augsburg, Augsburg, Germany, ²EBMT Paris Study Office, Hôpital Sain-Antoine, Paris, France, ³INSERM UMR 938, Sorbonne University, Paris, France, ⁴Hospital Clinic, Barcelona, Spain, ⁵University Hospital Eppendorf, Hamburg, Germany, ⁶Erasmus MC Cancer Institute, University Medical Center, Rotterdam, Netherlands, ⁷Oslo University Hospital, Oslo, Norway, ⁸University Hospital Maastricht, Maastricht, Netherlands, ⁹University of Freiburg, Freiburg, Germany, ¹⁰Nijmegen Medical Centre, Nijmegen, Netherlands, ¹¹University Medical Center Utrecht, Utrecht, Netherlands, ¹²University Hospital Essen, Essen, Germany, ¹³Universitätsklinikum Ulm, Ulm, Germany, ¹⁴Chaim Sheba Medical Center, Tel Aviv University, Tel-Hashomer, Israel

Background: Acute myeloid leukemia with RUNX1 gene mutation (RUNX1+ AML) has been proposed as a provisional entity in the 2016 WHO classification. Inferior response rates and outcome after conventional chemotherapy have been detected in patients with RUNX1 gene mutation and accordingly, RUNX1+ AML is allocated in the unfavorable prognostic category of the 2017 European Leukemia Net classification. Following allogeneic stem cell transplantation (alloSCT), RUNX1 mutation was an unfavorable factor in one study in MDS/secondary AML, while data in de novo AML are scarce. In this retrospective study by the EBMT Acute Leukemia Working Party, we elucidate the prognostic value of RUNX1 mutation in patients undergoing alloSCT for AML in first complete remission (CR1).

Methods: Adults undergoing alloSCT for AML in CR1 from matched related or unrelated donors between 2013 and 2018 with complete information on conventional cytogenetics and RUNX1 mutational status were selected from the EBMT registry. Variables of interest were overall and leukemia-free survival (OS/LFS), GvHD/relapse free survival (GRFS), cumulative relapse incidence (RI), non-relapse mortality (NRM) and GvHD. Log rank test, Gray test and Cox regression models were used for statistical analysis.

Results: A total of 516 patients were included, 128 RUNX+ and 388 RUNX-, with >80% of both subgroups presenting as de novo AML. As expected, RUNX1+ patients rarely had co-mutations in NPM1 (6% vs. 26%, p=10^-3), and showed a positive correlation with ASXL1 mutations (50% vs. 16%, p=10^-4). Cytogenetic categories and other mutations (FLT3-ITD, CEBPA) were equally distributed between the two groups, as were age, donor and graft type, CMV, conditioning and T cell depletion (TCD).

Median follow-up was 16.4 (RUNX+) and 19.8 (RUNX-) months. 2y OS/LFS of the entire cohort were 64% [59-69]/57% [52-62], with no difference between RUNX1+ and RUNX1- patients either in univariate or multivariate analysis (2y OS: 67.9% [57.3-78.5] vs. 63.1%v[57.4-68.7]p=0.15; 2y LFS: 57.6% [46.4-68.7] vs. 57% [51.4-62.6], p=0.38]). RUNX1 mutation neither had any impact among patients with normal karyotype. Furthermore, no other outcome parameter was influenced by RUNX1 mutational status. Instead, multivariate analysis revealed age and donor type as risk factors for OS, LFS and NRM. Poor cytogenetic was associated with higher RI and inferior LFS/GRFS, in vivo TCD with a lower rate of aGvHD II-IV, cGvHD, and better GRFS. Among patients with available information, FLT3-ITD was an independent risk factor for relapse, LFS and GRFS. RUNX1 did not modify the role of FLT3-ITD.

Conclusions: Within the limits of a retrospective registry analysis, we could not find a negative influence of RUNX1 mutation on outcome after allogeneic SCT in CR1. Hence, transplantation in CR1 might overcome the unfavorable prognostic value of RUNX1 mutation and can be recommended as consolidation treatment in this entity.

Disclosure: Nothing to declare.

P002 Graft Failure after Unmanipulated haplo-hsct with pt-cy in Patients with Acute Myeloid Leukemia in Complete Remission, on behalf of the ALWP-EBMT

Annalisa Ruggeri ¹, Myriam Labopin², Emanuele angelucci³, Didier Blaise⁴, Fabio Ciceri⁵, Yener koc⁶, Jose Luiz Diez-Martin⁷, Luca castagna⁸, Benedetto Bruno⁹, Zafer Gülbas¹⁰, Andrea Bacigalupo¹¹, Arnon Nagler¹², Mohamad Mohty¹³

¹OPBG, Roma, Italy, ²EBMT ALWP Office, Saint Antoine Hospital, Paris, France, ³San Martino, Genova, Italy, ⁴Paoli-Calmettes Institute, Inserm CBT1409, Marseille, France, ⁵San Raffaele Hospital, Milano, Italy, ⁶BMT Unit, Antalya, Turkey, ⁷BMT Unit, Madrid, Spain, ⁸HUMANITAS Cancer Center, Milano, Italy, ⁹BMT Unit, Torino, Italy, ¹⁰BMT Unit, Anadolu, Turkey, ¹¹BMT Unit, Rome, Italy, ¹²Sheba University Hospital, Tel Aviv, Israel, ¹³Saint Antoine Hospital, Paris, France

Background: Graft failure (GF) is a life threatening complication following hematopoietic stem cell transplantation (HSCT). Its incidence depends on multiple parameters including type of donor, HLA disparity, stem cell source, graft composition and conditioning regimen. Incidence of GF in T-cell-depleted haploidentical-transplantations (Haplo-HSCT) can reach up to 10-20%. The use of Haplo-HSCT with post-transplant-cyclophosphamide (PTCy) as graft-versus-host-disease (GVHD) prophylaxis is a new standard in the treatment of hematological diseases. Paucity of data exists on GF in Haplo-HSCT with-PTCy.

Methods: To evaluate the incidence and risk factors of GF after Haplo-HSCT with-PT-Cy, we analyzed 1270 adults with acute myeloid leukemia (AML) reported to ALWP-EBMT who received a first Haplo-HSCT from 2010-2018. GF was defined as neutrophil count lower than 500 micro/L at day+45, competing risk was death without engraftment.

Results: Disease status was CR1 in 73% of patients and CR2 in the remaining. Secondary AML was reported in 13.7%. Median follow-up is 22 months and median age at Haplo-HSCT 54 years. Stem cell source was bone marrow (BM) in 41.4% and 44.6% of patents received a myeloablative conditioning regimen (MAC) with TBF(thiotepa, Bulsulfan and Fludarabine) in 59%. PT-Cy in association with calcineurin inhibitors and MMF was the most frequent GVHD-prophylaxis. Cumulative incidence of GF was 6.6 % (95%CI:5.3-8.1), median time to engraftment was 19(1-45) days. Nine patients engrafted after day+45(47-79), 43 patients experienced primary GF and 41 died before day+45 with no sign of donor engraftment. Of the 43 patients with GF, 7 subsequently engrafted after day+45, 29 patients were rescued with a second HSCT. Overall 18 patients are alive at last fu, 2y OS being 32%. CI of engraftment was lower in patients transplanted for secondary AML (91% vs 94%, p=0.003) and was 95% in MAC versus 92.6% in RIC, p< 0.001. CI of day-100 grade II-IV and grade III-IV aGVHD was 29.1 % (95% CI: 26.5 - 31.6) and 10.4 % (95% CI: 8.7 - 12.2), respectively, and 2 years chronic and extensive GVHD was 31.6 % (95% CI: 28.6 - 34.6) and 11.5 % (95% CI: 9.5 - 13.7). At 2 years GRFS, LFS, and OS were 47.1 % (95% CI: 43.9 - 50.2), 55.8 % (95% CI: 52.7-59) and 61 % (95% CI: 57.9-64.1), respectively. Two-year CI of relapse and NRM were 21.2 % (95% CI: 18.7-23.8) and 23 % (95% CI: 20.4-25.6). Disease recurrence was the most common cause of death, with infections and GVHD being the most frequent transplant related causes. In multivariate analysis, factors independently associated with the risk of GF were: secondary-AML (HR 1.28, p=0.007), use of RIC (HR 1.32, p< 0.001), and use of BM (HR 1.21, p=0.002). RIC and adverse cytogenetic risk were associated with relapse and age, performance status and cytogenetic risk with OS.

Conclusions: Incidence of GF after haplo-HSCT with PT-Cy is lower than in T-cell depleted Haplo. Optimization of conditioning regimen and graft source should be considered for reducing the risk GF in Haplo-HSCT recipients using PT-Cy. Comparison of GF in the different platforms of GVHD prevention (PT-Cy and ATG) is warranted.

Disclosure: Nothing to declare.

P003 Implications of Novel Risks Scores (AML-DRG and AML-HCT-CR) in Allogeneic CD34+ Selected Graft Transplant Outcomes

Rosalia Alonso Trillo ^1,2, Marta Garcia Recio³, Martina Pennisi^2,4, Christina Cho², Sean M. Devlin², Josel D. Ruiz², Molly A. Maloy², Ana Alarcon Tomas¹, Nerea Castillo⁵, Richard J. Lin², Ioannis Politikos², Miriam Sanchez Escamilla⁶, Michael Scordo², Gunjan L. Shah², Juliet N. Barker², Hugo Castro-Malaspina², Boglarka Gyurkocza², Parastoo B. Dahi², Ann A. Jakubowski², Esperanza B. Papadopoulos², Doris M. Ponce², Craig S. Sauter², Brian C. Shaffer², Roni Shouval², Roni Tamari², Marcel R. M. van den Brink², James W. Young², Sergio A. Giralt², Miguel Perales²

¹Hospital Puerta de Hierro Majadahonda, Majadahonda, Spain, ²Memorial Sloan Kettering Cancer Center, New York, NY, United States, ³Son Espases University Hospital, IdISBa, Palma de Mallorca, Spain, ⁴University of Milano-Bicocca, Milan, Italy, ⁵Hospital Vall d’Hebron, Barcelona, Spain, ⁶IDIVAL, Santander, Spain

Background: Several prognostic models to stratify allogeneic hematopoietic cell transplantation (allo-HCT) outcomes have been developed in recent years. Despite evidence that minimal residual disease (MRD) is an independent predictor of survival in patients with AML, MRD is excluded from most models. Two novel AML-specific disease scores that incorporate disease data, AML-specific disease risk group (AML-DRG) and AML-HCT-CR, have been shown to be predictive of survival in patients with AML who received an of unmodified HCT (Piyanuch et al. BBMT. 2019). T cell depletion (TCD) using ex vivo CD34 selection has been shown to decrease acute and chronic GVHD without increasing relapse in selected patients with AML, ALL and MDS, and results of a completed phase 3 trial are pending (NCT02345850). Our proposal is to validate both scoring systems in a cohort of patients who underwent ex vivo CD34 selected HCT.

Methods: We included 279 patients age > 18 years who underwent a first CD34+ selected allo-HCT for AML between 2008 and 2018 and calculated their AML-DRG and AML-HCT-CR scores. AML-DRG variables included: secondary AML, adverse European LeukemiaNet2017 genetic risk and MRD status. The AML-HCT-CR model also included HCT-CI score ≥ 3 and age ≥ 60 years. MRD was assessed pre HCT by flow cytometry and/or PCR or NGS as indicated. The primary outcome was survival (OS) and secondary outcomes were progression-free-survival (PFS), and incidences of non-relapsing mortality (NRM), and relapse.

Results: Median age was 55 years (range 19 to 73 years), 45.5% (n = 127) were females and median HTC-CI was 2. All patients received myeloablative conditioning. At time of HCT 20.8% patients had MRD+ status and 5.4% had active disease (Table 1). Median follow-up was 5.5 years (95% CI: 5.1-6.3). For the AML-DRG model, the 3-year OS in the low, intermediate, and high-risk groups were 65%, 52%, and 13%, respectively. PFS at 3 years were 63%, 43%, and 15% in the same groups. The OS predictive accuracy measured by c-statistic was 0.588. In the AML-HCT-CR model, patients in low, intermediate, high risk and very high risk had a 3 year OS of 72%, 58%, 39%, and 51%, respectively. The corresponding PFS at 3 years were 68%, 56%, 36% and 43%. The OS predictive accuracy measured by c-statistic was 0.615. Both scores significantly predicted relapse incidence (AML-DRG model p value= < 0.001; AML-HCT-CR model p value= 0.04), but AML-DRG model was not associated with NRM (p = 0.993).

Conclusions: The AML-DRG and AML-HCT-CR models are predictive of outcomes including OS, PFS, and relapse incidence in a large cohort of patients receiving TCD HCT with CD34+ selected allografts. These data should therefore lead to better patient selection for ex vivo CD34-selected allo-HCT. The predictive accuracy for both scoring systems is modest, however; and there remains a need for innovative models incorporating new clinical and genomic characteristics to achieve a scoring system with improved accuracy.

Disclosure:

Marta Garcia Recio, MD:

Janssen and Takeda Honorary

Ioannis Politikos, MD:

Funding from Angiocrine Bioscience, Inc.InvestigatorResearch: MerckInvestigatorResearch

Michael Scordo, MD:

Consultancy: McKinsey & CompanyConsultancy and Angiocrine Bioscience, Inc.Consultancy

Gunjan L. Shah, MD:

Funding JanssenInvestigatorResearch and AmgenInvestigatorResearch

Juliet N. Barker, M.B.B.S (Hons), FRACP Doctor:

Funding: Merck & CoInvestigatorResearch, AngiocrineInvestigatorResearch, MerckInvestigatorResearch, GamidaInvestigatorResearch,

Boglarka Gyurkocza, MD:

Actinium Pharmaceuticals Inc.nonemy institution receives research funding from Actinium Pharmaceuticals Inc.

Craig S. Sauter, MD:

Board, Honoraria and Research Funding: Spectrum PharmaceuticalsadvisorAdvisory, NovartisadvisorAdvisory, GenmabadvisorAdvisory, Precision Biosciencesadvisor and research fundsAdvisory

Board and Honoraria: Kite, a Gilead CompanyadvisorAdvisory, Gamida CelladvisorAdvisory, PfizeradvisorAdvisory, GSKadvisorAdvisory Board and Honoraria

Marcel R. M. van den Brink, MD, PhD:

Seres InvestigatorHonoraria, Intellectual Property Rights, Research Funding and Stocks

EveloHonorariaHonoraria

Honoraria: Jazz Pharmaceuticals, Therakos, AmgenHonoraria, Merck & Co. Inc, Magenta Therapeutics

Smart ImmuneInvestigatorStocks, JunoInvestigatorIntellectual Property Rights

DKMSChairmanAdvisory Board

Sergio A. Giralt, MD:

Consultancy: Amgen, Actinuum, Celgene, Johnson&Johnson, JAZZ pharmaceutical, Milteny, Takeda, Novartis, Kite and Spectrum Pharma.

Miguel Perales, MD:

Honoraria from Abbvie, Bellicum, Celgene, Bristol-Myers Squibb, Incyte, Merck, Novartis, Nektar Therapeutics, Omeros, and Takeda. He serves on DSMBs for Cidara Therapeutics, Servier and Medigene, and the scientific advisory boards of MolMed and NexImmune. He has received research support for clinical trials from Incyte, Kite/Gilead and Miltenyi Biotec. He serves in a volunteer capacity as a member of the Board of Directors of American Society for Transplantation and Cellular Therapy (ASTCT) and Be The Match (National Marrow Donor Program, NMDP), as well as on the CIBMTR Cellular Immunotherapy Data Resource (CIDR) Committee

P004 Downregulation of HLA-DR in Blasts of Patients with Acute Leukaemia Relapsing after Allogeneic Haematopoietic Stem Cell Transplantation

Memnon Lysandrou¹, Maria Liga ¹, Eleni Gavriilaki², Nikolaos Spyridis¹, Alexandra Siorenta³, Eleni Kapsali⁴, Evgenia Verigou¹, Vassiliki Douka², Georgios Vartholomatos⁴, Ioanna Sakellari², Achilles Anagnostopoulos², Alexandros Spyridonidis¹

¹University of Patras, Rio, Greece, ²G.Papanicolaou Hospital, Thessaloniki, Greece, ³Hellenic National Centre of Histocompatibility, G. Gennimatas Hospital, Athens, Greece, ⁴University Hospital of Ioannina, Ioannina, Greece

Background: Relapse following allo-HSCT in patients with acute leukaemia remains to date a challenge in clinical practice and is associated with ominous prognosis. Identifying the mechanism leading to relapse will morph our therapeutic armamentarium in accordance with the underlying pathophysiology. Amongst recent studies, HLA Class II downregulation has emerged as a major mechanism of immune evasion after allo-HSCT in patients with AML. However, relapses of patients with ALL after allo-HSCT have not yet been studied in an identical manner. Our goal was to identify the downregulation of HLA-DR in blasts of patients with acute leukaemia after allo-HSCT using flow cytometry.

Methods: For this study, we retrospectively selected patients with a diagnosis of AML, ALL or MPAL who relapsed following allo-HCT for which raw flow cytometry data were available both at a pre-transplantation active disease and at relapse. Blast cells were gated, then analyzed based on their HLA-DR expression and a Mean Fluorescence Intensity was calculated for both timepoints (preMFI & relMFI). Analysis was performed using the FlowJo software (Version 10.5.3, FlowJo LLC). Normalisation of the MFI values was performed using the median HLA-DR MFI of blasts from 31 newly diagnosed acute leukaemias calculated as MFI/median. We defined HLA-DR Downregulation as the reduction of the normalized value at the time of relapse by at least 50% (preMFI-n/relMFI-n < = 0.5). Statistical analysis was performed using Graph Prism.

Results: We analyzed 16 patients (9 male, 7 female) median age of 44 years old (range 32-65) who underwent allo-HSCT for AML (n=12), ALL (n=3) and MPAL (n=1). Four patients received graft from a compatible sibling, 2 from an haploidentical donor and 10 from unrelated donors (7 from 7/8 HLA match, 3 from 8/8 HLA match). At the time of transplantation, 5 patients achieved CR1, 7 achieved CR2 and 4 had refractory disease. The median day of relapse was day 147 (60-405). Median preMFI and preMFI-n values were 10.035 (range 81-14818) and 1.01 (0.008-6.5) respectively, median relMFI and relMFI-n were 7.919 (69-62055) and 0.8 (0.007-6.2). In 8 out 16 paired samples we observed a reduction of the HLA-DR MFI and MFI-n by at least 50% at the time of relapse (median relMFI/preMFI 0.37, range 0.001-0.5). Moreover, HLA-DR downregulation was observed in 2 out of the 3 patients with ALL. There was no correlation between donor-recipient HLA incompatibility and HLA-DR downregulation (p=ns).

Conclusions: HLA-DR Downregulation represents a common mechanism of immune escape in acute leukaemias relapsing after allo-HSCT that accounts to 50% of our patients. We first describe this mechanism to be present in cases of ALL. Identifying this phenomenon in patients using flow cytometry provides valuable information concerning their treatment choices as they will obviously not benefit from donor lymphocyte infusions.

Disclosure: no disclosures

P005 Establishment of a National Stem Cell Transplant Clinical Trials Network: The UK Impact Partnership for Accelerated Cellular Therapies

David I Marks¹, Shamyla Siddique², Ronjon Chakraverty³, Aimee Jackson², Victoria Potter⁴, Ram Malladi⁵, Andy Peniket⁶, Paresh Vyas⁷, Pamela Kearns^2,8, Charles Craddock ^2,5

¹University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom, ²University of Birmingham, Birmingham, United Kingdom, ³University College London Hospitals NHS Foundation Trust, London, United Kingdom, ⁴King’s College Hospital NHS Foundation Trust, London, United Kingdom, ⁵Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom, ⁶Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom, ⁷University of Oxford, Oxford, United Kingdom, ⁸NIHR Birmingham Biomedical Research Centre, Birmingham, United Kingdom

Background: Stem cell transplantation (SCT) plays a central role in the management of haematological malignancies and is increasingly utilised in the management of non-malignant disorders. Treatment toxicity and disease relapse remain major causes of treatment failure after both autologous and allogeneic SCT. In contrast to other areas of haemato-oncology where clinical practice is informed by large prospective randomised trials, transplant practice is largely informed by retrospective registry studies and local practice. Very few patients undergoing stem cell transplantation enter prospective randomised trials aimed at improving transplant outcome. Reasoning that major barriers to transplant trial delivery was the twin absence of resource for trial development and research nurse capacity within a large networked population, a 4-year pilot was established in 2017 to create a national transplant trials network in the UK.

Methods: The IMPACT partnership was established in 2017 and £3.4 million was awarded for a 4-year pilot by NHSBT and the charities Anthony Nolan and Leukaemia UK. Funding was awarded with the aim of recruiting at least 500 patients to 9 prospective trials with embedded sequential collection of clinical samples. The IMPACT grant funded a central Hub within a well-established Clinical Trials Unit which was responsible for clinical trial design, set-up, management, and publication of trial results. The Hub was linked with a Trials Network consisting of 10 major transplant centres each staffed by a dedicated IMPACT research nurse chosen through an independent peer review process. 12 additional UK centres were awarded Affiliate status. This effectively created a funded trials network able to recruit to transplant trials in a cohesive manner across a 20 million patient population.

Results: In the 24 months since its establishment the IMPACT network has received 28 proposals for transplant trials - 12 of which have been developed with expert statistical and clinical input from the IMPACT team through national workshops. Rapid feasibility assessments were performed for 10 of these trials. To date 7 trials have been submitted for independent peer review and six have been approved. Key transplant questions addressed include defining the optimal conditioning regimen in acute myeloid leukaemia and acute lymphoblastic leukaemia, studying the role of post-transplant maintenance and donor lymphocyte infusion (DLI) and optimising graft-versus-host disease prophylaxis. 3 trials have been opened with a mean of 12 months to set-up (range 8-18). In its first two years, the IMPACT network has randomised 183 patients to 3 trials. Of note, one trial - Pro-DLI, a randomised trial of DLI administration post-transplant-has fully recruited within 24 months - 8 months ahead of its scheduled target.

Conclusions: Investment in the IMPACT trials hub and network has rapidly transformed set-up and recruitment to prospective randomised trials in SCT within the UK. Key to this success has been its ability to accelerate and coordinate both trials set up and recruitment across a 20 million population. Further investment in such accelerated trial models is required across Europe if patient outcomes after stem cell transplantation are to be improved.

Clinical Trial Registry: N/A

Disclosure: Nothing to declare.

P006 A region-wide Retrospective Analysis of Outcome for Patients with Newly Diagnosed Acute Lymphoblastic Leukemia

Shuichi Ota ¹, Akio Shigematsu¹, Ryoji Kobayashi², Takeshi Kondo³, Tomoyuki Endo⁴, Yutaka Tsutsumi⁵, Hajime Kobayashi⁶, Yasutaka Kakinoki⁷, Satoshi Yamamoto⁸, Yuichi Konuma⁹, Takuto Miyagishima¹⁰, Tetsuyuki Igarashi¹¹, Takanori Oda¹², Hajime Sakai¹³, Toshimichi Ishihara¹⁴, Masahiro Yoshida¹⁵, Takahiro Nagashima¹⁶, Kazuya Sato¹⁷, Yuji Kanisawa¹⁸, Yoshihito Haseyama¹⁹, Yasuo Hirayama²⁰, Mitsutoshi Kurosawa²¹

¹Sapporo Hokuyu Hospital, Sapporo, Japan, ² Sapporo Hokuyu Hospital, Sapporo, Japan, ³Aiiku Hospital, Sapporo, Japan, ⁴Hokkaido University, Sapporo, Japan, ⁵Hakodate Municipal Hospital, Hakodate, Japan, ⁶Obihiro Kosei Hospital, Obihiro, Japan, ⁷Asahikawa City Hospital, Asahikawa, Japan, ⁸Sapporo City General Hospital, Sapporo, Japan, ⁹Asahikawa Red Cross Hospital, Asahikawa, Japan, ¹⁰Kushiro Rosai Hospital, Kushiro, Japan, ¹¹Tenshi Hospital, Sapporo, Japan, ¹²Hokkaido Medical Center for Child Health and Rehabilitation, Sapporo, Japan, ¹³Teine Keijinkai Hospital, Sapporo, Japan, ¹⁴Kin-ikyo Chuo Hospital, Sapporo, Japan, ¹⁵Steel Memorial Muroran Hospital, Muroran, Japan, ¹⁶Japanese Red Cross Kitami Hospital, Kitami, Japan, ¹⁷Asahikawa Kosei Hospital, Asahikawa, Japan, ¹⁸Oji General Hospital, Tomakomai, Japan, ¹⁹Tonan Hospital, Sapporo, Japan, ²⁰Higashi Sapporo Hospital, Sapporo, Japan, ²¹National Hospital Organization, Hokkaido Cancer Center, Sapporo, Japan

Background: Recently, the prognosis for patients with acute lymphoblastic leukemia (ALL) has been improved by the introduction of tyrosine kinase inhibitors for Philadelphia chromosome-positive (Ph+) ALL patients and pediatric-inspired protocol for adolescent/young-adult (AYA) patients, and the indication of allogeneic stem cell transplantation (allo-SCT) at first complete remission (CR1) needs to be reassessed. We therefore retrospectively analyzed the impact of allo-SCT for patients with ALL in the era of TKIs and pediatric-inspired protocol for AYA.

Methods: Clinical data for 512 patients who were diagnosed as having ALL between 2007 and 2017 were collected from 21 centers in Hokkaido, Japan.

Results: The median age of the patients was 55 years (range: 15-84 years). Ninety-two of the patients were pediatric (0-14 years), 86 were AYA (15-35 years), 195 were adult (36-65 years) and 148 were elderly patients (66- years). Cytogenetic (G-banding) results were available in 486 patients. Three hundred forty-seven patients had abnormal karyotypes (AK), and 139 patients had normal karyotype (NK). The BCR-ABL fusion gene, including masked Ph+, was positive in 193 patients, and 181 (93.8%) of them were more than 36 years. Abnormalities of complex karyotype were seen in 94 of the patients. After a first remission induction therapy, 418 of 467 (89.5%) evaluable patients achieved complete remission (CR), and BCR-ABL positive patients showed better CR rate than those without BCR-ABL (93.7% vs. 87.4%, P=0.04). At the median follow-up of 1180 days (9-4049 days), overall survival (OS) was superior in patients with NK than those with AK (P=0.01), and BCR-ABL positive patients showed poorer OS than those without BCR-ABL (P=0.01). One hundred fifty-three patients received allo-SCT at CR1. The median age of those patients was 44, and BCR-ABL was positive in 53.9% of those patients. Allo-SCT did not improve overall survival (OS) for patients aged below 35 years. However, allo-SCT significantly improved OS in patients aged over 36 years with or without BCR-ABL (p< 0.01and p=0.03). In BCR-ABL positive patients, allo-SCT improved OS even for patients who achieved molecular remission after first course of chemotherapy (P=0.006). By subgroup analyses of the age groups (pediatric, AYA, adult and elderly), there were no difference of OS between NK and AK. In adult and elderly patients, OS was not different between BCR-ABL positive and negative patients, though in patients over 70 years, BCR-ABL positivity was associated with superior OS (Hazard ratio, 3.2; 95% confidence intervals, 1.04-4.78, P=0.02). In adult or elderly BCR-ABL negative patients, OS of patients with complex karyotype was inferior to those without complex karyotype. Among those patients who achieved CR1 after a first induction therapy, allo-SCT at CR1 was associated with superior OS [HR, 0.40; 95%CI, 0.39- 0.96, P=0.03].

Conclusions: Allo-SCT improved OS for patients with ALL aged over 36 years regardless of BCR-ABL positivity in the era of TKI. Allo-SCT at CR1 should be considered for adult BCR-ABL negative ALL patients, especially in patients who have received non-AYA chemotherapy regimen.

Disclosure: Shuichi Ota received the honoraria of lecture fee from Novartis.

P007 Pre-harvest Higher Donor Foxp3 Mrna and Lower CD4+ T Cell Concentration Predict Increased Risk of all Relapse after Myeloablative Hct with T-replete Bone Marrow Grafts

Niels Jacobsen ¹, Tina Frisch¹, Niels Keiding², Carsten Heilman¹, Henrik Sengeløv¹, Hans Madsen¹, Hanne Marquart¹, Mette Andersen¹, Claus Christiansen¹, Lars Ryder¹

¹Rigshospitalet University Hospital, Copenhagen, Denmark, ²University of Copenhagen, Copenhagen, Denmark

Background: The curative effect of HCT for acute leukaemia is due in part to the donor T cell-mediated graft-versus-leukaemia reaction (GvL). Yet, post-HCT relapse remains a major cause of treatment failure. Donor regulatory T cells expressing the transcription factor Foxp3 (Tregs) have been found to reduce donor T cell-mediated GvHD without compromising GvL.

Methods: We have obtained contrasting results by assessment of the level of Foxp3 mRNA expression by qPCR in pre-harvest donor blood CD4+ T cells in a consecutive series of 45 children and adults, median age 16.7 years, with ALL in 1^st or 2^nd CR who received myeloablative HCT using T-replete bone marrow grafts and post-HCT cyclosporine GvHD prophylaxis. Donor was an HLA identical sibling (N = 11) or an alternative, unrelated (N = 33) or other family (N = 1) donor. Anti-thymocyte globulin (ATG) was given during the pre-HCT conditioning to 28 of 34 patients with an alternative donor.

Results: Post-HCT relapse, defined morphologically, occurred in 17 patients median 363 days post-HCT. By Cox multivariate proportional hazard regression, the effect of donor blood Foxp3 mRNA level on relapse did not meet the proportionality assumption. Proportionality was achieved after dichotomy at the median time of relapse. No effect of donor Foxp3 mRNA level was demonstrated within the first 363 days after HCT. However, after day 363 a higher donor Foxp3 mRNA level was associated with an increased risk of relapse. Thus, seven of eight late relapses occurred in recipients from donors with pre-harvest Foxp3 mRNA level above the median. In contrast, a higher pre-harvest donor CD4+ T cell concentration was associated with a reduced relapse risk. In the multivariate regression analysis, a significant interaction between the pre-harvest donor CD4 T cell concentration and the use of ATG in the conditioning regimen was observed, indicating that the effect associated with donor CD4 T cells was modified by ATG, compatible with the notion that the effect associated with donor CD4 T cell concentration was abrogated in recipients who received conditioning including ATG. However, due to the small sample size it is premature to draw definite conclusions regarding the effect of ATG. Cumulative relapse incidence curves supported the Cox univariate and multivariate regression analysis. Furthermore, we observed a reduction of the probability of surviving in continuous CR associated with higher pre-harvest donor Foxp3 mRNA level and decreased pre-harvest donor CD4 T cell concentration.

Conclusions: A higher Foxp3 mRNA level in CD4+ T cells isolated from pre-harvest donor blood was associated with an increased risk of late relapse in patients with ALL after myeloablative HCT with T-replete bone marrow graft, suggesting that donor Tregs may inhibit GvL. In contrast, a higher pre-transplant donor CD4+ T cell concentration was associated with a reduced relapse risk. The donor CD4 T cell effect was restricted to patients who did not receive ATG during pre-transplant conditioning.

Disclosure: Nothing to declare.

NJ and TF contributed equally to this work.

P008 Epidemiology, Management and Economic Impact of Acute Myeloid Leukaemia and Myelodysplastic Syndrome in Spain: A Claims Database Analysis

Alicia Marsà ¹, Meritxell Ascanio¹, Teresa Briones², Josep Darbà³

¹BCN Health Economics & Outcomes Research SL, Barcelona, Spain, ²Jazz Pharmaceuticals Iberia, Barcelona, Spain, ³Universitat de Barcelona, Barcelona, Spain

Background: To review epidemiology, management, use of resources, and costs of acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) via the evaluation of patient records.

Methods: Data were extracted from the Ministry of Health records via the Spanish claims database Minimum Basic Data Set. The database contains patient records compiled in 192 private and 313 public hospitals, covering all Spanish regions, between 1997 and 2015 for AML and between 2008 and 2015 for MDS, according to data availability. All records corresponding to AML and MDS were identified using the International Statistical Classification of Diseases and Related Health Problems version 9 (ICD9) codes: 205.00, 205.01, 205.02, 238.72, 238.73, 238.74, and 238.75. The costs of healthcare usage were calculated based on the mean costs of medical procedures as determined by the Spanish Ministry of Health, which exclude prescription medication.

Results: Overall, records of 39,568 patients with AML and 33,091 with MDS were analysed. In most cases, the AML type was not registered; 9% of the patients were registered as in remission and 1% in relapse at first entry within the study period. When MDS was specified, 18% of the patients were registered with low-grade MDS lesions, 8% with high-grade lesions, and 1% with 5q deletion. Mean age at AML diagnosis was 59 years (SD=21), whereas for MDS it was 78 years (SD=13). Patients were mostly between 70 and 89 years of age and predominantly male. In terms of disease management, of the 102,783 and 64,556 admissions registered for AML and MDS, respectively, 79% and 48% were attributed to haematology services and 58% and 83% of admissions were not scheduled; the median length of hospital stay was 17 days (IQR=26) for AML and 7 days (IQR=9) for MDS. Chemotherapy was the most common procedure performed in patients with AML (44%), followed by platelets transfusion (31%). Transfusion of packed cells (41%) and chest x-ray (20%) were the most common procedures in patients with MDS. There was an increase in bone marrow and hematopoietic stem cell transplants over time in Spain during the study period, from 171 in 1997 (1,494 patients) to 477 in 2015 (3,611 patients). Mean annual direct medical costs were measured throughout the study period and were €66,422,245 for AML and €42,635,313 for MDS; both displayed an increasing tendency over time, with the costs of AML increasing 3.7-fold between 1999 and 2011. Of these, €15,843,982 and €2,705,791 were directly linked to transplants. Mean annual costs per patient were €1,821and €1,288, respectively. In most admissions, (>96%) costs were financed by the Spanish social security system.

Conclusions: This retrospective study identifies patient characteristics, disease management, and health resource use related to AML and MDS treatment in Spain. AML and MDS represent a large burden for the National Spanish Healthcare System, with substantial costs incurred in secondary care settings. A large portion of these costs can be attributed to the increasing number of bone marrow and hematopoietic stem cell transplants.

Disclosure: Teresa Briones is an employee of and holds stock/stock options in Jazz Pharmaceuticals. The other authors have no conflicts of interest to declare.

P009 Pre-transplant Bone Marrow Cellularity and Blood Count Recovery are not Associated with Relapse or Survival Risk following Allogeneic Stem Cell Transplant for AML In Cr1

Igor Novitzky Basso ^1,2, Shiyi Chen^1,2, Jeffrey Lipton^1,2, Dennis Kim^1,2, Auro Viswabandya^1,2, Rajat Kumar^1,2, Wilson Lam^1,2, Arjun Law^1,2, Zeyad Al-Shaibani^1,2, Armin Gerbitz^1,2, Ivan Pasic^1,2, Jonas Mattsson^1,2, Fotios Michelis^1,2

¹Princess Margaret Cancer Centre, Toronto, Canada, ²University of Toronto, Toronto, Canada

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) can be curative for acute myeloid leukemia (AML). Novel therapies may render patients’ bone marrows profoundly hypocellular and be associated with prolonged post-therapy pancytopenia. In individual patients, bone marrow cellularity (BMC) at pre-transplant assessment (PTP) and post-treatment pancytopenia (leading to classification as CR-incomplete [CRi] as per ELN 2017 criteria) may be a manifestation of disease persistence, and this clinical response to chemotherapy is concerning for treating physicians.

Methods: In the present retrospective study, we examined the impact of BMC and post-treatment blood count recovery on a single-center cohort of 342 patients who underwent HSCT for AML in CR or CRi from January 2013 until December 2018. Data was updated as of November 2019. Median age was 57 years (range 18-73). Disease status at PTP was first complete remission (CR1) in 86% and CR2 or beyond in 56% of patients. Myeloablative conditioning was administered to 31% of patients while 69% received reduced-intensity conditioning. In vivo T-cell depletion was given to 75% of patients. Donors were matched-unrelated, matched-related and haplo-identical related (200, 108 and 34). The median follow-up of survivors was 31 months (10-81).

For BMC, patients were grouped as scoring aplastic (< 10%), hypocellular, normocellular and hypercellular for age (22, 89, 174 and 52 patients respectively; 5 patients had missing data); BMC was assessed by established pathology criteria. For ELN response (ELNr) at PTP, all patients had BM blasts fewer than 5%, and those having neutrophils ≥ 1 and platelets ≥ 100 at PTP were deemed as CR, otherwise CRi (190 and 152 patients respectively). MRC cytogenetic risk as per Grimwade, et al 2010 was favorable=21, intermediate=227, adverse=66 and unknown=28.

Cox proportional hazard model was used to analyze the effects of variables on overall survival (OS) and Fine and Gray’s competing risk regression model was used to examine the effect of variables on cumulative incidence of relapse (CIR).

Results: OS of the whole cohort at 2y was 56.08%, while CIR was 20.31%. CIR for BMC groupings was aplastic 17.28%, hypocellular 22.60%, normocellular 19.63%, hypercellular 21.89%, p not significant (ns), see Figure 1; and for ELNr, CR 18.41%, CRi 22.69%, p ns. OS for BMC was aplastic 63.64%, hypocellular 49.39%, normocellular 56.34%, hypercellular 60.42%, p ns, and for ELNr, CR 56.97%, CRi 55.06%, p ns.

The distribution of MRC cytogenetic risk by BMC was not significantly different (p=0.26) nor was primary induction failure (p=0.759), HCT-CI (p=0.495) or usage of myeloablative conditioning vs reduced-intensity (p=0.988). ELNr CRi was more likely in BMC aplastic and hypocellular, than CR (p< 2.62e-8).

Multivariate analysis confirmed that neither BMC nor attainment of ELNr CR vs CRi had an impact on OS or relapse. Other factors such as age at transplant (p< 0.0001) and chronic GvHD (p=0.0003) influenced OS, while MRC cytogenetic risk (p=0.0009) and chronic GvHD (p=0.0011) affected relapse.

Conclusions: Neither ELN response status (CR vs CRi) nor bone marrow cellularity at pre-transplant assessment influence relapse post-transplant or OS. Hypocellularity and CRi should not be considered negative prognostic factors for post-transplant outcomes of AML.

[Figure 1: Cumulative incidence of relapse of bone marrow cellularity groupings.]

Disclosure: Nothing to declare.

P010 Immunotherapy Salvage for b-precursor Acute Lymphoblastic Leukemia Relapsing after Allogeneic Stem Cell Transplantation: A Retrospective Analysis by the Alwp of the Ebmt

Gesine Bug ¹, Myriam Labopin², Ali Bazarbachi³, Eolia Brissot⁴, Stephen Robinson⁵, Alessandro Rambaldi⁶, Ben Carpenter⁷, Riccardo Saccardi⁸, Nicolaus Kröger⁹, Michael Potter¹⁰, Ibrahim Yakoub-Agha¹¹, Laimonas Griskevicius¹², Sebastian Giebel¹³, Arnon Nagler¹⁴, Mohamad Mohty⁴

¹Goethe University Frankfurt, Frankfurt, Germany, ²EBMT Paris Study Office, Saint Antoine Hospital, INSERM UMR 938, Sorbonne University, Paris, France, ³American University of Beirut Medical Center, Beirut, Lebanon, ⁴Hopital Saint Antoine, Paris, France, ⁵Bristol Royal Hospital for Children, Bristol, United Kingdom, ⁶University of Milan and ASST Papa Giovanni XXIII, Bergamo, Italy, ⁷University College London Hospital, London, United Kingdom, ⁸Azienda Ospedaliera Universitaria Careggi, Firenze, Italy, ⁹University Hospital Eppendorf, Hamburg, Germany, ¹⁰Royal Marsden Hospital, London, United Kingdom, ¹¹CHU de Lille, LIRIC, INSERM U995, Université de Lille, Lille, France, ¹²Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania, ¹³Maria Sklodowska-Curie Institute, Gliwice, Poland, ¹⁴Chaim Sheba Medical Center, Tel Hashomer, Israel

Background: Blinatumomab (BLINA) and inotuzumab ozogamicin (INO) have been used for relapsed and refractory B precursor acute lymphoblastic leukemia (ALL) with or without prior allogeneic hematopoietic stem cell transplantation (HSCT). In an international phase II study of 64 patients relapsing after HSCT and treated with blinatumomab, 1-year OS was 36% (Stein AS et al., BBMT 2019), which compared favorably with historical cohorts treated with chemotherapy, donor lymphocyte infusions or a 2^nd HSCT (Spiridonidis A et al., Leukemia 2012). Our retrospective analysis evaluates (i) the impact of BLINA and INO as salvage therapy post-HSCT on OS in a larger patient cohort, (ii) the safety of additional DLI and (iii) the outcome of patients undergoing a 2^nd HSCT.

Methods: We identified 133 adult patients median age 36 (range, 18-68) years with Philadelphia-negative ALL who were treated with either BLINA (n=93, 70%), INO (n=34, 26%) or both (n=6, 4%) within 180 days after their first molecular or hematologic relapse following a first HSCT, performed 2012-2018. Patients were transplanted in CR1 (53%), CR2 (34%) or CR3 (13%) from a matched sibling (32%), matched unrelated donor (55%), other relative (11%) or umbilical cord blood (2%) using myeloablative or reduced-intensity conditioning (77% and 23%, resp.). OS was calculated by Kaplan-Meier analysis. In the multivariate Cox analysis, patient age, CR1 at HSCT, donor type as well as factors associated with a p value < 0.10 in the univariate analysis were included.

Results: Relapse occurred at a median of 7.1 (range, 0.8-80.6) months post-HSCT and immunotherapy was started a median of 15 (range, 0-172) days after relapse. With a median follow-up of 14.8 (range, 7.7-28.3) months after immunotherapy, 1-year OS in all patients was 30.9% (95% CI: 21.7-40.2). In patients treated with either INO or BLINA, probability of 1-year OS was 20.4% (95% CI: 3.6-37.2) and 36.4% (95% CI, 25.2-47.6), resp. (Figure 1, p=0.041). Immunotherapy was applied as monotherapy (n=81, 61%) or associated with chemotherapy (n=52, 39%). Additional cellular therapy included DLI prior to (n=6, 5%) or subsequent to immunotherapy (n=24, 18%) and probability of 2^nd HSCT within one year was 26% (95% CI: 18.8-33.8); these 39 patients had a 1-year OS of 42.4% (95% CI: 23.8-61.1) after 2^nd HSCT. However, neither additional chemotherapy nor DLI or 2^nd HSCT (as time-dependent variable) had a statistically significant effect on OS.

A total of 85 patients died, mostly from leukemia (n=53, 63%) or infection (n=20, 24%). Out of all 40 patients treated with INO, two were reported as dead due to SOS (both received a 2^nd HSCT). In multivariate analysis, female gender (HR 0.45, p=0.001), sibling vs other donors (HR 0.52, p=0.009) and longer time to relapse (HR 0.96, p=0.012) proved to be independently associated with better OS.

Conclusions: In patients relapsing after an allogeneic HSCT, BLINA or INO immunotherapy was associated with 1-year OS rates of 20-36%. Additional DLI or subsequent HSCT seemed to be safe, but did not improve outcome.

[Fig. 1: Overall survival for patients receiving either INO or BLINA after relapse.]

Disclosure:

Gesine Bug: Pfizer: advisory board

Sebastian Giebel: Amgen: honoraria, advisory boards, travel grants; Pfizer: honoraria, advisory baords.

P011 Comparison of pre-transplant Comorbidity Indices in Acute Leukemia Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Zeynep Arzu Yeğin, Asena Dikyar, Lale Aydın Kaynar, Zübeyde Nur Özkurt, Münci Yağcı

Gazi University, Ankara, Turkey

Background: In 2005, Sorror et al introduced a new prognostic scale for the candidates of allogeneic

hematopoietic stem cell transplantation (allo-HSCT). Since then, several methods were developed to predict the risk of transplant related mortality. This retrospective study was designed to evaluate and compare the efficacy of the conventional and novel prognostic tools including hematopoeitic cell transplant (HCT)-comorbidity index (HCT-CI), HCT-CI/Age and HCT-composite risk (HCT-CR) indices.

Methods: A total of 215 acute leukemia (acute myeloid leukemia / acute lymphoblastic leukemia:

129/86) patients [median age: 37(18-71) years; M/F: 135/80] were included in this study. Medical records of the patients were retrospectively reviewed. Besides European Society for Blood and Marrow Transplantation (EBMT) score, Eastern Cooperative Oncology Group (ECOG) and Karnofsky scales; pre-transplant risk evaluation was performed using HCT-CI, HCT-CI/Age and HCT-CR, as previously described. Disease risk stratification was based on European Leukemia Net guidelines.

Results: Pre-transplant risk scales including EBMT [median score: 3(0-7)], HCT-CI [median score: 1(0-6)], HCT-CI/Age [median score: 1(0-7)] and HCT-CR [Low: 84(39.1%); Intermediate: 11(5.1%); High: 112(52.1%); Very high: 8(3.7%)] were evaluated as well as ECOG [median score: 1(0-4)] and Karnofsky scales [median score: 40(40-100)]. Pre-transplant disease status was first complete remission (CR1) in 150 patients (69.8%), CR2 in 29 patients (13.5%), >CR2 in 1 patient (0.4 %), partial remission in 10 patients (4.7%) and progressive disease in 25 patients (11.6%). A total of 162 HSCTs (75.3%) were related, 44(20.5%) were unrelated and 9(4.2%) were haploidentical transplants. Graft source was peripheral blood in 208 (96.7%) and bone marrow in 7 transplants (3.3%). Conditioning regimen was myeloablative in 158(73.5%) and reduced intensity in 57 patients (26.5%). Patients were divided into two subgroups based on HCT-CR. Group 1 represented low-risk patients, whereas Group 2 was composed of intermediate, high and very-high-risk patients. Sinusoidal obstruction syndrome was found to be more frequent in Group 2 (11.2% vs 2.8%; p=0.021). Prevalence of cytomegalovirus reactivation and acute/chronic graft versus host disease was similar in both groups. At a median 681(4-4774) days of follow-up, patients with low HCT-CR scores represented significantly higher probability of progression free survival (70% vs 53.5%; p=0.016) and overall survival (60% vs 41%;p=0.007) (Figure 1). In univariate analysis, HCT-CI (p=0.002), HCT-CI/Age (p=0.015), HCT-CR (p=0.009), EBMT (p=0.007), ECOG (p< 0.001), Karnofsky (p< 0.001) and C reactive protein levels had significant impact on survival. The significant impact of HCT-CI (p=0.018), HCT-CI/Age (p=0.008) and EBMT (p< 0.001) was confirmed in multivariate analysis.

Conclusions: To date, a variety of factors have been defined to determine allo-HSCT outcome. Both patient and disease related factors may have a role in predicting transplant related morbidity and mortality. This retrospective study underlines the importance of pre-transplant risk evaluation, although more experience is required to identify the better approach in order to improve our foresight in allo-HSCT setting.

[Figure 1. Impact of Risk Groups on Overall Survival]

Disclosure: Nothing to declare.

P012 Salvage use of venetoclax-based Therapy for Relapsed AML Post Allogeneic Hematopoietic Stem Cell Transplant

Joselle Cook, Maansi Joshi, Naseema Gangat, Animesh Pardanani, Ayalew Tefferi, Kebede Begna, Michelle Elliot, Aref Al-Kali, Mrinal Patnaik, Mithun V. Shah, William J. Hogan, Mark Litzow, Hassan B. Alkhateeb

Mayo Clinic, Rochester, MN, United States

Background: Relapsed acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplant (alloHCT) has a dismal prognosis. The efficacy of venetoclax (VEN) in post alloHCT relapse is understudied. Here we analyze the efficacy and application of VEN in this setting.

Methods: After IRB approval, retrospective analysis was performed for patients with de-novo or secondary AML who received alloHCT, and experienced relapse and were salvaged with VEN+ hypomethylating agent (HMA)/Cytarabine

Results: We identified 12 pts (50% female); median age 57 years (range 30 - 70). Five pts had de-novo AML (ELN adverse risk cytogenetics=2, intermediate risk cytogenetics =3) & 7 pts had secondary AML (ELN adverse risk=5, intermediate risk =2). The donor source was matched unrelated donor (n=7), matched related donors (n=2), haploidentical (n=2) and 1 umbilical cord transplant. 8 pts were in CR1, 3 pts were in CR2, and 1 with persistent residual disease at the time of transplant. Time from transplant to relapse was 196 days (range 77-1142). Time from alloHCT to VEN initiation was 378 days (range 104-1153). Median # of VEN cycles was 2 (1-5). Overall response rate (PR+CR) was 33% (n=4). Median time to CR was 82 days (range 38-125) with median duration of CR of 91 days (1 pt continuing in CR). The Grade 3 or 4 toxicities were infection (n=3) and neutropenia (n=5). Two pts had flare of GVHD on VEN requiring treatment: liver GVHD (n=1); skin, ocular GVHD (n=1). Full molecular information was available for 10 pts at diagnosis and in relapse post-alloHCT: 3 pts acquired TP53 mutations at relapse. Figure 1 outlines evolution of molecular abnormalities in the rest of the cohort, associated venetoclax doses and best responses. None of the pts experienced graft failure after salvage therapy. Estimated median overall survival after VEN was 73 days (Range 2- 403). Nine pts progressed on VEN, 2 pts received subsequent therapy [DLI (n=1), gemtuzumab ozogamicin (n=1)]; 8 of the 9 pts died. Median time from progression on VEN to death was 13 days (IQR 2-43). The most common molecular mutation among responders was TP53. Among 5 pts with TP53 mutation in our cohort; 3 achieved CR. Responders had a better survival compared to non-responders with a median OS 403 days vs 43 days respectively (Log-Rank p=0.011). Responders were naïve to HMA.

Conclusions: VEN-based therapy achieved an ORR of 33% in AML pts with post-transplant relapse, and prolonged survival in responders despite the presence of TP53 mutations. Our observations provides evidence that even in the context of post-transplant relapse with adverse mutations and limited treatment options, VEN- based therapy may be effective in inducing CR and possibly improves survival in responding patients.

Disclosure: Mark Litzow: Astellas: Research Funding; Amgen: Research Funding; Abbvie: Research Funding; Novartis: Research Funding; Sanofi: Consultancy; NewLink Genetics: Consultancy; Actinium: Research Funding; Pluristem: Research Funding; Servier: Consultancy

Mrinal Patnaik: Stem Line Pharmaceuticals.: Membership on an entity´s Board of Directors or advisory committees.

P013 Factors Predicting the Outcome of Allogeneic Stem Cell Transplantation in ph-negative Acute Lymphoblastic Leukemia

Olga Pirogova, Ksenia Afanaseva, Elena Morozova, Sergey Bondarenko, Inna Markova, Ivan Moiseev, Boris Afanasyev

First Pavlov State Medical University of St. Petersburg, Saint-Petersburg, Russian Federation

Background: In modern practice, a significant proportion of adult patients with acute lymphoblastic leukemia (ALL) undergo allogeneic bone marrow transplantation (allo- HSCT). The technology of allo- HSCT is improving, therefore it is necessary to evaluate the results and factors affecting the outcome of allo- HSCT in patients with ALL.

Methods: In the study included 191 patients with Ph-negative ALL with median age of 25 years (range, 18-61) who received allo-HSCT undergoing allo-HSCT from HLA-matched sibling (n=38), unrelated (n=123) or haploidentical (n=30) donor in R.M.Gorbacheva Memorial Institute between 2007 and 2019. Median follow-up time was 30 months (range, 2-148 months). By the time of allo-HSCT 41 (21,5%) of patients were in first remission, 80 (41,9%) in second remission, 26 (13,6%) in third or more remission, 44 (23%) in active disease. Reduced intensity conditioning (RIC) was performed in 90 patients (47,1%), myeloablative - in 101 patients (52,9%). Conventional calcineurin-based graft-versus-host disease (GVHD) prophylaxis was used in 90 patients (47,1%). Posttransplant cyclophosphamide(Cy) GVHD prophylaxis was used in 101 patients (52,9%).

Results: 5-years OS and EFS were 44,5% and 37,7%, accordingly, whereas 5-year incidence of relapse was 28,8%. Disease status was the main factor determining the results of transplantation in Ph-negative ALL patients. 5-years OS, EFS and relapse rate (RR) were 73,1%, 56,2%, 34,6%, 2,3% (HR=1,772, 95%Cl 1,46-2,151, p< 0,001) and 68,3%, 45%, 26,9%,2,3% (HR=1,764, 95%Cl 1,469-2,119, p< 0,001), 17,1%, 21,2%, 38,4%,47,7% (HR=2,528, 95%Cl 1,37-4,735, p< 0,001) in 1^st, 2^nd, 3^d and active disease, respectively. RIC was associated with worse survival and increased transplant-related mortality (TRM), 5-years OS, EFS and TRM were 35,3% vs 52% (HR=1,64, 95%Cl 1,113-2,417, p=0,01), 28,8% vs 45% (HR=1,538, 95%Cl 1,069-2,213, p=0,02), 43,4% vs 25% (HR=1,817, 95%Cl 1,073-3,129, p=0,01) for RIC and MAC, respectively. TRM was higher after haplo than after unrelated and HLA-matched sibling allo-HSCT (50% vs 32,5% vs 23,7%, p=0,04). Positive minimal residual disease (MRD) before allo-HSCT determined high RR: 57,1% vs 7,1% (HR=8.119, 95%Cl 2,809-23,21, p< 0,001) for MRD positive and MRD negative. GVHD prophylaxis with posttransplant Cy significantly improved relapse-free and GVHD-free survival (GFRS) and reduced TRM. GFRS in1^st, 2^nd remission was 45,9% vs 10,8% (p< 0,001) patients for Cy and standard GVHD prophylaxis, respectively.

Conclusions: Allo-HSCT in patients with Ph negative ALL is low efficacy. MAC and posttrsnsplant Cy can improve results of Allo-HSCT in patients with Ph negative ALL. Achievement of MRD-negative status is crucial for the outcome thus the studies of bridging strategies are warranted.

Disclosure: Nothing to declare.

P014 Role of Chimerism and flow-cytometric Monitoring of Measurable Residual Disease(MRD) after Allogeneic Hematopoietic Stem Cell Transplantation(Allo-HSCT) in Predicting Relapse in Acute Myeloid Leukemia(AML)

Guldane Cengiz Seval, Eliz Bahar Ulas, Selami Kocak Toprak, Sinem Civriz Bozdag, Meltem Kurt Yuksel, Pervin Topcuoglu, Klara Dalva, Onder Arslan, Muhit Ozcan, Taner Demirer, Osman Ilhan, Hamdi Akan, Meral Beksac, Gunhan Gurman

Ankara University, Ankara, Turkey

Background: Allo-HSCT is a well-established postremission therapy in adults with AML with certain high-risk features. Two different techniques are currently available for posttransplantation surveillance of disease remission: characterization of posttransplantation chimerism and specific detection of MRD. In this retrospective single-center study, we have attempted to evaluate the impact of both chimerism and flow-cytometric MRD in relapse in a population of patients with AML who received an allo-HSCT.

Methods: A total of 65 patients with AML who achieved complete remission at day+100 after allo-HSCT were included. Chimerism and MRD analysis were performed routinely at 1, 3, 6, 9, 12 months after transplantation at our hematology laboratories. Flow cytometry analyses were done using the flow cytometry system FACSCalibur(BD Biosciences, San Jose, CA). Presence of donor chimerism was determined with microsatellite analysis of short tandem repeats(STR) by PCR(Qiagen Plex Plus Kit(100) PCR Assay, genemapper v3.2). We used our institutional database to evaluate details and characteristics of patients and transplant outcomes.

Results: A total of 194 consecutive patients with AML underwent allo-HSCT at our center between January 2010 and August 2019. For the present study, 65 patients (Female/male: 29/36; median age: 40.5 years(range: 18-67 years)) who had relapsed after Allo-HSCT were evaluated. Median follow up from allo-HSCT was 10.3 months(4-104 months). A total of 36(55.3%) patients underwent allo-HSCT from related donor while 29(44.7%) patients were transplanted from unrelated donors, respectively. The stem cell source was peripheral blood stem cells in 63 patients(96.9%). Fifty-patients received myeloablative conditioning, whereas 15 received a reduced intensity regimen. With regard to MRD status before transplantation, 37 of 65 patients were MRD-negative and 12 patients were MRD-positive and remaining 16 patients had active disease at the time of allo-SCT. After transplantation, 4 of the 37 patients who were initially MRD-negative changed to MRD-positive, whereas 9 of the 12 initially MRD-positive patients achieved at least temporary MRD negativity. Six of the patients with active disease achieved MRD negativity after Allo-HSCT. The relapse rate was 60% at 1 year and higher in the patients with mixed CD3 chimerism(n=20) compared with those with complete chimerism(n=45) at day+90. In addition, at time of relapse among study population only 33 patients had mixed CD3 chimerism. Patients with MRD positivity at day +28 after HCT had the highest incidence of relapse among all prognostic groups analyzed. The median time to hematologic relapse after detection of MRD relapse was median 62 days. Among all patients, 23 patients with MRD relapse and subsequent hematologic relapse also have been detected via a decrease in chimerism. Twenty-one patients had received DLI for MRD-positivity. During follow up 41 deaths were noted.

Conclusions: In light of recent advances in therapeutic options for post-transplantation relapse, improving our understanding of the available relapse prediction tools is becoming increasingly important. Our data presented here show the superiority of flow cytometric MRD over chimerism analysis to predict relapse after allogeneic stem cell transplantation. Therefore, further studies of larger randomized cohorts with high quality data management are required to clarify the role of post-transplantion MRD and chimerism in predicting relapsed in AML.

Disclosure: Nothing to declare.

P015 Sorafenib Prolonged Maintenance in flt3-mutated AML Post Transplantation

Carmine Liberatore ^1,2, Matteo Giovanni Carrabba¹, Federica Ardizzoia^1,2, Andrea Assanelli¹, Carlo Messina¹, Consuelo Corti¹, Massimo Bernardi¹, Jacopo Peccatori¹, Fabio Ciceri^1,2, Maria Teresa Lupo Stanghellini¹

¹IRCCS San Raffaele Scientific Institute, Milan, Italy, ²Vita-Salute San Raffaele University, Milan, Italy

Background: FLT3-mutated acute myeloid leukemia (AML) has high risk of relapse and still poor outcomes despite allogeneic stem cell transplantation (HSCT). Sorafenib is a multi-kinase inhibitor active in FLT3+ AML both in the pre- and post-HSCT setting.

Methods: from June 2017 to September 2019, 10 patients with advanced FLT3+ AML at transplantation received sorafenib as maintenance therapy after HSCT. Sorafenib was given off-label after provision of an informed signed consent and in the absence of alternative therapeutic options in all patients. Indications were both achievement of complete morphological remission (CR) and hematological engraftment. Exclusion criteria were active GvHD, infections and non-hematological toxicities. Sorafenib administration was prolonged until intolerance or disease progression.

Results: clinical-biological features at baseline and at sorafenib initiation are reported in Figure 1. Median time from HSCT to sorafenib initiation was 121 days (range 75-250). Nine out of 10 patients were still on GvHD prophylaxis. Sorafenib starting dosage ranged from 200 mg QD (6 patients) to 200 mg BID (4 patients) depending on clinical conditions and concomitant medications. Maximal dosage in our series was 200 mg BID in 6 patients and 200 mg QD in 4 patients.

Sorafenib was well tolerated: no hematological toxicity was observed. Most common grade I-IV adverse events (AE) were skin rash (20%), arterial hypertension (10%), sinus bradycardia (10%), diarrhea (10%), hyperbilirubinemia (10%) and peripheral neuropathy (10%). Most common grade III-IV AE was arterial hypertension (10%). Any patient died because of treatment. Four patients had dose reduction and 2 patients had temporary interruption of sorafenib because of AE.

Two patients developed acute GvHD grade 2 overall: no one had previous GvHD; one patient obtained complete remission with steroid treatment, the second completely resolved GvHD after second line therapy (infliximab). Three patients developed chronic GvHD: 2 classic and 1 overlap, maximal overall severity was moderate, 2/3 patients received ≥2 treatment lines.

After a median follow up of 15 months (range 6-36), all patients were alive. Nine patients were still on therapy while 1 patient finally stopped sorafenib after 4 days of administration due to a drug-related grade II sinus bradycardia.

Median duration of maintenance was 360 days (range 4-886). At last bone marrow evaluation, all patients were in CR and all evaluable patients (8/10) obtained MRD negativity.

Conclusions: post-transplantation maintenance with sorafenib proved feasible in FLT3+ AML: we did not reported major toxicity or adverse events. Sorafenib was effective both in preventing relapses and obtaining deep and durable remission.

Disclosure: Nothing to declare.

P016 Pulmonary Complications (PC) after Allogeneic Hematopoietic Stem Cell Transplantation (Allo-HSCT) in Children with high-risk Acute Leukemia (AL)

Anastasia Frolova, Olesia Paina, Alisa Volkova, Polina Kozhokar, Zhemal Rakhanova, Lubov Tsvetkova, Kirill Ekushov, Inna Markova, Elena Babenko, Aleksandr Alyanskiy, Ildar Barkhatov, Maria Vladovskaya, Elena Semenova, Ludmila Zubarovskaya, Boris Afanasyev

Pavlov First Saint Petersburg State Medical University, Saint-Petersburg, Russian Federation

Background: Despite advanced effective prophylaxes, PC occur in 40-60% of allo-HSCT recipients, accounting for considerable morbidity and mortality. Transplant procedure influence on development of PC, eg conditioning regimen, immunosuppresive therapy, status of diseases, but complex of these aspects didn’t analyzed in children underwent allo-HSCT. Primary end point:to determine effect of PC in children with AL after allo-HSCT on overall survival (OS). Secondary end points:to describe causes, incidences rates PC and risk factors of such complications following allo-HSCT.

Methods: We included children (n=173) with ALL (n=99) and AML (n=74), median age 11(0-18)y.o. Remission of disease (CR) at allo-HCST was in 108 pts (62%). Related compatible donor-in 16(9%) patients, 80(46%) haploidentical, and 77(45%) matched unrelated donor. Source of HSC was bone marrow (BM) n=138, peripheral blood stem cells (PBSC) n=35 cases. Myeloablative conditioning regimen (MAC) based on busulfan (Bu) (10-16 mg/b.w.) received 105(92%) patients on treosulfan-9(8%) pts., reduced intensity conditioning (RIC) based on melphalan-37(63%) pts, based on Bu(8 mg/b.w.)-22(37%) pts. GVHD prophylaxis was mono-PTCy in 25pts (15%), PTCy±CNI±m-TOR in 68 pts(39%), PTCy±CNI±MMF in 80 pts(46%). Clinical data were analyzed to determine whether the incidence of PC was correlated with risk factors such as age, sex, underlying disease type, transplant type, conditioning regimen, prophylaxis of GVHD using SPSS 23. Kaplan-Meier curves were used to estimate the probability of OS. A p value of < 0.05 was considered statistically significant.

Results: Among 173 pts 121(69%) had PC. Early pulmonary complications (EPC) (before D+100) occurred in 81% (n=98) of pts. Infections EPC observed in 97%(n=95): bacterial complications in 23pts(24%), fungi in 13pts(14%), viruses in 15pts (16%), combined infections: viruses+bacteria in 19pts (20%), viruses+fungi in 7(7%), bacteria+fungi in 11(11%), and combination of viruses, bacteria and fungi in 7(7%) cases. Non-infectious EPC occurred in 39%(n=38)pts: engraftment syndrome 40%(n=15), pulmonary edema 39%(n=15), pulmonary bleeding 3%(n=1), respiratory distress syndrome 13%(n=5). Late pulmonary complications (LPC) (after D+100) occurred in 66%(n=80) pts., infectious LPC observed in 30% (n=24), non-infectious LPC observed in 26%(n=21)pts. According to our data pulmonary changes were seen in 80 pts. In 24(30%) cases were focal, in 17(21%) infiltrative, in 26(33%) interstitial, and 10(13%) cases fibrotic. Three pts developed hydrothorax. 41 pts had no complications. Development of EPC in underlying diseases significantly affects overall survival (p=0.001). 5-OS in patients with early mild complications is 55%vs92.1% without complications. The OS of pts with LPC is 72,7% compared 61.5% of patients who had EPC and LPC (p=0.001). Incidence of PC in remission after МАС is 67,5%(n=77)vs72,9% (n=43) after RIC(p>0,05). Incidence of PC in pts with active underlying disease after MAC-70%(n=31) vs 95%(n=20) after RIC. Type of allo-HSCT, source of transplant, sex, age at the moment of allo-HSCT in CR pts didn’t affect on development of PC(p>0,05).

Conclusions: Incidence of PC was significantly lower in patients receiving allo-HSCT in CR. Intensity of conditioning regimen does not affect the incidence of PC in patients with CR. The use of RICs in relapse increases incidence of PC. Development of early PC in patients after allo-HSCT worsens the prognosis and reduces significantly OS.

Disclosure: Nothing to declare.

P017 More than two Cycles of Consolidation Therapy pre-transplantation Benefits AML Patients in Cr1 Who Underwent HLA-matched Sibling Allografts: A Multicenter Study

Jing Liu ¹, De-Pei Wu², Qi-Fa Liu³, Yang Xu⁴, Fen Huang³, Xiao-Jun Huang¹, Yu Wang⁴

¹Peking University People’s Hospital & Peking University, Beijing, China, ²Affiliated Hospital of Soochow University, Soochow, China, ³Nanfang Hospital, Southern Medical University, Guangzhou, China, ⁴First Affiliated Hospital of Soochow University, Soochow, China

Background: Although the need for consolidation chemotherapy after successful remission induction therapy is well established in patients acute myeloid leukemia (AML) in first complete remission (CR1), the value of consolidation chemotherapy before HSCT remains controversial.

Methods: Our study retrospectively compared the effect of the number of pre-transplant consolidation on outcome after HLA-matched sibling stem cell transplantation (MSDT) for AML patients in CR1 in multicenters across China. In addition, our multicenter study also compared the effect of the consolidation therapy pre-transplant between MRD negative patients and MRD positive patients with AML in CR1 who received MSDT.

Results: In our study, we analyzed data of 373 patients with AML in CR1 from three centers across China. All of these 373 patients received MSDT in different centers. With a median follow-up of 969 days, those patients with ≧ 3 cycles of consolidation chemotherapy had higher incidences of LFS (85.6% vs. 67.0%, p< 0.001) and OS (89.2% vs. 78.5%, p=0.007), and better cumulative incidences of relapse rate (10.5% vs. 19.6%, p=0.020) and NRM (4.2% vs. 14.9%, p=0.001). For pre-MRD (minimal residual disease) negative AML patients in CR1 receiving MSDT with ≧ 3 cycles of consolidation chemotherapy had better LFS (85.9% vs. 67.7%, p=0.003) and lower cumulative probabilities of relapse (9.6% vs. 23.3%, p=0.013) than those with ≦ 2 cycles, but the two groups had comparable probabilities of OS (90.0% vs. 80.3%, p=0.051) and NRM (4.9% vs. 10.9%, p=0.127).

Conclusions: In conclusion, our results indicated that AML patients in CR1 who received MSDT might benefit from pre-transplant consolidation chemotherapy.

Disclosure: All authors declare. no competing financial interests.

P018 What can Cnv Analysis add to the Routine Genetic Description of AML Cases?

Emilia Jaskula ^1,2, Mariola Sedzimirska², Monika Mordak-Domagala², Janusz Lange², Krzysztof Suchnicki², Anna Sobczynska-Konefal², Marta Lemieszewska², Helena Pakos², Agnieszka Tarnowska², Andrzej Lange^1,2

¹Polish Academy of Sciences, Wroclaw, Poland, ²Lower Silesian Center for Cellular Transplantation with National Bone Marrow Donor Registry, Wroclaw, Poland

Background: Genetical description of AML cases belong now to the standard diagnostic procedure, however it includes mainly chromosome banding assay (CBA) or FISH. In the present study we added information from microarray CNV analysis.

Methods: 127 AML cases (age:21-84, median:59 yrs, 62F/65M) diagnosed in years 2008-2019 (FAB M0=11, M1=37, M2=25, M3=6, M4=27, M5=11, M6=2, secondary=20, primary=107), classified (ELN genetic guidelines) as favourable=17.3%, intermediate=51.2%, unfavourable=31.5%, received treatment according to the PALG guidelines. Genetic work in addition to the CBA, 83 cases or FISH analysis (33 cases) included the microarray analysis of copy number variations (CNV).

Results: 1. The observed survival pattern of the patients followed that seen in the ELN analysis on the dependence of CBA and FISH alterations with survival.

2. CNV number (Catalog Agilent Cancer CGH+SNP 180K (74 patients) or Roche-WG Catalog NimbleGene 12x270K (53 patients)) was worked out using the Partek program (segmentation algorithm with default settings). Numbers of CNVs deletions in the patients varied from 3-104 (median: 22), amplifications from 6-172 (median: 26). Only autosomes were analysed.

3. 197 CNVs> 5 Mbp found in 38 patients could be compared to the picture of CBA in 14 and that of FISH in 24 patients. It appeared that CNV detected were seen either in the CBA or in the FISH in 86 situations. 111 identified CNVs were missed in CBA or FISH among which in 73 instances because the FISH probes are not suited for detection of these particular CNV, the rest 38 CNV which might be seen either in CBA or FISH were missed likely due to the technical reasons. A majority of discrepant results between the FISH or CBA and microarray were likely due to difficulties in proper identification of a part of additional or deleted chromosome seen (6 patients). Altogether, the results of CNV and the standard techniques were the same in 25 cases.

4. In a univariate analysis of the survival risk factors, it was found that better overall survival enjoyed patients:

· under 48 years of age (39 vs 16%, p< 0.001),

· with primary AML (23% vs 15%, p=0.084) compared to secondary AML,

· lacking NPM1 gene mutation (25 vs 11%, p= 0.044),

· who received allogeneic hematopoietic stem cell transplantation (28 vs 19%, p< 0.001),

· having more CNV aberrations in the group with normal karyotype or FISH (50 vs 16%, p=0.008),

· having t(8:21) (RUNX1/RUNXT1, 67 vs 20%, p=0.004). 67% of patients with t(8:21) had an aberrant expression of CD19 (>22% in the blasts) compared to 5% incidence in the patients without translocation (p< 0.001). CNV amplification in the RUNX1 gene was associated with aberrant CD19 expression (40% vs 7%, p= 0.054). In opposite CNV amplifications in the KMT2A gene (9 cases), independently if seen in the FISH assay (3 cases) or not, inversely affected the survival (0 vs 43%, p= 0.032, at the 18 month time point).

Conclusions: CNV analysis offers some information which are clinically valid but missed by CBA or FISH due to the technical reasons.

Supported by RPDS.01.02.01-02-0177/17 “Stawreg” grant.

Clinical Trial Registry: no applicable

Disclosure: The authors declare. that they have no conflict ofinterest.

P019 Comparison of the Prognostic Ability of the HCT-CI the Modified EBMT and the EBMT-ADT Pre-transplant Risk Scores for Acute Leukemia

Eshrak Al-Shaibani ^1,2, Sunu Cyriac^1,2, Shiyi Chen^1,2, Jeffrey H. Lipton^1,2, Dennis D. Kim^1,2, Auro Viswabandya^1,2, Rajat Kumar^1,2, Wilson Lam^1,2, Arjun Law^1,2, Zeyad Al-Shaibani^1,2, Armin Gerbitz^1,2, Ivan Pasic^1,2, Jonas Mattsson^1,2, Fotios V. Michelis^1,2

¹Princess Margaret Cancer Centre, Toronto, Canada, ²University of Toronto, Toronto, Canada

Background: Allogeneic hematopoietic cell transplantation (HCT) may provide cure for acute leukemia where indicated. However, its use is limited by transplant-related complications which lead to increased mortality. This has prompted the development of pre-transplant risk scores such as the Hematopoietic Cell Transplantation-Comorbidity Index (HCT-CI) and the modified European Group for Blood and Marrow Transplantation (mEBMT) score (that examines recipient age, remission status of leukemia, donor-recipient gender combination and donor match). In a large EBMT study Shouval et al (Journal of Clinical Oncology, 2015) developed a machine learning-based prediction model for mortality (EBMT-ADT) that can be used online.

Methods: In the present retrospective study, we examined the impact of the HCT-CI, mEBMT and EBMT-ADT on a single center cohort of 231 patients who underwent allogeneic HCT for acute leukemia from August 2014 until December 2017. Data was updated as of October 2019.

Results: Median age was 56 years (range 19-72). Acute myeloid leukemia (AML) was diagnosed in 200 patients, acute lymphoblastic leukemia (ALL) in 31 patients. Disease status at the time of HCT was first complete remission (CR1) in 81% and CR2 or beyond in 19% of patients. Myeloablative conditioning was administered to 31% of patients while 69% received reduced intensity conditioning. In vivo T-cell depletion was given to 76% of patients. Donors were HLA matched related in 33%, 10/10 matched unrelated in 44%, 9/10 unrelated in 12% and haploidentical in 11% of patients. The median follow up of survivors was 37 months (15-62 months).

For the HCT-CI, patients were grouped as score 0-1, 2-3 and >3 (116, 75 and 40 patients respectively). For the mEBMT score, patients were grouped as 0-2, 3 and 4-5 (76, 121 and 34 patients respectively), while for the EBMT-ADT the respective 100-day mortality was calculated for each patient (excluding haploidentical) and grouped as ≤4.1%, 4.1-11.5% and >11.5%. Patients with higher HCI-CI score demonstrated lower probability for OS (p=0.038, c-statistic 0.57), while neither mEBMT nor EBMT-ADT significantly stratified patients into prognostic groups (p= 0.09, c-statistic 0.54 and p=0.28, c-statistic 0.53 respectively). Multivariable analysis for OS demonstrated that leukemia type (HR 1.82 for ALL, 95% CI 1.16-2.85, p=0.01), HLA matching (HR 0.61 for all fully matched donors, 95% CI 0.41-0.90, p=0.01) and HCT-CI (HR 0.50 for 0-1, 95% CI 0.31-0.81, p=0.004) had significant impact. Based on the HR, a new weighted score was developed for this cohort including leukemia type (AML=0, ALL=1), HLA matching (fully matched=0, mismatch unrelated or haploidentical=1) and HCT-CI (0-1=0, 2-3=1 and ≥4=2). The new score demonstrated improved prognostic capability compared to the other scores (p=0.0004, c-statistic 0.60) (Figure 1).

Conclusions: The mEBMT score and the EBMT-ADT do not adequately prognosticate OS in our cohort of acute leukemia patients undergoing allogeneic HCT. The HCT-CI performs better, however is not a powerful predictor. New approaches are required to develop a pre-transplant risk calculation tool that can be widely applicable to patients from various centers characterized by heterogeneous practices.

[Figure 1: stratification of OS by score based on leukemia subtype, mismatch and HCT-CI”]

Disclosure: Nothing to declare.

P020 GO-FLAG Regimen as a Bridge Therapy to Allogeneic Stem Cell Transplantation in Refractory/relapsed AML Patients

Bella Ayubova ¹, Sergey Bondarenko¹, Ivan Moiseev¹, Olga Uspenskaya², Elena Karyagina³, Elena Misyurina⁴, Evgenia Zhelnova⁴, Alexander Alyanskiy¹, Elena Babenko¹, Ildar Barkhatov¹, Tatyana Gindina¹, Alexander Kulagin¹, Boris Afanasyev¹

¹Pavlov First State Medical University of St. Petersburg, St. Petersburg, Russian Federation, ²Leningrad Regional Clinical Hospital, St. Petersburg, Russian Federation, ³City Hospital No.15, St. Petersburg, Russian Federation, ⁴City Clinical Hospital No.52, Moscow, Russian Federation

Background: The patients (pts) with refractory or relapsed AML (r/rAML) have poor outcomes with 3-year overall survival (OS) no more than 10%. The main goal of therapy in pts with r/rAML is to achieve remission followed by allogeneic hematopoietic stem cell transplantation (alloHSCT). Introduction of targeted drugs is the most promising strategy in the modern therapy of hematological malignancies. Gemtuzumab ozogamicin (GO) is a recombinant, humanized anti-CD33 monoclonal antibody covalently attached to the cytotoxic antitumor antibiotic calicheamicin, which effectiveness depends on more than 75% expression of CD33-glycoprotein on leukemic blasts.

Methods: The study included 39 pts with median age 34 (18-61) years, 12/39, 31% pts were with primary refractory AML (RefAML), 27/39, 69% pts were with relapsed AML (RelAML). The first relapse (Rel1) had 19/27, 70% pts and two or more relapses (Rel>2) - 8/27, 30%. The early relapse (eRel) was observed in 23/27, 85% and late relapse (lRel) were in 4/27, 15% of cases. Based on the ELN 2017 classification, the prognosis was favorable for 10 pts (26%), intermediate for 8 pts (20%), and adverse for 21 pts (54%). All pts treated by the combination of fractionated GO with regiment FLAG (GO-FLAG).

Results: The follow-up period was 27 month. The overall response rate (OR) was 69% (95% CI 54-81): complete remission was achieved in 63%, remission with incomplete hematologic recovery - 37%. The high OR was in pts with extramedullary disease - 85% (95% CI 58-96). AlloHSCT was performed after GO-FLAG in 17 (44%) pts (4- related, 4 - unrelated, 9 - haplo). In two cases alloHSCT was done in active disease. The median time from OR after GO-FLAG to HSCT was 61 (36-148) days. Overall survival and disease-free survival at 1 years (OS1 and DFS1) was 64% (95% CI 48-77) and 63% (95% CI 44-78), respectively. In the allogeneic group the median OS1 was 6 months and in the group without alloHSCT - 2 months. The median DFS1 in pts with and without alloHSCT after GO-FLAG was 4 and 3 months, respectively. The predictive factors associated with a higher response rate were: favorable ELN genetic group (favorable-90% vs intermediate-75% vs adverse-57%, p=0,05); RelAML (RefAML-42% vs RelAML-81%, р=0,02); blast level less than 60% (< 60% level -83% vs >60% level -50%, р=0,03). In all cases we observed neutropenia of 4 gr. and thrombocytopenia 4 gr. Severe hemorrhagic complications (subdural hematoma) was in 1 pts (2,6%). Sepsis was in 13% (95% CI 19-46); fungal infections were in 10% (95% CI 4-24). Hepatotoxicity was presented as a transient increase in ALT level (< 10ULN) in 10% (95% CI 4-24). Sinusoidal obstruction syndrome did not occur in any of the patients. Early mortality was 10% (95% CI 4-24), 4/39 pts. Causes of death were leukemia progression (1 pt), infectious complications (3 pts). No direct association with the GO and death was observed.

Conclusions: GO-FLAG demonstrated the efficacy and acceptable toxicity in pts with r/rAML and can be used as a bridge to alloHSCT.

Disclosure: Nothing to declare.

P021 The Impact of Allogeneic Transplantation in AML and Mds with Chromosome 3 Abnormalities

Maria Rhida Bautista ¹, Shiyi Chen², Wilson Lam¹, Fotios Michelis¹, Dennis Kim¹, Jeffrey Lipton¹, Auro Viswabandya¹, Rajat Kumar¹, Ivan Pasic¹, Armin Gerbitz¹, Jonas Mattson¹, Zeyad Al-Shaibani¹, Arjun Law¹

¹University of Toronto, Toronto, Canada, ²Princess Margaret Cancer Center, Toronto, Canada

Background: Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS) with chromosome 3 abnormalities are associated with adverse outcomes. The benefit of allogeneic stem cell transplantation (AlloHCT) in this setting is controversial. This study aims to assess outcomes in this group of patients undergoing AlloHCT.

Methods: This is a single-center retrospective study including 52 patients with AML and MDS with chromosome 3 abnormalities by conventional karyotyping, who received Allo-HCT from October 2000 to August 2019.

Results: The median age of patients was 50 years old (range 19-72). There were 38 patients with AML and 14 patients with MDS. Concurrent presence of monosomy 7 and complex cytogenetics was found in 15 (29%) and 36 (69%) patients respectively. Majority of patients with AML were in first complete remission (CR1) at the time of AlloHCT. Patients with MDS were Intermediate-2 (13%) or High risk (12%) by the International Prognostic Score System (IPSS). Patient and transplant characteristics are summarized in Table 1.

With a median follow up of 4 years, 2-year relapse free survival (RFS) was 33.65% (95% CI, 20.75-47.03), overall survival (OS) was 32.46% (95% CI, 19.63-45.95), cumulative incidence of relapse (CIR) was 48.08% (95% CI, 35.39-65.31), non-relapse mortality (NRM) was 17.57% (95% CI, 10.18-30.33) and graft vs host disease relapse free survival (GFRS) was 22.94% (95% CI 12.17-35.75). Compared to other chromosome 3 abnormalities, patients with monosomy 3 showed the highest risk of relapse and death with 2 year RFS 11.53% (95% CI, 0.86% - 37.51%) and OS 10.26% (95% CI, 0.67% - 35.53%).

On univariate analysis, age greater than 50, monosomy 3, the presence of monosomy 7 and Allo-HCT in AML in CR2 or not in remission, were associated with increased risk of relapse and death. On multivariate analysis, AML in CR1 showed a trend towards improved RFS and OS, however, this was not statistically significant (HR 0.45 (0.20 - 1.04), P= 0.06 and HR 0.45 (0.20 - 1.02), P=0.056 respectively). The presence of monosomy 7 also showed a trend towards increased risk of relapse, however, this was also not statistically significant (HR 2.13 (0.96 - 4.7), p=0.06) (Table 2).

Conclusions: AlloHCT may improve outcomes in select patients with AML/MDS with chromosome 3 abnormalities. Further studies with a larger sample size and the inclusion of molecular mutations are recommended.

Disclosure: Nothing to declare.

P022 Allogeneic Hematopoietic Stem Cell Transplantation Versus chemotherapy-alone in the Treatment of Pediatric Acute Myeloid Leukemia Patients with Mixed Lineage Leukemia (Mll) Rearrangements: Single Center Experience

Ibtisam AlQahtani, Amal Al-Seraihy, Ali Alahmari, Mouhab Ayas, Khawar Siddiqui, Ibrahim Ghemlas

King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia

Background: Acute myeloid leukemia (AML) represents 15%-20% of childhood leukemia. Despite substantial progress in the treatment of pediatric AML, approximately 40% of patients die from disease recurrence or treatment-related toxicities. Cytogenetic aberrations and response to the treatment are important prognostic factors in AML. MLL gene rearrangements in AML patients result in unique clinical and molecular genetic characteristics and generally indicate a poorer prognosis. At King Faisal Specialist Hospital and Research Centre (KFSH&RC), Riyadh, we examined the incidence and treatment outcome of MLL-rearranged AML pediatric patients.

Methods: We retrospectively reviewed the clinical data of pediatric patients (age at presentation ≤ 14 years) who were diagnosed and managed at KFSH&RC from January 2005 to December 2016. A total of 201 de novo AML patients´ profiles were reviewed, MLL-rearranged AML patients were identified based on the cytogenetic results. The median follow-up was 104±37.4 Months (95% CI: 30.5-177.6) Months.

Results: A total of 21 out of 201 (10.4%) AML patients found to have MLL gene rearrangements, 52%(11) were female, with a median age at diagnosis of 3.83 years (0.54-13.56). French-American-British (FAB) classification was M5 in17 patients(81%), M4 in 2(9.5%), M7 in 1(4.8%), and M1 in 1(4.8%). The commonest identified partner was t(9,11) in 8 patients(44.4%), followed by t(1,11) and t(11,19) in 4 patients (22.2%) each, t(11,18) and t(6,11) in 1 patient (5.6%) each. Three patients died early within 1 month from diagnosis. 14 out of 18 (77.8%) patients achieved complete remission 1 (CR1) after AML induction chemotherapy with cytarabine/daunorubicin/etoposide (ADE 10+3+5) and cytarabine/daunorubicin/etoposide (ADE 8+3+5).

Three out of 18 (16.6%) required second-line chemotherapy to achieve CR1. One patient failed to achieve CR despite second-line chemotherapy.

The 5-year Overall Survival (OS) for all MLL-rearranged AML patients was 42.9±10.8%. A total of 10 patients treated with chemotherapy alone without hematopoietic cell transplantation HSCT in complete CR1, 5 out of 10 patients have died with progressive disease (PD) /early relapse within an average of 6 months (1-9 months) from CR. 8 patients underwent HSCT in CR1, 4 died with relapse within an average of 13 months (6-18 months), 3 of them failed induction and got second-line chemotherapy before HSCT. All relapsed patients failed to achieve CR2 and died with PD.

Conclusions: Incidence of MLL gene rearrangements in our Centre was 10.4% and associated with poor outcomes. MLL-rearranged AML patients associated with increased risk of early relapse and re-induction failure. CR1 after first-line chemotherapy is an independent prognostic factor.

Disclosure: nothing to declare.

P023 Posttransplantation Bendamustine for GVHD Prophylaxis in Refractory Acute Leukemia Patients

Ivan Moiseev, Sergey Bondarenko, Elena Darskaya, Alexandr Alyanskyi, Anastasiya Beynarovich, Evgeniya Borzenkova, Anna Dotcenko, Olga Kudyasheva, Varvara Ovechkina, Olga Pirogova, Valentina Porunova, Tatyana Rudakova, Olesya Smikova, Boris Afanasyev

Pavlov First Saint Petersburg State Medical University, Saint-Petersburg, Russian Federation

Background: Results of allogeneic stem cell transplantation (SCT) in primary or secondary refractory leukemia patients remain unfavorable despite the studies of new conditioning regimens. Preclinical studies by Stokes et al. (2016) indicate that substitution of posttransplantation cyclophosphamide with bendamustine (PTbenda) can possibly augment graft-versus-leukemia (GVL) effect in active leukemia mouse model. We conducted a study to evaluate the potential of PTbenda to prevent graft-versus-host disease (GVHD) and potentiate GVL.

Methods: The prospective (NCT02799147) Phase I de-escalation study evaluated 140-100-70 mg/m2 of PTbenda administered on days +3,+4 with or without additional immunosuppressive agents. All patients received myeloablative conditioning with fludarabine and busulfan. Inclusion criteria were diagnosis of acute lymphoblastic (ALL) or acute myeloblastic leukemia (AML), failure of at least to previous induction courses of chemotherapy or immunotherapy, more than 5% of clonal blasts in the bone marrow and good somatic status. The study enrolled 26 patients (pts), enrollment to the 140 mg/m2 group was halted due to stopping rules. Five pts had ALL and 21 - AML. Median blast count was 19% (6-97%). Four pts had matched sibling donor, 15 - matched unrelated donor and 7 - haploidentical, 10 pts had primary refractory and 16 secondary refractory disease. Half of patients received systemic antimicrobial therapy at the time of enrollment. Median age was 27 years (20-56).

Results: All patients but two with ALL disease progression engrafted and 89% had complete remission (CR) after engraftment, while 62% were MRD-negative. The evidence of augmented GVL was supported by the presence of cytokine-release syndrome in 73% of patients: 3 pts had grade 5 CRC, 5 pts - grade 4, 7 - patients grade 3 and 4 pts - grade 1-2. The pattern of CRC was distinct from BiTe and CAR-T one, with fever in all patients, skin vasculitis in 50%, liver function test elevation in 50%, polyserositis in 15% and neurotoxicity in 15%. CRC was associated with significant elevation of serum ferritin (mean 20188 vs 4915 ng/ml, p=0.005). 1-year overall survival was 29%, 40% and 70% in 140, 100 and 70 mg/m2 groups, respectively, but event-free-survival was 29%, 40% and 27% (Figure 1). None of ALL patients had long-lasting CR (0% vs 45%, р< 0.001). In the whole group relapse incidence was 19% and non-relapse mortality (NRM) - 43%. Grade III-IV acute GVHD was observed in 43%, 30% and 33% pts, with significantly higher incidence after haploidentical transplantation (75% vs 22%, p=0.046). Seventy percent of long-term survivors had chronic GVHD with higher incidence after single-agent PTbenda (100% vs 40%, р=0.038).

Conclusions: PTbenda is a promising strategy for refractory AML, but elucidation of the optimal immunosuppressive agent combination is required to control GVHD, CRC and reduce NRM.

[Figure 1. Event-free survival]

Clinical Trial Registry: NCT02799147, clinicaltrials.gov

Disclosure: The authors declare. no conflicts of interest.

P024 Immediate Allogeneic Hematopoietic Stem Cell Transplantation for NPM1-mutated AML in Molecular Relapse

Kerstin Schaefer-Eckart ¹, Knut Wendelin¹, Sabine Dressler¹, Johannes Gaertner¹, Christian Thiede²

¹Paracelsus Medizinische Privatuniversität, Nürnberg, Germany, ²Universitätsklinikum Dresden, Dresden, Germany

Background: NPM1-mutations can be identified in about 30% of adult AML patients (pts). According to ELN 2017 classification they are characterized as favorable or intermediate risk depending on the coexistence of FLT3 mutations. For pts with a favorable risk profile an allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission (CR) is not recommended, but can be an option for the intermediate risk group, depending on risk factors like comorbidity. Approximately 30% of NPM1-mutated AML pts will relapse after chemotherapy. Because NPM1 mutations are stable, and persisting or increasing levels are a strong predictor of relapse, monitoring of minimal residual disease (MRD) by quantitative PCR (qPCR) is recommended. With this strategy relapse can be detected earlier with lower leukemia burden. HSCT in molecular relapse could avoid possible complications of reinduction chemotherapy, but there are no data for this strategy. In 2014 we decided to start donor search immediately after molecular relapse and proceed to HSCT without reinduction chemotherapy. Here we report our experience with the first 6 pts treated with this strategy.

Methods: Between January 2014 and December 2018 28 patients under the age of 70 years, who were fit for intensive chemotherapy were diagnosed with NPM1-mutated AML. All pts received induction with DA 3+7 followed by consolidation with high-dose AraC in 15 pts. In 10 pts HSCT as consolidation treatment was performed. 3 pts had induction failure. MRD was monitored at least every 3 months (mos) after end of consolidation therapy by qPCR in bone marrow or peripheral blood in all pts in hematological CR. Relapse was defined as an increase of MRD over a cut-off of 1% NPM1/ABL1. The conditioning regimen consisted of Treosulfan (Treo, 30g/m²) and Fludarabin (Flu, 120mg/m²). In pts with hematological relapse at the time of HSCT Melphalan (Mel, 100mg/m²) before Treo/Flu was added to induce aplasia. Immunosuppression consisted of ATG and Ciclosporin in combination with MTX or MMF.

Results: 25/28 pts achieved hematological CR after induction therapy, 24/25 pts showed molecular CR after the end of consolidation treatment. 10 pts (40%) relapsed. 4/10 pts developed an overt hematological relapse and are not part of this analysis. In 6 pts molecular relapse was detected. 5/6 pts relapsed after complete molecular remission, 1 pt relapsed after MRD positive remission. The median time to molecular relapse was 8 (7-42) mos after diagnosis. Median time from first positive MRD to HSCT was 2 (2-4) mo. 3/6 pts received conditioning with Treo/Flu only. 3/6 pts had hematological relapse at time of HSCT and received Treo/Flu after induction of aplasia with Mel. All pts reached complete hematological and molecular remission after HSCT. After a median follow-up of 15 (8-47) mos all pts are in ongoing CR. In all but one pt the remission free survival is longer than after primary treatment.

Conclusions: Although the number of pts is small and the follow-up short, this analysis shows the efficacy and feasibility of early allogeneic HSCT in molecular relapse for NPM positive AML pts and should be confirmed in a greater number of pts.

Disclosure: No disclosure

P025 Flat Regimen as Myeloablative Conditioning with Limited Toxicities for Autologous Stem Cell Transplantation in Patients with Acute Myeloid Leukemia: Results in 30 Patients

Massimo Bernardi, Carlo Messina, Sara Mastaglio, Francesca Lorentino, Francesca Pavesi, Matteo Giovanni Carrabba, Jacopo Peccatori, Andrea Assanelli, Luca Vago, Bernhard Gentner, Raffaella Milani, Paola Ronchi, Fabio Giglio, Carmine Liberatore, Federico Erbella, Daniela Clerici, Fabio Ciceri

IRCCS San Raffaele Scientific Institute, Milan, Italy

Background: consolidation of complete remission (CR) with autologous stem cell transplantation (ASCT) is an option for patients (pts) with acute myeloid leukemia (AML), in particular for those with a favourable genetic risk (ELN 2017). Most conditioning regimens for ASCT contain at least one alkylating agent, usually busulfan, cyclophosphamide or melphalan. Up to now, no regimen has proved preferable in terms of toxicities and improvement of event free survival (EFS). Treosulfan is an alkylating agent which demonstrated to achieve maximum disease control with minimal toxicity in combination with fludarabine prior to allogeneic SCT. We designed and tested a new treosulfan-based conditioning regimen (FLAT) prior to ASCT in AML pts in first complete remissione (CR1). Preliminary data on the feasibility and efficacy of the FLAT regimen are here presented.

Methods: period 7/2006-7/2019, 30 pts with AML in CR1, median age 68 y (18-76), 14 pts £ 65 y (group A: median 49 y, 19-65), 16 pts > 65 y (group B: median 73 y, 68-77). Cytogenetics: favourable 1, intermediate 26 (normal karytotype 25), complex 1, not evaluable 2. Molecular (21 pts): CBFB-MYH11 1, RUNX1-RUNX1T1 1, NPM1mut alone 5, CEBPAmut alone 4, FLT3ITD/NPM1mut 5 (FLT3ITD low ratio 3, unknown ratio 2), negative 5. Prognostic risk (ELN 2017): favourable 14, intermediate 7, adverse 1, not evaluable 8. At ASCT all pts were in CR1 after a median number of 2 chemo cycles (2-4). FLAT regimen: treosulfan 10 gr/sqm for 3 days, fludarabine 30 mg/sqm for 5 days, cytarabine 2 gr/sqm for 5 days, PEG filgrastim 1 vial s.c. after autoSCT (27 pts). Graft: PBSC, median CD34+ 5x10⁶/kg of BW (3.3-8.5). Time from CR1 to autoSCT: median 99 days (44-266).

Results: at day +100 after ASCT 29 pts were alive, 24 in CR, 5 relapsed. One 75-yo patient died for invasive fungal infection at day +31 (she was still in G4 pancytopenia). Median time to hematopoietic recovery: neutrophils (> 500/mcl) day +11 (8-38), platelets (> 20.000/mcl) day +20 (13-103). Neutrophils recovery in 3 pts who did not receive any growth factor was slower (day +26, 33, 38). Extra-hematologic toxicities (CTCAE v4.0): median grade 1 (0-4). Median EFS from ASCT was 1123 days (31-4808), for group A 1123 days (84-4808), for group B 653 days (31-4789); projected 3y EFS from ASCT was 51.2%, for group A 57.1%, and group B 47.8% (p=ns). At last update 15 pts (50%) are alive, 13 in CR1, 2 in second CR, with a median follow up of 1561 days (146-4810). Overall non-relapse mortality was 3%.

Conclusions: consolidation of AML in CR1 with the new myeloablative FLAT regimen and ASCT was feasibile and well tolerated, even in patients above 65 years of age. Around 50% of pts, regardless of age, mostly with favourable or intermediate genetic risk, obtained prolonged survival without relapse.

[EFS from ASCT]

Disclosure: nothihg to declare.

P026 Tyrosine Kinase Inhibitor Treatment after Allogeneic Hematopoietic Stem Cell Transplantation for Philadelphia Chromosome‐positive Acute Lymphoblastic Leukemia

Yu-Hsiang Chang ^1,2, Xiu-Wen Liao¹, Jia-Hau Liu^1,2, Ming Yao², Bor-Sheng Ko², Chi-Cheng Li³, Cheng-Hong Tsai², Shang-Ju Wu², Hui-Hsuan Huang², Tai-Chung Huang², Hsin-An Hou², Wen-Chien Chou², Feng-Ming Tien^1,2, Yun-Chu Lin², Meng-Yao Lu², Kai-Hsin Lin², Jih-Luh Tang^1,4

¹National Taiwan University, Taipei City, Taiwan, Republic of China, ²National Taiwan University Hospital, Taipei City, Taiwan, Republic of China, ³Hualien Tzu Chi Hospital, Hualien City, Taiwan, Republic of China, ⁴National Taiwan University Cancer Center, Taipei City, Taiwan, Republic of China

Background: Introduction of tyrosine kinase inhibitor (TKI) for the treatment of Philadelphia chromosome‐positive acute lymphoblastic leukemia (Ph+ ALL) has dramatically improved the survival outcomes. However, TKI therapy for Ph+ ALL has yielded controversial results evaluating the efficacy of post-hematopoietic stem cell transplantation (HSCT). The CIBMTR analyzed 197 patients with Ph+ ALL undergoing allo-HCT in first complete remission, 43 of whom received post-transplant therapy with TKIs. There was no difference in the 3-year cumulative incidence of relapse. In contrast, an EBMT study of 473 patients showed that post-transplant TKI was associated with a lower relapse rate and better overall survival. Recently, Akahoshi et al reported that TKI prophylaxis was not associated with a decreased risk of relapse or superior overall survival in the whole cohort. Therefore, we conducted a retrospective study of Ph+ ALL patients at our hospital to evaluate whether TKI prophylaxis after allogenic HSCT would reduce relapse and improve overall survival.

Methods: The Institutional Research Board approved the retrospective study. We identified 68 patients over 14 years of age with Ph+ ALL who received allo-HSCT from 1993 to 2001 (n=3) and from 2002 to 2019 (n=65) at National Taiwan University Hospital. Univariate and multivariate analysis was performed using Cox proportional hazard regression model.

Results: Before allo-HSCT, 8 of 68 patients (12%) didn’t receive any TKI treatments, whereas the remaining 60 patients received imatinib (24%), dasatinib (54%), nilotinib (6%), and ponatinib (4%). After allo-HSCT, 28 patients (41%) didn’t receive TKI treatments, and 40 patients (59%) received TKI treatment, including 2 patients (3%) with flank relapse, 17 patients (25%) with TKI prophylaxis and 21 patients (31%) with pre-emptive treatment because of positive-minimal residual disease (MRD) detected by quantitative PCR. The median time from HSCT to TKI treatment was 52 days (range, 21-542 days). Imatinib (15%), dasatinib (38%), nilotinib (4%), and ponatinib (2%) were given as TKI treatment. The median duration of TKI treatment of the patients was 453 days (range, 7-1775 days). Multivariate analysis identified advanced disease status before HSCT (primary induction failure, active disease) to be a risk factor for overall survival (OS) (HR=7.156; P=0.0002), disease-free survival (DFS) (HR=4.829; P=0.0113), and cumulative incidence of relapse (CIR) (HR=5.3; P=0.0188). Importantly, in the post-transplant period, the multivariate analysis identified TKI administration to be a significant factor for OS (HR=0.30; P=0.0014), DFS (HR=0.25; P<0.001), and CIR (HR=0.343; P=0.0039). Molecular relapse detected by quantitative PCR after HSCT was correlated with increased risk of hematological relapse (CIR, HR=8.158; P=0.005), but not associated with a worse DFS (HR=1.042; P=0.8827). This result could be explained by the fact that 21 of the 32 patients with molecular relapse received TKI treatment and 9 of them returned to negative MRD in a later follow-up assessment.

Conclusions: Despite the limitation of small sample size and the potential bias of patient selection by the physician, our study showed TKI treatment after allogeneic HSCT would reduce relapse and improve overall survival, indicating the potential benefit of TKI treatment in the post-transplant setting.

Disclosure: Nothing to declare.

P027 Outcomes of Allogeneic Transplantation for Cytogenetic intermediate-risk AML According to the Molecular Risk Based on ELN 2017 Risk Stratification System; Single Center Experience in Korea

Haerim Chung, Ji Eun Jang, SooJeong Kim, Jin Seok Kim, Yoo Hong Min, June-Won Cheong

Yonsei University, Seoul, Korea, Republic of

Background: Acute myeloid leukemia (AML) has been recognized as a clinically and genetically heterogeneous disease entity. Cytogenetic abnormalities that are associated with the prognosis of AML have been identified. However, as there are limitations for patients in the cytogenetic intermediate-risk group, more precise risk stratification systems based on genetic status have been proposed especially in nest-generation sequencing (NGS) era. In this study, we evaluated the usefulness of the European Leukemia Network (ELN) 2017 risk stratification system and transplant outcomes in the cytogenetic intermediate-risk group.

Methods: We performed a retrospective analysis of a total of 143 patients who diagnosed with cytogenetic intermediate-risk AML and received intensive standard ‘7+3’ chemotherapy for remission induction from 2012 to 2018 at Yonsei university Severance hospital in Korea.

Results: According to the ELN 2017 risk stratification system, 30 (21.0%), 80 (55.9%), and 33 (23.1%) patients were allocated to the molecular favorable, intermediate, and adverse risk group. The 5-year overall survival (OS) rate was 78.5% in molecular favorable group, 51.2% in molecular intermediate group, and 33.1% in molecular adverse group (P = 0.010) The 3-year progression free survival (PFS) rate in molecular favorable group were also significantly higher than those in intermediate and adverse group (85.3% vs 56.0% and 49.1%, P = 0.021). The outcome of allogeneic hematopoietic stem cell transplantation (HSCT) was evaluated in 124 patients who achieved complete remission. Among them, 71 (57.3%) patients received allogeneic HSCT as post-remission therapy, and the remaining 53 (42.7%) patients received consolidation chemotherapies only. Despite the higher proportion of patients receiving more than 2 cycle of induction chemotherapy (21.1% vs 5.7%, P = 0.016), the 3-year PFS was significantly higher in the transplant group than non-transplant group (71.2% vs 50.3%, P = 0.013). In molecular risk subgroup analysis, molecular favorable-risk subgroup showed about 80% PFS in both groups and transplantation did not show superiority (P = 0.853). In molecular intermediate-risk group, allogeneic HSCT resulted a longer PFS (P = 0.003) than chemotherapy as a post-remission treatment. For patients with molecular adverse-risk, poor prognosis could not be overcome neither chemotherapy nor transplantation (P = 0.198).

Conclusions: The molecular risk stratification of the ELN 2017 successfully distinguished long term prognosis in cytogenetic intermediate-risk AML patients and validated in our center. Because molecular evaluation using NGS technique recently became one of standard pre-treatment evaluation for AML patients in Korea, clinical benefit of HSCT should be carefully and precisely evaluated for cytogenetic intermediate-risk patients according to the molecular risk stratification. Furthermore, more effective post-remission treatment strategy should be determined especially for cytogenetic intermediate- and molecular poor-risk AML patients.

Clinical Trial Registry: This study was approved by the institutional review board of Severance Hospital (4-2010-0669, NCT 02344953).

Disclosure: There is no funding to declare.

P028 The Prognostic Significance of Minimal Residual Disease Monitoring by Wt1 Gene Expression in Peripheral Blood Before and after Allogeneic Stem Cell Transplantation in AML Patients

Veronika Valkova, Jan Vydra, Marketa Markova, Antonin Vitek, Ela Cerovska, Monika Belickova, Ludmila Novakova, Barbora Cemusova, Mariana Koubova, Petr Cetkovsky

Institute of Haematology and Blood Transfusion, Prague, Czech Republic

Background: The aim was to confirm our previous experience with prognostic relevance of WT1-MRD status before allo-SCT in AML patients in complete remission. Another aspect was to assess the significance of WT1-MRD monitoring in these patients after allo-SCT.

Methods: The expression of WT1 gene was measured by real-time polymerase chain reaction in peripheral blood according the European Leukemia Net recommendations. Between 2005-2019, we have analyzed 147 consecutive AML pts with high WT1 expression at diagnosis, transplanted in CR1 or CR2. Median age was 46 years (range; 21-66), 76 men, 21 good risk, intermediate risk 91, high risk 35. A total of 116 pts were transplanted in CR1 and 31 pts in CR2. In 128 pts PBPC were used, in 19 pts bone marrow. The donors were identical siblings in 30 pts, 9 haploidentical, matched unrelated donors in 73 pts and mismatched UDs in 35 pts. Conditioning was myeloablative in 117 pts, RIC in 30 pts. At the time of allo-SCT 107 pts were WT1-negative (WT1< 50 copies) and 40 pts were WT1-positive.

Results: Median follow-up was 21 months. Estimated 5-years OS and EFS was signifcantly better in WT1 neg cohort (65% and 57% vs 37% and 25% resp, p= 0,0003 and < 0,0001), as well as 5-years RI was significantly lower in WT1 neg group (25% vs 60%, p< 0,0001). 5-years NRM was not significantly different (24% and 27%). Multivariate analysis revealed WT1-MRD positivity and aGVHD grade 3-4 as a significantly negative prognostic factors for OS. Overall 50 pts developed WT1-MRD positivity in post-transplant period, in forty cases the therapeutical intervention was done. Haematological relapse occurred in 42 pts, in all relapsed patients where WT1-MRD was monitored (38 pts) we detected the positivity, in median of 28 days (0-485) before haematological relapse. 3-years OS in pts with molecular relapse only (12 pts) was 56% vs 74% in non-relapsed group (p=ns).

Conclusions: The results of the analysis confirmed our previous experience that WT1 status before allo-SCT is a strong prognostic factor for both OS and relapse risk. Our experience suggests that this marker is also useful for monitoring MRD after allo-SCT. Well-defined clinical studies will be needed to assess the importance of therapeutic intervention based on WT1-MRD positivity.

Disclosure: nothing to declare.

P029 Impact of Posttransplant Tyrosine Kinase Inhibitors Administration on Long Term Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in ph-positive Acute Lymphoblastic Leukemia Patients

Kseniia Afanaseva, Elena Morozova, Olga Pirogova, Yulia Vlasova, Anna Smirnova, Sergey Bondarenko, Ivan Moiseev, Boris Afanasyev

First Pavlov State Medical University of St. Petersburg, Saint-Petersburg, Russian Federation

Background: Widespread use of targeted therapy with tyrosine kinase inhibitors (TKIs) in combination with allogeneic hematopoietic stem cell transplantation (allo-HSCT) has dramatically improved therapy results in the majority of Ph-positive acute lymphoblastic leukemia (ALL) patients, so nowadays their survival may be comparable with Ph-negative ALL patients in most cases. Nevertheless, relapses remain a major cause of treatment failure even after allo-HSCT that lead to dismal prognosis. One of the possible strategies to prevent relapse includes posttransplant TKIs maintenance, but the data about its application regimens is still controversial. The aim of our study was posttransplant TKIs impact evaluation on outcomes of alloHSCT in Ph-positive ALL recipients.

Methods: This study analyses the data in retrospective cohort of 96 Ph-positive ALL patients with median age of 30 years (range, 18-57) undergoing allo-HSCT from HLA-matched sibling (n=24), haploidentical (n=12) or unrelated donor (n=60) in R.M.Gorbacheva Memorial Institute between 2007 and 2019. Median follow-up time was 24,8 months (range, 1-98 months). At the time of allo-HSCT 54 (56%) of patients were in first remission, 16 (10%) in second remission, 10 (16%) in third or subsequent remission, 16 (10%) in active disease (relapse/resistance/progression). 88 (92%) patients received 1^st, 2^nd or 3^rd generation TKI prior to allo-HSCT. 36 (38%) patients were MRD-negative before allo-HSCT, while 39 (40%) had MRD-positive status, measured by PCR analysis. In posttransplant period 60 (63%) patients received TKIs (imatinib or dasatinib). The goal of posttransplant TKIs administration was prophylactic in 43 (72%) patients, preemptive in 8 (13%) and relapse treatment in 9 (15%). Median time of TKIs administration was 60 (range 30-125) days after allo-HSCT. Landmark analysis was used for comparison with patients without TKIs. Non-engrafted patients were excluded from analysis.

Results: 5-year OS and EFS were 59,4% and 45,8%, accordingly, whereas 5-year incidence of relapse was 35,4%. Comparing patients, who received posttransplant TKIs as prophylaxis with those, who did not receive prophylactic TKIs, we observed that 5-year EFS in 1^st group was 63,3% vs 29% in 2^nd (p< 0,001). 5-year incidence of relapse in 1^st and 2^nd groups were 51,6% vs.28,6%, accordingly (p< 0,001). We also estimated, that TKIs generation after allo-HSCT did not influence the results.

Conclusions: In our study 5-year EFS was twice better in patients, who received TKIs after allo-HSCT as prophylaxis, regardless the generation. Moreover, 5-year incidence of relapse was more than 20% lower in this group of patients. Thus, we can suggest that in order to reduce risk of relapse, it is preferable to prescribe TKIs no later than 60 days after allo-HSCT, before measurable residual disease appear, if there are no other factors that limit TKIs administration (toxicity of TKIs, poor graft function, etc.).

Disclosure: Nothing to declare.

P030 The Influence of anti-thymocyte Globulin(ATG) on the Outcomes of Patients with AML W/wo Measurable Residual Disease(MRD) at the time of Unrelated Donor Transplantation

Guldane Cengiz Seval, Ekin Kircali, Mehmet Akif Baltacı, Sinem Civriz Bozdag, Meltem Kurt Yuksel, Pervin Topcuoglu, Klara Dalva, Onder Arslan, Muhit Ozcan, Taner Demirer, Gunhan Gurman, Osman Ilhan, Hamdi Akan, Meral Beksac, Selami Kocak Toprak

Ankara University, Ankara, Turkey

Background: Anti-thymocyte globulin(ATG) is a very effective form of in vivo T-cell depletion and has been extensively used for GVHD prevention. However, ATG can potentially eliminate alloreactive donor T cells and reduce the graft-versus-leukemia(GVL) effect and increased disease relapse and reduced overall survival(OS). Herein, we aimed to investigate the impact of ATG on the outcomes of patients with AML stratified by flow cytometric MRD status who underwent Allo-HSCT from unrelated donor (UD).

Methods: This was a retrospective single center analysis using the data set of our institutional database. Eligibility criteria for this analysis included 75 adult patients with AML who underwent allo‐HSCT from either a HLA 10/10matched(n=34) or 9/10mismatched(n=41) UD, between October2012 and June2019. All recipients received peripheral blood stem cells grafts. Recipients of UD Allo-HSCT were routinely given rabbit Jurkat cell line-reactive ATG(ATG Fresenius®) in doses of 10mg/kg/day IV on days -3, -2, -1. Flow cytometry analyses were done using the flow cytometry system FACSCalibur(BD Biosciences, San Jose, CA) and sensitivity theresholds was 10^-6. All analyses were done separately in patients achieving or not MRD negativity before transplant.

Results: A total of 75 consecutive patients with AML who underwent allo-HSCT from an UD were evaluated. Median age was 48 years(range:19-71) and 40(53.3%) were females. Median follow up from allo-HSCT was 9.8 months(4-80.9 months). There were 43 MRD^-and 11 MRD⁺patients and 21 patients who were transplanted in the setting of active disease also included in this analysis. Fifty-five(73.3%) patients received myeloablative conditioning(MAC) and 20(26.7%) reduced-intensity conditioning(RIC) regimens. The most common MAC and RIC regimens were busulfan/cyclophosphamide(BuCy,60%) and busulfan/fludarabine(BuFlu,25.3%), respectively. The common GVHD prophylaxis were cylosporinA(CSA) and methotrexate(Mtx) in 64(85.3%) of the patients. Eight patients out of 21 patients with active disease underwent to allo-HSCT after FLAMSA-based high-dose sequential conditioning regimen. The use of ATG was associated with a lower incidence of chronic GVHD(18.7%). We investigated the influence of ATG on transplant outcomes separately in MRD^-, MRD⁺and active disease cohorts. As expected, lowest incidence of relapse was observed in MRD^- groups(MRD^-; 23.3%(10/43) vs MRD⁺; 45.5%(5/11); p=0.168). MRD status at the time of allo-HSCT impact the leukemia free survival(LFS) significantly; MRD^-(not reached) or MRD⁺(median 34.8(95% CI, 14.4-55.1)) or active disease(median 8.9 months(95% CI, 5.5-12.3))(p=0.021). In the group of MRD⁺patients, the OS was 21.6 months(95 % CI, 0.60-31.5) with 1- and 3- year OS rates of 72.7 ± 0.8 % and 31.2 ± 1.7 %, respectively(p=0.117). For the MRD^-group, median OS after allo-HSCT was not reached versus 8 months in the active disease group(p=0.053). No outcome differences were found between MAC and RIC regimens. In addition, we did not find any association between type of HLA matched, relapse or GVHD incidences. Infection was the most common cause of death in the both groups.

Conclusions: Based on this single center study, the use of ATG was associated with a lower incidence of chronic GVHD. Most importantly, ATG could increase the risk of disease relapse or mortality in patients with pre-transplant MRD⁺and active diseases. However, further prospective, randomized studies on a large number of patients are warranted to clarify these findings.

Disclosure: Nothing to declare.

P031 MLL-AF6 Fusion Gene Positive AML Treated by Allogeneic Hematopoietic Stem Cell Transplantation has Excellent Overall Survival

Wei Ma, Xingyu Cao, Wei Zhang, Min Xiong, Jianping Zhang, Yue Lu, Ruijuan Sun, Zhijie Wei, Deyan Liu, Yanli Zhao, Jiarui Zhou

Hebei Yanda Lu Daopei Hospital, Sanhe, China

Background: Acute leukemia with MLL-AF6 fusion gene positive is the adverse factor of prognosis. The purpose of this study is to evaluate the outcome of allo-HSCT in the treatment of MLL-AF6 fusion gene positive acute leukemia.

Methods: The clinical characteristics and prognosis of 32patients with MLL-AF6 fusion gene positive acute leukemia from May 2012 to September 2019 were retrospectively analyzed. Twenty four patients received allogeneic hematopoietic stem cell transplantation, including 21patients with AML and 3 patients with T-ALL. 13 were males and 11 were females. Median age was 22(4-48) years old. The disease status before transplantation was CR1 (n = 10) CR2 (n = 2), NR (n = 12). The median time from diagnosis to HSCT was 24(4-352) months.

Patients underwent matched sibling donors HSCT (MSD-HSCT)(n=4), haploidentical HSCT (Haplo-HSCT)(n=20). The conditioning regimens are based on BU/Cy (n=20) and TBI/Cy (n=4). GVHD prophylaxis consisted of ATG, CSA, MMF and MTX.

Results: The number of mononuclear, CD34+ and CD3+ cells was (9.3±1.42)×10⁸/kg, (4.1±1.1)×10⁶/kg, and (1.6±0.5)×10⁸/kg, respectively. White blood cells were successfully engraftment in 22 patients and the median time of ANC≥0.5×10⁹/L was day 12(9-16). One patient failed to engraftment and one patient was not engraftment. Median time of platelet≥20×10⁹/L was day 13(9-30) except 2 case. One patient failed to engraftment and one patient was not engraftment. DLI infusion was used to prevent recurrence in most patients after transplantation. The cumulative incidence of grade II - IV aGVHD was 41%, and the incidence of cGVHD was19%. Five-year overall survival(OS) rate and disease free survival(DFS) were 52.2% and 52% respectively. The five-year OS of allogeneic hematopoietic stem cell transplantation in CR1-2 and NR was 83.3% and 25%, respectively (P = 0.001). The mortality rate was 17% within 100 days. Transplant related mortality: 37%. Ten patients died, the causes of death were infection (n=2), IV aGVHD(n=3), and relapse(n=5). Eight patients received chemotherapy, all of them were AML patients, 5 males and 3 females, the median age was 26.5 (3-52) years old; eight AML patients were not relieved after the first chemotherapy, 3 patients only achieved remission after 2-4 chemotherapy, 5 patients were not relieved after multiple chemotherapy, 6 patients died, the cause of death: the primary disease was not relieved or relapsed; the overall survival was 2 cases. The OS rate was 52.2% in the transplantation group and 25% in the chemotherapy group (P = 0.237).

Conclusions: This study shows that MLL-AF6 acute leukemia has poor response to conventional chemotherapy and poorprognosis, so it is necessary to carry out allogeneic hematopoietic stem cell transplantation in remission state as early as possible.

Disclosure: Nothing to declare.

P032 Beneficial Outcome of Allogeneic Stem Cell Transplantation for Blastic Plasmacytoid Dendritic Cell Neoplasm

Ji Hyun Lee ¹, Seok Jin Kim², Won Seog Kim², Dok Hyun Yoon³, Cheolwon Suh³, Sung-Soo Yoon⁴, Youngil Koh⁴, Ja Min Byun⁵, Hyeon Seok Eom⁶, Hyewon Lee⁶, Jong Ho Won⁷, Ho Sup Lee⁸, Deok-Hwan Yang⁹, Ho-Young Yhim¹⁰, Ji Yun Lee¹¹, Jae-Cheol Jo³, Yoo Jin Lee^3,12

¹Dong-A University, Busan, Korea, Republic of, ²Sunkyunkwan University, Seoul, Korea, Republic of, ³University of Ulsan, Seoul, Korea, Republic of, ⁴Seoul National University, Seoul, Korea, Republic of, ⁵Seoul National University Hospital, Seoul, Korea, Republic of, ⁶National Cancer Center of Korea, Goyang, Korea, Republic of, ⁷Soonchunhyang University, Soonchunhyang University Hospital,, Seoul, Korea, Republic of, ⁸Kosin University Gospel Hospital, Busan, Korea, Republic of, ⁹Chonnam National University, Hwasun, Korea, Republic of, ¹⁰Chonbuk National University, Jeonju, Korea, Republic of, ¹¹Seoul National University Bundang Hospital, Seoul, Korea, Republic of, ¹²Ulsan University Hospital, Ulsan, Korea, Republic of

Background: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare aggressive hematologic neoplasm which originates from the professional type I interferon-producing cells or plasmacytoid monocytes. The prerequisite for its diagnosis is the CD4+ and CD 56+ co-expression without common lymphoid or myeloid lineage markers. Recently, targeted therapy with Tagraxofusp (SL-401), an IL-3 fusion protein which binds to CD123, has proved its efficacy with an overall response rate (ORR) of 90% in 32 untreated and 67% in 15 previously treated BPDCN patients. Although several retrospective and small case series has been published so far, there is few population-based study on BPDCN classified after 2008 WHO classification in Asian populati.

Methods: Data of 35 patients who were diagnosed with BPDCN from April, 2002 to February 2019 in 11 centers of South Korea were retrospectively collected and analyzed. Pathologic slides were reviewed in the central lab by the 2 pathologic experts and were finally confirmed for diagnosis. Overall survival was defined by the period from the date of the initial diagnosis to death by any cause or follow-up loss.

Results: The median age of the patients was 54.5 years (range, 17 - 84 years) with a male preponderance of 71.4% (25 of 35). 5 patients were preceded with hematologic malignancies. The most common initial presenting site was skin followed by lymph nodes, bone marrow, spleen, and liver. 32 of the included patients proceed to treatment with acute lymphoblastic leukemia (ALL)-like regimen (19 patients), acute myeloid leukemia (AML)-like regimen (5 patients) and lymphoma-like regimen (8 patients). Baseline characteristics of age ≥ 65 years, liver involvement and induction chemotherapy with lymphoma-like regimens expected worse prognosis in both univariate and multivariate analysis. Among the 32 patients who received induction chemotherapy, 11 cases proceeded to allogenic stem cell transplantation (SCT) and 3 received autologous SCT. With a median follow-up of 16.60 months (range, 0.53-79.73 months), patients who had been treated with leukemia-like induction regimen compared with lymphoma-like induction regimen (39.30 vs. 6.33 months, P=0.005) and allogeneic SCT compared with autologous SCT (54.13 vs. 7.70 months, P=0.015) showed markedly prolonged overall survival.

Conclusions: Induction treatment with leukemia-like regimen and proceeding to allogeneic stem cell transplantation can prolong overall survival in Asian patients with BPDCN.

Disclosure: There is nothing to declare.

P033 Nduction of Synergistic Apoptosis and Overcoming of Drug Resistance by Cotargeting of BCL-2 and Na/H Exchanger 1 Pathway in Acute Myeloid Leukemia Cells

Shin Young Hyun, Eun Jung Na, Ji Eun Jang, Haerim Chung, Soo Jeong Kim, Jin Seok Kim, Yoo Hong Min, June-Won Cheong

Yonsei University, Wonju, Korea, Republic of

Background: Anti-apoptotic proteins like Bcl-2, Bcl-Xl, or Mcl-1 play an important role in tumor cell survival and has been considered attractive drug targets. Especially, Bcl-2 selective inhibitor, venetoclax, has been showing significant effects on hematologic malignancies, but lower sensitivity and resistance gain have to be overcome to achieve durable response in acute myeloid leukemia (AML). Because intracellular pH is one of important modulators for Bcl-2 or Bax via deamidation process, in this study, we examined whether the cotreatment of Na/H exchanger 1 (NHE1) inhibitor, HMA [5-(N, N-hexamethylene)-amiloride] can overcome the resistance to venetoclax in AML cell lines.

Methods: Based on the preliminary experiments, venetoclax were treated to both venetoclax sensitive cell lines (MOLM13, MV4-11, and RS4-11) and venetoclax resistant THP1 cell line (THP1 and U937) with various concentration, and HMA was co-treated with 10 uM. Apoptotic cells were measured after 24 hr treated with each agent or combination. Apoptosis was analyzed using Annexin-V assay.

Results: As expected, venetoclax monotherapy induced concentration-dependent apoptosis in venetoclax sensitive MOLM13, MV4-11, and RS4-11 cells. For these cell lines, cotreatment of HMA to venetoclax synergistically potentiated apoptosis, and relatively lower concentrations of both drugs could induce almost complete apoptosis. For venetoclax resistant THP-1 and U937 cells, venetoclax could not induce sufficient apoptosis even with higher concentration. However, the combination treatment of HMA overcome venetoclax resistance, and induced apoptosis with 80% of THP-1 cells and 90% of U937 cells.

Conclusions: Our study suggests that co-targeting of Bcl-2 and NHE1 pathways not only sensitized the AML cells to venetoclax but also suggests that it could be one way to overcome venetoclax resistance in AML.

Disclosure: Nothing to declare.

P034 Gemtuzumab-ozogamicin for Bridging to Transplant in Refractory/relapsed CD33 Positive Acute Leukemia - is it Worthwhile?

Michael Stadler, Vanessa Oberstaedt, Elke Dammann, Lothar Hambach, Eva M. Weissinger, Catherina Lueck, Gernot Beutel, Matthias Eder, Arnold Ganser

Hannover Medical School, Hannover, Germany

Background: Outcome of allogeneic hematopoietic stem cell transplantation (alloHSCT) for acute leukemia (AL) is superior when performed in complete remission. Therefore, in refractory or relapsed patients not in remission after induction, consolidation or re-induction treatment, salvage strategies are being employed to reach at least marrow aplasia without residual blast morphology. Gemtuzumab-ozogamicin (GO), a humanized anti CD33 monoclonal antibody linked to calicheamicin, with a twisted drug history of early approval, withdrawal from the market, and renewed licensing for AML induction, has been an interesting candidate for such a strategy of “bridging to transplant” in CD33 positive AL patients.

Methods: We retrospectively evaluated overall (OS) and disease-free survival (DFS) of all adult refractory/relapsed AL patients having received GO for bridging to transplant at Hannover Medical School between 10/2004 and 12/2018. They were compared to a matched cohort of AL patients not reaching complete remission, but transplanted without bridging, since off-label GO could not be obtained for all refractory/relapsed patients.

Results: 232 refractory/relapsed AL patients underwent alloHSCT between 10/2004 and 12/2018 at our institution. 133 patients among them were CD33 positive. GO could be obtained for bridging to transplant in 32 patients, whereas 101 patients had to be transplanted without bridging. Both cohorts of CD33 positive patients were comparable for age, gender, disease subgroups, donor source, HLA matching, and conditioning intensity. GO salvage successfully induced marrow aplasia without residual blasts in 63% of evaluable patients. However, survival of CD33 positive AL patients after GO bridging (OS 29% at 5 and 10 years; DFS 27% at 5 years, 21% at 10 years) was not different from CD33 positive AL patients without GO bridging (OS 38% at 5 years, 28% at 10 years; DFS 32% at 5 years, 24% at 10 years). Of the total cohort of 232 refractory AL patients, 39% survived for 5 years and 32% for 10 years.

Conclusions: In our single center retrospective analysis of CD33 positive AL patients, bridging to transplant with GO seemed to have limited impact on long-term OS and DFS. However, even in refractory/relapsed AL, alloHSCT was able to rescue about one third of patients.

Disclosure: No conflicts of interest.

P035 Azacytidine and Donor Lymphocytes Infusions in Relapsed AML after Allogeneic Hsct: Results in 40 Patients

Carmine Liberatore, Francesca Lorentino, Matteo Giovanni Carrabba, Carlo Messina, Luca Vago, Sara Mastaglio, Raffaella Greco, Francesca Pavesi, Sarah Marktel, Francesca Farina, Raffaella Milani, Consuelo Corti, Massimo Bernardi, Jacopo Peccatori, Maria Teresa Lupo Stanghellini, Fabio Ciceri

IRCCS San Raffaele Scientific Institute, Milan, Italy

Background: azacytidine (AZA) alone or with donor lymphocytes infusions (DLI) is an option for the treatment of acute myeloid leukemia (AML) relapsing after allogeneic stem cell transplantation (HSCT).

Methods: according to institutional policy, from 2012 to 2019 we treated 40 patients with AML relapsed after HSCT with AZA +/- DLI. Indications were either minimal residual disease positivity (MRD+) (evaluated by qPCR, flow cytometry or cytogenetical analysis) or morphological relapse not eligible for intensive chemotherapy. AZA dosage ranged from 32 mg/mq G1-5 to 75 mg/mq G1-7 q28 days. DLI was given every 2 cycles of AZA at escalating dose as per institutional guidelines. Indication to DLI relied upon clinical-biological features of patient, disease and HSCT (active GvHD and HLA loss were contraindications).

Results: clinical-biological features at baseline and at relapse are reported in Figure 1. Median time from HSCT to relapse was 10 months (range 1-55). Fourteen patients had MRD+ (group 1) and 26 patients had morphological relapse (group 2). Nine patients (23%) received AZA 32 mg/mq while 31 patients (77%) received AZA 75 mg/mq. Median number of AZA cycles was 4 (range 1-28). Sixteen patients (40%) received AZA+DLI, median number of DLI was 2 (range 1-4), median amount of CD3+ cells/Kg per patient was 3,8 x10^6 (range 0,1-76).

Overall response rate was 55% (22 pts): 57% (8 pts) in group 1 vs 54% (14 pts) in group 2 (p=0.87). Complete response rate was 33% (13 pts): 43% (6 pts) in group 1 and 27% (7 pts) in group 2 (p=0.43).

Progression free survival (PFS) at 1-year was 32%: 57% in group 1 vs 19% in group 2. At 2-years PFS was 23%: 57% in group 1 vs 7% in group 2 (p=0.01). In group 1, 7 patients maintained CR (4/7 received DLI) after a median follow up of 22 months (range 11-64). In group 2, 1-year PFS in patients with < 20% blast at relapse was 22% vs 12% in patients with ≥20% (p=0.24).

Overall survival (OS) at 1 year was 60%, respectively 85% in group 1 vs 46% in group 2. At 2-years OS was 41%: 77% in group 1 vs 22% in group 2 (p=0.01).

Most common grade 3-4 adverse events were neutropenia (80%), thrombocytopenia (55%), anemia (45%) and febrile neutropenia (35%). Acute GvHD developed in 3 patients (no one had previous GvHD, 1 received DLI) while 5 patients had chronic GvHD (2 had previous acute GvHD, 2 had previous chronic GvHD, 1 received DLI). No patient died because of treatment.

Conclusions: AZA +/- DLI is a feasible salvage therapy in relapsed AML after HSCT. AZA +/- DLI was rarely curative in morphological relapse - independently by blast counts - while long-term remissions were achieved in patients treated for MRD+ after transplant.

Disclosure: Nothing to declare.

P036 The Results of AML Relapse after Allogeneic Transplantation Treatment, Single Centre Approach Evaluation

Markéta Šťastná Marková, Veronika Válková, Antonín Vítek, Ludmila Nováková, Barbora Čemusová, Michal Kolar, Jan Vydra, Petr Cetkovský

Institute of Hematology and Blood Transfusion, Praha, Czech Republic

Background: Although allogeneic transplantation brings a substantial survival benefit in AML, post-transplant relapse remains one of the major events leading to treatment failure. Together with non-existing definite approach guidelines it causes difficulties in further treatment decision.

Methods: A retrospective survival evaluation of relapsed AML (n=148) patients after allogeneic transplantation between the years 1990 and 2019 was done. The decision of relapse treatment was performed individually with the respect to biological parameters of the disease, patient´s physical status and will. For the evaluation purpose the whole cohort was divided to 3 groups -1) no chemotherapy treatment except of immunosuppression tapering and DLI administration (n=44), 2) “low intensity “ treatment including low dose ARA-C, 5-azacytidine with immunosuppression modification and with or without DLI administration (n=36) and 3) “high intensity” treatment including intensive regimens with high dose ARA-C and anthracyclines preferentially with DLI or second transplant (n=68).

Results: The overall survival in 1, 2 and 5 years was 32%, 20% and 16%. There was an expected significant difference between not treated group (2%, 1%, and 1%) and treated group with no significant further difference between low intensity and high intensity groups (48%, 29% and 16% in high intensity group and 31%, 21% and 16% in low intensity group). Patients who relapsed earlier from transplant did worse in the first two years, but the difference disappeared in surviving patients after 24 months of relapse treatment. Not surprisingly patients who had achieved complete remission had significant OS advantage (71% vs 6% in 1 year and 52% vs 1% in 2 years). There was no survival advantage in treated patients without remission achievement to untreated patients at all, though among untreated patients there was one (1/36) fully responding to immunosuppression tapering. 34% of patients with remission achievement relapsed again. Treatment toxicity related death was in 21%. Another major contributor to death was GVHD.

Conclusions: The outcome of AML patients relapsing after allogeneic transplantation is very poor despite various treatment approaches. The survival benefit was seen in patients who achieved further remission, though the subsequent relapses were frequent. Treatment toxicity was rather high in this group of patients. The emphasis on prophylactic and preemptive treatment together with tight minimal residual disease monitoring should be carried out, and the introduction novel drugs (e.g. venetoclax, gilteritinib etc.) should be evaluated.

Disclosure: Nothing to declare.

P037 Allogeneic Hematopoietic Stem Cell Transplantation for Relapsed or Refractory Acute Myeloid Leukemia: A Single Center Analysis

Paul Deschamps, Claude-Éric Bulabois, Martin Carré, Anne Thiebaut-Bertrand, Jean-Yves Cahn

CHU de Grenoble, La Tronche, France

Background: Approximately 60-70% of adult patients with newly diagnosed acute myeloid leukemia (AML) will achieve a complete remission after induction regimen. However resistant disease or relapse (R/R) remain a significant cause of treatment failure and a major unfavorable prognostic factor. Role and timing of allogeneic hematopoietic stem cell transplantation (HSCT) remains a matter of debate for these patients with R/R AML, as well as their transplant outcome. For these reasons, we have retrospectively analyzed the outcome of adult patients who underwent HSCT for R/R AML in our center at Grenoble University Hospital from 2007 to 2017.

Methods: Adults who had received HSCT in our center between 01/01/2007 and 12/31/2017 for R/R AML, at time of transplantation, were included. Progression-free survival (PFS) was the primary end point, while secondary endpoints assessed overall survival (OS), graft-versus-host disease (GVHD) relapse-free survival (GRFS), and cumulative incidences of GVHD, relapse and non-relapse mortality (NRM).

Results: This retrospective study reports data from 56 patients receiving HSCT for de novo or secondary R/R AML. The median age at transplantation was 56 years (range, 20-69 years). Median of marrow blasts was 13% (range, 5,5-78%). Half of the cohort underwent a myeloablative conditioning regimen, while 29% of the patients received a sequential regimen approach. Median follow-up was 52 months for surviving patients (range, 24-132 months), and the PFS at 1 year was 21,4% (95% Confidence Interval [CI], 11,9-32,9%), with a median of 98 days (95% CI, 64-149 days). Overall survival was 25% (95% CI, 14,6-36,8%) at 1 year, GRFS was 10,7% at 1 year (95% CI, 4,4-20,4%). Cumulative incidence of acute GVHD II-IV reached 47,8% including 13,6% of grade III-IV at 1 year, while 28,6% of patients were reported for chronic GVHD. Twenty four per cent of patients had a refractory disease at first assessment after HSCT. Relapse incidence was 62,7% (95% CI, 49,1-76,3%) at 1 year and progression of the disease was responsible for 53% of the whole cohort mortality. 88,5% of relapses occurred within the 6 first months following HSCT, and none appeared after the 8th month. NRM at 1 year was 32% (95% CI, 9,9-51,5%).

Conclusions: This study confirms the role of HSCT in R/R AML patients as the best curative approach available today, with similar outcome rates than previously published. No specific subgroup of patients was identified in terms of better outcome. However, the high incidence of early post-transplantation relapse reveals the persistent need to improve the procedure. The key points reported in larger trials are early donor identification, easier with the availability of haplo-donors, use of sequential conditioning regimen, early tapering of immunosuppression and post-transplantation maintenance, such as targeted therapies, hypomethylating agents, donor lymphocytes infusions or other forms of immunotherapies.

In conclusion allogeneic HSCT remains feasible in this poor prognosis subgroup of AML and a multicentric program is underway in Auvergne-Rhone-Alpes region, France, based on the harmonization of HSCT practices in this very high-risk AML patients.

Disclosure: No disclosure to declare.

P038 The Optimal Time for Allogeneic Hematopoietic Stem Cell Transplantation in Adult Patients with Acute Myeloid Leukemia

Sergey Bondarenko, Ivan Moiseev, Elena Morozova, Olga Pirogova, Elena Darskaya, Anna Smirnova, Nikolai Tsvetkov, Anastasiya Beynarovich, Irina Samorodova, Tatyana Gindina, Elena Babenko, Ildar Barkhatov, Alexander Alyanskiy, Alexander Kulagin, Boris Afanasyev

First Pavlov State Medical University of St. Petersburg

Background: AML is the most common indication for alloHSCT. The EBMT manuscripts estimate the intermediate-risk ELN2017 patients as candidates for alloHSCT in CR1 from MSD. AlloHSCT from MUD is still a clinical option for this prognostic group. However, the outcome of relapsed AML remains poor, both due to low incidence of achieving a CR2 and higher NRM.

Methods: The study included 298pts for the period 2005-18, median(m) age was 36(18-70)years. The m follow-up was 24(13-168)months. Disease status: CR1 - 234(78%)pts, CR2 - 64(22%)pts. The favorable risk group(fav) included 50(17%)pts, the intermediate(int) - 200(67%)pts, and the unfavorable(unfav) - 48(16%)pts. AlloHSCT underwent 242pts, 178(74%)pts in CR1, according to ELN2017 fav - 21(12%)pts, int - 121(68%)pts and unfav - 36(20%)pts; in CR2 - 64(26%)pts, which were fav - 16(25%)pts, int - 36(56%)pts and unfav - 12(19%)pts. In int group alloHSCT was performed from MSD in 36pts and from MUD - 85pts. Chemotherapy (CT) received 56pts in the CR1 - 13(23%)pts in fav and 43(77%)pts in int ELN2017. Since 2013 PTCy has been used for the prevention of GVHD in alloHSCT and, since 2016 MAC consisted of fludarabine and busulfan14mg/kg.

Results: OS and RFS in fav were: after CT - 78%(95%CI57-99) and 72%(95%CI53-99), after allotHSCT in CR1 - 76%(95%CI59-95) and 71%(95%CI51-91), in CR2 - 86%(95%CI73-99) and 71%(95%CI48-94), p=.7 and p=.9. Relapse rate(RR) and NRM were 28%(95%CI6-56) and 10%(95%CI1-39), 24%(95%CI8-44) and 5%(95%CI1-20), 22%(95%CI5-48) and 13%(95%CI2-35), p =.6.

In int OS and RFS were: after CT - 42%(95%CI17-67) and 34%(95%CI15-53), after alloHSCT in CR1 - 77%(95%CI70-84) and 72%(95%CI65-79), in CR2 - 46%(95%CI27-65) and 45%(95%CI31-59), p=.02 and p=.03. RR and NRM - 60%(95%CI38-77) and 6%(95%CI6-19), 16%(95%CI10-25) and 12%(95%CI7-18), 26%(95%CI11-43) and 29%(95%CI15-45), p=.09 and p=.06.

After alloHSCT in unfav OS and RFS in CR1 were 43%(95%CI26-60) and 34%(95%CI17-51), in CR2 - 31%(95%CI4-58) and 30%(95%CI3-57), p=.4. RR and NRM were 60%(95%CI40-75) and 6%(95%CI1-17), 52%(95%CI18-77) and 18%(95%CI2-47), p=.8 and p=.2.

In int the year of alloHSCT was evaluated 2005-12 vs 2013-18. In CR1 the OS, RFS, RR and NRM were 64%(95%CI51-77) vs 85%(95%CI78-92), p=.01, 62%(95%CI48-76) vs 76%(95%CI64-88), p=.05, 20%(95%CI10-33) vs 16%(95%CI7-29) and 18%(95%CI8-30) vs 8%(95%CI3-16). In CR2 OS, RFS, RR and NRM were 30%(95%CI8-52) vs 65%(95%CI44-86), p=.3, 29%(95%CI7-51) vs 64%(95%CI42-86), p=.2, 34%(95%CI13-57) vs 12%(95%CI2-32) and 33%(95%CI13-55) vs 23%(95%CI7-45). In case of MSD 2005-12 vs 2013-18 in CR1 OS, RFS, RR and NRM were 58%(95%CI32-83) vs 78%(95%CI60-96), p=.2, 54%(95%CI29-79) vs 59%(95%CI34-84), p=.5, 32%(95%CI11-55) vs 36%(95%CI12-61) and 14% (95%CI2-36) vs 5% (95%CI1-21). After MUD alloHSCT 2005-12 vs 2013-18 in CR1 OS, RFS, RR and NRM were 67%(95%CI51-83) vs 87%(95%CI79-95), p=.07, 67%(95%CI50-84) vs 81%(95%CI67-95), p=.07, 13%(95%CI4-28) vs 10%(95%CI2-26) and 20%(95%CI8-36) vs 9%(95%CI3-18).

Conclusions: AlloHSCT should be delayed to CR2 for patients in the favorable risk group. In the unfavorable group, alloHSCT is indicated in CR1. Given the improvement of transplantation methods for patients of the intermediate group, alloHSCT is recommended in CR1. The outcome of alloHSCT from matched unrelated donor comparable with matched sibling donor. Patients with intermediate ELN risk AML should perform alloHSCT in CR1 despite of donor type (MSD or MUD).

Disclosure: Nothing to declare.

P039 Impact of ABO Mismatch Allogeneic Transplant in Acute Myeloid Leukemia -A Single Centre Experience

Fahad Shaikh, Ganapathi Bhat, Suresh Advani, Samir shah, Reetu Jain

Jaslok Hospital and Research Center, Mumbai, India

Background: Post remission therapy in patients with acute myeloid leukemia (AML) consist of giving maintenance chemotherapy or allogeneic hematopoietic stem cell transplantation (AlloHSCT) in high risk patients as a curative therapeutic option. Conflicting results have been reported on the impact of ABO mismatch on various transplant outcomes such as neutrophil and platelet engraftment, acute and chronic graft versus host disease (GvHD), non-relapse mortality and overall survival.

Methods: We analyzed data of 58 AML (Acute Myeloid Leukemia) patients who had undergone Allo HSCT, between 2005 to 2019, at our Centre. In this study, we evaluated the demographic and clinical characteristics of patients, the effect of ABO mismatch and graft source on HSCT outcomes, such as engraftment and graft versus host disease (GvHD)

Results: Out of 58 patients, 30 (51%) were males, 28 patients were female. The median age was 31 years (range 3- 60) years. PBSC was the major source of graft, and matched sibling were the predominant donor type (97.1%). There were 26 patients with gender mismatch (44.8%). Among the recipients, ABO group mismatch was seen in 15 patients (25.8%), of which 12 cases were major blood group mismatch. Majority of patients received Bu-Cy as conditioning regimen (65.5%). The mean time to neutrophil engraftment was 14.6 days (SD 3.08) and platelet engraftment was 15.8 days (SD 4.69), which were similar in all patients irrespective of ABO match/mismatch status. (p=0.04 and p=0.05 respectively). 75.5% patients developed febrile neutropenia, of which 15% had documented infection with an identifiable microorganism. 13 cases (22.4%) developed acute GvHD, while 4 cases had VOD. 3 patients had transplant related mortality. Patients with fully matched sibling donor had statistical significant association with improved survival outcome (p 0.017). Both major and minor blood group mismatch were associated with increased mortality (p=0.05). On comparing different variables in terms of standard deviation using unpaired t test, age at transplant was the only variable with significant association with survival outcome (p.0.003).

Conclusions: Our experience with ABO mismatch is encouraging with good tolerability and disease control even in the advanced stage heavily pre-treated patients. More aggressive strategies including second transplants and novel agents are needed in these patients on relapse.

[overall survival]

Disclosure: No conflict of interest. This study was not funded

P040 Donor Source Impacts on Long Term Survival following Reduced Intensity Allogeneic Stem Cell Transplant in AML Patients Aged 60 and Above

William Hayhurst, Asterios Giotas, Chloe Anthias, Sandra Easdale, David Taussig, Mike Potter, Mark Ethell, Joy Brennan, Maria Mulligan, Kim Davis, Emma Thistlethwayte, Emma Nicholson

Royal Marsden Hospital, London, United Kingdom

Background: Outcomes in elderly AML remain poor due to high risk of relapse, higher incidence of adverse cytogenetics and of chemotherapy resistance. The advent of reduced intensity conditioning (RIC) regimens has led to increasing use of allogeneic transplant in patients over the age of 60. This can lead to durable disease free survival in this age group and improved outcomes compared to that achieved with chemotherapy alone

Methods: This retrospective study analysed outcomes of 100 consecutive patients over the age of 60 years old undergoing RIC SCT for AML between June 2006 and June 2018. Patients were conditioned with Fludarabine/Melphalan/Alemtuzumab (n=94) or Fludarabine/Cyclophosphamide/2GyTBI (n=6). Data was collected from Electronic patient records. Probability of Overall Survival (OS), Progression Free Survival (PFS) were calculated by Kaplan Meier method and log rank test performed. Cumulative Incidence (CI) of relapse risk (RR), non-relapse mortality (NRM) and GVHD was calculated using competing risk analysis

Results: 100 patients were included in the study with a median age of 65 years (range 60-1 - 71.8). 77% had De Novo AML, 13% had a preceding diagnosis of MDS or MPD, 10% had therapy related AML. 79% of the patients were transplanted in CR1 and 21% were transplanted in CR2. 34 patients relapsed at a median of 0.96 years post transplant (range 0.11-5.37). 53% of patients had a matched Unrelated Donor (MUD) SCT, 23% sibling donor, 18% Mismatched unrelated donor (MMUD) and 6% umbilical cord blood (UCB) donor. 39% of patients had adverse prognostic markers at diagnosis as per ELN 2017 guidelines.

2 year OS was 41% and 2 year PFS was 36%. RR at 2 years was 25% and 2 year NRM was 38%. CI of Grade 2-4 acute GVHD at Day 100 was 15% (9-23) and 2 year CI of chronic GVHD was 30%. 2 year OS for patients with sibling, MUD, MMUD and cord donors was 61%, 40%, 67% and 22% respectively and 2 year PFS for patients with sibling, MUD, MMUD and cord donors was 56%, 35%, 67% and 17% respectively. OS was significantly reduced in those with MMUD donors compared to sibling (p=0.009%) and MUD donors (p=0.04%) due to higher NRM. Age at transplant (< 65 years versus >/=65 years), transplant in CR1 versus CR2 and adverse versus non adverse risk group had no significant impact on OS or PFS.

Conclusions: T cell depleted RIC allogeneic HSCT can lead to durable disease free remissions in older patients with AML including patients with adverse risk disease or therapy related or secondary AML. Patients with MMUD had inferior OS and PFS compared to those with a sibling or MUD donor in this age group and the decision to perform a mismatched unrelated donor transplant in this age group should be carefully assessed. Whilst numbers of UCB were small, the of use of alternative donors rather than MMUD in this age group should be considered and warrants further evaluation in randomised setting

Disclosure: Nothing to declare.

P041 Extra-medullary Recurrence of Acute Myeloid Leukemia as Myeloid Sarcoma after Allogeneic Stem Cell Transplantation: A Case Series

Jochen Frietsch ¹, Friederike Hunstig^1,2, Sebastian Scholl¹, Andreas Hochhaus¹, Inken Hilgendorf¹

¹Universitätsklinikum Jena, Jena, Germany, ²Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany

Background: Myeloid sarcoma (MS) as a solid extra-medullary manifestation of acute myeloid leukemia (AML) is a rare presentation of relapse after allogeneic hematopoietic stem cell transplantation (HSCT). It may occur as an isolated extra-medullary relapse, multilocular or in association with a medullary relapse.

Methods: All patients aged 18 years or older who have received HSCT for AML at our center since 2002 (n = 327) were screened for onset of MS after HSCT. Of those, 12 patients (3.7%) suffered from MS as extra-medullary relapse after HSCT and were included in this study.

Results: We identified 12 patients (median age 53 years) with MS. They all received reduced intensity conditioning (RIC). 58.3% (7/12) received HSCT from a matched-unrelated, 33.3% (4/12) from a matched-related and 8.3% (1/12) from a mismatched-related donor. The median onset of MS was 490.5 days after HSCT (range: 134 and 1276 days). The regions and organs affected varied from very typical tissues such as skin, bone or lymph node up to extremely rare presentations of MS affecting the pituitary gland, breast tissue, the thoracic wall or the paranasal sinuses. Eight (66.7%) patients developed MS despite a history of graft-versus host-disease (GvHD).

Concerning the treatment, various therapy options were considered. The most frequently applied treatment options were intrathecal triple therapy, cytarabine and azacytidine. None of the patients received another HSCT. Irradiation was implemented where possible. Although MS is associated with a poor prognosis, three patients (3/12) survived more than two years and one more than 11 years after diagnosis of MS. The median overall survival since diagnosis of MS was 255.5 days (Kaplan-Meier).

Conclusions: These observations demonstrate the limitations of graft-versus-tumor effects after HSCT, since extra-medullary relapse did occur in the presence of GvHD. The results may also indicate that reduced intensity conditioning protocols are associated with a higher rate of extra-medullary relapse.

Single isolated manifestations are more frequently treated successfully compared to multilocular manifestations of MS. This is in part due to fewer issues regarding accessibility by local therapies such as irradiation or intrathecal therapy (in cases of involvement of the central nervous system). Altogether occurrence of MS after HSCT is associated with a poor prognosis as curative concepts including intensive chemotherapy and another HSCT are often not viable.

Disclosure: The authors do not declare. any conflicts of interest.

P042 Allogeneic Stem Cell Transplants in Acute Myeloid Leukaemia; A Single Centre Experience

Tomas Kupsa ^1,2, Jan Vanek², Benjamin Visek¹, Miriam Lanska¹, Alzbeta Zavrelova¹, Ladislav Jebavy^1,2, Jakub Radocha¹, Jan M Horacek^1,2, Pavel Zak¹

¹Charles University Prague, Hradec Kralove, Czech Republic, ²University of Defence, Hradec Kralove, Czech Republic

Background: Allogeneic stem cell transplant remains the best consolidation therapy in intermediate and high-risk AML patients with a suitable donor. We conducted a retrospective analysis to identify those who may benefit from further intensification of therapy.

Methods: Eighty patients, aged 53.5 ± 12.6 years, diagnosed in period 2010-2016 were studied. All were treated with a curative approach with “3+7” induction therapy, followed by consolidation only of allogeneic stem cell transplantation. All living patients have been observed for at least two years. The FLT3 inhibitors were not used in this cohort.

Results: 55 patients (69%) achieved complete remission (CR) by induction therapy. 57 patients (71%) were allografted. Hematologic relapse (P < 0.001), high-risk cytogenetics (P = 0.001) and age (P = 0.033) influenced overall survival (OS). Patients relapse-free for at least two years (irrespective of consolidation by chemotherapy only or allografted) had low risk of relapse and longer OS (P < 0.001). Allografted patients were younger (P = 0.009) and had improved OS (P = 0.010). Patients aged ≥ 65 years had lower probability of prolonged remission and inferior outcome. Primary induction failure (PIF) in low- and intermediate risk AML (n = 8/47, 17%) was not associated with inferior OS. In high-risk AML and PIF (n = 14/33, 42%) the median OS was 6.7 months in the whole cohort, respectively 12 months in 8 allografted individuals.

Conclusions: In patients with low- and intermediate risk AML and PIF the allogeneic stem cell transplant may overcome the resistance to induction therapy. A substantial proportion of PIF patients have high-risk AML. The efficacy of allogeneic stem cell transplant is limited in this cohort and the overall survival is poor. These patients may most benefit from innovative treatment approaches.

The work was supported by program PROGRES Q40/08, and by DZRO 1011 (FMHS).

[PIF in high-risk AML]

Clinical Trial Registry: Not applicable.

Disclosure: Nothing to declare.

P043 Allogeneic Hematopoietic Cell Transplantation for Patients with Acute Myeloid Leukemia not Responding to First Induction Therapy

Annalisa Natale ¹, Stefano Angelini¹, Mauro Di Ianni¹, Gabriele Papalinetti¹, Doriana Vaddinelli¹, Paolo Di Bartolomeo¹, Giuseppe Calabrese², Stella Santarone¹

¹Unità di Terapia Intensiva Ematologica per il Trapianto Emopoietico, Ospedale Civile, Pescara, Italy, ²Laboratorio Genetica Molecolare Onco-Ematologica, Ospedale Civile, Pescara, Italy

Background: Patients with acute myeloid leukemia (AML) who did not achieve remission after first induction chemotherapy have a dismal prognosis. Prior reports have shown that these patients could be rescued with allogeneic hematopoietic cell transplantation (HCT). The aim of this retrospective study was to determine the clinical outcome of 34 AML patients who failed first induction chemotherapy and were treated with HCT (n=40) in our center between June 1995 and April 2019.

Methods: 34 patients with AML who did not achieve complete remission (CR) after first induction chemotherapy with “7+3” regimen (cytarabine associated to either daunorubicin or idarubicin) were enrolled in this study. As second induction chemotherapy, most patients received high dose cytarabine-based regimen. The median number of chemotherapy lines before transplantation was 2 (range, 2-3). The median time from diagnosis to first CR was 106 days (range, 63-225). At time of HCT, 30 patients were in CR1, 2 in CR2 and 2 in partial remission (marrow blasts 6-10%). Table 1 shows some characteristics of patient population at time of first transplant.

Results: Full engraftment of donor cells was evident in 31 evaluable patients (91%). 2 patients died before engraftment and 1 patient showed primary graft failure. The median time to reach >0.5 x10⁹/L neutrophils was 23 days (range, 13-35). The CI of either acute (grade II-IV) or chronic (limited + extensive) GvHD was 32% and 21% respectively. Leukemia relapse occurred in 13 patients at a median of 411 days (range, 67-1824) after transplant for a CI of 42%. Of them, 5 died for leukemia, 6 underwent a second transplant after achieving second CR, 1 is waiting for second HCT and 1 is leukemia-free after sorafenib therapy. Among 6 patients who received a second transplant, 2 are living and cured, 2 died for infections, 1 died for VOD and 1 died for leukemia relapse. Nine patients died for transplant-related causes at a median of 53 days (range, 8-740) after transplant. Causes of death were infection in 5, acute GvHD in 2, and heart failure in 2. The 3-year-CI of transplant-related mortality was 27%. As of November 2019, 16 patients are living and doing well after a median follow-up of 116 months (range, 7-264). Of them, 15 (44%) are cured and 1 is waiting for second transplant. The 5-yr Kaplan-Meyer overall survival and disease-free survival were 47% and 29% respectively.

Conclusions: This study demonstrates that allogeneic HCT may produce durable remission and cure in patients with AML who failed first induction chemotherapy.

N. of patients/ transplants	34/40
Gender, male/ female	20/14
Median age, years (range)	44 (5-66)
2017 ELN risk: favorable/intermediate/adverse/not determined	2/17/6/9
Donors: HLA id sibling/unrelated/haploidentical	12/11/11
Stem cell source: BM/PBSC/CB	23/10/1
Conditioning: MAC/RIC	27/7
Conditioning: TBI/Busulfan/Melphalan/Treosulfan/Thiotepa	3/27/2/1/1
GvHD prophylaxis: CSA/CSA+MTX/T-reg	2/31/1

[Table 1]

Disclosure: Nothing to declare.

Aplastic anaemia

P044 Salvage Allogeneic Hematopoietic Stem Cell Transplantation for Severe Aplastic Anemia Patients with Refractory Active Infection: A Prospective Multicenter Clinical Study in China

Xia Qin ¹, Xiangfeng Tang², Yiping Zhu³, Rongmu Luo⁴, Ting Yang⁵, Zimin Sun⁶, Shaoyan Hu⁷, Yuan Sun⁸, Shunqing Wang⁹, Weiping Zhang¹⁰, Xianmin Song¹¹, Jiong Hu¹², Ke Huang¹³, Jing Chen¹

¹Shanghai Children’s Medical Center, National Children’s Medical Center, Shanghai, China, ²The Sixth Medical Center of PLA General Hospital, Beijing, China, ³West China Second University Hospital/West China Women and Children’s Hospital, Chengdu, China, ⁴BaYi Children’s Hospital, The Seventh Medical Center of PLA General Hospital, Beijing, China, ⁵Fujian Medical University Union Hospital, Fuzhou, China, ⁶Anhui Provincial Hospital, University of Science and Technology of China, Hefei, China, ⁷Children’s Hospital of Soochow University, Soochow, China, ⁸BeiJing JingDu Children’s Hospital, Beijing, China, ⁹Guangzhou First People’s Hospital, Guangzhou, China, ¹⁰Changhai Hospital, Naval Medical University, Shanghai, China, ¹¹Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China, ¹²Ruijin Hospital, Shanghai Jiao Tong University, Shanghai, China, ¹³Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China

Background: It is generally recognized that allogeneic hematopoietic stem cell transplantation (allo-HSCT) should not be managed to patients with active infection. However, in patients with severe aplastic anemia (SAA) especially very severe aplastic anemia (VSAA), it is usually difficult to control the infection without neutrophil. Rapid recovery of neutrophil by allo-HSCT might be a salvage treatment to control infection and rescue the patients. To evaluate the efficacy of allo-HSCT for SAA patients with refractory active infection, we designed this multicenter prospective clinical study in China.

Methods: Refractory active infection was defined as persistent fever without response to broad-spectrum antibacterial and antifungal treatment for more than three weeks with or without a definite infected site, or there was a definite infected site with fever less than 3 weeks. The probabilities of overall survival (OS) were calculated using the Kaplan-Meier estimator and compared between two groups using the log-rank test. The cumulative incidences were calculated using competing-risk models and analyzed by the Grey test between groups.

Results: Totally 75 patients were enrolled in this study from April 2014 to July 2018. All patients had persistent fever, including 52 (69.3%) with pneumonia (13 also accompanied with other site infection), 16 (21.3%) with other site infection and another 7 (9.3%) without a definite infected site. 51 (68.0%) patients received HSCT from a haploidentical family donor, 15 (20.0%) from an unrelated donor and only 9 (12.0%) from a sibling donor. For the prompt engraftment, peripheral blood stem cells (PBSCs) were given to all of our patients. Meanwhile, bone marrow was co-transplanted with PBSCs in 40 (53.3%) patients. The median age was 6.3 years (range, 1.0-38 years). Seven (9.3%) patients died of infection before engraftment. Two (2.7%) patients got primary mixed chimerism at day 28, and one developed secondary graft failure. The other patients sustained complete donor chimerism after HSCT. The median time for myeloid engraftment was 13 days (range, 9 to 32). The cumulative incidences (CI) of II-IV acute GVHD and chronic GVHD were 18.7±4.5% and 24.0±5.0% respectively. With a median follow-up of 730 days (range, 2 to 1568), the probability of OS was 77.2±4.9%. Because 68% of patients underwent haploindetical transplant, we compare the outcomes of patients receiving haploindetical transplant with active infection (n=51) to that of patients receiving haploindetical transplant without active infection (n=73) during the same period. There were no statistic differences in the CI of II-IV acute GVHD (17.6±5.4% vs 19.2±4.6%, p=0.771), CI of chronic GVHD (25.5±6.2% vs 20.5±4.8%, p=0.371), and the probability of OS (78.3±5.8% vs 89.0 ±3.7%, P=0.096) between the two groups. Compare to the other donor, the FFS II-IV, aGVHD and chronic GVHD with haploidental donor HSCT is simila to other donors.

Conclusions: Allo-HSCT is a feasible therapeutic option for SAA patients with refractory active infection. Haploidentical family donor is a good donor if without matched sibling donor. Peripheral blood stem cell may be the better graft source for this salvage HSCT owing to the rapidly engraftment.

Clinical Trial Registry: Clinical Trail registry number: ChiCTR-OCH-14005190

http://www.chictr.org.cn

Disclosure: Nothing to declare.

P045 Incidence and Management of Aplastic Anemia in Spain (IMAS). An Ambispective Study of Biodonostia / Pethema

Carlos Vallejo ¹, Ana Rosell², Blanca Xicoy³, Carmen García⁴, Carmen Albo⁵, Marta Polo⁶, Isidro Jarque⁷

¹University Hospital Donostia, Donostia, Spain, ²Hospital Virgen de la Victoria, Málaga, Spain, ³ICO-Hospital Germans Trias i Pujol, Badalona, Spain, ⁴Hospital General de Alicante, Alicante, Spain, ⁵Hospital Álvaro Cunqueiro, Vigo, Spain, ⁶Hospital Clínico San Carlos, Madrid, Spain, ⁷Hospital La Fe, Valencia, Spain

Background: Aplastic anemia (AA) is a rare, and life-threatening hematological disease. It is known that its incidence and prevalence might vary substantially among different geographic regions, and its presentation has been sometimes linked to environmental exposures. Montané et al reported an incidence of 2.34 per million inhabitants per year in the metropolitan area of Barcelona (Haematologica 2008). In the north of Spain, our group found 2.49 new cases/year (EBMT 2016). In Sweden, an incidence of 2.35 new cases/year has been recently reported (Vaht, Haematologica 2017). Our aim was to know the incidence and epidemiology of AA in a well-defined population.

Methods: In an ambispective study (IMAS), 7 general hospitals from 7 provinces situated in different geographical regions, that take care of a population of around 3.91 million inhabitants, participated in this study. All the patients diagnosed with AA were included. Data bases of the Hematology, Pathology, and Pharmacy Departments were used as a source of information.

Results: During the period 01/01/201031/07/2019, 103 new cases were identified (3-14 cases/year). The incidence of AA was 2.75 per million inhabitants per year. The median age at diagnosis was 56 years old (11-85), and gender was distributed almost equally between females and males. More than half of the cases were severe or very severe, and 9 out of 10 of the patients had transfusion needs. The most frequently employed approach at first line was immunosuppressive therapy with ATG/cyclosporine A (CsA). HSCT was a very infrequent 1st line therapy. At 1 year, two-thirds of the patients were in response (partial or complete). With a median follow-up of 6 years, threequarters of the patients were alive. See table.

N = 103
Period	01/01/2010-31/07/2019
Age (years) (median; range)	56 (11-85)
Gender (female/male)	52.8% / 47.3%
Severity of the disease (very severe and severe/moderate)	57.3% / 42.7%
Transfusion needs (yes/no)	90.3% / 9.7%
First line treatment	ATG/CsA: 52.4%; Allo-HSCT: 1.9%; Others: 45.7%
RR at day + 90	50.6% (45.4% PR / 5.2% CR)
RR at day + 180	53.3% (44.0% PR / 9.3% CR)
RR at day + 365	61.3% (46.8% PR / 14.5% CR)
Survival at last visit	75.3%
Follow-up (months) (median; range)	60 (5-115)

[Table. Description of the series]

Conclusions: 1) Worldwide, there are few studies focus on the epidemiology and management of AA patients. Particularly, this is the first national study of these characteristics ever performed in Spain; 2) We found an incidence of AA of 2.75 new cases/year; 3) No differences in gender were found; 4) ATG/CsA was the most frequently employed first-line therapy; 5) Long term response rate we found are similar to those shown in previous international reports of AA patients, and clearly show that there is an important room for improvement with new therapeutic approaches.

Disclosure: Nothing to declare.

P046 Allogeneic Stem Cell Transplantation from Alternative Donors for Children with Aplastic Anemia

Atsushi Narita, Hideki Muramatsu, Masayuki Imaya, Ayako Yamamori, Taro Yoshida, Manabu Wakamatsu, Shunsuke Miwata, Koutaro Narita, Hironobu Kitazawa, Rieko Taniguchi, Motoharu Hamada, Daisuke Ichikawa, Eri Nishikawa, Nozomu Kawashima, Yusuke Okuno, Nobuhiro Nishio, Seiji Kojima, Yoshiyuki Takahashi

Nagoya University, Nagoya, Japan

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for children with severe aplastic anemia (AA). With the improvement in HLA typing resolution and advancement of supportive care for graft-versus-host disease (GVHD), various donor options are available for patients without HLA-matched sibling donors, such as unrelated donors, HLA-mismatched family (haploidentical) donors, and cord blood (CB). This retrospective study aimed to evaluate the HSCT outcomes from these donors.

Methods: Treatment outcomes of 65 children with AA (aged < 20 years) who underwent HSCT between 1991 and 2018 in our institute were analyzed. Unrelated donors were matched to patients at the allele level of HLA-A, HLA-B, HLA-C, and DRB1. Patients were divided into three groups: serologically matched or one-locus mismatched related donors (MRD/1MMRD, n = 37), 8/8-matched unrelated donors (MUD, n = 9), and alternative donors (AD, n = 19). AD was further divided into 7/8-matched unrelated donors (7/8MMUD, n = 9), serologically 2-3 mismatched related donors (Haplo, n = 6), and CB (n = 4). Treatment failure was defined as death from all causes, graft failure, and second malignancy.

Results: The median age at HSCT was 11.2 (range, 1.3-18.8) years. The median follow-up period was 69 (range, 1-196) months. Differences were found in the median follow-up according to the donor source, which was longer in MRD/1MMRD and AD, 93 and 45 months, respectively, and shorter in MUD, 18 months (P < 0.001). The median time from diagnosis to HSCT was 9 (range, 0-135), 11 (2-78), and 11 (0-69) months for MRD/1MMRD, MUD, and AD groups, respectively (P = 0.627). Neutrophil engraftment was achieved after HSCT in all patients. The median day of neutrophil recovery was day+18 (range, +11 to +36). Two patients experienced second graft failure, and all of them were in the AD group (Haplo, n = 1; 7/8MMUD, n = 1). Cumulative incidences of grade II-IV acute GVHD were 5% (95% confidence interval [CI], 0%-12%), 0%, and 21% (95% CI, 0%-37%) for MRD/1MMRD, MUD, and AD, respectively (P = 0.092). The 3-year cumulative incidences of chronic GVHD were 8% (95% CI, 0%-17%), 30% (95% CI, 0%-58%), and 16% (95% CI, 0%-32%) for MRD/1MMRD, MUD, and AD, respectively (P = 0.241). The 5-year overall survival was not significantly different among the three groups (MRD/1MMRD, 97% [95% CI, 82%-100%]; MUD, 88% [95% CI, 39%-98%]; AD, 100%; P = 0.266). The cause of death was infections without graft failure in two patients (MRD/1MMRD, n = 1; MUD, n = 1). Failure-free survival (FFS) was tended to be lower in the AD group (MRD/1MMRD, 97% [95% CI, 82%-100%]; MUD, 88% [95% CI, 39%-98%]; AD, 79% [95% CI, 53%-92%]; P = 0.082).

Conclusions: The overall survival rate of HSCT from both MUD and AD in children with AA is comparable to those from MRD/1MMRD. However, the algorithm for donor selection should be considered according to FFS. Further study with a larger number of patients is needed to determine the preferable AD.

Disclosure: The authors declare. no conflict of interest.

P047 Outcome of Pediatric Acquired Aplastic Anemia: Single Center Experience

Elaf Al nasser, Ibraheem Abosoudah, Naif Aljohani, Hassan Altrabolsi, Ali Alharbi, Mohamed Bayoumy

King Faisal Specialist Hospital & Research Center, Jeddah, Saudi Arabia

Background: Severe Aplastic Anemia (SAA) is a rare hematological disease characterized by pancytopenia and a hypo cellular bone marrow in the absence of abnormal infiltrates. Allogeneic hematopoietic stem cell transplantation (HSCT) is the current available curative treatment, however for patients who lack matched sibling donor (MSDs), immunosuppressive therapy (IST) is widely accepted as an alternative first-line treatment. Outcome data of children with acquired aplastic anemia (AA) are lacking from our region.

Methods: Laboratory and clinical information of all children < 18 years of age with acquired SAA diagnosed between January 2005 and December 2015 at KFSH&RC were retrospectively collected. Relevant details about treatment given i.e. IST and HSCT, treatment outcome, overall survival (OS) and event free survival (EFS) were also recoded. An events were defined as death, treatment failure, or rejection.

Results: Thirty children were included in the study. Fifteen (50.0%) patients were female and 18 (60.0%) patients underwent matched family donor (MFD) HSCT while the remaining patients received upfront IST. Three-year OS and EFS for children undergoing upfront MFD HSCT was 100%. Out of twelve children treated with IST, three were evaluable for response. Two children died before receiving a rescue transplant. Seven of the patients failed upfront IST and received rescue transplants, of these two children died with infection and rejection. The OS of the patients who received rescue after failed IST was 70% and there EFS was 71%. The overall response to IST was seen in three out of twelve (25%) patients with two patients achieving complete response while one patient had a partial response. The 3-year estimated OS and EFS for children treated with IST was 66.6% and 15% respectively.

Conclusions: We observed an inferior outcome in patients who received immunotherapy in our study comparison to published international literature. This could be explained by higher prevalence of consanguineous marriages in the Saudi population and their genetic background. Alternative transplant modalities should be considered for those who lack matched family donor.

Disclosure: no conflict of interest

P048 Impact of CD34⁺-Stem Cell Boost on Outcome and Hematological Reconstitution in Patients with Severe Aplastic Anemia after Allogeneic Stem Cell Transplantation - A Retrospective Study

Rashit Bogdanov, Mareike Gocht, Amin Turki, Markus Ditschkowski, Dietrich W. Beelen

University Hospital Essen, Essen, Germany

Background: Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is still the standard treatment for acquired severe aplastic anemia (SAA) in patients younger than 40 years with sibling donors. Sufficient and durable reconstitution of haematopoietic donor stem cells is important for successful allo-HSCT. Poor graft function (PGF) after allo-HSCT is characterized by persistent pancytopenia, immunodeficiency and dependence on blood transfusions, despite of a complete donor chimerism. The probability of developing PGF seems to be increased in the absence of a regulatory bone marrow stromal microenvironment, even in cases where bone marrow is used as a source of stem cells.

Aim: To evaluate in a single-center retrospective analysis the long-term transplant outcome considering haematological recovery and overall survival (OS) in patients (pts) with SAA after allo-HSCT requiring CD34⁺-selected stem cell boosts.

Methods: The analysis comprises data of 35 pts with aplastic anemia after allo-HSCT from HLA-matched sibling (n=14) or unrelated (n= 21) donors, who underwent allo-HSCT between 2006 and 2018. The median age of the 26 male and 9 female pts was 28 years (range, 17 to 66). A myeloablative conditioning regimen was used in 6 pts, while 29 pts were treated with a reduced intensity immunosuppressive conditioning regimen. Bone marrow (n=20) or peripheral blood stem cells (n=15) with a median of 3.89 x 10⁶ CD34⁺ cells/kg bodyweight (BW) (range, 1.4 to 14.6) were transplanted. PGF was diagnosed in 16 pts with a median of 46 days (range, 40 to 106) after allo-HSCT by bone marrow biopsy. The stem cell boost was performed using immunomagnetically selected CD34⁺ stem cells from original donors. The boost stem cell dose was 6.1 x 10⁶ CD34⁺ cells/kg BW (range, 0.95 to 13.25). Statistical analysis was performed on with SAS 9.4 using the method of Fine and Gray for competing risk cumulative incidences and Kaplan Meier estimates for overall survival.

Results: The rate of complete hematological engraftment was 94% (33 of 35 pts), including 16 pts with CD34⁺-selected stem cell boosts infusion for poor graft function performed. The median time to recovery was 34 days (range, 16-100) for neutrophils and 62 days (range, 11-175) for platelets. The current 10-year survival rate is 80%. (without boost - 89.5%, with boost - 68,7%, p=0.03). No relapse of SAA developed. Seven (20%) pts died as a result of infectious complications (n=6), hemolytic uremic syndrome (n=1).

Hematological reconstitution in patients with or without CD34+ stem cell boosts - is presented in table 1.

Conclusions: The use of CD34+-selected peripheral blood stem cell boosts from the original donor allows a complete, albeit delayed regeneration of haematopoiesis in the majority of aplastic anemia patients with PGF after allo-HSCT. The leading causes of deaths were severe infectious complications due to prolonged cytopenia after allo-HSCT in this patient subset.

[Table 1. Hematological reconstitution after allo-HSCT in patients with SAA]

Disclosure: Bogdanov: Neovii Biotech, Jazz Pharmaceuticals, MSD.: Other: Travel subsidies. Beelen: Medac GmbH Wedel Germany: Consultancy, Honoraria. Turki: Jazz Pharmaceuticals, CSL Behring, MSD.: Consultancy; Neovii Biotech, all outside the submitted work: Other: Travel subsidies.

P049 Hematopoietic Stem Cell Transplant in Adults with Acquired Severe Aplastic Anemia

Gilbert Wilfred, Sen Mui Tan, Tee-Chuan Ong, SH. Shahnaz Syed Abd Kadir, Kim Wah Ho, Boon Liaw Kian, Jameela Sathar

Ampang Hospital, Ampang, Malaysia

Background: Hematopoietic stem cell transplant (HSCT) provides curative therapy in almost 90% of patients with severe aplastic anemia (SAA). Older age, long duration of disease with consequent heavy exposures to transfusion and active infection at the time of HSCT have a negative influence on outcome, favouring graft failure (GF) and graft versus host disease (GVHD). This study aimed to evaluate outcome of all SAA patient who received hematopoietic stem cell transplantation at a tertiary centre in Malaysia.

Methods: Data was obtained from transplant database and patients’ medical record at Ampang Hospital, Malaysia. Patients with acquired SAA who underwent HSCT between January 1999 until November 2019 were included. Demographics, clinical characteristics and treatment outcomes were collected and analyzed using descriptive statistics.

Results: A total of 84 cases were identified for this study with mean age of 23.7 ± 10.0 years. Fifty-eight percent of the cases were male (n=49). Malay ethnicity were the highest (51.8%) followed by Chinese (24.1%) and Native Sabah (14.4%). Majority were transplanted within 6 months of diagnosis (n=58, 69%) and out of this number, 20% received transplantation within six weeks. Forty-five cases (53.6%) used peripheral blood as stem cell source, 36 cases (42.%) used bone marrow and three cases (3.5%) used both. Most of the patients (60.7%) received non-Fludarabine based, Cy (cyclophosphamide)-ATG (anti thymocyte globulin) as their conditioning regime. Mean engraftment for neutrophil was 14.9 (range 6 - 29) days and 15.1 (range 8 - 35) days for platelet. Patients who underwent peripheral blood stem cell transplant had significant early engraftment for neutrophil (p < 0.01) in comparison to bone marrow. However, this finding is not observed with platelet engraftment. Twenty-nine cases (34.5%) died within 100 days of transplant from treatment-related complications (n=23), disease progression (n=4) and others (n=2). Four of the transplanted patients required second allogeneic transplant due to secondary graft failure, however only one survived.

Conclusions: This study shows that only small percentage of cases were transplanted less than six weeks from diagnosis. Early transplant strategy is necessary to improve outcome among patients with SAA. Further study is required to look into the factors leading to delay in diagnosis and treatment among them.

Disclosure: Nothing to declare.

P050 Hematopoetic Stem Cell Transplant in Fanconi Anemia using Matched Related and Haploidentical Donors- A Single Centre Experience

Ajeitha Loganathan, Pooja Mallya, Prathip Kumar, Shobha Badiger, K S Nataraj, Sharat Damodar, P K Vasundhara, Arun Danewa, Mohammed Salmaan, Mohana Reddy, Sunil Bhat

Mazumdar Shaw Medical Center, Narayana Health City, Bengaluru, India

Background: Hematopoetic stem cell transplant (HSCT) is the only curative option for progressive marrow failure in Fanconi Anemia (FA). There is paucity of data on HSCT for FA from India, especially using haploidentical donors. We report our experience of allogeneic transplants for FA.

Methods: We retrospectively analyzed the records of 13 children who underwent 15 HSCTs from 2014 to 2019.

Results: A total of 13 children underwent 15 HSCTs. The median age was 92 months (27-235). The donors were: Haploidentical donor (n=6), HLA matched siblings (n=5) and HLA matched related donor (n=2). Graft source: Bone Marrow (n=7); PBSC (Peripheral blood stem cells) (n=-8). Among haploidentical transplants, the graft source was T-cell depleted (TCD) PBSC in five and T-Cell replete (TCR) in one. The depletion method was TCR alpha/beta with CD19 + cell depletion using CliniMacs system. Conditioning regimen: Fludarabine/Cyclophosphamide (total dose of 40 mg/kg) and ATG in 14 (along with TBI in one), Treosulphan-Flu-Cy-ATG in one and Fludarabine-Busulfan-ATG in one. GvHD prophylaxis: Cyclosporine & Mycophenolate Mofetil in MSD/MRD HSCTs, Sirolimus in Haploidentical HSCTs with TCD grafts and Post-transplant cyclophosphamide (25mg per kg for 2 days), CSA and MMF in Haploidentical HSCT with TCR graft. The median infused CD34+ cell count was 7.8 × 10⁶/kg (range 3.42-21.5× 10⁶/kg). Of the 13 patients who underwent transplant, 10 engrafted with a median neutrophil and platelet engraftment at day 11 and 12 respectively. Three did not engraft (2-Haplo with TCD PBSC, 1-MRD with Marrow) -of which two engrafted after second transplant, one child had donor specific antibodies and expired secondary to infection. All the four who had acute GvHD received TCR stem cells (3-marrow, 1-TCR PBSC from haploidentical donor). Four patients had chronic GvHD (all were matched sibling/related, 3-Marrow, 1-PBSC) of whom one expired from severe bronchiolitis obliterans and the rest are alive with moderate skin GvHD. Interestingly, none of the patients who received TCD PBSC developed either acute/chronic GvHD. All alive patients developed full donor chimerism and are disease free. One achieved full donor chimerism after donor lymphocyte infusions for mixed chimerism. Day 100 survival rate was 76.9%. (10/13). OS: For entire cohort - 69.2 %, for haploidentical HSCT cohort -66.7% (4/6) at a median follow up of 211 days.

Mean follow up (days)	211 (30-570)
Neutrophil engraftment (in days)	11 (9-13)
Platelet engraftment (in days)	12 (8-18)
Acute GvHD Grade III-IV	4/13 (30.7%) 3/13
Chronic GvHD	4/10 (3-alive, 1-expired)
Primary graft failure	3/15 transplants, 2 underwent retransplant and alive, 1 expired
Expired	4
Cause of death	Rejection/Infection-2, GVHD-2
Chimerism	11/11 full donor chimerism, One achieved after four DLI
OS	69.2%

[Allogenic transplant outcomes in Fanconi Anemia (N=13, Number of transplants=15)]

Conclusions: HSCT for FA has good outcomes with reduced intensity conditioning regimens. Haploidentical donors are alternatives in the absence of matched donors with reasonably good outcomes and minimal GVHD rates using TCD stem cell source.

Disclosure: Nothing to declare.

P051 Hematopoietic Stem Cell Transplantation for Pediatric Severe Aplastic Anemia: Results of a Single Center

Gulen Tuysuz Kintrup, Hilal Akbas, Funda Tayfun Kupesiz, Ayse Nur Akinel, Cigdem Sivrice, Serife Kaya, Elif Guler, Alphan Kupesiz

Akdeniz University, Antalya, Turkey

Background: Aplastic anemia (AA) is a life-threatening form of bone marrow failure characterized by pancytopenia and hypo cellular marrow. The pathogenesis of the disease is thought to involve autoimmune process and it is associated with very high mortality if left untreated. Allogenic hematopoietic stem cell transplantation from a HLA-MRD is the preferred treatment in children and young adults. But when MRD is not available immunosuppressive therapy with CsA and ATGAM or transplantation from an alternative donor are the therapeutic options.

Methods: We retrospectively analyzed the data of AA patients who underwent HSCT at Pediatric Stem Cell Transplantation Unit of Akdeniz University Hospital from January 2000 to December 2017.

Results: A total of 31 HSCT was conducted over 28 patients during this period. There were 19 boys and 9 girls with a median age of 10 years (range: 3.4-19.8) at transplantation. Eighteen patients have previously received immunosuppressive agents but were unresponsive to the treatment. Ten patients were receiving regular blood products before transplantation. The source of HSCT was PBSC in 16 and BM in the rest 15 transplantations. Patients received HSCT as graft from a matched unrelated donor (n:15), from a matched sibling donor (n:10), from a matched family donor (n:5), and from a haploidentical donor (n:1). All patients received FLU or CY based reduced intensity conditioning regimens and GVHD prophylaxis comprised a calcineurin inhibitor plus methotraxate in 90% of patients. The median infused CD34+ cell dose was 4.9 ×10⁶/kg (range:1.2-18.2×10⁶/kg). Within a median follow up of 55 months (range: 2-206) after transplantation, 5-year overall survival was 78% in the total group and there was no statistical significant difference between the MRD and MUD groups (92% vs. 53% p=0.13). Grade III-IV aGVHD occurred after 3 of the transplantations (10%). Six patients died at a median of 9 months (range: 2-88) after transplantation.

Conclusions: Our results show that HSCT for AA patients has promising results and transplantation from unrelated donors are approaching those of MRD transplants. Application of immunosuppressive drugs, treatment rabbit ATG instead of ATGAM in previous years, and delay of transplantation waiting for appropriate donor might be the reasons for poor survival in MRD group.

Disclosure: Nothing to declare.

P052 Immunosupressive Therapy in Peadiatric Aplastic Anemia, Single Centre Experience

Wafaa Ezzat Ibrahim mohamed Abou Sayed Ahmed, Safa Matboly

Ain Shams University, Cairo, Egypt

Background: Aplastic anemia (AA) is life threatening disorder in pediatric age group with increasing incidence nowadays, with hematopoietic stem cell transplant being the 1st line therapy; immunosuppressive therapy (IST) is the alternative therapy and is the most commonly used modality of treatment especially. in the developing countries

Methods: We aimed to assess the outcome of IST in children with AA. Data for 25 children treated with IST from January 2014 to January 2019 (5 years) were retrieved from clinic records. IST included rabbit anti thymocyte globulin (ATG) along with cyclosporine A and another group were treated by sand immune alone

Results: Patient characteristics include median age (9) with 73 %male and 26.1 %female. with median interval between diagnosis and start of IST(0.5 -1) and around 30.4 % with hepatitis A associated aplastic anemia. Complete response, partial response and nonresponse was seen in 4 (37.5) (0%) and 1(12.5%) patients, respectively in patients received ATG and sandimune. while in patients received sandimune alone complete response and no response was seen in 7(46.7Z%) and 8 (53.3%) respectively. The median time to best response in the whole cohort was 12 months. There was no difference in outcome related to severity of AA, or higher ALC. There was a significantly better rate of response (p value: .03) in both groups of patients with higher Hb level, HCT, and PLT level before start of IST. An overall response rate in both groups around of 39.5% reported a 5-year OS of 50% with 16% of patients with complete response with HAAA. A delayed time to complete response with prolonged requirement of cyclosporine therapy was detected

Conclusions: In a developing country setting, IST with ATG and cyclosporine seems to be an alternative treatment for aplastic anemia in children lacking MRD.

Clinical Trial Registry: not applicable

Disclosure: Nothing to declare.

P053 Cyclosporine, Danazol and Romiplostim in Severe Aplastic Anemia in Prettansplant Period: Retrospective Analysis of Five Cases

Nilesh Wasekar, Girish Badarkhe, Sudarshan Pandit, Raj Nagarkar

HCG Manavata Hospital Nashik, Nashik, India

Background: Treatment of Aplastic anemia mainly consist of ATG+CSA or Hematopoietic stem cell transplantation. Due to financial constraints majority of patients cannot opt for these available treatment options. The patients who arrange the cost of HSCT, needs supportive care until the definitive treatment (transplant or ATG) is done. The cost of SDP and PCV and antibiotics for infection is a major hurdle to arrange the funds for BMT. To reduce that, we have used combination of CSA, Danazol and Romiplastim as a bridge to BMT in our five patients of Aplastic anemia.

Methods: A retrospective study in a cohort of patients with AA. The study was conducted from January 2018 to December 2019. Romiplostim (5ug/kg) SC once a week was used for 4-8 weeks. Cyclosporine 5mg/kg per day was used to keep level between 150-200. Danazol was used 100 mg TDS, dose was increased upto 600 mg/day after monitoring liver function test.

Results: Five patients with a mean age of 47 (18-83) years were included in the study. Four patients achieved some form of remission (partial/complete), one patient died, one patient is in complete remission, and one underwent HSCT successfully. Two patients are in partial remission waiting for the HSCT.

Conclusions: Improved response rates with triple therapy was observed in patients with severe AA. The triple therapy can be used as a bridge for definitive treatment in Aplastic Anemia.

Disclosure: None

Autoimmune diseases

P054 The long-term Safety and Efficacy of Autologous Haematopoietic Stem Cell Transplantation for relapsing-remitting Multiple Sclerosis Indirectly Compared to Alemtuzumab: A Systematic Review

Owain Greaves ¹, Amit Patel^1,2

¹University of Liverpool, Liverpool, United Kingdom, ²The Christie NHS Foundation Trust, Manchester, United Kingdom

Background: Multiple Sclerosis (MS) is a chronic, progressive, central neurological disease mediated by autoimmunity. Despite availability of anti-inflammatory drugs such as alemtuzumab, disease progression still occurs with minimal initial reversal of symptoms. Autologous haematopoietic stem cell transplantations (aHSCT) for treatment of MS has seen more dramatic reversal in symptoms but have not been previously directly compared to alemtuzumab.

Methods: Systemic review of cohort studies and randomised control trials (RCTs) of Relapsing Remitting MS (RRMS) patients treated with alemtuzumab or aHSCT.

Results: aHSCT.

A total of 144 studies met the search criteria. After application of eligibility criteria and removal of duplicate data, six studies including 277 patients with RRMS, who failed initial DMTs, were included in the review. All patients were initially alemtuzumab naïve. Mean baseline EDSS was 1.5-6.3. Three studies used myelo- and lympho-ablative BEAM-ATG conditioning; the others used lympho-ablative cyclophosphamide (50mg/kg/day for 3-5 days) with ATG (or alemtuzumab in a minority of patients). Both rabbit and horse ATG were used with dosing between 2.5-10mg/kg/day for 2 days or 0.5-1.5mg/kg/day for 5 days.

The available data showed a mean EDSS reduction from a baseline of 3.89 (3sf) to 2.96 at five-year follow-up.

Studies with lower pre-aHSCT EDSS experienced the greatest reduction in EDSS. Event-free survival (EFS) to five years was variable between studies ranging from 0% if high pre-aHSCT EDSS, to 85% if low EDSS pre-aHSCT. Studies with the lowest initial EDSS experienced higher progression-free survival (PFS) to five years, around 90%.

All-cause mortality across the studies was 2.6%; treatment related mortality (TRM) was 0.7%.

The percentage of patients retained in the studies after five years stood at only 28.9% compared to the alemtuzumab arm where retention stood at 83.0% (p< 0.001). Comparison of EDSS at five-year follow-up between the two study arms may therefore be misleading due to survivorship bias in the aHSCT arm.

Alemtuzumab.

A total of 39 studies met the search criteria. After application of eligibility criteria and removal of duplicate data, three studies included 759 patients treated with alemtuzumab: CAM MS223, CARE-MSII, and CARE-MSI, were used in the study. Both CAM MS223 and CARE-MSI included treatment naïve patients; CARE-MSII (357 patients) included previously DMT exposed patients.

Mean EDSS pre-alemtuzumab was 1.9-2.7; only 6 patients had an EDSS >5.0. Peak post-alemtuzumab EDSS reduction occurred at 2 years with the CAM MS223 study; the best mean EDSS reduction was 0.3. The improvements at two years were negated by five years.

Mean EDSS across the studies progressed from a baseline of 2.31 (3sf) to 2.34 at five-year follow-up representing a mean increase of 0.03.

All-cause mortality across studies was 0.5%; TRM was 0.1%.

Conclusions: While it is imperfect to indirectly compare treatments from different studies, EDSS outcome patterns between aHSCT and alemtuzumab differed remarkably. aHSCT, in contrast to alemtuzumab, was associated with the largest magnitude of fall in EDSS that was sustained in the long-term to five years. A direct comparison of aHSCT with alemtuzumab in a RCT seems warranted to confirm these observations of long-term benefit with aHSCT.

[Mean change in EDSS post-HSCT or alemtuzumab]

Disclosure: Nothing to declare.

P055 Reconstitution of Natural or vaccination-driven Immunity after aHSCT in Multiple Sclerosis

Chiara Innocenti, Elio Ingenito, Maria Pia Amato, Alessandro Barilaro, Gaetano Bianchini, Teresa Capobianco, Maria Antonia Calia, Romina Ceschini, Arianna Fani, Marta Giannini, Antonella Gozzini, Stefano Guidi, Alice Mariottini, Luca Massacesi, Francesca Materozzi, Chiara Nozzoli, Anna Maria Repice, Gian Maria Rossolini, Serena Urbani, Riccardo Saccardi

Careggi University Hospital, Florence, Italy

Background: In the last 20 years, high dose chemotherapy with autologous hematopoietic stem cell transplantation (aHSCT) has emerged as an effective and safe treatment for aggressive forms of multiple sclerosis (MS). Nevertheless, no data have been published about reconstitution of either natural or vaccination-driven immunity after aHSCT and the consequent indication to re-vaccinate patients. We report an updated analysis of antigen-specific immune recovery in a series of MS patients after aHSCT, having increased the subset of patients included in the study.

Methods: Blood samples from 32 MS patients who underwent aHSCT in our Center between 2006 and 2017 were analyzed. Each patient underwent mobilization with cyclophosphamide (CTX) 4gr/sqm + GCS- F and was conditioned with BEAM/ATG regimen. Antibody titres for varicella-zoster, measles, rubella, and hepatitis B viruses were analysed before mobilization (baseline) and at 6 months, 1 year and then yearly after aHSCT. Chemiluminescent Microparticle Immunoassays (CMIA) were performed to determine Rubella and hepatitis B surface antigen antibodies (anti-HBsAg). Chemiluminescent Immunoassays (CLIA) were performed to assess Varicella Zoster and Measles. All patients received prophylaxis with acyclovir and Thrimethoprim-Sulphametoxazole for six months after aHSCT. Patients did not receive any re-vaccinations in the follow-up period.

Results: All patients showed a complete and sustained engraftment: median (range) time to PMN≥0.5x10⁹/L and platelets≥20x10⁹/L were 12(9-15) and 11(7-14) days, respectively. Patients showed also a complete return to a normal lymphocyte subset counts within two years from transplant. No case of measles, rubella, or chickenpox occurred after transplant, with a median follow-up of 40 (17-124) months. Table 1 reports the number of patients with positive or negative antibodies titres at baseline, 6 months and 2 years after aHSCT, respectively. A loss of serum protective immunity was observed in a variable rate of patients with all the tested agents: 14% in measles, 16% in rubella, 20% in hepatitis B, and 7% in Varicella Zoster.

Conclusions: Re-vaccination in patients who underwent an autologous HSCT for a severe autoimmune disease is a common practice in many centers and is also recommended in the EBMT guidelines. However, some concerns about this practice were raised for the putative role of vaccinations as an autoimmunity trigger. In the literature there is no study on the loss of protective antibody titer in either natural or vaccination-driven immunity with regards to patients transplanted for autoimmune diseases. In our series a high variability in antibodies titers at baseline was shown. The larger subset analysed confirms that most patients showing a protective titre against the tested agents, show a trend to maintaining it. A possible approach might be to revaccinate the patients with unprotective titre at 2 years after HSCT, taking into account the individual risk of being exposed to the infection; a larger series of data is necessary to provide conclusive evidences on this topic.

Disclosure: No disclosures

P056 High-dose Immunodepletion with Autologous Stem Cell Rescue for Treatment of Aggressive Multiple Sclerosis

Antonia Mueller, Ilijas Jelcic, Panos Stathopoulos, Nathan Wolfensberger, Katharina Ritter, Urs Schanz, Roland Martin

University Hospital Zurich, Zurich, Switzerland

Background: Multiple sclerosis (MS) is the most common chronic inflammatory demyelinating disease of the CNS and the leading cause of non-traumatic neurological disability of young adults. Inflammatory forms of MS respond to immunomodulation with disease modifying treatments (DMTs), but some subgroups of patients continue to have clinical and/or MRI disease activity despite DMTs. There is increasing evidence, including randomized controlled trials, that demonstrates robust clinical efficacy of high-dose chemotherapy (HDCTx) with autologous stem cell rescue (ASCT) in patients with highly active MS.

Methods: In 07/2018 the Swiss Federal Office of Public Health approved the treatment of MS patients with HDCTx+ASCT at our single center (University Hospital Zurich). To be eligible for reimbursement (i) patients must have inflammatory breakthrough activity of MS despite highly effective DMT; (ii) the indication needs to be confirmed by our interdisciplinary hemato-neuroimmunological board; (iii) patients are required to participate in a registry study for 5 years post-ASCT. Patients are mobilized with 2 days of cyclophosphamide 2g/m² and Filgrastim. HDCTx comprises BEAM (BCNU, etoposide, cytarabine, melphalan) and ATG 3.75 mg/kg on d+1 and +2 post stem cell infusion.

Results: So far 20 patients (10 females, 10 males) with a mean age of 40.6 years (+7.5y) and disease duration of 8.4 years (+4.4y) were enrolled into the registry. On the “Expanded Disability Status Scale” (EDSS) patients had a mean score of 5.0 (+1.2). 6/20 (30%) patients had relapsing remitting MS (RRMS), 7/20 (35%) had secondary progressive (SPMS) and primary progressive (PPMS) disease, respectively. The indication for HDCTx+ASCT was clinical progression in 14/20 patients (70%), clinical disease activity in the form of relapses in 5 (25%), and/or radiological activity (new or contrast-enhancing lesions) in 7 patients (35%). Last treatments prior to ASCT were fingolimod (15%), rituximab (40%), ocrelizumab (30%), or natalizumab (15%).

Overall, treatment was tolerated well, although the majority of patients developed adverse events (AE). Most common AEs were oral mucositis/pharyngitis and/or enteritis in 18/20 patients. Upper airway and urinary tract infections were each observed in 4 patients, respectively. CMV reactivations occurred in 4/20 patients and were severe in 2 (including CMV enteritis and hospitalization for intravenous antiviral therapy). HSV reactivations (n=2) and BK cystitis (n=2) were also observed. A total of 9 serious AEs were recorded (CMV n=2; hemorrhagic cystitis, gastroenteritis with ileus, laryngitis, cervical abscess (post mobilization, prior to ASCT), pulmonary embolus (several months post ASCT), gastrointestinal bleeding, manic episode). Six patients experienced transient neurological deterioration. Other AEs were hypotension (n=3), cholecystolithiasis (n=1), and epistaxis (n=1). With the limitation of short follow-up, a substantial proportion of patients reported improvements of neurological functions and less fatigue, however, longer observation periods are needed to evaluate the potential benefits of this intensive treatment.

Conclusions: Here, we report on the establishment of a national registry program for MS patients undergoing ASCT. The fast recruitment indicates an unmet need for a subgroup of young patients with aggressive, conventional DMT-refractory MS. The safety profile is acceptable from a transplanter’s perspective - however, bacterial and viral infections are common and require particular attention and prophylactic care.

Clinical Trial Registry: BASEC-number: 2018-01854 (Data and Biomaterial Collection for the Evaluation of Autologous Hematopoietic Stem Cell Transplantation in Relapsing Remitting and Progressive Multiple Sclerosis Patients (Registry))

Disclosure: Nothing to declare.

P057 Hematopoietic Stem Cell Transplantation does not Change the Expression of Endothelial Markers in Skin Biopsies of Systemic Sclerosis Patients

Maynara Santana, Djulio Zanin, Deisy Silva, Marianna Vasconcelos, Daniela Moraes, Juliana Dias, Vanessa Leopoldo, Marília Oliveria, Álvaro Henrique-Neto, Kelen Farias, Leandra Ramalho, Maria Carolina Oliveira

University of São Paulo, Ribeirão Preto, Brazil

Background: Systemic sclerosis (SSc) is an autoimmune disease characterized by vascular damage, deregulation of the immune system and fibrosis of the skin and internal organs. The injury and apoptosis of microvascular endothelial cells are indicated as initial events of the disease, leading to physiological changes in the endothelium and vasculopathy. Autologous Hematopoietic Stem Cell Transplantation (AHSCT) promotes resetting of the immune system and has emerged as a treatment option for patients with severe and progressive SSc. Although AHSCT leads to clinical improvement, the mechanistic effects are still not completely understood. In this study, we aimed to investigate if AHSCT modifies the expression of endothelial markers in skin biopsies.

Methods: Samples of skin from the forearms of 27 SSc patients were evaluated by immunohistochemistry (IHC) before and at 6 and 12 months after AHSCT. Biopsies were marked with anti-CD31, -VEGF, -VEGFR2, -ANGIOPOIETIN 1, -ANGIOPOIETIN 2, -TIE, -ENDOTHELIN-1, -CD105 and -VE-CADHERIN antibodies and stained with Hematoxylin and Eosin (HE) and Picrosirius Red. The images were analyzed by ImageJ software

Results: Most participants were female (78%) with a mean (standard deviation, SD) age of 36 (9.4) years. The mean (SD) time between diagnosis of disease and transplantation was 3.2 (3.1) years. Clinical evaluation of fibrosis assessed by Rodnan´s score improved at 6 and 12 months compared to baseline (p< 0.0001). Histological analysis of fibrosis evaluated by HE and picrosirius red showed reduction of skin thickness (p< 0.0001) and collagen density (p=0.0193) after AHSCT.

The only endothelial marker that decreased after AHSCT was ANG1 (p=0.0001). All the other evaluated markers did not change (p>0.05) after AHSCT, when compared to baseline. Except for ANG1, our results indicate that ASHCT does not modify the expression of endothelial markers, anti-CD31, -VEGF, -VEGFR2, -ANGIOPOIETIN 1, -ANGIOPOIETIN 2, -TIE, -ENDOTHELIN-1, -CD105 and -VE-CADHERIN.

Conclusions: Our study shows that AHSCT therapy is able to improve fibrosis by reducing skin thickness and collagen fiber density, as assessed by Rodnan’s score and by histopathological analysis, respectively. However, no changes in markers of endothelial damage were detected, except for ANG1, which is related to vessel stabilization. Our data suggest that AHSCT may affect disease pathogenesis differently, concerning fibrosis and vasculopathy. Our results suggest that AHSCT does not improve SSc-associated endothelial damage, indicating that additional therapies may be warranted to more effectively treat the endothelial injury. The decrease in Rodnan´s score may be more associated with improvement of fibrosis than to a beneficial effect on the microvascular compartment.

Disclosure: Nothing to declare.

P058 Autologous Stem Cell Transplantation for Non Hematological Diseases. The Dutch Experience of MS Patients going Abroad

Ellen P.A. Kramer ¹, Bram Platel², Frederike J.A.E Ambagtsheer³, Gerald G.J.D Hengstman⁴, Otto O Visser⁵

¹Amsterdam UMC, Location VUmc, Amsterdam, Netherlands, ²Not Applicable, Manilla, Philippines, ³Erasmus MC, Rotterdam, Netherlands, ⁴Catharina Ziekenhuis, Eindhoven, Netherlands, ⁵Isala Ziekenhuis, Zwolle, Netherlands

Background: In the Netherlands, an unknown number of patients go abroad to fee for service clinics for stem cell transplantation for non-hematological diseases. In this IRB approved study, we gather information about patients that went abroad and how it affected their health care.

Methods: Patients going abroad for stem cell transplantation on their own initiative for any kind of disease were recruited through (social) media like Facebook communities and newspapers.

Patients were invited to contact the research team. To participants giving informed consent, a questionnaire was sent.

The survey consisted of 3 parts: one set of questions regarding the stem cell transplantation abroad. Additionally, two validated patient-reported outcomes were included: the EORTC30 and NeuroQoL54.

Results: To date out of 51 participating patients, 30 finished the survey. 91,4% underwent a stem cell transplantation for multiple sclerosis (MS), 2,9% for Lyme’s disease and 8,7% for other reasons

For the preliminary results presented here, we report on the first part of the questionnaire for 24 patients that had filled out the survey (before Dec. 2019) and received aHSCT treatment for MS.

A total of 24 people were included in this preliminary analysis (12 [50%] women; mean age, 46 [SD, 9.7]), 7 relapsing-remitting MS (RRMS, 7 secondary progressive MS (SPMS), 10 primary progressive MS (PPMS), (mean disease duration, 8 years [SD, 6.1], [Range 0-23]).

Most people were treated in Russia 10 [42%], Mexico 8 [33%], India 3 [13%]. The other three were treated elsewhere.

All except for one patient chose for their center based on “own research” or “success stories from other patients”. None of the patients were referred by their physician. In three cases, the participants were advised in their decision for a specific clinic by their neurologist.

None of the participants was treated as part of an RCT.

Thirteen participants arranged for follow-up visits with a hematologist, three were advised so by their neurologist. Five arranged these check-ups after their return. Six have not had any follow-up by GP or hematologist.

Sixteen participants did not feel supported by their treating physician in their decision.

The average cost was € 55000 [Range 27000-110000. Sixteen participants [67%] financed through crowdfunding. Others paid with their own means. In none of the cases, the health insurance contributed to financing the treatment. Aftercare was paid for by health insurance in 21 [87%] participants.

Conclusions: The decision to go abroad for HSCT for not supported indications is usually made by the patient, regardless of the advice of the treating physician. Many patients go abroad for SPMS and PPMS, whereas highly active RRMS is the only evidence-based indication. As a result, patients undergo high-risk treatment for non-evidence based indications (like progressive MS). Patients are easily lost to follow up, as they often arrange aftercare on their own. Central registration of people going abroad for this high-risk treatment could contribute to better safety with the ultimate goal to organize reimbursement for selected cases and attention to aftercare.

Clinical Trial Registry: Not applicable

Disclosure: nothing to declare.

P059 Analysis of Cost and Charges for non-myeloablative Hematopoietic Stem Cell Transplantation for Relapsing Remitting Multiple Sclerosis in the United States

Richard Burt, Kathleen Quigley, Indira Arnautovic, Xiaoqiang Han

Northwestern University, Chicago, IL, United States

Background: Multiple sclerosis (MS) afflicts 2.5 million people worldwide (400,000 in the United States), and is a chronic disease, second only to congestive heart failure in cost of health care for a chronic illness. Lifetime direct costs per patients are greater than 4 million dollars and disease modifying therapy (DMT) is approximately 75% of the direct costs. DMT cost $80,000.00 per year (with a few costing more). We reported that after hematopoietic stem cell transplantation (HSCT) for frequently relapsing MS, only 16% relapsed and needed to restart DMT after 5 years. We now evaluated cost/ charges for HSCT on 42 consecutive patients treated with a non-myeloablative cyclophosphamide (200 mg /kg) and rabbit antithymocyte (ATG) (6.0 mg/kg) regimen.

Methods: Peripheral blood stem cells were collected 10 days after intravenous cyclophosphamide (2 g/m2) and 5 to 10 µg/kg per day of subcutaneous filgrastim beginning 5 days after cyclophosphamide. The immune ablative regimen was intravenous cyclophosphamide, 50 mg/kg per day on days −5 to day −2 before stem cell infusion (day 0) and rabbit antithymocyte globulin, 0.5 mg/kg on day −5, 1.0 mg/kg on day −4, and 1.5 mg/kg on days −3, −2, and −1. Methylprednisolone (1000 mg) was infused 30 minutes prior to rabbit antithymocyte globulin infusion.

Charges included all tests including blood draws, MRI imaging, echocardiograms, electrocardiograms, and chest radiograph, and all treatments and interventions including pre-HSCT evaluation, hematopoietic stem cell mobilization and cryopreservation, inpatient transplant admission charges, and all medications, nursing care, and room charges. The only charges not captured were physician history and physical and physician progress notes. Analysis was separated into direct costs (costs directly related to patient care (e.g. medications, laboratory tests, transfusions, nursing care), indirect costs (cost necessary to operate a hospital but not directly related to patient care e.g. managers, supervisors, medical records, accounting, information systems, marketing, legal, malpractice insurance, building maintenance and depreciation, house-keeping), total cost (sum of direct and indirect), net revenue collected, and net income (profit).

Results: Mean direct costs were $42,295 (range $33, 887 to $57,704), mean indirect costs were $42,888 (range $33,653 to $62,555), and mean total costs were $85,184 (range ($70,635 to $120,260). Mean revenue collected was $95,268 (range $16,544 to $173,204) and mean net income (profit) per patient was $10,084.

Conclusions: The mean costs and charges of HSCT using this non-myeloablative regimen are equivalent to DMT charges for one year (approximately $80,000) but comparable DMT charges do not include physician, laboratory, imaging, or hospitalization fees, if any. Since after a one-time treatment with a non-myeloablative HSCT regimen, the majority of patients remain treatment-free beyond 5 years, non-myeloablative HSCT with a cyclophosphamide ATG regimen appears to be cost effective.

Clinical Trial Registry: None

Disclosure: Nothing to declare.

P060 Autologous Stem Cell Transplantation in Behçet´s Disease: A Retrospective Study

Mathieu Puyade ^1,2,3, Amit Patel⁴, Yeong Ler Lim⁵, Norbert Blank⁶, Manuela Badoglio⁷, Francesca Gualandi⁸, David Ma^9,10,11, Natalia Maximova¹², Tobias Alexander¹³, John Snowden¹⁴

¹CHU de Poitiers, Poitiers, France, ²CHU de Poitiers, Poitiers, France, ³MATHEC, Hôpital Saint Louis, Paris, France, ⁴The Christie NHS Foundation Trust, Manchester, United Kingdom, ⁵University of Liverpool, Liverpool, United Kingdom, ⁶Heidelberg Hospital, Heidelberg, Germany, ⁷EBMT ADWP Office, Paris, France, ⁸IRCCS Ospedale Policlinico San Martino, Genova, Italy, ⁹St Vincents Hospital, Sydney, New South Wales, Sydney, Australia, ¹⁰University of New South Wales, Sydney, Australia, ¹¹St Vincent’s Hospital, Darlinghurst, Sydney, Australia, ¹²IRCCS Burlo Garofolo, Trieste, Italy., Trieste, Italy, ¹³Charité - University Medicine Berlin, Berlin, Germany, ¹⁴Sheffield Teaching Hospitals NHS Foundation, Sheffield, United Kingdom

Background: Behcet´s disease (BD) is a rare autoimmune disease mostly presenting with recurrent oral and genital aphthous ulcers, and uveitis. Other common symptoms include gastrointestinal, vascular, neurological and articular manifestations¹. Treatment is based on chronic immunosuppression with conventional disease modifying or targeted biologic drugs², although some refractory patients have been treated by autologous hematopoietic stem cell transplantation (AHSCT)³. This study aims to evaluate the outcome of AHSCT in adult patients with BD.

Methods: Adults who received AHSCT primarily for BD (according to International Classification Criteria) were identified retrospectively within the EBMT registry. Treating physicians were surveyed to produce a retrospective evaluation of outcomes. Complete Remission (CR) was defined as no evidence of disease activity and Partial Remission (PR) was defined as any documented clinical and/or laboratory response in patients that is less than CR.

Results: We retrospectively collected the data from 8 out of 9 cases reported to the EBMT registry and extracted data of 2 further patients from published literature⁴. Four were female, median age at onset of BD was 24 years (range 9-50). Median age at AHSCT was 32 years (27-51). Patients had received median 4 (2-12) prior lines of therapy: 89 % of the patients were treated with corticosteroids, and 50 % received either methotrexate, antiTNFa or cyclophosphamide. All had active disease before mobilization, which was performed with cyclophosphamide and G-CSF in 9 patients and G-CSF alone in 1 patient. Conditioning regimen was Melphalan 200mg/m² in 5 patients, BEAM in 3 patients, and Cyclophosphamide 200mg/kg plus antithymocyte-globulin (ATG) in 2 patients. Median follow-up was 48 months (range 6-120 months). No TRM was reported, three patients had infectious complications and a single patient had paroxysmal atrial fibrillation, line-associated deep venous thrombosis and depression. At 6 months, 6 patients were in PR with corticosteroid maintenance and 3 in CR without any further treatment. There was one relapse with pan-uveitis. One patient failed to respond to AHSCT and proceeded to rescue with allogeneic HSCT, but died five years post-transplant from chronic GvHD and CMV infection. Otherwise, no late complications in patients treated with AHSCT were reported.

Conclusions: AHSCT is feasible and safe in multi-refractory patients with BD. Although treatment-free CR was achieved in only 3 of 10 patients analyzed, AHSCT has the potential to stabilize BD in patients who fail to respond to conventional therapies. Further evidence, ideally from prospective studies, are warranted to determine whether AHSCT should be considered a standard of care in treatment-resistant BD.

Disclosure: No disclosure

P061 Safety and Tolerability of Autologous Hematopoietic Stem Cell Transplant in Multiple Sclerosis: A Single Center Experience

Pawan Kumar Singh, Isha Gambhir, Ragesh Radhakrishnan Nair, Rohan Halder, Zahier Ahmad Shekib, Manish Mahajan, Sumit Singh

Artemis Hospital, Gurugram, India

Background: Multiple Sclerosis (MS) is an autoimmune disease in which there is both B and T cell mediated destruction of the nervous system. Historically it was observed that Autologous Hematopoietic Stem Cell Transplant (HSCT) is safe and effective in achieving long term Disease Modifying Therapy (DMT) free survival. Initially myeloablative conditioning with BEAM-ATG (BICNU, Etoposide, Ara-C, Melphalan - Anti Thymocyte Globulin) was used, but the mortality rates were high, so the non-myeloablative conditioning with Cyclophosphamide-ATG (Cy-ATG) was used, showing almost same outcome and with low mortality rates.

Methods: Seventy one consecutive patients of MS who underwent AHSCT were prospectively enrolled at a single center tertiary hospital.

Results: A total of 71 patients were of MS with median age 48 years (range 25-67 years) and a total of 65 patients underwent AHSCT out of which 36 (51%) males were included. Six patients were rejected due to various reasons. The diagnosis of MS was confirmed by clinical evaluation, MRI, VEP and BERA. Of these, 36(51%) were SPMS, 22 (31%) were RRMS and 13(18%) were PPMS with a median EDSS score of 5 (range 1 - 8.5). the median time from diagnosis to AHSCT was 11 years (range 0 - 37 years). In majority of these patients; 53(81%) stem cell mobilization was done with G-CSF and in remaining either Cyclophosphamide + G-CSF 11(17%) or G-CSF + Plerixafor 2(3%) was used. Regimen related toxicity was seen in 9 patients in the form of anaphylaxis (5), hemorrhagic cystitis (3) and AKI (1). The median CD34 dose was 7.17 (range 2.82 - 13.84). The median time to neutrophil engraftment was 9 days (range 6 - 12 days) and platelet engraftment was 12 days (range 9 - 18 days). The median number of blood components transfused included RBC 2 units (range 0 - 7), RDPs [14 units (range 0 - 38) and SDPs 1 units (range 0 - 8). There was a significant improvement in the EDSS score [mean 5.07 SD 1.77 to mean 4.73 SD 2.09; p value < 0.001] till the discharge. There was only one death. Thirteen (20%) patients had transient worsening of MS related symptoms post-AHSCT which resolved completely before discharge. The most common type of infection was urinary (50%).

Conclusions: HSCT is a safe and effective treatment option in improving disability scores in patients of MS with refractoriness to DMTs. Our study showed that HSCT is well tolerated treatment option in MS with acceptable mortality of 1-2 %. However, long term follow up is needed to look for the response.

Disclosure: Nothing to declare.

P062 Outcome of Autologous Hematopoietic Stem Cell Transplantation for Refractory Takayasu Arteritis, A Retrospective Survey from the Autoimmune Diseases Working Party (ADWP) of the Ebmt

Charlotte Laurent¹, Zora Marjanovic², Laure Ricard², Joerg Henes³, Remy Dulery², Manuela Badoglio², Dominique Farge⁴, John Snowden⁵, Dania Moraes⁶, Juliana Dias⁶, Mohamad Mohty², Michael Soussan⁷, Renate Arnold⁸, Olivier Fain¹, Tobias Alexander⁸, Maria Carolina Oliveira⁶, Arsene Mekinian ²

¹Saint Antoine Hospital, INSERM UMR 938, Sorbonne University, Paris, France, ²Saint Antoine Hospital, Paris, France, ³University Hospital Tuebingen, Tuebingen, Germany, ⁴Hôpital Saint-Louis, Paris, France, ⁵Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom, ⁶University of São Paulo, Ribeirão Preto, Brazil, ⁷AP-HP, Hôpital Avicenne, Paris 13 University Bobigny, France, ⁸Charité - Universtiy Medicine Berlin, Berlin, Germany,

Background: Takayasu arteritis (TAK) is a chronic granulomatous large-vessel vasculitis, commonly affecting young women, characterized by arterial thickening and fibrosis leading to stenosis and vascular occlusions. More than 10% of patients are refractory to conventional immunosuppressive disease-modifying drug (DMARD) therapy and are at high risk for vascular complications. Autologous hematopoietic stem cell transplantation (AHSCT) has emerged as a promising treatment option in severely affected and refractory patients with various autoimmune diseases. Several case-reports and small case series demonstrated the potential efficacy and safety of AHSCT for systemic vasculitis, particularly ANCA-positive vasculitis and Behçet’s disease. This study, approved by the ADWP, aims to evaluate the use and outcome of AHSCT in adult TAK patients.

Methods: This is a retrospective survey of patients reported to the EBMT data management between 1998 and 2018, who received AHSCT primarily for TAK. A specifically designed questionnaire was sent to each referring transplant centre to obtain all relevant clinical and laboratory data. Remission was defined as no evidence of inflammation or worsening of vessel disease.

Results: Data from six adult patients treated with AHSCT between 2003 and 2018 for refractory Takayasu have been identified. Median (range) follow-up was 9.9 (1-14) years. Five patients were female (83%), median age was 25 (9-39) years at diagnosis and 28 (22-41) years at AHSCT. All patients were pretreated with a median of 6 (4-8) lines of therapy, including systemic corticosteroids (in 6 patients), methotrexate (5 patients), cyclophosphamide, mycophenolate mofetil or infliximab (4 patients), tocilizumab or etanercept (2 patients), and other biologic or conventional-synthetic DMARDs. Mobilization was performed with cyclophosphamide 2g/m² (4 patients) or 4g/m² (2 patients) in combination with granulocyte-colony stimulating factor (G-CSF). The graft was CD34 positive selected in 2 cases. Conditioning included cyclophosphamide 200 mg/kg in 5 patients, and cyclophosphamide 120 mg/kg plus fludarabine 90 mg/m2 in one patient. All patients received rabbit anti-thymocyte globulin. After AHSCT, 4 patients received G-CSF during a median of 5 (5-6) days. A median of 3.9 (2-4.20) x 10˟6 CD34+cells /per kilogram were reinfused. Engraftment, defined as neutrophils ³0.5 x10^9/L and platelet ³20 x10^9/L were detected at a median of 8 (5-13) and 8 (5-11) days, respectively. All patients had active disease before AHSCT. At six months post-transplantation, remission was obtained in all cases, which persisted at 12 months in 5 cases. Four patients reactivated TAK at a median time of 27 (7-52) months after AHSCT, and 3 resumed disease-modifying therapy. During follow-up none of the patients developed secondary malignancy and one patient had a miscarriage. At last follow-up, all patients were alive, 2 patients were in remission (off-therapy), 2 patients improved compared to baseline, and 2 patients were in complete and partial remission, respectively, under immunosuppressive treatment.

Conclusions: This small retrospective series demonstrates that AHSCT has the potential to provide significant clinical responses in TAK patients who had been unresponsive to previous immunosuppressive therapy, with an acceptable safety profile. Therefore, AHSCT may be considered as a ‘clinical option’ for patients with severe, treatment-resistant and poor-prognosis TAK, ideally before the development of compromised vital organ function.

Clinical Trial Registry: na

Disclosure: JAS declare.s speaker fees at educational events supported by Sanofi, Janssen, Jazz, Mallinckrodt and Gilead

P063 The use of Autologous Haemopoetic Stem Cell Transplantation (aHSCT) in Multiple Sclerosis after Alemtuzumab Treatment Failure: A Case Series

Simon Bell ¹, Helen Jessop², Andrew Chantry², Basil Sharrack^1,2, John Snowden²

¹University of Sheffield, Sheffield, United Kingdom, ²Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom

Background: Disease modifying therapies (DMT) for RRMS have been the mainstay of treatment for 20 years. Alemtuzumab is one of the most highly efficacious DMT for RRMS. However some patients continue to experience disease activity despite adequate Alemtuzumab therapy. AHSCT has been used with increasing frequency over the last decade to treat very active RRMS despite the use of DMTs. However efficacy and timing of delivering treatment in patients who failed Alemtuzumab remains unclear. Here we report a case series of patients with RRMS who received AHSCT after failing to respond to Alemtuzumab treatment.

Methods: A case series of all patients who received AHSCT for RRMS after failing to respond to a full course of Alemtuzumab was compiled. Details of 4 cases were collected from a national referral centre in the north of England. Clinical details, MRI changes, efficacy and safety data related to the use of Alemtuzumab and AHSCT were recorded. AHSCT was performed using a standard Cyclophosphamide / ATG mobilization and conditioning regime.

Results: All patients experienced clinical and radiological evidence of disease activity and progression whilst on Alemtuzumab. The mean treatment period with Alemtuzumab was 27 months (SD 23.2 months). Mean treatment courses was 2.5. Mean follow up after AHSCT was 48.5 months (SD 32.7). No patient experienced further relapses or MRI disease activity following AHSCT. EDSS scores improved in all patients following AHSCT (mean 1.12 points, SD 0.62). Patients experienced routine grade 1-3 complications during transplantation period. No autoimmune complications were recorded.

Conclusions: Our data suggests that AHSCT use is effective and safe in patients who failed to respond to Alemtuzumab.

Clinical Trial Registry: No Applicable

Disclosure: John Snowden declare.s speaker fees at educational events supported by Sanofi, Janssen, Jazz, Mallinckrodt and Gilead.

P064 Autologous Hematopoietic Stem Cell Transplantation for Treatment of Systemic Sclerosis, an Option for Refractory Patients

Claudia Sossa ^1,2, Javier Figueroa³, Juan Manuel Herrera⁴, Angela M Peña¹, Luis A Salazar¹, Manuel Rosales¹, Enrique Pedraza³, Elena Mora³, Xueyi Chen², Maria Luna-Gonzalez², Jose Patricio Lopez-Lopez¹

¹FOSCAL, Bucaramanga, Colombia, ²Universidad Autónoma de Bucaramanga, Bucaramanga, Colombia, ³Clínica de Marly, Bogotá, Colombia, ⁴Centro Médico Imbanaco, Cali, Colombia

Background: Autologous hematopoietic stem cell transplantation (aHSCT) is a promising therapeutic modality for severe autoimmune diseases, especially as a treatment option for systemic sclerosis (SS). The aim of this study was to describe clinical experience in the use of aHSCT for SS in three centers in Colombia.

Methods: We conducted an observational study of adult patients diagnosed with SS and treated with aHSCT at centers from three different cities of Colombia from 2010 to 2019. Patients with SS were autografted in the centers with peripheral blood stem cells. The autografts were performed after conditioning with cyclophosphamide and BEAM chemotherapy. Laboratory results and complications after aHSCT were evaluated. Patients were follow-up to 3 years.

Results: Information from 13 patients were collected from the three centers. Median age was 44 years (27-53). We included 11 females (85%) and 2 males (15%). As a first-line treatment, 11 patients (84,6%) were treated with steroids. Median dose for cyclophosphamide at mobilization was 2,3 mg/m2 (2-3,5 mg/m2). About conditioning treatment, cyclophosphamide was performed in 12 patients (92,3%), while BEAM chemotherapy was performed in 1 patient (7,7%). The total number of viable CD34+ infused cells ranged between 3,1-25,57x10⁶ (average 8,1). Patients recovered ≥0.5x10⁹/L absolute granulocytes by day 14 (8-43 days), and platelet values were also ≥20x10⁹/L by day 14 (6-43 days). Febrile neutropenia presented in 4 patients (30,7%), mucositis in 2 patients (15,3%), Pneumocystis jiroveci Pneumonia in 4 patients (30,7%) and 1 patient presented cytomegalovirus reactivation (7,7%). Only 1 patient (7,7%) presented cardiovascular complications and another patient (7,7%) presented endocrine complications. To date, there have been no deaths attributable to the transplant, yielding a 3 years overall survival of 100% and progression-free survival was 92,3% for all the patients.

Conclusions: AHSCT reduces the risk of all-cause mortality and has properties of a disease-modifying antirheumatic treatment in SS patients, leading to a high overall survival time. AHSCT should be proposed for carefully selected patients with refractory SS, therefore, optimal patient selection, pre-transplantation workup and posttransplant management need to be stablished.

Disclosure: Nothing to declare.

P065 A Pilot Feasibility Study of non-myeloablative Allogeneic Hematopoietic Stem Cell Transplantation for Refractory Crohn Disease

Richard Burt, Kathleen Quigley, Indira Arnautovic, Xiaoqiang Han

Northwestern University, Chicago, IL, United States

Background: Autologous hematopoietic stem cell transplantation (HSCT) induces remission of refractory Crohn disease (CD) but approximately 50% and 80% relapse and restart standard therapies at 3 and 5 years, respectively, post HSCT. We, therefore, undertook a pilot study of allogeneic HSCT using either matched sibling donor or umbilical cord blood (UCB), if a matched donor was not available.

Methods: Eligible patients were 18 to 45 years old, had an established diagnosis of Crohn disease, failed corticosteroids, 5-aminosalicylate, and at least two anti-TNF (infliximab, adalimumab, or certolizumab) drugs with a Crohn disease activity index (CDAI) between 250 to 400 or Craig Severity Score (CSS) > 17. Donor preference was given for unmanipulated healthy adult HLA 6 / 6 matched sibling, followed by unrelated 6/6 matched UCB and then unrelated 5/6 matched UCB. When available two UCB units were infused. The conditioning regimen was dose escalated during the protocol’s duration in an attempt to maximize donor engraftment. Conditioning drugs were: 1) cyclophosphamide 200 mg/kg divided as 50 mg /kg on days -5,-4,-3 and -2, 2) fludarabine (75 to 150 mg / m2) divided as 25- 30 mg /m² /day (between days -7 to -3), and alemtuzumab (60 mg to 90 mg) divided 30 mg day (between days -3 to -1). Cyclosporine (100 mg po bid) or tacrolimus (1.0 mg bid) was initiated on day -2 and continued for 9 months.

Results: Average time of hospital engraftment and hospital discharge was day 13 and 14, respectively, with no difference in mean day of engraftment or discharge between matched sibling versus UCB transplantation. The mean number of red blood cell and platelet transfusions were both 3.4. Neutropenic infections included one case each of diarrhea due to clostridium difficile, and blood cultures positive for Escherichia coli, Enterococcus faecalis, and extended broad spectrum beta-lactamase producing Escherichia coli. Late post discharge events were tacrolimus-induced chronic renal failure mandating renal transplantation in a patient with a history of pre-transplant tacrolimus induced acute renal failure, surgery for colonic stricture without evidence of active Crohn disease that was complicated by bowel perforation and pseudomonas sepsis, and one death 3 months post HSCT from disseminated adenovirus infection. Following the patient’s death enrollment was terminated. There was no acute GVHD and one case of possible limited chronic GVHD.

Despite no evidence of donor engraftment, all patients entered and maintained without treatment a clinical remission (CDAI < 150), MRI imaging remission, endoscopic and histologic remission for the 5 years of study follow-up.

Conclusions: Complete treatment-free 5-year remissions without donor engraftment suggests that the conditioning regimen and nine months of maintenance tacrolimus, not the allogeneic hematopoietic stem cells, were responsible for remission. Alternatively, the infused donor graft may have provided a non-CD3+, non-CD33+ non-hematopoietic type of stem cell such as donor mesenchymal stem cells that in theory could facilitate a durable remission

Clinical Trial Registry: FDA IND 16908, www.clinicaltrials.gov NCT 01288053

Disclosure: Nothing to declare.

CAR-based Cellular Therapy – clinical

P066 National Implementation of the use of Tisagenlecleucel in Paediatric and Young Adult Patients with Acute Lymphoblastic Leukaemia (ALL) in National Health Service England (NHSE)

Caroline Louise Furness ^1,2, Rachael Hough³, Michelle Cummins⁴, Gillian Murphy⁵, Sara Ghorashian⁶, Persis Amrolia⁶, Claire Roddie³, Maeve O’Reilly³, Robert Wynn⁷, Denise Bonney⁷, David Marks⁴, Sridhar Chaganti⁸, Geoff Shenton⁹, Anna Castleton¹⁰, Eleni Tholouli¹¹, Deborah Yallop¹², Peter Clark¹³, John Snowden¹⁴

¹Royal Marsden Hospital, Sutton, United Kingdom, ²The Institute of Cancer Research,, London, United Kingdom, ³University College London Hospitals, London, United Kingdom, ⁴University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom, ⁵Patient Representative, NCCP ALL Panel, United Kingdom, ⁶Great Ormond Street Hospital, London, United Kingdom, ⁷Royal Manchester Children’s Hospital, Manchester, United Kingdom, ⁸Queen Elizabeth Hospital, Birmingham, United Kingdom, ⁹Newcastle Upon Tyne NHS Foundation Trust, Newcastle upon Tyne, United Kingdom, ¹⁰Christie NHS Foundation Trust, Manchester, United Kingdom, ¹¹Manchester University NHS Foundation Trust, Manchester, United Kingdom, ¹²Kings College Hospital NHS Foundation Trust, London, United Kingdom, ¹³Cancer Drugs Fund, NHS England, London, United Kingdom, ¹⁴Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, United Kingdom

Background: Following European Medicines Agency (EMA) approval of Tisagenlecleucel (KYMRIAH^®) for the treatment of relapsed/refractory acute lymphoblastic leukaemia (ALL) in children and young adults in 2018, England established a structured funding programme via the National Health Service England (NHSE) Cancer Drugs Fund.

Methods: NHSE established a national CAR-T clinical panel for ALL (NCCP ALL). The aim of the NCCP ALL was to review cases to confirm eligibility against published criteria in line with the ELIANA study inclusion criteria and ensure prompt national access to Tisagenlecleucel. All CAR-T centres (3 open at NCCP set up and 9 open at 1 year review) were accredited for the Immune Effector Cell Standards in the 7^th edition of the JACIE Standards in line with EBMT/JACIE recommendations (Yakoub-Agha et al 2019). The NCCP ALL consisted of representatives from NHSE, CAR-T centres, patient representation and independent ALL clinical experts. We describe panel experience over a one year period.

Results: The NCCP met by weekly teleconference to review cases referred by individual CAR-T centre lead clinicians who endorsed eligibility. Approval for access to Tisagenlecleucel was granted through unanimous panel consensus agreement following review of eligibility criteria (according to disease and CD19+ status, absence of CNS disease, performance status and organ function). Allocation to centre was achieved by review of geography, slot availability and patient preference.

From 19.11.2018-18.11.2019 34 patients were approved (age range 9 months - 21 years, median age 10.5 years). 5 did not proceed to leukapheresis (2 incorrect diagnosis of relapse, 1 received alternative CAR-T clinical trial product, 2 unable to proceed due to disease progression/complications). At time of abstract submission 23/29 (79.3%) patients had undergone CAR-T infusion. 3 patients who underwent leukapheresis were unable to proceed to infusion (1 patient due to emergence of CD19 negative disease, 1 patient due to CNS disease progression, 1 patient received cranial radiotherapy to control CNS disease and suffered frank bone marrow relapse treated with Inotuzumab followed by a failed manufacture). 3 patients await infusion. Mean time from panel approval to leukapheresis was 15 days (range 0-47 days) and mean time from leukapheresis to CAR-T infusion for patients infused was 64 days (range 35 - 92 days) Of 15 patients evaluable beyond 100 days (8 patients yet to reach this time point), 11 have a documented status of ‘alive in MRD negative remission’. This represents 73% patients infused (11/15). Brief toxicity and follow up data will be reported at EBMT 2020 with future planned efficacy analysis.

Conclusions: The establishment of a national panel in England for Tisagenlecleucel approval has allowed prompt, equitable and trackable access to this CAR-T product for ALL. From a worldwide perspective, NHSE is one of the first health services to introduce a national co-ordinated access programme of care and will utilise programme data to assess real world outcomes for patients treated with Tisagenlecleucel.

Disclosure: Nothing to declare.

P067 Real-world Clinical Features of Neurotoxicity Complicating CD19-targeted Chimeric Antigen Receptor (CAR) t-cell Therapy for High Grade Lymphoma and Management Including the off-label use of Anakinra

Shafqat Inam, Sean Apap Mangion, Victoria Potter, Reuben Benjamin, Andrea Kuhnl, Robert Hadden, Robin Sanderson

King’s College Hospital NHS Foundation Trust, London, United Kingdom

Background: Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are the main toxicities complicating CAR T-cell therapy. High dose steroids are the current standard of care, though there remains a clinical need for patients that are refractory to front line treatment. Animal models have supported cytokine targeting therapies that can cross the blood brain barrier such as the IL-1 receptor antagonist anakinra. We report our experience with ICANS in a cohort of patients receiving CD19 CAR T-cells, including the first series of patients treated with anakinra for ICANS.

Methods: Patients with relapsed/refractory B cell non-Hodgkin lymphoma received axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisagen) between Jan 2019 and September 2019. Eligibility was determined independently by a panel of clinical experts from NHS England and data collected prospectively. ICANS was graded according to ASTCT Consensus Grading.

Results: A total of 43 patients received treatment (14 transformed FL, 2 PMBCL and 27 DLBCL): 38 received axi-cel and 5 tisagen. 14 of 43 patients (33%) experienced any grade of neurotoxicity, with 7 of 43 (16%) grade 3 or 4, lower than the rate reported in previous trials and real-world data. The most common clinical features were disorientation or confusion, dyspraxia and expressive dysphasia (n=9). Intensive care admission was required for 8 patients, with 3 requiring intubation.

Neuroimaging was performed in 13 patients: five patients with CT brain, five with CT and MRI brain, and three MRI. The only clear acute change was bilateral hippocampal enhancement for one patient on MRI, subsequently attributed to viral encephalitis. Lumbar puncture was performed in six patients: glucose and cytology was normal, with a mild rise in CSF protein (mean 0.96g/L, range 0.25-0.45g/L). One patient was diagnosed with HHV6 encephalitis. EEG was performed in 12 patients, with almost all (92%) displaying encephalopathic features (generalised rhythmic delta activity) and 2 (17%) with epileptiform foci over the left fronto-temporal region. No periodic discharges or seizures were captured.

High dose steroids (dexamethasone up to 40mg daily) was started for 11 patients for treatment of ICANS; all patients had received tocilizumab for prior or concurrent CRS. Anakinra was administered to five patients concurrently with steroids for ICANS that was high grade or not responsive to initial therapy with dexamethasone. The ICANS grade for these five patients at time of treatment was grade 3 for two patients, and grade 4 for three patients. Anakinra was given as 200mg daily subcutaneously, started at a median of 3 days (range 1 to 5) after the commencement of dexamethasone for ICANS treatment, and median number of 5.4 doses given (range 3 to 8). ICANS resolved in all patients surviving to day 30 (n=13), with persistent neurological features in one patient likely sequelae of viral encephalitis and one treatment related death (sepsis).

Conclusions: We describe the clinical features of ICANS in our real-world cohort of patients receiving standard of care CD19 CAR T-cells, and demonstrate the feasibility of anakinra in combination with dexamethasone for treatment ICANS that is severe or not initially responsive to high dose steroids.

Disclosure: Nothing relevant to declare.

P068

Abstract already published.

P069

Abstract already published.

P070 Association of axi-cel CAR-T Cell Concentration with Treatment Response and Side Effects and Impact of Dexamethasone Treatment on Kinetics

Francis Ayuk ¹, Anita Badbaran¹, Carolina Berger¹, Tanja Sonntag¹, Kritoffer Riecken¹, Maria Geffken¹, Dominic Wichmann¹, Nicolaus Kröger¹, Boris Fehse¹

¹University Medical Center Hamburg-Eppendorf, Hamburg, Germany

Background: Chimeric-antigen-receptor (CAR-) T cells have demonstrated remarkable efficacy in the treatment of B-cell hematological malignancies, leading to the recent approval of two CD19-CAR-T cell products (Tisagenlecleucel/Kymriah and Axicabtagene ciloleucel/Axi-cel/Yescarta) in the US and Europe. CAR-T cell engraftment and expansion represent crucial parameters for efficacy of treatment. Monitoring of CAR-T cell concentrations has however been limited by the lack of diagnostic assays.

Methods: We performed prospective serial measurements of CAR-T cell levels in blood and body fluids of 18 patients treated with Axi-cel. Informed consent was obtained from all patients and the study approved by the ethics committee. Per protocol, blood samples are collected on days 0, 3, 7, 10, 14, 21, 28, 35, 56, 84, 180 and 365 after CAR-T cell infusion. In case of ICANS and lumbar puncture, cerebrospinal fluid (CSF) is also analyzed for CAR-T cell numbers. Quantification of CAR-T cells was performed using a newly developed digital PCR assay (Fehse et al., EBMT 2020).

Results: We have treated 18 patients with diffuse large B cell lymphoma with Axi-Cel. Sixteen of these patients were evaluable for day 30 response at time of abstract submission. CAR-T cells could be detected in the blood of all 16 patients, expansion and contraction followed the expected kinetics with median peak value of 11.2 CAR-T cells on (median) day 11.5 after infusion. Clinically, we observed only 2 responses (1PR, 1 CR) in 7 patients who had poor expansion of CAR-T cells (defined as peak numbers below and peak time-points above median), while 9 out of 10 patients with comparatively good expansion showed response (5 CR, 4 PR) on day 30. Seven out of 10 patients with good expansion experienced CRS and/or ICANS whereas only 2 of 7 patients with poor expansion had CRS or ICANS. CSF was collected from 3 patients with ICANS. In all 3 cases, high concentrations of CAR-T cells were detected in CSF. Two patients received dexamethasone for the treatment of ICANS. In both cases, treatment with dexamethasone (1 dose and 6 doses of 10mg respectively) led to a drop in the concentration of CAR-T cells, followed by recovery after discontinuation of dexamethasone (Figure 1). Data on more patients and cytopenias will be presented at the meeting.

Conclusions: Despite the relatively small patient number, our data emphasize the importance of monitoring CAR-T concentrations after infusion and indicate an association with response and side effects. CAR-T cell proliferation appears to bounce back after treatment with dexamethasone.

[Figure 1]

Disclosure: FA has received honorarium from Kite/Gilead for advisory board. NK has received honorarium from Kite/Gilead for advisory board. The dPCR assay used in this work has been made available as an “Expert Design Assay” based on agreement with Bio-Rad. BF, AB, CB, and KR would profit from potential future commercialization of the assay.

P071 Nivolumab as Salvage Therapy in Patients who Failed to Achieve Complete Remission after anti-CD19 CAR T-cell Therapy for DLBCL

Nicolas Gazeau ¹, David Beauvais¹, Salomon Manier¹, Marie De Charette de la Contrie¹, Micha Srour¹, Pauline Varlet^1,3, Myriam Labalette^1,2, Franck Morschhauser¹, Ibrahim Yakoub-Agha^1,2

¹CHU de Lille, Université de Lille, Lille, France, ²LIRIC, INSERM U995, Lille, France

Background: We report the efficacy and tolerance of nivolumab (Nivo) in patients who did not achieve a complete response (CR) at one month after Yescarta^TM infusion.

Methods: Thirty-two patients with R/R DLBCL (13 male/19 female) were candidate for Yescarta^TM and underwent leukapheresis between November 2018 and December 2019 in our center. As of December 15, 2019, 29 were infused, 2 patients are waiting to be infused and one patient never got infused because CAR T-cell production failed twice. Twenty-five patients are evaluable for response at one month post CAR T infusion since one patient died at day 21 of septic shock. Median follow-up was 152 days (range, 39-354 days).

Results: Response rates according to IWC 2014 (Cheson 2014) at one month after CAR T-cell infusion were CR (n=11; 42%), partial response (PR) (n=5, 19%), stable disease (SD) (n=3: 12%), progressive disease (PD) (n=6; 23%). One patient with PR converted to CR two months after CAR T-cell infusion without subsequent treatment. All patients who achieved CR are alive and received no further treatment. All but 4 of the 13 patients who did not achieve CR received salvage therapy with Nivo. The 9 patients (3 PR, 3 SD and 3 PD) received Nivo at the dose of 240 mg/2 weeks. All patients received prophylaxis with valaciclovir and cotrimoxazole. Median time of the onset of Nivo was 60 days (range, 37-144 days) after CAR T-cell infusion. Median number of Nivo injections was 5 (range, 2-9). Two out of the 3 patients with PR achieved CR 60 days after initiation of Nivo. One of them subsequently received allogeneic hematopoietic cell transplantation and one is still receiving Nivo. In this latter patient, circulating CAR T-cells, mainly CD8⁺, dramatically increased following Nivo administration. One out of the 3 patients with PD experienced PR 60 days after Nivo. The 6 remaining patients with PR, SD and PD progressed after Nivo, of whom 2 died at day 90 and 173 after initiation of Nivo. Table 1 depicts outcomes of all patients who received Nivo. Three patients developed grade 2 bacterial pneumonia and one patient who received subsequent allo-HCT developed grade 1 psoriasis that was probably linked to Nivo. Overall, response to Nivo was recorded as CR (n=2, 22%) and PR (n=1, 11%). Six patients (67%) progressed.

Conclusions: Nivo seemed to be effective and safe in a small number of patients who did not achieve CR after CAR T-cell therapy.

Table 4

Disclosure: Nothing to declare.

P072 Surveillance of Minimal Residual Disease (MRD) in Diffuse Large B Cell Lymphoma (DLBCL) by Circulating Tumor Dna (CTDNA) Profiling after Chimeric Antigen Receptor T (CAR-T)

Houli Zhao ^1,2,3, Yongxian Hu^1,2,3, Wei Ding¹, Arnon Nagler⁴, He Huang^1,2,3

¹The First Affiliated Hospital, Zhejiang University, Hangzhou, China,²Zhejiang Province Engineering Laboratory for Stem Cell and Immunity Therapy, Hangzhou, China, ³Institute of Hematology, Zhejiang University, Hangzhou, China, ⁴Chaim Sheba Medical Center, Tel Hashomer, Israel, Tel Hashomer, Israel

Background: CAR-T therapy has become an ultimately effective solution for relapse or refractory (r/r) DLBCL. Therefore, after successful CAR-T therapy, patients are carefully monitored by positron emission tomography-computed tomography (PET-CT) instead of other treatment. Besides high cost, risk of ionizing radiation also limit the use of PET-CT in surveillance follow-up DLBCL. CtDNA derives from disrupted tumor cells preserving the characteristic of alteration in tumor genome. With the application of next generation sequencing (NGS), analysis large-scale sample of DNA become cheaper and faster showing great potential prospect in “liquid biopsy” avoiding the risk of failure of biopsy, surveillance of MRD in lymphoma, and observation of lymphoma subclone evolvement with early precise intervention.

Methods: We retrospectively collected clinical data, tumor sample preserved in formalin fixed paraffin-embedded tissue or liquid nitrogen storage and serum preserved in liquid nitrogen storage from the prospective clinical study aiming to evaluate the safety and efficacy of anti-CD19 CAR-T for r/r B cell lymphoma (ChiCTR-OCC-15007008). We profiled genome aberration with NGS in the baseline, relapsed, and progressive tumor sample after CAR-T therapy and ctDNA in baseline serum and reviewing serum in accordance with reviewing PET-CT scan. 8 DLBCL patients received CAR-T therapy between December 2016 and November 2017 were included in this analysis.

Results: The baseline characteristics are listed in table. The median follow-up is 322.5 days. 4 (50%) patients achieved complete response (CR), 1 (12.5%) patient achieved partial response and the rest of 3 (37.5%) patients showed no response 1 month after CAR-T therapy. 3 of 5 patients who achieved response relapsed within 4 months after CAR-T therapy while the rest of 2 patients remain CR for more than 20 and 27 months respectively.(Figure A) Grade 1, 2, and 3 cytokine release syndrome occurred in 2, 1, and 3 patients respectively. 89 and 446 hotspot genes NGS were performed in 1 and 7 patients respectively. Compared to PET-CT scan, the sensitivity and specificity of ctDNA profiling in detecting MRD is 94% and 64% respectively. Among 3 patients who relapsed from CAR-T, positive posttreatment ctDNA detection preceded PET-CT progression in patient 6 by 1.4 months (Figure B). The median number of abnormal genes in baseline tumor tissue is 4 and 15.5 (P=0.012) in the patients remained long-term CR and the patients failed from CAR-T therapy respectively. XPO1 E571K mutation was observed in 3 of 6 patients failed from CAR-T therapy.

Conclusions: CtDNA profiling is a promising new technique for surveillance of MRD in DLBCL after CAR-T therapy. In some cases, ctDNA can predict the disease progression earlier than PET-CT scan. A much number of abnormal genes in baseline particularly XPO1 E571K mutation may be a poor prognostic factor after CAR-T therapy in DLBCL.

Patient No.	1	2	3	4	5	6	7	8
Age	35	27	36	44	43	60	33	50
Disease stage	IVB	IVB	IVA	IVA	IIIA	IIISB	IVA	IIA
Prior lines of therapy	7	4	3	3	5	2	3	4
Prior ASCT	Yes	No	No	No	Yes	No	No	No

[Baseline characteristics]

[Figure 1A. | Figure 1B. Positive posttreatment ct]

Clinical Trial Registry: ChiCTR-OCC-15007008

http://www.chictr.org.cn/

Disclosure: Nothing to declare.

P073 A digital-pcr Assay for Precise in-vivo Quantification of Adoptively Transferred CD19-car T Cells after Treatment with Axicabtagene Ciloleucel (AXI-CEL)

Boris Fehse, Anita Badbaran, Carolina Berger, Tanja Sonntag, Kristoffer Riecken, Maria Geffken, Nicolaus Kröger, Francis A. Ayuk

University Medical Center Hamburg-Eppendorf, Hamburg, Germany

Background: Adoptive immunotherapy with CD19-specific CAR-T cells has shown excellent efficacy in late-stage relapsed/refractory B-cell cancers leading to the recent approval of two CD19-CAR-T cell products. Being ‘living drugs’, the in-vivo expansion, migration, contraction and persistence of CAR-T cells after infusion are important variables most probably impacting both disease response and treatment toxicity. Remarkably, widely available diagnostic tools to rapidly assess CAR-T-cell ‘drug levels’ in the clinical setting are largely missing. Digital PCR (dPCR) represents an advancement of quantitative PCR and is characterised by excellent sensitivity, specificity, and reproducibility making it an ideal tool for real-time diagnostics of rare events. Here we aimed at developing and evaluating a novel dPCR assay for detection and quantification of Axi-cel CAR-T cells in vivo.

Methods: To establish a CAR-specific dPCR assay, we first cloned and sequenced the complete cDNA of the Axi-cel vector construct. We designed different combinations of primers and dual-labelled hydrolysis probes, each amplicon spanning at least two different regions of the CAR vector. Three combinations of primers (A, B, C) were successfully tested on CAR-T cells, post-infusion PBMC, and negative controls in duplex reactions with the HCK reference (REF) gene; assay C was chosen for further application.

Results: For all three dPCR assays clear separation of negative and positive signals was observed (Fig. 1A) resulting in perfect specificity. Reproducibility tested on individual patient samples was excellent with neglectable intra- and inter-assay variations. Based on dilution curves (Fig. 1B) and the established negativity of non-transduced cells, the limit of detection was determined to be one single CAR copy. Considering Poisson distribution this translates into a limit of quantification of three copies, i.e. any sample containing a mean of three target copies in the test volume could be expected to become positive with a likelihood >95%. In 100 ng genomic DNA (gDNA; approximately 30,000 haploid genome equivalents) this corresponds to a sensitivity of 0.01%. For male patients, a Y-chromosome located haploid reference gene was employed, which allows doubling the gDNA input and thus dPCR sensitivity. After thorough assay validation, we proceeded to monitor adoptively transferred Axi-cel T cells in 16 patients with advanced B-cell lymphoma treated at our centre (with informed consent) using assay C. Mean vector copy numbers were first assessed in the Axi-cel products, using leftovers from the infusion bags. CAR-T cells were reliably detectable in post-infusion samples of peripheral blood, bone marrow, and body fluids. Actual CAR-T numbers were calculated taking into account vector copy and PBMC numbers at the time point of analysis. We found robust CAR-T-cell expansion in 10 of our 16 patients with peak levels of up to 132 CAR-T cells/µL. The pattern of early CAR-T cell expansion and long-term persistence followed the kinetics previously described for Axi-cel patients.

Conclusions: We have established a novel dPCR assay for sensitive detection of Axi-cel CAR-T cells in vivo. Our assay is excellently suited as a diagnostic tool to monitor the infused cells in real-time in different body fluids.

[Figure 1]

Disclosure: The described dPCR assay is available as an ‘Expert Design Assay from Bio-Rad. BF, CB, AB, and KR would profit from commercialisation of the Assay.

P074

Abstract already published.

P075 Axicabtagene Ciloleucel CD19 CAR T-Cells for Relapsed/refractory Large b-cell Lymphoma: real-world Outcomes, Toxicity and Predictors of Response from a Prospective UK Cohort

Robin Sanderson, Reuben Benjamin, Piers Patten, Victoria Potter, Deborah Yallup, Kirsty Cuthill, Orla Stewart, Tony Pagliuca, Pramila Krishnamurphy, Shafqat Inam, Mili Shah, Shu Wong, Catherine Hockings, Victoria Metaxa, Andrea Kuhnl

King’s College Hospital NHS Foundation Trust, London, United Kingdom

Background: King’s College Hospital was an early UK commissioned centre delivering licensed axicabtagene ciloleucel (axi-cel) for the treatment of relapsed/refractory high-grade lymphoma starting in January 2019. Eligibility was determined through both NHS England’s National CAR Clinical panel and King’s College Hospital CAR multi-disciplinary team meeting for NHS and private patients respectively. Real-world European data is required to validate trial data and look for predictors of response and toxicity.

Methods: Eligible patients were aged >18 with diffuse large B-cell lymphoma (DLBCL), transformed follicular lymphoma (tFL) or primary mediastinal B-cell lymphoma (PMBCL), post 2 previous lines of treatment including anthracyclines. Adequate organ function was determined by King’s College Hospital and data on outcomes were collected prospectively.

Results: As of December 2019, 42 patients have been infused with axi-cel with a median follow-up of 6 months. The median age was 55 (range 18-73), 63% were male and 19% were aged 65 or over at infusion. All patients had ECOG performance status of 0-1 at time of referral. 27 (64%) had DLBCL, 12 (29%) transformed follicular lymphoma and 3 (7%) PMBCL. 11 patients had previous transplants (26%), 3 allogeneic and 8 autologous.

Median time from leukapheresis to infusion was 36 days. Most patients received bridging therapy between leukapheresis and infusion, 20 (47%) with chemotherapy, 8 (19%) with radiotherapy and 10 (23%) with steroids only.

Toxicity was graded as per consensus ASTCT guidelines (Lee et al. BBMT 2019) with 41 patients evaluable. Grade 3 cytokine release syndrome (CRS) occurred in 5 patients (12%) with no grade 4 or 5 events. 40 patients (98%) had CRS of any grade, with 32 patients (78%) being treated with tocilizumab for CRS grade 2 or above. 7 patients (17%) had grades 3 or 4 immune effector cell associated neurotoxicity syndrome (ICANS) with 14 patients (34%) experiencing any grade. 41% of patients received steroids for CRS or ICANS management. There was one grade 5 event from pneumonia and sepsis. 16 patients were treated on intensive care (39%), however 8 of these patients only required observation.

38 patients had an evaluable response at 1 month, with 82% overall response rate (ORR) and 37% complete metabolic remission (CMR), at 3 months of 34 evaluable patients 44% ORR and 23% CMR. Overall survival of the infused cohort was 67% and 14 (33%) patients have moved to further therapies. Median progression free survival (PFS) was 3.6 months and was significantly inferior in patients with 3+ prior therapies, with extranodal disease and with DLBCL compared to tFL.

Conclusions: CD19 CAR T cells have been safely delivered in the NHS and our large single centre cohort demonstrates lower toxicity with axi-cel, particularly of ICANS then described in a recent large CIBMTR cohort (Pasquini et al. ASH 2019). Initial response rates are high although PFS is lower than expected. Interestingly, 3+ prior therapies were associated with inferior PFS, implying patients may benefit from earlier referral for consideration of CAR T cells. By EBMT further follow-up will allow 6-month outcomes and predictors of response to be presented.

Disclosure: Sanderson, Robin - Advisory boards/honoraria: Novartis, Kite/Gilead.

Benjamin, Reuben - Advisory boards/honoraria: Novartis, Kite, Celgene, Takeda, Jannsen, Amgen. Research funding: Servier, Allogene, Pfizer.

Kuhnl, Andrea - Honoraria: Kite. Research funding: Novartis.

P076

Abstract already published.

P077 Sinusoidal Obstruction Syndrome in Patients with Relapsed/Refractory (R/R) b-cell Acute Lymphoblastic Leukemia (B-all) Treated with ari-0001 Cells

Valentín Ortiz-Maldonado ¹, Anna Alonso-Saladrigues², Miguel Caballero-Baños³, Maria Castella³, Anna Boronat³, Enric García-Rey⁴, Tycho Baumann¹, Marina Díaz-Beyá¹, Montserrat Torrebadell², Anna Faura², Albert Català², Federico Ramos², Alicia Palomino¹, Marta Gómez-Hernando¹, Carlos Jiménez-Vicente¹, Joan Cid¹, Miquel Lozano¹, Cristina Llanos², Adrián Téllez¹, Sara Fernández¹, Pedro Castro¹, Iolanda Jordán², Jordi Esteve¹, Josep Maria Canals⁵, Esteve Trias⁴, Jordi Yagüe¹, Maria Suárez-Lledó¹, Montserrat Rovira¹, Alvaro Urbano-Izpizua¹, Manel Juan³, Susana Rives², Julio Delgado¹

¹Hospital Clinic, Barcelona, Spain, ²Hospital Sant Joan de Déu, Barcelona, Spain, ³Immunotherapy Platform Clínic-Sant Joan de Déu, Barcelona, Spain, ⁴Banc de Sang i Teixits, Barcelona, Spain, ⁵University of Barcelona, Barcelona, Spain

Background: Sinusoidal obstruction syndrome (SOS) is a life-threatening adverse event occurring mostly in the context of allogeneic hematopoietic stem cell transplant (alloHCT), with a mean incidence of approximately 14% (2-31%, depending on conditioning regimen and individual patient risk factors). Novel immunotherapy agents like inotuzumab-ozogamicin (IO) can also increase the risk of SOS in this setting. In the pivotal trial, the risk of SOS was 8.6% for patients who received standard of care therapy plus alloHCT and 24.6% for those who received IO plus alloHCT (Kantarjian HM, 2019). However, there is little data on the incidence of SOS after other novel agents like CAR-T cells.

Methods: The first academic pilot clinical trial (clinicaltrials.gov NCT03144583) using our fully academic (A3B1:CD8:4-1BB:CD3Z) CAR19 (ARI-0001 cells) finished recruitment in June/2019. Eligibility criteria included CD19+ R/R B-ALL (adult and pediatric), NHL and CLL who had failed standard available therapy. Lymphodepletion was with fludarabine (90 mg/m²) and cyclophosphamide (900 mg/m²), and the cell dose was 0.4-5 x10⁶ ARI-0001 cells/kg, first as a single infusion (first 15 patients, cohort 1), and then in 2-3 fractions (last 23 patients, cohort 2). Here we report a descriptive analysis on the incidence of SOS in B-ALL patients included in this trial.

Results: We treated 38 R/R B-ALL patients with ARI-0001 cells. Median age was 24.5 years (3-68). All but 5 patients had relapsed after alloHCT (33/38 = 86.8%), and among patients with history of IO treatment (15/38 = 39.4%) only one had not previously undergone an alloHCT. We observed a total of 3 (7.9%) cases of SOS (see table 1) after ARI-0001 treatment, all occurring at cohort 2. The first 2 cases where 2 adult patients of 54 and 68 years diagnosed using the modified Seattle criteria in the context of weight gain, ascites, severe thrombocytopenia, increase in transhepatic gradient, and finally, confirmed by transjugular liver biopsy at day +31 and +49 after ARI-0001 cell infusion. Both patients had previous history of alloHCT and IO treatment with an inconclusive history of liver toxicity after IO treatment. They improved clinically from their SOS with support treatment and were eventually discharged from hospital. The third SOS case occurred in a post alloHCT young female patient (19 years) that after receiving ARI-0001 cell therapy was treated in another hospital with IO (day +161) and shortly after was diagnosed and treated as a SOS at day +171. This patient improved clinically after defibrotide treatment and was eventually discharged from hospital.

Conclusions: The incidence of SOS in patients with R/R B-ALL treated with ARI-0001 cells was 7.9%. However, it was 20% among those patients with both alloHCT and IO treatment. No SOS occurred in patients without prior alloHCT plus IO treatment. These results led us to incorporate liver imaging studies to our screening tests in patients with prior alloHCT/IO history who are referred for ARI-0001 cell therapy.

Clinical Trial Registry: Phase I, CART19-BE-01 clinical trial (EudraCT: 2016-002972-29, NCT03144583) for relapsed/refractory CD19+ leukemia and lymphoma at the Hospital Clínic de Barcelona and Hospital Sant Joan de Déu, Barcelona (Spain).

Disclosure: Source of funding: Proyecto ARI; Fundació Gloria Soler; ISCIII; CatSalut; FEHH; Generalitat de Catalunya

P078 Humoral Immune Response in Patients with CD19-positive Relapsed/refractory B-cell Malignancies Recruited into the CART19-be-01 Clinical Trial, an Academic CAR19

Nela Klein-González ¹, E. Azucena González-Navarro¹, Ariadna Bartoló-Ibars¹, Valentín Ortiz-Maldonado¹, Montserrat Torrebadell², Maria Castellà^1,3,4, Daniel Benítez¹, Miguel Caballero-Baños¹, Raquel Cabezón¹, Marta Español-Rego¹, Tycho Baumann¹, Eva Giné¹, Pedro Castro^1,3,5, Jordi Esteve^2,3,5, Jordi Yagüe^1,3,5, Susana Rives², Álvaro Urbano-Ispizua^1,3,5, Julio Delgado^1,3, Manel Juan^1,3

¹Hospital Clínic, Barcelona, Spain, ²Hospital Sant Joan de Déu, Barcelona, Spain, ³Institut d’Investigacions Biomèdiques August Pi i Sunyer IDIBAPS, Barcelona, Spain, ⁴Banc de Sang i Teixits (BST), Barcelona, Spain, ⁵University of Barcelona, Barcelona, Spain

Background: Chimeric Antigen Receptor (CAR)-T cells directed against CD19 have induced high rates of response in patients with relapsed/refractory (R/R) B-cell malignancies. Two CD19-targeting constructs have been approved by the FDA and EMA for B lymphoblastic leukemia (B-ALL) and aggressive lymphoma. Despite deep remissions, there are still major challenges and disparate data are reported about the immunogenicity induced by CART-cell therapy. The Spanish Agency of Medicine approved our first clinical trial with a fully academic CART-19 on May/2017.

Methods: Patients with R/R B-ALL (adult and pediatric), non-Hodgkin’s lymphoma (NHL) and chronic lymphocytic leukemia(CLL) who failed standard therapy were included in the trial. The primary objective of the study was safety; secondary objectives were response rate and its duration. After lymphodepletion with fludarabine (90 mg/m2) and cyclophosphamide (900 mg/m2), a total dose of 0.5-5 x10⁶ ARI-0001 cells/kg was infused (CAR-T with a single-chain variable fragment (scFv) with anti-CD19 specificity, conjugated with the co-stimulatory regions 4-1BB and CD3z; the scFv was originated from a mouse monoclonal antibody A3B1). The humoral anti-CART response was assessed by a cell-based fluorescence assay to detect human anti-murine antibodies (HAMA) in patients´ sera. Assessment was conducted at different time points: 1) at baseline (pre-dose), 2) on day 14 after the administration of ARI-0001 cells, 3) on day 28, 4) on day 100, and 5) every 3 months thereafter.

Results: Forty-seven patients (37 adults/10 pediatrics) received ARI-0001 cells. Thirty-eight patients had a diagnosis of R/R B-ALL (28 adults and 10 children); all but 5 had relapsed after allogeneic hematopoietic stem cell transplant (HCT). Seven patients had a diagnosis of NHL, four of them (57%) had relapsed after HCT, and 2 patients had a diagnosis of CLL. Median age was 27 years (3-68). Twenty-five per cent of the patients tested positive for the presence of anti-CAR antibodies, all of them post-dose, in contrast to previous data reported on Kymriah ® with a significant presence of pre-dose anti-murine CAR19 antibody. Of these patients, 8 patients presented with a weak, and 4 patients with a strong presence of HAMA. The last had lost the effectiveness of the CART-therapy at that time point since a simultaneous B-cell recovery was observed in the periphery. Moreover, three of them received a second dose of CART-19, which did not revert the relapse.

Conclusions: These data suggest the importance of the immunogenicity induced by CART-cell therapies. Immune monitoring should include the assessment of humoral response, especially before considering a second dose after relapse.

Clinical Trial Registry: Identifier: NCT03144583

https://clinicaltrials.gov/ct2/show/NCT03144583

Disclosure: Nothing to declare.

P079 Real-world Data from Kings College Hospital: Infection Complications Post CAR-T Treatment in high-grade B Cell non-hodgkin Lymphoma

Shu Min Wong, Mili Shah, Shafqat Inam, Andrea Kuhnl, Robin Sanderson

Kings College Hospital NHS Foundation Trust, London, United Kingdom

Background: Chimeric antigen receptor T (CAR-T) cells have shown promising results in treating patients with relapsed/refractory (R/R) B cell malignancies. With the recent approval of both axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisagen) for the treatment of R/R high-grade B non-Hodgkin lymphoma (NHL), we see more patients being referred for this novel therapy. There have been some published data looking at short- and long-term infection risks with this therapy and hypogammaglobulinaemia associated with B cell aplasia.^1,2

We look at our cohort of patients being treated at Kings College Hospital with Axi-cel or Tisagen for R/R NHL to identify our incidence of short- and long-term infections and to identify risk factors that may contribute.

Methods: We collected our single centre’s data on patients treated with CD19 CAR-T cells from Jan-Aug 2019. Eligibility is determined independently by a panel of clinical experts from NHS England and clinical data collected prospectively.

Results: A total of 31 patients were treated with axi-cel and 3 patients with tisagen during this period. All developed neutropenic fevers with at least Grade 1 cytokine release syndrome (CRS). A total of 26 patients required tocilizumab for CRS and 12 patients needed steroids for Grade 2 CRS unresponsive to tocilizumab. 3 patients had positive blood cultures within the first 28 days of CAR-T infusion and only 1 patient required treatment for proven fungal chest at D28. In regards to late infections, one patient had pneumocystis pneumonia at 6 months and another had line associated acinetobacter sepsis at 2 months in the setting of persistent neutropenia. 8 patients had positive respiratory viruses with 5 achieving lymphocyte recovery post CAR-T. 25 patients had B cell aplasia pre-CAR-T therapy and by 1 month nearly all patients had B cell aplasia. Pre-CAR-T 10 patients had IgG levels < 4g/L with 2 having regular immunoglobulin replacement prior and at 1-month post treatment 14 patients had levels < 4g/L. 2 patients required regular immunoglobulin replacement post CAR-T; one was for bronchiectasis. The other patient had significant infections within the first 100 days, this included HHV6 encephalitis, recurrent E. coli UTIs, Kliebsiella bacteraemia and pneumonia; he was treated with antibiotics as well as immunoglobulin replacement. One patient in remission died suddenly in their local hospital of sepsis at 7 months. All patients had routine prophylaxis with aciclovir, co-trimoxazole and fluconazole; patients were changed over to posaconazole as per hospital policy if evidence of prolonged neutropenia.

Conclusions: In our cohort most patients treated with CAR-T cells did not appear to have an increased risk of early or late infections and this is despite CRS and administration of tocilizumab and steroids. There was 1 patient who had significant infections post CAR-T likely due to persistent neutropenia and lymphopenia and another who died of late sepsis. Despite significant B cell aplasia pre and post CAR-T the immunoglobulin levels in most patients remained >4g/L which suggests that the humoral immune system can remain intact despite B cell aplasia. Immunoglobulin levels will be correlated with 6-month outcomes in final analysis.

Disclosure: Nothing to declare.

P080 Senescent/exhausted Phenotype of CD19-targeted CAR-T Cells and Immunoregulatory Environment Correlate with Reduced Response to car-t Cell Therapy in Relapsed/Refractory B Cell Malignancies

Katia Beider, Michal J. Besser, Jacob Schachter, Ania Hava Grushchenko-Polaq, Valeria Voevoda-Dimenshtein, Maayan Ulman, Olga Ostrovsky, Elad Jacoby, Avichai Shimoni, Abraham Avigdor, Arnon Nagler

Sheba Medical Center, Tel Hashomer, Israel

Background: Chimeric antigen receptor (CAR) T cells have shown promising results in patients (pts) with B cell malignancies, yet up to 60% of the pts with diffuse large B cell lymphoma (DLBCL) will eventually relapse. Therefore, future efforts are needed to improve the outcomes of these pts.

Methods: A total of 22 pts with relapsed/refractory B cell malignancies, DLBCL (n=21) and ALL (n=1), were enrolled on a phase 1b/2 study (NCT02772198) of locally produced CD19 CAR T cells. All pts received a lymphodepleting preparative regimen with cyclophosphamide and fludarabine, followed by intravenous infusion of autologous CD19 CAR-T cells with a CD28 costimulatory domain. Clinical response was determined at 28 days following cell administration. Blood samples obtained prior to the lymphodepleting conditioning and at days 7, 14, 21, 30 and 60 after CAR T administration were collected. The manufactured CAR T products (n=11) were also subjected to immunophenotypic analysis.

Results: Clinically, 14 of 22 pts (63.7%) responded to CAR T therapy, 6 (27.3%) with complete response (CR), and 8 (36.4%) with partial response (PR). Analysis of the manufactured CAR T products revealed high CXCR3 expression (76% and 95% positive within the CD4+ and CD8+ subsets), indicating high migratory capacity of CAR T cells toward inflamed tissues. Furthermore, co-expression of CXCR4 (54% and 52% positive within the CD4+ and CD8+ cells) suggests increased homing ability of the manufactured CAR T toward CXCL12-rich bone marrow and lymph nodes. Interestingly, higher CCR7 expression (27.5% vs 8.5%) and lower CCR6 levels (14% vs 28%) were detected on CD8+ CAR T cells from responding pts who achieved CR and PR (n=8) versus non-responders (n=3), suggesting that less differentiated phenotype together with increased trafficking of CAR T to lymphoid tissue corresponds with improved clinical outcome.

Additionally, we assessed the immunoregulatory and senescent/exhausted phenotype in the CAR T products. Low percentage of CD4+CD25+CD127- Treg cells (13.5%, range 7-18%) was detected, with no correlation to clinical response. However, significantly higher frequency of exhausted CD57+CD39+CD28- cytotoxic CD8+ cells stand out as signature population in CAR T products of non-responders in comparison to CR pts (37% vs 9.5%, p< 0.02).

It is known that immunosuppressive environment affects CAR T cell activation. Notably, responding and non-responding pts presented distinct Treg patterns. Pts achieving CR demonstrated modest and delayed increase in Treg cells, reaching maximal frequency of 23% Treg out of CD4+ cells (range 17-30%) at day 21 post-CAR-T infusion, declining to basal low levels (12.5%) at day 30. In contrast, non-responders possessed rapidly increasing % of Treg cells (35%, range 25-50%, at day 14 post-infusion). In line with this finding, notable increase in proportion of immunosuppressive CD11b+CD14+CD163+CD206+ myeloid cells was detected in blood of non-responders, while pts achieving CR experienced transient increase in myeloid suppressor cells at day 7 that went back to normal levels at day 14.

Conclusions: Overall, these results elucidate in part the mechanisms of CAR T traffic, immunosuppressive responses as well as induction of T cell senescence/exhaustion that most probably downregulate CAR T effectiveness as observed in non-responding pts.

Clinical Trial Registry: NCT02772198

Disclosure: Nothing to disclose

P081 Characterisation of Early and Late Cytopenias in Lymphoma Patients following Treatment with anti-CD19 CAR-T Therapy

Catherine Hockings, Andrea Kuhnl, Shu Wong, Mili Shah, Shafqat Inam, Piers Patten, Kirsty Cuthill, Tony Pagliuca, Deborah Yallop, Reuben Benjamin, Victoria Potter, Robin Sanderson

King’s College Hospital NHS Foundation Trust, London, United Kingdom

Background: The anti-CD19 CAR-T therapies Axicabtagene ciloleucel and Tisagenlecleucel are now in use in the UK for patients with high grade lymphoma refractory to chemotherapy. As part of their treatment schedule patients receive lymphodepletion with Fludarabine and Cyclophosphamide prior to CAR-T infusion. However, as well as early haematological toxicity attributable to these agents, a second wave of cytopenias is observed in some patients after initial count recovery.

Methods: 39 patients were admitted to King’s College Hospital between January and September 2019 and received anti-CD19 CAR-T therapy. Haemoglobin, neutrophil and platelet counts were interrogated from commencement of lymphodepletion until latest follow-up or myelosuppressive therapy for disease progression. Haematological toxicity was graded as per EORTC. Further clinical information was collected from electronic patient records.

Results: Of the 39 patients diagnoses totalled 28 DLBCL, 14 transformed FL and 1 PMBCL. 38 patients received Axi-cel, the remaining 5 received tisagen. Patients had follow up duration of between 2 and 11 months post infusion, median follow-up 169 days. Maximal early haematological toxicity, as well as at the time of response monitoring at day+28, day+100 and 6 months post treatment is summarised in the table below.

Almost all patients (38 of 39) experienced grade 3/4 neutropenia during the first 28 days post infusion. No patients were given GCSF prior to D+14 due to concerns regarding exacerbation of CRS but 18 received it subsequently. Despite this, grade 3/4 neutropenia persisted in almost half of patients at D+28 (43%, 16/37). Grade 3/4 haematological toxicity persisting at D+28 occurred in 43% of patients (9/21) with < /=3 prior lines of treatment compared to 56% (9/16) of patients with >/=4 previous regimens. Incidence was also equivalent in patients with or without prior HSCT: 44% (12/27) without, 50% (5/10) with. 13 patients received bridging chemotherapy between apheresis and lymphodepletion, whereas 26 received no bridging, steroids or radiotherapy. Recent chemotherapy correlated with cytopenia at D+28: no bridging chemotherapy 36% (9/25), bridging chemotherapy 75% (9/12) (P=0.029).

Rates of grade 2 or worse CRS were similar in those with or without cytopenias at D+28: 61% (11/18) vs 47% (9/19) patients. ORR was 80% on D+28 PET imaging in patients without grade 3 or 4 cytopenias (16/20) and 94% in those with cytopenias (16/17) (p=0.22). Haematological toxicity at D+28 was also compared to D+100 outcomes. 47% (8/17) of patients without D+28 cytopenias had a maintained response, compared to 44% of those with progressive disease (7/16).

Conclusions: Many patients experience late cytopenias following CAR-T, therefore close monitoring of blood counts is required following discharge. Persistent cytopenias on discharge appear to correlate with prior bridging chemotherapy and are not associated with responses at 3 month follow up. Further work, including correlation with cytokine levels, is needed to determine the cause of late cytopenias. With maturation and expansion of the patient cohort we hope to determine whether cytopenias may be related to expansion and persistence of CAR-T and correlate with positive outcomes.

Clinical Trial Registry: n/a

Disclosure: Nothing to declare.

P082 Impact of Ethnicity in R/R DLBCL and B-cell all Patients Treated with Tisagenlecleucel

Ahmed Abdelhady ¹, Hidefumi Hiramatsu², Takanori Teshima³, Koji Izutsu⁴, Koji Kato⁵, Satoshi Saida⁶, Tatsuya Kamitori², Keiji Tasaka², Itaru Kato², Katsutsugu Umeda², Souichi Adachi⁷, Karen Thudium⁸, Edward Waldron⁸, Alessandra Forcina⁹, Andrea Chassot Agostinho⁸, Stephan Grupp^10,11, Richard T. Maziarz¹²

¹Novartis Pharmaceuticals, East Hanover, NJ, United States, ²Kyoto University, Kyoto, Japan, ³Hokkaido University Hospital, Sapporo Hokkaido, Japan, ⁴National Cancer Center Hospital, Tokyo, Japan, ⁵Kyushu University Hospital, Fukuoka Prefecture, Japan, ⁶Kyoto University, Kyoto, Japan, ⁷Kyoto University, Kyoto, Japan, ⁸Novartis Pharmaceuticals Corporation, East Hanover, NJ, United States, ⁹Novartis Pharma AG, Basel, Switzerland, ¹⁰Children’s Hospital of Philadelphia, Philadelphia, PA, United States, ¹¹University of Pennsylvania, Philadelphia, PA, United States, ¹²Oregon Health and Science University, Portland, OR, United States

Background: We assessed the impact of ethnicity on efficacy, safety, and cellular kinetics in Asian and non-Asian relapsed/refractory (r/r) DLBCL or B-cell ALL patients infused with tisagenlecleucel (anti-CD19 CAR-T cell therapy).

Methods: Data were obtained from r/r DLBCL (JULIET, NCT02445248) and B-cell ALL (ELIANA, NCT02435849; ENSIGN, NCT02228096) patients.

Results: Safety, efficacy, cellular kinetics, transduced dose range, and immunogenicity in the Asian and non-Asian subgroups are summarized in the Table. The assessed product attributes (eg, total cell count, % T cells, viability, and transduction efficiency) were comparable between Asian and non-Asian patients.

Conclusions: Asian and non-Asian patient populations in both indications were comparable with respect to safety, efficacy, dose-response, product attributes, and cellular kinetics of tisagenlecleucel.

	ELIANA and ENSIGN		JULIET
	Asian (N=14)	Non-Asian (N=123)	Asian (N=10)	Non-Asian (N=105)
Tisagenlecleucel transduced cell dose, median (range)	1.00 x 108 cells (0.05 - 2.50 x 108)	1.08 x 108 cells (0.03 - 2.60 x 108)	2.10 x 108 cells (1.00 - 4.90 x 108)	3.00 x 108 cells (0.10 - 6.00 x108)
Within target dose range of cells transduced, n (%)	12 (85.7)	107 (87.0)	10 (100)	99 (94.3)
Efficacy
ORR, % [95% CI]	64.3 [35.1-87.2]	78.3 (n=115) [69.6-85.4]	70.0 [34.8-93.3]	50.5 [40.5-60.4]
DOR at 18mo, % [95% CI]	70 [22.5-91.8]	63.6 (n=115) [51.0-73.7]	55.6 [7.3-87.6]	62.4 [47.5-74.2]
OS at 18mo, % [95% CI]	66.8 [32.4-86.6]	64.4 [53.9-73.1]	51.4 [14.3-79.6]	43.1 [33.3-52.5]
Safety
Any-grade CRS by Penn scale, n (%)	11 (78.6)	97 (78.9)	7 (70)	59 (56.2)
Any-grade neurologic event by CTCAE v4.03, n (%)	3 (21.4)	57 (46.3)	1 (10)	30 (28.6)
AUC 0-28d (copies/ug*days), geo-mean (CV%)	562000 (126.1)	303000 (179.2)	71800 (357.3)	63900 (223.0)
Cmax (copies/ug), geo-mean (CV%)	59900 (78.3)	33300 (153.4)	4520 (464.5)	5740 (283.1)
Immunogenicity post infusion, positive n (%)	4 (28.6)	52 (42.3)	1 (10)	9 (8.6)

1. AUC 0-28d, area under the curve of CAR-T cell numbers between day 0 and 28; CRS, cytokine release syndrome; CTCAE, Common Terminology Criteria for Adverse Events; CV, coefficient of variation; DOR, duration of remission/response; ORR, overall remission/response rate; OS, overall survival.

[Table: Safety, efficacy, cellular kinetics, transduced dose range, and immunogenicity in the Asian and non-Asian subgroups]

Clinical Trial Registry: NCT02445248, NCT02435849, NCT02228096

Disclosure: Ahmed Abdelhady: Employment: Novartis.

Hidefumi Hiramatsu: No relationship to disclose.

Takanori Teshima: Grants from Kyowa-Hakko Kirin, Novartis, Chugai, Sanofi, Astellas, Teijin Pharma, Fuji Pharma, Nippon Shinyaku; personal fee (honoraria and advisory board) from Merck Sharp & Dohme, Kyowa-Hakko Kirin, Takeda, Novartis, Pfizer, Bristol-Myers Squibb.

Koji Izutsu: Grants and personal fees from Novartis during the conduct of the study; grants and personal fees from Eisai, MSD, Takeda, Janssen, Mundipharma, Chugai, AbbVie, Bayer, Ono, Celgene; personal fees from Kyowa Hakko Kirin, Bristol Myers Squibb, Dainihon Sumitomo, Nihon Mediphysics, AstraZeneca; grants from Gilead, Zenyaku, Solasia, Symbio, Astellas, Amgen, Bayer, Daiichi Sankyo, outside the submitted work.

Koji Kato: Consulting or advisory role with AbbVie, AstraZeneca, Celgene, Chugai, Eisai, Janssen, and Novartis. Honoraria from Chugai, Takeda, MSD, Kyowa-Kirin, Janssen, Celgene, Ono, Dainippon-Sumitomo, AbbVie, Novartis. Research funding from Chugai, Takeda, Kyowa-Kirin, Abbvie, Eisai, Janssen, Novartis, Mundi, AstraZeneca, Celgene, Ono, MSD, Otsuka.

Satoshi Saida: No relationship to disclose.

Tatsuya Kamitori: No relationship to disclose.

Keiji Tasaka: No relationship to disclose.

Itaru Kato: No relationship to disclose.

Katsutsugu Umeda: No relationship to disclose.

Souichi Adachi: No relationship to disclose.

Karen Thudium: Employment: Novartis.

Edward Waldron: Employment: Novartis.

Alessandra Forcina: Employment: Novartis.

Andrea Chassot Agostinho: Employment: Novartis.

Stephan Grupp: Grants and personal fees from Novartis Pharmaceuticals, during the conduct of the study; personal fees from Jazz Pharmaceuticals, personal fees from Adaptimmune, personal fees from TCR2 Therapeutics, personal fees from Eureka Therapeutics, personal fees from Cellectis/Servier, outside the submitted work; In addition, Dr. Grupp has a patent Toxicity management for anti-tumor activity of CARs (WO 2014011984 A1) issued.

Richard T. Maziarz: Honoraria, Membership on an entity’s Board of Directors or advisory committees and Research Funding: Novartis; Consultancy and Honoraria: Incyte, Juno; Honoraria: Kite; Jazz Pharmaceuticals.

P083 Impact of different Chemotherapy Regimens and Duration of DLBCL on Lymphopheresis and car-t T-cell Immunophenotyping

David Hagin, Tal Freund, Liav Sela, Rinat Eshel, Odelia Amit, Yael Bar-On, Irit Avivi, Ron Ram

Tel Aviv University, Tel Aviv, Israel

Background: CD19-directed CAR T-cell therapy becomes a standard of care treatment for relapse/refractory DLBCL. Production of CAR-T cells requires transduction and expansion of the collected lymphocytes. However, little is known about the impact of disease duration and specific treatment regimens on the harvested lymphocytes. Additionally, no sufficient data on the impact of the lymphopheresis product on treatment outcome.

Methods: Tisagenlecleucel (Kymriah^TM, Novartis) was commercially approved in Israel on May-2019. Since June-2019, we performed in all sequential patients flow-cytometry-based-T cell subsets (naïve-cell, central-memory (Tcm), effector-memory (Tem) and terminally-differentiated-CD45RA+ cells (Temra)) in the apheresis and in the CAR-T. In addition, activation marker HLA-DR and exhaustion marker PD-1 were also evaluated in the paired samples. All patients had a follow-up PET-CT scan one-month post infusion for response evaluation. We analyzed the effect of disease duration and the pre-apheresis treatment regimens being administered on the apheresis T-cell immunophenotyping, as well as the correlation between immunophenotyping and treatment outcome.

Results: Between May and December 2019, 35 DLBCL patients were screened and considered for Tisagenlecleucel treatment. 29 (83%) patients underwent lymphopheresis and 21 patients received the product. The study cohort included 20 sequential patients for whom complete flow-based T cell immunophenotyping data were available. 30-day PET-CT was available in 12. Median age was 71 (range, 20-84) years and median duration of disease was 12 (range, 4-68) months. 38% received >3 lines of chemotherapy and 33% failed autologousHCT.

Of the different variables evaluated we observed statistically significant effect of bendamustine treatment(n=9) on apheresis T cell immunophenotyping resulting in lower percent of naïve CD4 T cells (CD45RA+CCR7+; 4.15±4.2% vs 10.4±7.5%, p=.05), higher percent of Tem CD4s (CD45RA-CCR7-; 71.3±15.9% vs 52.7±12.6%, p=.01), higher percent of PD1+ CD4 T cells (66.8±14.6% vs 41.5±17.9%, p=.27) and higher percent of activated HLA-DR+ CD4s and CD8s (68.2±17.5% vs 41.9±13.7%, p=.01 for CD4s, 63.7±20.8% vs 39.2±19.1%, p=.13 for CD8s). Prior autologous HCT was associated with a trend toward lower CD4 to CD8 ratio (0.459±0.146 vs 1.00±0.748, p=.076). Although immunophenotyping was not affected by the number of pre-pheresis treatment-lines, disease duration was correlated with lower percent of naïve CD4 (Spearman´s correlation coefficient=-.5, p=.02) and naïve CD8 T-cells (Spearman´s correlation coefficient=-.46, p=.04) (Figure 1).

[Figure 1: Scatter plot of correlation between duration of disease and naïve CD4 and CD8 count]

Among all analyzed T cell characteristics, only higher percent of pre-pheresis HLA-DR+ CD4s and CD8s were associated with higher incidence of CR (beta .78, p=.05 and .47, p=.09, respectively).

Conclusions: While there remains insufficient data to solidly confirm our hypothesis, it is reasonable to assume that pre-lymphopheresis disease duration and treatment history may affect pheresis product, which in-turn, determines the final CAR T-cell product and response to treatment. Preliminary data from our small cohort suggests that pre-pheresis bendamustine treatment is associated with more mature, activated and exhausted CD4 T-cell phenotype. Improved phenotyping to include additional exhaustion markers, as well as follow-up post CAR T-cell infusion (by evaluating peripheral blood CD19-Ig binding T cells) is ongoing.

Disclosure: Nothing to declare.

P084 Chimeric Antigen Receptor (CAR) T Cell Therapy Followed by Hematopoietic Stem Cell Transplantation May Improve Progression free Survival in Patients with Relapse/Refractory B-cell Non-hodgkin Lymphoma

Haiwen Huang, Shuo Liu, Qian Zhu, Yishan Duan, Depei Wu

First Afilliated Hospital of Suzhou University, Suzhou, China

Background: Chimeric antigen receptor (CAR) T cells are emerging as a novel treatment modality that highly effective in the treatment of relapse/refractory B-cell lymphoma, providing alternative therapeutic options for patients who failed to respond to conventional treatment or relapse. Although highly remission rates have been reported with CAR-T cell therapy in relapse/refractory B-cell lymphoma, relapse or disease progression is common after CAR-T therapy. This current study is to better our understanding of whether consolidative hematopoietic stem cell transplantation(HSCT) confers superior survival outcomes to patients who got remission by CAR-T cells therapy.

Methods: Compare the efficacy and survival of CAR-T therapy followed by HSCT and CAR-T alone in patients with relapsed/refractory B-cell lymphoma. 30 cases with CR or PR disesse status after CAR-T cells therapy in the First Affiliated Hospital of Soochow University from 2017 to 2019 were included. 11 of these cases (36.7%) were treated with HSCT after CAR-T therapy, of which 7 cases were treated with autologous stem cell lymphoma(ASCT), and 4 cases were treated with allogeneic stem cell transplantation(Allo-SCT). 19 of these cases (63.3%) were treated with CAR-T only. Overall survival(OS) and progression-free survival(PFS) rates were estimated by the Kaplan-Meier method, and Survival comparison was analyzed by using the log-rank test.

Results: Kaplan-Meier survival curve indicated that PFS of the HSCT following CAR-T group were higher than the CAR-T group, and log rank test showed that the difference of survival curve was statistically significant (P = 0.044). The estimated 1-year and 2-year progression-free survival(PFS)were 90.9%and 50% respectively in the CAR-T followed by HSCT group. The estimated 1-year and 2-year progression-free survival(PFS)were 71.6% and 27.8% respectively in the CAR-T group. Kaplan-Meier survival curve analysis indicated that OS of the HSCT following CAR-T group were higher than the CAR-T group, while log rank test showed that the difference of survival curve was no statistically significant (P = 0.250). The estimated1-year and 2-year overall survival(OS) were 90% and 89.4% respectively in the HSCT following CAR-T group, the estimated1-year and 2-year overall survival(OS) were90%and66.2% respectively in the CAR-T group.

Conclusions: Hematopoietic stem cell transplantation(HSCT) appear to improve progression-free survival (PFS) for the patients achieving remission following CAR-T therapy with relapse/refractory B-cell lymphoma. Future prospective studies needed to clearly define the role of consolidative HSCT in the relapse/refractory B-cell lymphoma patients who attained remission from CAR-T infusion and importantly, better identify this strategy whether exhibits superior overall survival outcomes.

Disclosure: there is no conflict of interest or source of funding

P085 Challenges in providing good Leukapheresis Products for the Production of Car T Cells for Patients with Relapsed/Refractory NHL or ALL

Felix Korell ¹, Sascha Laier², Sandra Sauer¹, Sonia Jaramillo-Segura¹, Elisabeth Lasitschka¹, Kaya Veelken¹, Hannah Hennemann¹, Marie-Luisa Schubert¹, Tim Sauer¹, Petra Pavel², Carsten Müller-Tidow¹, Peter Dreger¹, Michael Schmitt¹, Anita Schmitt¹

¹University Hospital Heidelberg, Heidelberg, Germany, ²Insitute of Clinical Transfusion Medicine and Cell Therapy (IKTZ), Heidelberg, Germany

Background: In patients with relapsed or refractory B-lineage acute lymphoblastic leukemia (ALL) or B-cell non-Hodgkin’s lymphoma (NHL) therapy with chimeric antigen receptor T (CAR-T) cells has proven to be highly effective. As starting material for the production of CAR-T cells T lymphocytes from the patients are mandatory. To harvest sufficient lymphocytes, leukapheresis as first step in the production process has to be performed. This constitutes a challenge to the treating physicians with regard to timing of the apheresis in heavily pretreated patients suffering from rapid progressive disease and being treated by drugs with negative impact on T cells.

Methods: Data from 45 adult patients suffering from r/r DLBCL (68%), PMBCL (2%), MCL (4%), FL (2%), CLL (4%), ALL (13%) or multiple myeloma (5%) who received a leukapheresis for CAR-T cell production were analyzed. Apheresis procedures were effective using the Spectra Optia™ device. Peripheral blood counts pre- and post-apheresis, as well as leukapheresis product parameters were assessed. Further important tasks were the analysis of the medication used prior to apheresis and the optimization of the apheresis procedure. Fourteen leukapheresis products were produced for clinical trials including 11 patients in our in-house production HD-CAR-1 study.

Results: All patients qualified for leukapheresis due to the following criteria: hemoglobin > 8g/dl, platelets > 75/nl, ANC > 1/nl, ALC > 0.3/nl, negative PCR for HBV, HCV, HEV and HIV; no active GvHD, no florid infection, no severe impairment of cardiac or pulmonary function. Leukapheresis was feasible in all patients and could be performed through peripheral venous access using the Spectra Optia™ device without any serious side effects. In total we performed 48 leukaphereses. 45 patients received a single apheresis and in three patients a later second apheresis was required due to infectious complications or electrolyte disturbance leading to a manufacturing failure. CAR T cell production was feasible for 44 of 45 patients. A mean blood volume of 11.8 (range 5.8-15) L was processed over a time of 238 (120-326) minutes. The leukapheresis product contained a mean of 11.8 x 10^9 (0.9-34.1 x 10^9) total nucleated cells and 4.9 x 10^9 (0.4 - 23.2 x 10^9) CD3+ T cells with a viability of 99.9 (99.6 - 100) % in a mean volume of 235 (136 - 310) ml with a hematocrit of 3 (1.1 - 7.4) %.

Conclusions: Leukapheresis was feasible in all patients in an out-patient setting. To harvest a sufficient number of lymphocytes for CART cell production, a minimum of 12 -15 L total blood volume should be processed in patients with an ANC 1-3/nl and ALC 0.3-1/nl. We established therefore a standardized procedure for the apheresis handling and developed a recommendation list for the timing of the medication before apheresis.

Disclosure: MS: Apogenix: Funding for collaborative research. Hexal: Financial support for research on biosimilars, travel grants. Kite: Financial support of educational activities and conference, travel grants. Co-PI of clinical trials on CAR-T cells. MSD: Ad board member, PI of clinical trials on letermovir. Novartis: Collaborative research grant. Co-PI of clinical trials on CAR-T cells. TolerogenixX: Co-Founder and shareholder.

AS: TolerogenixX: Co-Founder and shareholder, Mallinckrodt-Therakos: research grant, Jazz: travel grant.

PD: Advisory boards Novartis, Kite/Gilead

P086 NKG2D Car T Cells are not affected by Soluble NKG2D Ligands

Adrián Fernández ¹, Lucía Fernández¹, Isabel Mirones², Adela Escudero^2,3, Leila Cardoso^2,3, Gloria Esteso⁴, Raquel De Paz², Joaquín Martínez-López⁵, Mar Valés⁴, Antonio Pérez-Martínez^2,6

¹CNIO, Madrid, Spain, ²Hospital Universitario La Paz, Madrid, Spain, ³INGEMM, Madrid, Spain, ⁴CNB, Madrid, Spain, ⁵Hospital 12 de Octubre, Madrid, Spain, ⁶Idipaz, Madrid, Spain

Background: NKG2D is an NK cell activating receptor that recognizes different stress-induced ligands (NKG2DL) that are overexpressed in different pediatric and adult tumors, while their expression in healthy tissues is rare. NKG2D-CAR T cells have shown potent antitumor effects against different types of cancer. However, tumor cells may develop immune escape strategies such as ligand release (sNKG2DL), whose effect on NKG2D-CAR has not been studied and could affect their clinical efficacy.

Methods: Clinical grade NKG2D-CAR memory (CD45RA^-) T cells were produced by lentiviral transduction (NKG2D-41BB-CD3z, MOI = 2) and expansion in CliniMACS Prodigy. NKG2D-CAR memory T cells were infused in two patients excluded from CD19 CART cell trial with refractory relapse after hematopoietic stem cell transplantation. Patient#1 suffered from r/r biphenotypic ALL. She received two cycles of CAR T cells infusions. In the first cycle, a total of 3x10⁷ cells/kg were infused into three weekly doses with no conditioning. In the second cycle, a total of 2x10⁷ cells/kg were administered weekly into two doses after lymphodepleting conditioning with Cy/Flu and low dose bortezomib. Patient#2 suffered from r/r B-ALL and bronchopulmonary aspergillosis. She received a single dose of 1x10⁷ cells/kg after lymphodepleting conditioning Cy/Flu and low dose bortezomib. sNKG2DL concentration was monitored in the patient´s sera by ELISA. The effects of sNKG2DL on NKG2D-CAR T cells (NKG2D expression, proliferation, cytokine release and cytotoxicity) were explored after exposition to different concentrations of sNKG2DL for 7 days, by flow cytometry, ELISA or LUMINEX, and a 2 hour-degranulation assay using K562 cells as target, respectively.

Results: NKG2D-CAR memory T cells were infused without severe side effects. Patient #1 showed no cytokine release syndrome (CRS), hypotension, pain or neurological events. At day +28 after the first infusion and one week after the first dose of the second cycle she developed pruriginous skin rash. Biopsy described toxicodermia versus grade I skin GvHD. Bone marrow evaluation described leukemia progression. Only 24 hours after infusion, patient #2 presented a respiratory impairment without fever and other CRS symptoms and required intensive care. Ten days after the CAR-T cell infusion, bone marrow aspiration revealed blast persistence and the family suggested to limit the therapeutic effort. Patient#2 showed an increase on sULBP2 compared to control. After NKG2D CAR T cells infusions, sNKG2DL trended to decrease in both patients. In vitro, physiological concentrations of sNKG2DL increased NKG2D-CAR expression. However, supra-physiological levels of sNKG2DL reduced NKG2D-CAR expression, increased cell proliferation, and stimulated TNF-a and IFN-g production, which was further increased in the presence of IL-2. High doses of sMICA decreased degranulation of NKG2D-CAR T cells, which was associated with receptor down-regulation. The effects of sNKG2DL were dose-dependent and slightly attenuated by IL-2.

Conclusions: NKG2D CAR memory T cells are essentially safe. Only supraphysiological levels of sNKG2DL caused NKG2D-CAR downmodulation, while normal levels induce cell proliferation and production of pro-inflammatory cytokines. Altogether these data suggest NKG2D CAR could be more resistant to the negative effects of sNKG2DL than endogenous NKG2D receptor. However, we did not observe a beneficial clinical effect in this advance situation.

Disclosure: The authors have nothing to disclose.

P087 Emerging Cytokine Release Syndrome is associated with Reduction of CD4+CD25high127dim T Regulatory Cells in Patients after Car T Cell Therapy

Christian R Schultze-Florey, Victoria Panagiota, Ivan Odak, Sultan Bektas, Tabea C Froehlich, Aleksandra Gladysz, Zhixiong Li, Gernot Beutel, Matthias Eder, Immo Prinz, Reinhold Foerster, Arnold Ganser, Christian Koenecke

Hannover Medical School, Hannover, Germany

Background: Chimeric antigen receptor (CAR) T cell therapy is often accompanied by potentially life-threatening cytokine release syndrome (CRS). The role of T regulatory cells (Tregs) during CRS remains to be elucidated. Here we prospectively investigated the Tregs population in patients with and without CRS after anti-CD19-CAR T Infusion.

Methods: The cohort consisted of 11 patients with relapsed or refractory transformed follicular lymphoma and diffuse large B cell lymphoma (DLBCL). All received anti-CD19-CAR T infusion (Tisagenlecleucel) after lymphodepletion with fludarabine and cyclophosphamide. All patients gave written informed consent to participate in the study. Patients were grouped based on emergence of CRS. Tregs were detected from peripheral blood via flow cytometry by staining for CD4+CD25+CD127dim- lymphocytes. To determine the absolute frequencies BD Trucount™ tubes were employed. Three time points were selected for analysis: baseline (d-1 - d+2 from Tisagenlecleucel infusion); 1 day prior or at the day of CRS diagnosis before start of CRS treatment (TP1, d+1 - d+6); after CRS clearance (TP2, d+3 - d+10). As control group served patients without CRS using comparable time points.

[Figure 1: Tregs frequencies in CRS vs no CRS patients.]

Results: Four patients met CRS criteria (Grade 1-4). On 3/4 CRS patients blood samples were available at all three time points and these were thus selected for analysis. Upon emergence of CRS (TP1) Tregs (measured in frequency of lymphocytes) showed a mean reduction of -46.91% compared to the baseline time point while the no-CRS controls increased their frequency by on average +10.57% (Figure 1A). Inter-group comparison at TP1 revealed differences of Tregs levels (0.87 vs. 3.10 % of lymphocytes) as well as in absolute Tregs count (1.79 Tregs/µl vs. 8.84 Tregs/µl, Figure 1B). Tregs frequencies in patients after CRS clearance (TP2) increased on average by 3.05-fold compared to TP1 while Tregs frequencies stayed stable in controls (Figure 1A). Based on this increase, Tregs frequencies at TP2 were similar to values of no-CRS patients. These findings are limited by the small patient number and in general low frequencies of Tregs early after CAR T infusion. Therefore, these pilot data need validation in a larger cohort.

Conclusions: In this prospective single center pilot study, blood samples of emerging CRS showed a reduction of Tregs frequencies and absolute numbers compared to no-CRS patients. After clearance of CRS, Tregs frequencies increased to values of no-CRS patients. Therefore, investigation of Treg frequencies as a predictive marker for CRS should be further investigated. However, future studies are needed to validate these findings in a larger cohort.

Disclosure: Nothing to declare.

P088 Excellent Proliferation and Persistence of Allogeneic CAR-T Cells Despite Immunosuppression with Cyclosporine A

Francis Ayuk, Boris Fehse, Dietlinde Janson, Carolina Berger, Kristoffer Riecken, Nicolaus Kröger

University Medical Center Hamburg, Hamburg, Germany

Background: Allogeneic CAR-T cell therapy bears the potential to combine graft-versus-malignancy effects and CAR-directed target killing, but comes with a considerable risk of graft-versus-host disease (GVHD). Animal studies indicate that the risk of GVHD after CAR-T infusion from an allogeneic donor may in part depend on the costimulatory domain used, first generation and 4-1BB-based CAR-T cells bearing an increased risk of GVHD [Gosh et al., 2017]. Interestingly, in the only report on donor-derived CAR-T cells with a 4-1BB costimulatory domain, both patients developed acute GVHD [Dai et al., 2015]. Use of immunosuppression to prevent GVHD after CAR-T cell infusion may prevent their expansion and efficacy. Here we present for the first time data on expansion and persistence of 4-1BB based CAR-T cells under immunosuppression with clinically relevant concentrations of cyclosporine A.

Methods: A 64-year old female with early relapse of follicular lymphoma grade 3A (day 65 after allogeneic hematopoietic stem cell transplantation, allo-HSCT) consented for compassionate-use treatment with CAR-T cells. CD19-CAR-T cells were manufactured from freshly collected allogeneic donor leukocytes using the CliniMACS Prodigy system and a lentiviral vector encoding the CD19-CAR containing a 4-1BB costimulatory domain.

The patient received lymphodepleting chemotherapy with cyclophosphamide and fludarabine and 1 x 10⁶ /kg BW CAR-expressing cells on day 0 (3 months after allo-HSCT). Because the patient had history of acute GVHD, we maintained her on GVHD prophylaxis with cyclosporine A at a mean cyclosporine A trough level of 170 µg/l (range 122-206 µg/l) until day 21 after CAR-T cell infusion. With no evidence of active GVHD, cyclosporine A was tapered off from day +21 and stopped on day +56 after CAR-T cell infusion.

[Figure 1: CAR-T cell expansion and persistence]

Results: No CRS or ICANS were observed. Haematopoietic recovery was expectedly slow despite use of G-CSF as from day +21. Stable neutrophil counts > 1000/µl without further G-CSF support was attained on day 32, platelet count > 50.000/µl on day 150 after CAR-T cell infusion.

FDG-PET scan on day +30 revealed complete resolution of most of the lymphoma manifestations seen in the CT scan, but also showed new bone lesions in both sacrum and femur. A follow-up FDG-PET scan on day 120 showed regression of all lymphoma manifestations with only residual manifestations in the left sacrum.

Highest CAR-T cell numbers were measured on day +9 (50 CAR-T cells/µl) with continuous persistence of CAR-T cells up to the last examination 6 months after infusion (figure 1). While overall T cell reconstitution was well evident, B cell aplasia is persistent. Interestingly, the analysis of the CAR-T cells for activation and exhaustion markers revealed a decline in the fraction of effector and effector memory and a relative increase in central memory CD4+ CAR-T cells.

Conclusions: In conclusion, we for the first time present data on proliferation and persistence of allogeneic donor-derived 4-1BB based CAR-T cells under therapeutic levels of cyclosporine A. This indicates that for patients with early relapse after allo-HSCT with ongoing immunosuppression donor CAR-T cell therapy may be a feasible Treatment.

Disclosure: Nothing to declare.

P089 A French Biobanking Network to Create a Unique Collection of Samples of Patients Treated with car-t Cells

Emilie Robert ¹, Claire Fontenille¹, Plotine Crochet¹, Régis Peffault de Latour², Jean-Hugues Dalle³, Boris Calmels⁴, Thierry Fest⁵, Loïc Ysebaert⁶, Catherine Thieblemont⁷, Cristina Castilla-Llorente⁸, Franck Morschhauser⁹, Steven Legouill¹⁰, Corinne Haioun¹¹, Emmanuel Bachy¹², Guillaume Cartron¹³, Roch Houot¹⁴

¹CRYOSTEM, Marseille, France, ²Hôpital Saint Louis, AP-HP, Paris, France, ³Hôpital Robert Debré, AP-HP, Paris, France, ⁴Institut Paoli-Calmettes, Marseille, France, ⁵CHU Rennes, Rennes, France, ⁶Institut Universitaire Cancerologie Toulouse-Oncopole, Toulouse, France, ⁷Hôpital Saint-Louis, AP-HP, Paris, France, ⁸Institut Gustave Roussy, Villejuif, France, ⁹CHRU Lille, Lille, France, ¹⁰Hôpital Universitaire de Nantes, Nantes, France, ¹¹Hôpital Universitaire Henri Mondor, AP-HP, Créteil, France, ¹²Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre-Bénite, France, ¹³CHU Saint-Eloi, Montpellier, France, ¹⁴CHU Rennes - Pontchaillou, Rennes, France

Background: Even if Chimeric Antigen Receptor (CAR)-T cells therapies are a promising way to treat relapsed/refractory hematologic cancers, authorities face major issues regarding their economic impact, the evaluation of their efficiency and adverse effects. Since their launch the number of patients with CAR-T cells indication is increasing, as well as the number of hematological cancers likely to be treated. Nationwide collections of biological resources are warranted to develop scientific projects to monitor CAR-T cells treatments and improve our understanding of the underlying biological mechanisms.

In this context, a biobanking initiative resulted from the collaboration of two French consortia : CALYM, gathering together the LYSA (Lymphoma Study Association), LYSARC (Lymphoma Academic Research Organization) and 18 academic laboratories in the field of lymphoma, and CRYOSTEM, a collaborative biobanking network. After demonstrating respectively their ability to set up the first collection of viable cells from lymphoma patients (CeVi_collection) and the first European collection of biological resources dedicated to Hematopoietic Stem Cell Transplantation, CRYOSTEM and CALYM joined their expertise to constitute a biocollection from lymphoma patients receiving CAR-T cells.

Methods: The collaboration between CRYOSTEM and CALYM networks brings together hematological clinical units and biological resources centers (BRCs) to include patients, collect and process samples. Any patient suffering from lymphoma, justifying a CAR-T cells treatment is eligible for inclusion. Several types of samples are collected and derived pre- and post-CAR-T cells administration following a specific timeline. CALYM BRCs are in charge of the treatment and storage of lymph nodes and bone marrow samples in viable cells whereas CRYOSTEM BRCs enrich this collection by processing blood samples in viable cells and plasma, and also stools and urines. Annotated biological samples are centralized in CALYM database.

Results: In less than one year, CRYOSTEM and CALYM set up the organizational and regulatory framework of the first collection of samples and associated data dedicated to CAR-T cells treated patients:

• Constitution of governing bodies including representatives from both organizations;

• Identification of the 9 clinical units and BRCs involved in the protocol;

• Practices harmonization and standardization regarding samples and protocols;

• Establishment of sampling kinetics integrated to patients’ care. Paired with lymph nodes, 8 blood sampling points are planned from apheresis to 6 months post-injection and/or at relapse;

• Estimation of the collecting rate of each sampling point according treatment failure and mortality rate;

• Evaluation of the annual number of inclusions.

First inclusions are planned in January 2020.

Conclusions: With the creation of the first biobank focused on CAR-T cells treated patients, the CALYM-CRYOSTEM collaboration opens new research perspectives by providing access to raw material. This approach would impact CAR-T cells treatments by providing a large amount of post-infusion data, contributing to consolidating knowledge on this recent cell-based therapeutic approach.

This initiative, focused on lymphoma, sets up the bases of the constitution of new type of collection integrating complementary expertise and actors in CAR-T care and research. It will constitute a proof of concept for other initiatives in this field, independently of the initial hematological disease.

Clinical Trial Registry: Non applicable

Disclosure: Any conflict of interest

P090 CAR T Cell Therapy Directed against CD19 in Patients with B-cell Lymphoma after an Allogeneic Hematopoietic Stem Cell Transplantation (AlloHCT) is Feasible and Safe

Maria-Luisa Schubert ¹, Sascha Dietrich¹, Anita Schmitt¹, Petra Pavel², Alexander Kunz¹, Andrea Bondong¹, Mandy Wegner¹, Peter Stadtherr¹, Susanne Jung³, Stephan Stilgenbauer⁴, Anthony Ho¹, Carsten Müller-Tidow¹, Michael Schmitt¹, Peter Dreger¹

¹University Hospital Heidelberg, Heidelberg, Germany, ²German Red Cross Blood Service Baden-Wuerttemberg-Hessen, Heidelberg, Germany, ³Diakonie Hospital Stuttgart, Stuttgart, Germany, ⁴Saarland University Medical Center, Homburg, Germany

Background: CD19-directed chimeric antigen receptor T cells (CARTs) have been successfully used in patients with acute lymphoblastic leukaemia (ALL) after a preceding allogeneic stem cell transplantation (alloHCT). However, data on feasibility and outcome of CARTs in patients previously allotransplanted for B-cell lymphoma are lacking. Here, we report our institutional experience in this setting.

Methods: Course and outcome of allo-grafted patients treated with CD19 CARTs for B-cell lymphoma between October 2018 and November 2019 were studied in a single-center retrospective analysis. CARTs were administered either as third-generation CARTs within the Heidelberg CART 1 (HD-CAR-1) clinical trial (Eudra-CT No. 2016-0048; NCT03676504), or with commercially manufactured second-generation CARTs Axicabtagene Ciloleucel (Axi-cel, Gilead). Number of infused CARTs ranged from 1x10⁶-2x10⁷/m² (HD-CAR-1) or were within the label-specified range (Axi-cel).

Results: 10 CART dosings using recipient leukapheresis products have been administered to 8 patients: 4 patients (2 mantle cell lymphoma (MCL), 2 CLL) received 6 infusions with HD-CAR-1 CARTs. 4 patients (all with DLBCL) received 4 infusions with Axi-cel. Lymphodepleting chemotherapy with flu/cy (30/500 mg/m²/d for 3 days) was administered to all patients prior to CART infusion. All 8 patients were male with a median age of 57 (27-70) years. A median of 4 (3-11) treatment lines had been administered during 5.8 (1.5-12.5) years from diagnosis. Median time from alloHCT to CART treatment was 2.4 (1.0-8.2) years. AlloHCT had been performed from matched related (MRD) (3), matched unrelated (MUD) (4), or haplo (1) donors after myeloablative conditioning. Acute and chronic GvHD after alloHCT had been observed in 2 and 6 patients, respectively. No patient had active GvHD or was under immune suppression at the time of leukapheresis and all patients had active disease. CART treatment was well tolerated with higher grade CRS and ICANS each being observed after 1 of 10 evaluable dosings. Patients had complete resolution of CRS and ICANS following administration of tocilizumab and steroids, respectively. A single patient had cutaneous and hepatic reactions suspicious of chronic GVHD early after dosing, whereas all other dosings were not accompanied by GVHD. CARTs were detectable in the peripheral blood (PB) in all but one patient. The patient developing ICANS displayed the highest CART frequency in the PB. With a median follow-up of 108 (18-314) days, all patients are alive with an overall best response rate of 88%. 3 of 7 evaluable patients achieved ongoing CRs. B cell aplasia and cytopenia were observed in all patients following CART dosings. B cell aplasia is ongoing in 8 instances and long-term (>1 month) leukopenia and thrombocytopenia were observed following 8 and 7 dosings, respectively.

Conclusions: Therapy with CARTs manufactured from recipient-derived leukapheresis products after prior alloHCT was feasible, safe and efficient. Therefore, CARTs as salvage treatment for patients with B-cell lymphoma relapsing after alloHCT constitute a justifiable treatment option. Cytopenia as a result of multiple myelotoxic treatments needs to be carefully monitored.

Disclosure: Dreger: AbbVie, AstraZeneca, Gilead, Janssen, Novartis, Riemser, Roche: Consultancy; AbbVie, Gilead, Novartis, Riemser, Roche: Speakers Bureau; Neovii, Riemser: Research Funding; MSD: Membership on an entity´s Board of Directors or advisory committees, Other: Sponsoring of Symposia. Schmitt: Therakos Mallinckrodt: Other: Financial Support. Sellner: Takeda: Employment. Müller-Tidow: MSD: Membership on an entity´s Board of Directors or advisory committees. Schmitt:Therakos Mallinckrodt: Other: Financial Support; MSD: Membership on an entity´s Board of Directors or advisory committees, Other: Sponsoring of Symposia. Stilgenbauer: Pharmacyclics: Other: Travel support; Gilead, Celgene, Amgen, AbbVie, Novartis, AstraZeneca, Hoffmann La-Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau.

P091 Lymphocyte Collection for Generation of CAR T-cells in Pediatric Patients: A Single Center Experience

Giovanna Del Principe ¹, Giovanna Leone¹, Annalisa Ruggeri¹, Simone Biagini¹, Elia Girolami¹, Stefania Lazzaro¹, Antonella Meschini¹, Francesca Del Bufalo¹, Manuel Broglia¹, David Malaspina¹, Katia Feri¹, Federica Galaverna¹, Pietro Merli¹, Valentina Bertaina¹, Mattia Algeri¹, Mauro Montanari¹, Andrea Onetti Muda^1,2, Giuseppina Li Pira¹, Franco Locatelli^1,3

¹Bambino Gesù Children’s Hospital, Rome, Italy, ²Campus Bio-Medico Univerisity, Rome, Italy, ³Sapienza University of Rome, Rome, Italy

Background: Chimeric antigen receptor (CAR) T-cell therapy is a novel anti-tumor strategy in which autologous T-cells are engineered to express a CAR construct targeting an antigen expressed on membrane malignant cells. The CAR T-cell manufacturing process consists of different steps performed by different units, namely apheresis, cell therapy laboratory and the clinical unit. The collection of patient’s T-cells by the apheresis unit is the first step, followed by the characterization and manipulation of the cell product.

Herein, we report on 70 apheresis procedures performed on children and young adults with hematological and non-hematological diseases who underwent PBMC purification and cryopreservation for subsequent CAR T-cell production for academic trials at our institution.

Methods: Seventy collections were performed between January 2017 and November 2019; 51 patients were males, 19 females, median age being 9 years (range, 3-25) and median body weight (BW) 24 kg (range, 11-106). Indication for CAR T-cell production was refractory/relapsed Acute Lymphoblastic Leukemia (ALL, n=27), non-Hodgkin’s lymphoma (NHL, n=6) or Neuroblastoma (NBL, n=37). Leukapheresis was performed by Spectra Optia using continuous and discontinuous mononuclear cell protocol (CMNC vs MNC), with a collection target >4x10*9 mononuclear cells (MC). In 37/70 (53%) cases, patients had a central venous double lumen catheter (CVC), 17/70 (24%) were collected through peripheral venous accesses (VP) and 16/70 (23%) using both approaches (CVC+VP). Sodium heparin and Acid Citrate Dextrose Solution-A (ACD-A) were used in combination as anticoagulants. After apheresis, a density gradient PBMC purification using the Sepax 2 device was performed and the MCs were eventually cryopreserved.

Results: The median lymphocyte counts before apheresis were 1080/ul (200-4070). Out of 70 collections, 34/70 were performed using MNC (49%) and 36/70 using CMNC (51%). For all patients, the median total blood volume (TBV) processed was 2.1L (0.59-4.3), while for patients < 15kg (11/70, 16%) the processed TBV was 2.7L (1.6-4.3). Apheresis bags contained a median of 5.2x10*9 nucleated cells (1.5-15.4). Lymphocyte collection efficiency (lympho-CE) had a median value of 68% (range, 24-100). 27 products from ALL patients, 6 products from NHL patients and 37 products from NBL patients underwent a density gradient purification for PBMC enrichment. For ALL and NHL patients, median recovery for MNC was 76% (61-93) and median red blood (RBC) depletion was 81% (45-94). Total MNC and CD3 cells were 2.75x10*9 (0.84-8.26) and 1.33x10*9 (0.58-2.74) respectively. For NBL patients, median recovery for MNC was 73% (54-89) and RBC depletion was 79% (64-96). Total MNC and CD3 cells were 2.7x10*9 (1.0-6.0) and 1.0 (0.4-8.0).

Conclusions: Sufficient numbers of cells can be obtained from pediatric patients with BW < 15 kg, with a median value of processed TBV of 2.7L (1.6-4.3), provided that their lymphocyte counts are >900/ul. All patients reached the target cells in a single apheresis, including 2 patients with lympho-CE < 30%. In 56/70 (80%) of collections, lympho-CE was ≥50%.

Density gradient purification with the Sepax device is helpful to remove a fraction of RBC, allowing subsequent cryopreservation of pure products in which CD3+ cell concentration is higher with respect to other cellular components.

Disclosure: Nothing to declare.

P092 Baseline Hypoalbuminemia does not appear to be an Adverse Prognostic Factor in Patients with Relapse/Refractory B-cell Lymphomas Treated with Axicabtagene Ciloleucel (Axi-cel)

Megan Melody ¹, Sangeetha Gandhi², Zaid Abdel Rahman¹, Paula Lengerke Diaz³, Nicole Gannon¹, Allison Rosenthal³, Taun Truong², Mattia Novo^2,4, Eva Brandes², Gina Lange², Breana Etsby², Patrick Johnston², Steve Ansell², N. Nora Bennani², Jonas Paludo², Jose Villasboas Bisneto², Ernesto Ayala¹, Han W. Tun¹, Hemant Murthy¹, Vivek Roy¹, James Foran¹, Januario Castro³, Yi Lin², Mohamed Kharfan-Dabaja¹

¹Mayo Clinic, Jacksonville, FL, United States, ²Mayo Clinic, Rochester, MN, United States, ³Mayo Clinic, Phoenix, AZ, United States, ⁴Azienda Ospedaliera Universitaria, Citta della Salute e della Scienza di Torino, Torino, Italy

Background: Axi-cel is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy that is approved for treatment of relapsed/refractory (R/R) large B-cell lymphoma and is associated with high response rates and durable remissions. Recent data show that axi-cel is effective across various adverse prognostic features, namely cell of origin, disease bulkiness, and extranodal disease, among others. Hypoalbuminemia is a known adverse prognostic factor in lymphomas. Yet, it is unknown if axi-cel overcomes the adverse prognostic feature of hypoalbuminemia in R/R large B-cell or transformed follicular lymphoma.

Methods: We conducted a retrospective analysis of patients treated with axi-cel across three Mayo Clinic campuses (Rochester, Jacksonville, and Phoenix) from 06/01/2016 until 12/01/2019. The primary objective of this analysis was to assess the correlation of hypoalbuminemia defined as a serum albumin levels ≤ 3.5 g/dL on day 0, prior to infusion on outcomes after axi-cel therapy.

Results: A total of 69 (male=48, 70%) patients (pts), median age of 53 (24-74) years received axi-cel. The median number of prior lines of therapy was 3 (2-8) (Table 1). Two pts had no available serum albumin levels at time of axi-cel infusion. Thirteen (19%) of 67 pts had hypoalbuminemia (median= 3.3 g/dL (range 2.5-3.5)) and the median follow-up of survivors in this group was 6.7 (1.7-17.8) months. The best overall response rate (ORR) and complete remission (CR) rates in these pts were 62% and 46%, respectively. One (8%) patient had stable disease and 4 (31%) had disease progression. On the other hand, 54 (81%) pts had a normal serum albumin (defined as > 3.5 g/dL) level (median=4.1 (range 3.6-5.1) g/dL) and the median follow up for survivors in this group was 5.4 (1.0-30.9) months. The best objective response rate (ORR) and complete remission (CR) rates in these pts were 81% and 41%, respectively. There was no difference in 1-year OS between the group with hypoalbuminemia (64% (95%CI=30-99%)) and the group with normal serum albumin level (57% (95%CI=34-79%), p=0.88. All grades cytokine release syndrome (CRS) was diagnosed in all 13 pts with hypoalbuminemia (100%) and in 48 of 54 (89%) pts without hypoalbuminemia. There was no difference in the median duration of CRS between pts with or without hypoalbuminemia [5 (1-11) days vs 5 (1-19) days, p=0.84]. Neurotoxicity (all grades) was observed in 8 (62%) pts with hypoalbuminemia compared 27 (50%) with normal albumin levels. There was no statistically significant difference in median duration of neurotoxicity between pts with hypoalbuminemia and those with normal baseline albumin levels [9 (range 1-56) days vs. 3 (range 0-25) days, p= 0.07].

Conclusions: Hypoalbuminemia does not have a significant impact on the outcomes of axi-cel therapy, including OS or the incidence of CRS or neurotoxicity. Large multicenter clinical trials are needed to validate these findings.

Clinical Trial Registry: None

Disclosure: Lin, Yi: Research funding: Janssen, Merck, Kite/Gilead, Celgene, BlueBird Bio, Takeda

Consulting: Janssen, Legend BioTech, JUNO, Celgene, BlueBird Bio, Kite/Gilead, Novartis, Gamida Cells, AlloGene.

DSMB: Sorrento

Steering committee: Celgene, Janssen, Legend Biotech

P093 Factors Predicting CD3+ Collection for the Production of Chimeric Antigen Receptor (CAR) T Cells

Silvia Monsalvo, Gonzalo Balsera, Gillen Oarbeascoa, Ana Perez-Corral, Mariana Bastos, Nieves Dorado, Rebeca Bailen, Ariana Ortuzar, Maria Reyes Martin, Maria Consuelo Vega, Carmen Granado, Carmen Falero, Nuria Ruano, Cristina Muñoz, Mi Kwon, Jose Luis Diez-Martin, Javier Anguita

Hospital Gregorio Marañón, Madrid, Spain

Background: Chimeric antigen receptor (CAR) T cells are a promising new immunotherapy. However, the challenges of collecting CD3+ lymphocytes in this population of patients have not been well-characterized. The aims of the study were to evaluate the feasibility of collection adequate numbers of CD3+ cells, analyze the rate of adverse events and to identify the variables that can predict inadequate collections.

Methods: We prospectively study the apheresis for lymphocyte collections (ALC) from patients in real live for CARs from May-19 to November-19. Collections were performed on the same Cobe Optia device, at hematocrit of 1 to 2% and collection flow rate of 0.8 mL/min. All patients had Hickman central venous catheters placed before the procedure, and received intravenous calcium gluconate as per SOP. The product goal was a target of 1 x 10⁹ CD3+ cells.

Results: 14 ALC were performed. Median age 59.5 years (28-69). 57%(n=8) were male. 57%(n=8) were sent for the production of axicabtagene ciloleucel, 43% for tisagenlecleucel. Diagnosis was 100% lymphoma, median of 16.4 months from the diagnosis to ALC (6-48.8). Ann arbor stage was 3 in 2 patients(14%), 4 in 11 patients(79%). 50%(n=7) received 3 or more prior lines of treatment. Potential treatment affecting the collection prior apheresis: 36%(n=5) purine nucleoside antimetabolites, 21% (n=3) received IMiDs, 50%(n=7) Autologous Stem cell transplant and 36% (n=5) radiotherapy. Last treatment before ALC was systemic chemotherapy in 7 patients (57%), radiotherapy 4 patients (29%), immunotherapy 2 patients (14%). Median of 45 days from the treatment to ALC (15-1000).

[Correlation between pre-apheresis CD3+ (cells/µL) neutrophils and CD3+ yield]

Pre-apheresis laboratory testing were : median leucocyte(x 10⁶/mL) of 4 (1-14.4), median hematocrit (%) 30.2 (25-41), median platelets (x10⁶/mL) 112 (25-345), median neutrophils (%) 63.5 (34.3-86), median lymphocyte (%) 20.2 (30.8-50), median NK (%) 3.2 (0.3-8.7), median (%) CD19+ 0(0-4.8), median CD3+ (cells/µL) 460 (147-2770), median CD3+(%) 12.2(4-38) of which median CD4+(%) 37.25(10-72) and CD8+(%) 55.9 (24.5-85)

Apheresis parameters were: median of 12 liters processed (5-15), collection efficiency median (%) 52.9 (40.9-75.5). One patient developed symptomatic hypotension during the procedure, other complications related to hypocalcemia including paresthesias were managed in the apheresis unit.

Apheresis collection yields from 13 products were: median volume of 199 mL (86-240), median hematocrit(%) 3.2 (1.8-17.7), median platelets(x10⁶/mL) 811(255-3784), median volume ACD-A(mL) 22(10-31), cell concentration (cellsx10⁶/mL) 58.9 (12.7-247.7), median total nucleated cells (x10⁹) 9.9 (2.8-52.5), median mononuclear cells(x10⁶/mL) 51.3(12.6-242.7). Median(%) CD3+ of CD45+ was 53(23-83.5) with a median total number of CD3+ (x10⁹) of 5.2 (1.1-17.3).

Univariate analysis showed that higher pre-apheresis CD3+ (cells/µL) was significantly correlated with CD3+ total collected cells in the apheresis product. Thus, there is an association with higher proportion of neutrophils in peripheral blood with lower pre-apheresis CD3+ counts (figure1).

Conclusions: In most patients undergoing CART cell therapy, leukapheresis is well-tolerated and adequate numbers of CD3+ lymphocytes are collected. A personalized approach to the collection process is the essential first step for CART cell immunotherapy. However, further studies of larger cohorts of patients including new variables are necessary to confirm this findings to ensure that all patients can have sufficient cells for manufacturing.

Disclosure: Nothing to declare.

P094 Cytopenias after Tisagenlecleucel in Paediatric/young Adult Patients with Refractory/relapse b-cell Acute Lymphoblastic Leukaemia (R/R B-all): A real-life Single-centre Experience

Ignacio Gómez-Centurión ¹, Saskia Burridge², Juliana Silva², Arina Lazareva², María Gabelli², Oana Mirci-Danicar², Giovanna Lucchini², Robert Chiesa², Kanchan Rao², Sujith Samarasinghe², Paul Veys², Ajay Vora², Persis Amrolia², Sara Ghorashian²

¹Hospital General Universitario Gregorio Marañón, Madrid, Spain, ²Great Ormond Street Hospital for Children, London, United Kingdom

Background: Tisagenlecleucel (Kymriah^TM) is a CD19-targeted CAR-T cell therapy approved for r/r B-ALL in paediatric/young-adult patients. Cytopenias following CAR-T cells are relatively common across multiple studies¹ including those targeting CD19 and CD22 and are therefore not antigen-specific. The incidence and clinical impact of persistent or recurrent cytopenias has been under-recognized in clinical studies to date and the aetiology is as yet unclear. The objective of this study is to describe cytopenias and related complications in paediatric/young-adult patients with r/r B-ALL treated with Tisagenlecleucel.

[1] Jacoby et al. https://doi.org/10.1038/s41409-019-0487-3

Methods: We retrospectively analyzed 12 consecutive patients with r/r B-ALL treated with Tisagenlecleucel between January 2019 and November 2019 in a single centre. Patients received lymphodepletion with fludarabine (120 mg/m2) and cyclophosphamide (1000 mg/m2). Cytopenias were graded according to CTCAE V-5.0. Persistent cytopenias were defined as grade 2-4 cytopenias after day-28. Recurrent cytopenias were defined as new-onset grade 3-4 cytopenias after day-28 when and after achieving normal counts on day-28. Cytopenias were considered resolved when grade 1 or normal counts were achieved.

Results: Patient characteristics are summarised in Table 1. Nine patients were diagnosed with relapsed B-ALL after HSCT, 2 had relapsed B-ALL with a contraindication for HSCT and 1 had primary refractory disease. With a median follow-up of 4 months (range 1-10) after CAR-T cell infusion, MRD was negative in 11 patients (92%), B cell aplasia was persistent in 10 (83%) and 1 (8%) had a relapse and died.

Eight patients (67%) presented with grade 2-4 cytopenias before lymphodepletion.

Before day-28, all patients developed grade 2-4 anaemia (9=75% grade 3-4), 8 patients (67%) developed grade 2-4 thrombocytopenia (6=50% grade 3-4), and all patients developed grade 3-4 neutropenia.

Four patients (33%) had persistent grade 2-4 anaemia, 2 (17%) grade 3-4. Five (42%) had persistent thrombocytopenia, all grade 3-4. Seven (58%) had persistent neutropenia, all grade 3-4. Two patients (17%) with normal counts on day-28, developed recurrent grade 3-4 neutropenia after day-28.

Secondary causes of cytopenias were excluded. Among patients with persistent cytopenias, 4 (50%) had a hypocellular marrow on histology of the BM trephine.

Eight patients (67%) received at least one RBC transfusion before day-28, and 2 (17%) after day-28. Three patients (25%) received at least one platelet transfusion before day-28, and 4 (33%) after day-28. Seven patients (58%) received at least one Filgrastim dose after day-28. Eight documented infections were diagnosed, 3 of them after day-28, with 0% of infection-related mortality.

At last follow-up, anaemia was resolved in all patients, 2 (17%) had ongoing thrombocytopenia, (1 with platelet transfusion dependence), and 3 (25%) ongoing neutropenia (1 with Filgrastim dependence).

Conclusions: Cytopenias were frequent in patients treated with Tisagenlecleucel. Whilst early cytopenias are expected due to lymphodepletion, mechanisms of persistent and recurrent cytopenias are unclear and might be related to CAR-T cells persistence. More studies are needed to determine etiology and risk factors for persistent cytopenias. Cytopenias are of relevance in terms of increased requirement for supportive care, however, in our cohort, were not associated with significant or persisting complications.

Disclosure: Nothing to declare.

P095 The risk of Hepatitis B Reactivation is controllable in B-cell Malignancies Patients with Concomitant Hepatitis B Virus Infection after Chimeric Antigen Receptor T Cell Therapy

Fang Ni ^1,2, Yongxian Hu¹, Alex Hong Chang³, He Huang¹

¹The First Affiliated Hospital, Zhejiang University, Hangzhou, China, ²Zhejiang University, Hangzhou, China, ³Shanghai YaKe Biotechnology Ltd, Shanghai, Shanghai, China

Background: Chimeric antigen receptor- modified (CAR) T-cell immunotherapy is a novel promising therapy for relapsed/refractory B cell malignancies. Prolonged B- cell aplasia is a common and expected toxicity after receiving CAR-T cell treatment. However, the risk of HBV reactivation after CAR-T cell therapy is still unknown. We summarized the risk of HBV reactivation in R/R B-cell Malignancies patients with Concomitant Hepatitis B Virus infection after Chimeric Antigen Receptor T Cell Therapy at our hospital.

Methods: Patients with R/R B-cell lymphoma, B-ALL and Multiple Myeloma who received CAR-T cell treatment in four clinical trials (ChiCTR-ORN-16008948, ChiCTR-OIC-17011310, ChiCTR1800015575, ChiCTR1800017404) in our center were retrospectively analyzed. All patients were screened for hepatitis B surface antigen (HBsAg), antibody to hepatitis B surface antigen (anti-HBs), antigen antibody to hepatitis B core antigen (anti-HBc) and HBV DNA copy numbers before and after CAR-T cell treatment. Those with positive HBsAg were eligible for this retrospective study.

Results: Between December 2017 and October 2019, 10 patients with relapsed or refractory B cell malignancies and concomitant HBV infection who were treated with CAR-T cells were included in this study. The median age was 50 years (range: 39-67 years), with 60% were male. Details are summarized in table I. All of the 10 patients with chronic HBV infection received prophylactic entecavir treatment. And at the time of CAR-T cell infusion, HBV DNA levels of all patients were lower than the normal limit. With median follow-up 7.77 months (range:1.43-23.8 months) from CAR-T cell infusion, 2patients (patient 9 and patient 10) had transient HBV reactivation. However, the HBV DNA copy numbers came back to lower than the normal limit with the entecavir and Adefovir treatment. All patients reminded on prophylactic NAT by the time of last follow-up. Figure1 showed the Time points of HBV detection and response after CAR-T cell treatment.

Conclusions: our results showed that CAR-T cell treatment could be safely administered in patients with Concomitant Hepatitis B Virus infection. Considering the small group sample size and retrospectively analysis, the risk of HBV reactivation with prophylactic entecavir treatment after CAR-T cell treatment should be further evaluated in large and prospective studies.

Patient1	39 y	Male	24 cycles treatment before CAR-T therapy	DLBCL	CD19-CD22	6.44*10^6/kg	No HBV reactivation
Patient2	60 y	Female	6	DLBCL	CD22	5.85*10^6/kg	No HBV reactivation
Patient3	55 y	Male	12	MM	BCMA	2.64*10^6/kg	No HBV reactivation
Patient4	49 y	Male	6	Aggressive B cell lymphoma	CD19-CD22	10.28*10^6/kg	No HBV reactivation
Patient5	43 y	Female	18	DLBCL	CD19-CD22	5.72*10^6/kg	No HBV reactivation
Patient6	47y	Male	5	B-ALL	CD19	5.6*10^6/kg	No HBV reactivation
Patient7	67 y	Male	7	MM	BCMA	3.49*10^6/kg	No HBV reactivation
Patient8	50 y	Female	9	MM	BCMA	5.59*10^6/kg	No HBV reactivation
Patient9	50 y	Female	6	Lymphoblast lymphoma	CD19-CD22	8.04*10^6/kg	Yes, and recovered after entecavir treatment
Patient10	53 y	Male	6	MM	BCMA	5.1*10^6/kg	Yes, and recovered after entecavir treatment

[Patient clinical characteristics before and after chimeric antigen receptor T cell therapy]

[Figure1. Time points of HBV detection and response after CAR-T cell treatment]

Clinical Trial Registry:

ChiCTR-ORN-16008948

ChiCTR-OIC-17011310

ChiCTR1800015575

ChiCTR1800017404

The website is http://www.chictr.org.cn

Disclosure:

Nothing to declare.

P096 Cumulative Rituximab Exposure Prior to Axicabtagene Ciloleucel is not associated with Persistent Leukopenia and Thrombocytopenia at Day +90 Post Infusion

Madiha Iqbal ¹, Sangeetha Gandhi², Abdullah Alselah², Muhamad Alhaj Moustafa¹, Ernesto Ayala¹, Hemant Murthy¹, Allison Rosenthal³, Jilan Kubusek², Justin Haynes², Tuan Troung², Patrick Johnston², Stephen Ansell², Nora Bennani², Jonas Paludo², Jose Villasboas Bisneto⁴, Breana Estby², Eva Brandes², Gina Lange², Januario Castro³, Yi Lin², Mohamed Kharfan-Dabaja¹

¹Mayo Clinic, Jacksonville, FL, United States, ²Mayo Clinic, Rochester, MN, United States, ³Mayo Clinic, Phoenix, AZ, United States, ⁴Mayo Clinic, Rochester, FL, United States

Background: Cytopenias occur frequently after axicabtagene ciloleucel (axi-cel), a recently approved anti-CD19 CAR-T cell therapy. The direct cause(s) of cytopenia (s) remains elusive. Rituximab has been associated with delayed onsent cytopenia in patients with non-Hodgkin lymphoma. Here, we investigate the impact of various patient- and pre-CAR-T treatment related factors including cumulative rituximab exposure, prior lines of treatment and prior auto-HCT on the persistence of cytopenia (s) in the setting of axi-cel.

Methods: We conducted a retrospective analysis of patients treated with axi-cel across three Mayo Clinic campuses (Rochester, Jacksonville, and Phoenix) from June 2016 until October 2019. Five patients received axi-cel in a clinical trial. The primary objective of this analysis was to identify factors associated with persistent cytopenias (leukopenia and thrombocytopenia) at day +90 in axi-cel recipients. Leukopenia was defined as less than 3 x10⁹/L and thrombocytopenia as a less than 100 x10⁹/L. Univariate analysis was used to analyze predictors and outcomes.

Results: A total of 57 patients, males (n=41, 72%), who had received a median of 3 (2-8) prior lines of therapy received axi-cel. Seventy three percent of patients (33/45, 12 patients had missing data) experienced at least a grade 1 cytopenia per CTCAE v5.0 at day+90. Twenty-four patients had failed a prior autologous transplant. The median number of prior rituximab doses was 8 (2-19). Pertaining to day +90 persistent leukopenia, age (≤ 52 vs. > 52 years, p=0.75), gender (p=0.72), number of prior therapies (p=0.80), a prior auto-HCT (p=0.66), and cumulative doses of rituximab (p=0.51) were not significant variables. None of these factors was predictive of persistent neutropenia (defined as less than 1.5 x10⁹/L) by day +90 post axi-cel. Pertaining to day +90 persistent thrombocytopenia, age (≤ 52 vs. > 52 years, p=0.3), gender (p=0.1), number of prior therapies (p=0.06), a prior auto-HCT (p=0.54), and cumulative doses of rituximab (p=0.06) were not significant variables.

Conclusions: Our analysis did not identify rituximab or any other patient- or pre-CAR-treatment related factors to be associated with persistence of leukopenia and thrombocytopenia at day +90 post axi-cel.

Characteristic	Total number of patients = 57
Age (years-range)	52 (25-68)
Gender (male)	41 (72%)
Histology	DLBCL:32(56%);PMBCL:6(11%);TFL: 11(19%);HGBCL:8(14%)
Prior lines of treatment (Median, range)	3 (2-8)
Autologous Stem Cell Transplant	24 (42%)
Number of Rituximab Doses (Median, range)	8 (2-19)
Time from initial diagnosis to CAR-T (Median, range)	13.7 months (3.2-193.6)

[Table 1]

Disclosure: YL declare.d the following conflicts of interest:

Research funding: Janssen, Merck, Kite/Gilead, Celgene, BlueBird Bio, Takeda

Consulting: Janssen, Legend BioTech, JUNO, Celgene, BlueBird Bio, Kite/Gilead, Novartis, Gamida Cells, AlloGene.

DSMB: Sorrento

Steering committee: Celgene, Janssen, Legend Biotech

MAK-D: consultancy for Daiichi Sankyo

Remaining authors disclose no relevant conflicts of interest.

P097 Comprehensive Immune Cell Monitoring Reveals an Altered Lymphocyte Subset Phenotype in Patients not Responding to Tisagenlecleucel One Month Post Infusion

Christian R Schultze-Florey, Victoria Panagiota, Ivan Odak, Sultan Bektas, Tabea C Froehlich, Aleksandra Gladysz, Zhixiong Li, Gernot Beutel, Matthias Eder, Immo Prinz, Reinhold Foerster, Arnold Ganser, Christian Koenecke

Hannover Medical School, Hannover, Germany

Background: Reconstitution of lymphocyte subsets following lymphodepletion and chimeric antigen receptor (CAR) T cell infusion is pivotal for pathogen control. Moreover, lymphocyte subsets are thought to support CAR T antitumor activity. In this prospective single center pilot study we aim to investigate whether failure of anti-CD19-CAR T cell (Tisagenlecleucel) response one month post infusion is associated with a specific lymphocyte subset phenotype.

Methods: Blood samples of eleven patients with relapsed or refractory transformed follicular lymphoma and diffuse large B cell lymphoma (DLBCL) were examined by multi-color flow cytometry. Following lymphodepletion with fludarabine and cyclophosphamide, all patients received Tisagenlecleucel. The institutional review board approved the study and all patients gave written informed consent for prospective immune cell monitoring. Lymphocyte subsets were detected from peripheral blood using a 10-color antibody mix for T, B, and NK cell subsets as well as activation markers via flow cytometry. For determination of absolute frequencies BD Trucount™ tubes were used. Treatment response to anti-CD19-CAR T therapy was assessed via PET-CT one month post infusion.

[Figure 1: Analysis of lymphocyte subsets in responders (R) vs. non-responders (NR) at day +28.]

Results: Blood samples and PET-CT data were available on 9 out of 11 patients one month post infusion of Tisagenleclucel. Disease progression or no response to therapy was observed in 3 patients, termed non-responders (NR). The remaining 6 patients, termed responders (R), all showed reduced PET activity, with two (33%) achieving complete metabolic remission and four (66%) achieving partial metabolic remission. We compared different lymphocyte subsets in non-resonders vs. responders on day +28 (range 11-34). Interestingly, non-responders displayed higher relative frequencies and absolute numbers of CD8+ and CD3+CD56+ cells and fewer CD3-CD56+ cells compared to responders, albeit lacking statistical significance, likely due to the small sample size (Figure 1A and B). Moreover, CD4:CD8 ratio was markedly lower in non-responders (0.53 vs. 2.73), implying a shift in immune response. Further analysis of activation markers in conventional CD4+ (CD4_conv) and CD8+ cells revealed a trend towards decreased central memory populations in non-responders (Figure 1C and D).

Conclusions: Immune cell monitoring of lymphocyte subsets in CAR T cell patients may provide important insights in immune function supporting CAR T cell activity. In this prospective single center pilot study we describe an altered lymphocyte subset phenotype in patients failing to respond to Tisagenlecleucel. The phenotype consisted of a reduced CD4:CD8 ratio, lower CD3-CD56+ frequencies and central memory populations together with higher CD8+ and CD3+CD56+ populations. However, these data are limited by the small cohort size and warrant further validation in a larger cohort.

Disclosure: Nothing to declare.

P098 Neurotoxicity associated with CAR T Cell Therapy: Neurological Management and work-up of 11 Adult Patients

Nora Moehn, Viktoria Bonda, Mike P. Wattjes, Victoria Panagiota, Sascha David, Gernot Beutel, Matthias Eder, Martin Stangel, Arnold Ganser, Christian Koenecke, Thomas Skripuletz

Medizinische Hochschule Hannover, Hannover, Germany

Background: Treatment with CD19 chimeric antigen receptor (CAR) T cells represents a novel treatment approach for patients with relapsed or refractory diffuse large B cell lymphoma (r/rDLBCL) or B-lineage acute lymphoblastic leukemia (ALL). However, impressive therapeutic response rates are often accompanied by specific and severe toxicities. Besides the common cytokine release syndrome (CRS) which is characterized by fever, hypotension, hypoxia, and in more severe cases multisystem organ dysfunction, specific neurotoxicity termed immune effector cell-associated neurotoxicity syndrome (ICANS) has been observed as well and is treated as a separate entity with distinct timing and treatment requirements. Although symptoms can be more diverse than those of CRS, many patients with neurotoxicity show specific clinical features with expressive aphasia being one of the most characteristic ones.

Methods: Eleven r/rDLBCL patients have been treated with Tisagenlecleucel at Hannover Medical School between April 2019 and November 2019. All patients received an extensive neurological examination prior to CAR T cell infusion. This included clinical examination, handwriting sample, cognitive testing (Montreal-Cognitive-Assessment (MoCA)), brain magnetic resonance imaging (MRI), electroencephalogram (EEG), electroneurography (ENG), and analysis of cerebrospinal fluid (CSF) in 8/11 patients. After CAR T cell infusion, patients were neurologically examined for 10 consecutive days. Up to 4 weeks following infusion, we assessed all patients at least once a week.

Results: Baseline clinical neurological examination and ENG showed signs of axonal polyneuropathy in 10 of 11 patients before CAR T cell therapy indicating damage due to prior chemotherapy. Two patients presented with slightly impaired MoCA-results (25/30 points) and 1 patient achieved only 23/30 points prior to CAR T cell treatment. Brain MRI was unremarkable in all cases. CSF did not show signs of inflammation in all 8 patients (cell count 1-3/µl, oligoclonal bands negative) and no relevant disturbance of the blood-CSF-barrier (Qalbumin 4.7-8.5). No one exhibited antineuronal or autoimmune encephalitis antibodies. During the four-week follow-up period one patient developed a severe CRS at day 5 accompanied by mild signs of cognitive impairment (MoCA minimum 23/30), but without abnormalities in brain MRI. He died on day 23 following CAR T cell therapy due to infection. Two patients exhibited signs of cognitive impairment at day 4 and 5, respectively. Both patients showed very similar symptoms including apraxia, expressive aphasia, disorientation, and hallucinations. Symptoms developed very quickly, while brain MRI was inconspicuous in either case. Grade 2 ICANS was assumed in both patients and both were treated with dexamethasone 40 mg/d. As symptoms rapidly resolved steroid treatment was quickly tapered and stopped after 5 days. Both patients showed neither signs of cognitive nor neurological impairment afterwards.

Conclusions: Neurotoxicity is a feared complication of CD19 CAR T cell therapy and initial symptoms can be very subtle. Our longitudinal examinations in 11 patients revealed specific clinical symptoms of ICANS in 2 patients without relevant radiological abnormalities. Further studies with higher numbers of patients including a structured and detailed neurological examination are required to uncover CD19 CAR T cell-related neurotoxicity and its especially pathogenesis.

Disclosure: Nothing to declare.

P099 Nutritional Assessment of Patients undergoing CD19-targeted CAR-T Therapy for Non-hodgkin’s Lymphoma and the Short Term Effect of Treatment on Nutritional Status

Katie Ahern, Shafqat Inam, Katie Walker, Orla Stewart, Victoria Potter, Piers Patten, Andrea Kuhnl, Deborah Yallop, Reuben Benjamin, Robin Sanderson

Kings College Hospital NHS Foundation Trust, London, United Kingdom

Background: Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 has demonstrated efficacy in the treatment of relapsed and refractory B cell non-Hodgkin lymphoma. In haematological cancers, nutrition is a concern, particularly in patients undergoing high dose therapies and haemopoietic stem cell transplantation (HSCT). The high-dose radiotherapy/chemotherapy associated with treatment and its typical spectrum of side effects, including nausea, vomiting, mucositis, diarrhoea and infections, further impacts oral food tolerance. This contributes significantly to weight loss (WL), particularly in the first 40 days of admission. As of yet, there have been no reports on the effects of CAR T-cell therapy on nutritional status.

The aim of this study is to report on the nutritional status of patients undergoing CAR T-cell therapy for CD19 positive non Hodgkin lymphoma, both prior to, and during their approximate 3-4 week inpatient admission for treatment.

Methods: 40 patients who underwent treatment between January and October 2019 had a comprehensive nutritional assessment prior to receiving CAR T-cell therapy. Of these patients, 39 had diffuse large B cell lymphoma and one patient mediastinal B cell lymphoma. They were reviewed during their inpatient admission stay and symptoms which impair nutritional intake (e.g. diarrhoea, poor appetite) were monitored, as well as WL and their requirement for oral, enteral and parenteral nutritional interventions.

Results: 25% of patients were identified as malnourished prior to treatment with poor nutritional status typically being related to pre-existing chronic illness e.g. inflammatory bowel disease or disease involving the GI tract. 38 patients were nutritionally assessed as inpatients in the 3-4 weeks after infusion of CAR T-cells. During this period, no significant impact on body weight (5% or more WL) was observed in 66% of patients who underwent therapy. This is hypothesised to be due to the reduced observation of side effects such as vomiting, diarrhoea and mucositis, which are frequently observed with other treatments for haematological cancers, in particular HSCT.^. Significant WL during this period (>10% of body weight) was observed in 8% (n=3) of patients.

50% of patient’s required nutritional supplements to meet their requirements and prevent unintentional WL during their admission. 18% (n=7), including all patients who suffered neurotoxicity required a period of enteral feeding via nasogastric tube. In the other 3 cases, nasogastric tube feeding was indicated due to severe anorexia/malnutrition or dysphagia due to disease being localised to the neck region.

Conclusions: CAR T-cell therapy appears to have a less significant impact on nutritional status than other similar treatments for haematological malignancies, primarily due to a lower incidence in adverse effects. However, all patients undergoing treatment should be nutritionally screened prior to treatment due to the high incidence of malnutrition in this population group. Patients who experience neurotoxicity are also at high risk of malnutrition and are likely to require nasogastric enteral feeding for a period to prevent significant WL. Further research on the impact of neurotoxicity on nutritional status, and longer term follow up on the nutritional impact of CAR T-cell therapy is required to influence future dietetic practice in this field.

Disclosure: Nothing to declare.

P100 Effectiveness of Autologous Leukapheresis Collections for CAR T-cell Manufacturing in Patients with B-cell Malignancies

Udo Holtick, Anja Jühling, Philipp Gödel, Hyatt Balke-Want, Nadine Kutsch, Özlem Aylikci, Linda Wilhelm, Hanna Birkholz, Christof Scheid, Peter Borchmann

Universität Köln, Köln, Germany

Background: Chimeric antigen receptor (CAR) T-cell therapy is a novel and promising cellular treatment modality for a variety of malignancies. So far, it is mainly being used in haematological malignancies including relapsed or refractory high-grade lymphoma, acute lymphoblastic leukemia (ALL) and multiple myeloma. An autologous leukapheresis product is collected as source material for the CAR T-cell manufacturing process. This cohort of patients is typically heavily pre-treated, cytopenic and presenting significant disease- or treatment related complications. The effectiveness and feasibility of leukapheresis procedures in this setting was analysed.

Methods: In this retrospective analysis, 66 leukapheresis collections from patients participating in CAR T-cell clinical trials or from patients in preparation for CAR T-cell treatment with tisagenlecleucel in the commercial setting were reviewed. Collections were performed on the COBE Spectra apheresis device by experienced nurses. Pre-apheresis peripheral blood counts, apheresis parameters, and product cell counts were analysed.

Results: Patients with relapsed or refractory diffuse large B-cell lymphoma including Richter’s transformation (n=57), ALL (n=1), mantle cell lymphoma (n=3), follicular lymphoma (n=1) underwent leukapheresis collection for CAR T-cell production. Median age of the patients was 60 years (range 20-83). The median body weight of the patients was 73kg (range 39-137). Median pre-collection CD3 and lymphocyte counts were 540/µl (range 30-3400) and 620/µl (range 90-4960), respectively. The median pre-collection leukocyte count was 5240/µl (range 700-52650) and the median hematocrit was 30% (range 18-44). A median number of 3,92 x10e9 CD3+ T-cells was collected (range 0,2-18,23 x10e9) by processing a median number of 2,1 total blood volumes (range 0,4-3,8). This corresponds to a collection of 0,37x10e9 CD3+ T-cells per liter blood processed. The collection efficiency was 60% (CE2). Only one patient failed to collect sufficient T-cells, in this case in the context of massive tumor progression and infection. Two patients had to be collected twice on consecutive days. Vascular access was a central line in 32 and a peripheral vein in 34 procedures. Leukapheresis was well tolerated in all cases.

Conclusions: Our data demonstrates that a standard leukapheresis is effective to collect sufficient CD3 T-cells for CAR T-cell production. Patients can be safely and successfully collected with CD3 counts down to 50-100 CD3 T-cells/ µl peripheral blood. Follow-up of completed infusion rates and reasons for infusion failure are currently under investigation and will be presented.

Disclosure: The authors have no conflict of interest to disclose.

P101 Definition and Implementation of Clinical and Quality Endpoints in Centers Administering a Commercial CAR-T Product

Ron Ram, Ronit Gold, Odelia Amit, Yael Bar-On, Rinat Eshel, Chava Perry, Nadav Sarid, Yair Herishanu, Noam Benyamini, Irit Avivi

Tel Aviv Medical Center, Tel Aviv University, Tel Aviv, Israel

Background: CAR-T (Chimeric Antigen Receptor Therapy) has become an acceptable therapy option in patients with chemo-refractory DLBCL. Patients in most cases have a rapidly progressive disease hence the CAR-T process should follow a very strict time course to ensure high percentage of patients receiving the final product, while maintaining patents’ safety and product integrity. We aim to develop a clinical and quality management system to ensure the overall success of the procedure.

Methods: We established a system to allow a CAR-T team to self-assess against a group of standard guidelines/procedures. This system will serve as a control process to review, analyse, implement and improve suboptimal results. All subprocesses of the CAR-T were identified and individually dissected into different parameters based on the CARTangle - our unique centre model based on 3 domains - patient, disease and logistics. Subprocesses and domains are prospectively monitored for defined endpoints, flaws, deviations and events, corrective actions and change control procedures are then implemented, when indicated.

Results: The following subprocesses were defined - 1. Referral of a patient and eligibility criteria for the CAR-T program, 2. Bridging to apheresis, 3. Bridging to infusion, 5. infusion of the product and short-term follow-up, and 6. Long-term follow-up. The correspondence clinical and quality management parameters are defined below (Table). Data of enrolled patients with the corresponding quality management parameters will be presented at the meeting.

Conclusions: This pivotal clinical and quality management system is an ongoing process and is obliged to maximize patients and products´ safety and performance.

Disclosure: Nothing to declare.

P102 CAR-T in Breast and other extra-medullary Relapsed/refractory All

Francesco Paolo Tambaro ^1,2, Sajad Khazal², Dristhi Ragoonanan², Priti Tewari², Demetrios Petropolous², Jeffrey A Miller², William G Wierda², Richard E Champlin², Kris M Mahadeo²

¹AORN Santobono-Pausilipon, Naples, Italy, ²Univeristy of Texas MD Anderson Cancer Center, Houston, TX, United States

Background: Extra-medullary ALL develops in sanctuaries including, CNS, genitourinary and “sequestered sites” (gut, breast, skin). Data regarding complete remission (CR) rates and durability of response among patients receiving CART with relapsed/refractory (r/r) ALL and extra-medullary disease is still emerging.

Methods: We report two AYA patients with r/r ALL and extra-medullary involvement who achieved CR after tisagenlecleucel.

Results: Patient 1 was refractory to 7 prior lines of therapy and developed CNS, liver, spleen and bilateral kidney involvement; He experienced CD19 negative relapse approximately 8 weeks later. He subsequently achieved CR following two doses of inotuzumab and then received a reduced intensity (RIC) related haplo-identical SCT. He experienced a CNS relapse approximately 2 months later and died shortly after. Patient 2 had isolated bilateral breast involvement following allogeneic stem cell transplantation (SCT). She experienced swelling and erythema of the breast tissue following CART and achieved MRD negative CR in the bone marrow with partial response in the breast. She subsequently received XRT to the breast and was consolidated with a RIC SCT. She died approximately 100 days post-SCT from sepsis.

Conclusions: The majority of 53 reported patients with ALL and extra-medullary breast involvement (22 occurred post-SCT) received combined radiation and chemotherapy; 4 received DLI and achieved CR but 2 died of severe GvHD. CAR-T cells, may likewise circulate and act in sequestered sites but without GvHD. Lympho-depletion preceding CAR-T may also eliminate regulatory T lymphocytes and potentially enhance the immune response. Combined treatment with CAR-T and radiation may help eradicate extra-medullary disease, taking advantage of the local death of dividing cells with radiation with potential enhancement of the microenvironment to facilitate CAR-T function and enhance anti-tumor immune response of resident T cells. Future studies will elucidate the optimal timing of CART among patients with extra-medullary disease, which may improve durability of response and long-term outcomes.

Disclosure: Nothing to declare.

P103 Predicting CAR T-cell Infusion after Successful Manufacturing: real-world Data

Georg-Nikolaus Franke, Eberhard Schleyer, Konstantin Weibl, Hansjakob Fries, Sophia Michel, Rosmarie Pointner, Dominic Brauer, Sandra Otto, Uwe Platzbecker, Vladan Vucinic

University of Leipzig Medical Center, Leipzig, Germany

Background: CAR T-cells directed against CD19 are a newly approved cellular therapy for treating patients (pts) with relapsed or refractory (r/r) pediatric and adolescent acute lymphoblastic leukemia or diffuse large B-cell lymphomas (DLBCL). Given the aggressive nature of the underlying diseases bridging pts from lymphapheresis (LA) to CAR T-cell infusion remains a challenging task. Very little is known on factors predicting successful bridging pts during this period in the real world population.

Methods: We evaluated clinical variables potentially affecting successful re-infusion of CAR T-cells in pts receiving CD19 CAR tisagenlecleucel at our CAR T-cell center.

Results: Ten pts were assigned to CAR T-cell therapy and underwent LA between May to August 2019 for r/r DLBCL. 3 pts died prior to infusion. 7 pts received CAR T-cells after a median time of 49 days after LA. Pts receiving the CAR T-cells presented with lower lactate dehydrogenase (LDH) and C-reactive protein (CrP), better ECOG performance score (PS) at the time of LA and had received fewer lines of therapy than patients not receiving CAR T-cells. We developed a scoring system, which included the mean LDH (>8.3 µkat/l) and CrP (>90 mg/l) at the time of LA forpatients that did not receive the CAR T-cells (2 points each), ECOG PS (1 point per ECOG PS), lines of therapy after 1^st salvage (1 point per line) and referral from an external hospital (1 point) in order to predict outcome. All but one patient receiving the CAR T-cells had a score of < 5.

Conclusions: Bridging eligible patients from LA to CD19 CAR T-cell infusion remains a challenge. Patients with a CAR T score >4 should be considered to be at higher risk for complications. The proposed score has to be evaluated in a larger cohort.

Disclosure: Franke: Novartis, Pfizer, Jazz, MSD, Takeda: Honorary. Gilead: travel support

Vucinic: Novartis, Gilead, Takeda, Abbvie: Honorary

P104 Evaluation of the Interest of a Drug Reconciliation Activity in Patients Treated with Car T-cells: A Descriptive Study

Flore Durieux ¹, Nicolas Simon^1,2, Héloïse Henry^1,2, Benjamin Podvin¹, Marc Ducatel¹, Amandine Legrain¹, Valentin Douilly¹, David Beauvais¹, Bertrand Décaudin^1,2, Ibrahim Yakoub-Agha^1,3, Pascal Odou^1,2

¹CHU Lille, Lille, France, ²University of Lille, Lille, France, ³LIRIC, INSERM U995, Université de Lille, Lille, France

Background: CAR T-cells (CARTc) are patient T-cells that express artificial chimeric antigenic receptors (CAR) capable of recognizing tumor cells antigen. Axicabtagene ciloleucel is indicated in patients with relapsed diffuse large B-cell lymphoma or those who are refractory to other treatments. A medication reconciliation activity has been carried out since the beginning of 2019. The objective is to assess the value of medication reconciliation at admission of patients receiving CARTc.

Methods: A medication reconciliation have been conducted by pharmacy students under the supervision of pharmacists for patients receiving CARTc. A medication history, including self-medication treatments, has been established according to at least 3 information sources. Intentional or unintentional discrepancies were underlined for each difference between the medication history and the first medical prescription at admission. Pharmaceutical interventions (PI) resulted from a discrepancy. Medication adherence was assessed according to the medication adherence scale of our national insurance system. Patients were considered: good, minimal or not adherent. In parallel, allergies and medication difficulties were reported. Data were prospectively recorded anonymously on an Excel^® datasheet.

Results: Between January 3^rd and October 30^th, 2019, 30 patients received CARTc. The age was 60±10 years and gender ratio was 0.7. Patients received 4±2 previous lines of treatment. Reconciliation could have been performed in 18 patients. They took an average of 6 medications ([1; 19]), notably anti-infectious prophylaxis: valaciclovir (N=12/18) and co-trimoxazole (N=9/18). Intentional discrepancies (N=93) and unintentional discrepancies (N=8) were found. Six PI were formulated, and 5 accepted: 1 discontinuation of lansoprazole (no indication found), 1 dose adjustment for irbesartan, 1 dosage error for morphine, 2 missed treatment continuations (pravastatin and isradipine). Patients were considered good adherent (N=4/18), minimal adherent (N=12/18) and not adherent (N=2/18). The main reasons for low adherence were notably: too many tablets to take, forgetfulness, and delays. No patients had any trouble for drug intake. Acetaminophen was the main self-medicating drug.

Conclusions: During the study period, some patients were not reconciled due to a lack of staff in the department, particularly at the beginning of the year. Usually, the studied population takes few drugs. Therefore, some patients took more than 10 drugs. In this study, drug adherence was often minimal as shown in a literature review that evaluates drug adherence in patients receiving hematopoietic stem cell transplantation¹. This shows that reconciliation activity for these patients appears essential in order to review treatments, insist on medication adherence and to prevent the risks of drug-drug interaction, especially with the conditioning regimen. The data from this preliminary study need to be confirmed on a larger population.

¹ Morrison CF, Martsolf DM, Wehrkamp N, Tehan R, Pai ALH. Medication Adherence in Hematopoietic Stem Cell Transplantation: A Review of the Literature. Biology of Blood and Marrow Transplantation. avr 2017;23(4):562-8.

Clinical Trial Registry: /

Disclosure: /

CAR-based Cellular Therapy – preclinical

P105 Breaking PD-l1-mediated Resistance in anti-CD19 and anti-CD22 Car T Cells with PD-1/CD28 Fusion Receptors

Franziska Blaeschke ¹, Antonia Apfelbeck¹, Dana Stenger^1,2, Jasmin Mahdawi¹, Mareike Lepenies¹, Felicitas Rataj³, Semjon Willier¹, Theresa Kaeuferle¹, Thomas G. P. Gruenewald^2,4, Robbie G. Majzner⁵, Dirk H. Busch^6,8, Sebastian Kobold³, Tobias Feuchtinger^1,2,7

¹Dr. von Hauner Children’s Hospital, Medical Center of the University of Munich, Munich, Germany, ²National Center for Translational Oncology Research (DKTK), Munich, Germany, ³Medical Center of the University of Munich, Ludwig-Maximilians University Munich, Member of the German Center for Lung Research, Munich, Germany, ⁴Max-Eder Research Group for Pediatric Sarcoma Biology, Ludwig-Maximilians University Munich, Munich, Germany, ⁵Stanford University, Stanford, CA, United States, ⁶Technical University Munich, Munich, Germany, ⁷National Center for Infection Research (DZIF), Munich, Germany

Background: Therapy with autologous T cells expressing an anti-CD19 chimeric antigen receptor (CAR) has been recently approved for patients with B-cell lymphoma and B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Despite tremendous success in pediatric BCP-ALL, 40 to 50% of the patients do not experience long-term relapse-free survival after CAR T-cell treatment. Allogeneic stem cell transplantation (allo-SCT) is offered to selected patients after CAR treatment to prevent relapse.

Methods: To increase functionality of conventional anti-CD19 and anti-CD22 CAR T cells pre allo-SCT and protect the T cell from leukemia-mediated inhibition, a PD-1/CD28 fusion receptor was designed. Fusion receptors convert an inhibitory signal into an intracellular activation cascade. PD-1/CD28 anti-CD19 and anti-CD22 CAR T cells were functionally characterized and compared to conventional CAR T cells in terms of cytotoxic capacity, proliferation, activation and cytokine release after single and multiple contact with leukemic cells.

Results: The impact of prominent co-inhibitory immune checkpoint axes (such as PD-1/PD-L1) for relapse or non-response to CAR T-cell therapy is not yet fully understood. Bone marrow analyses of >100 BCP-ALL patient samples pre allo-SCT showed substantial heterogeneity in initial PD-L1 expression levels of leukemic blasts and the ability to up-regulate PD-L1 upon T-cell attack. Cytokine release of conventional 2^nd generation anti-CD19 CAR T cells was significantly reduced after contact with a PD-L1 overexpressing ALL. We hypothesized that a PD-1/CD28 fusion receptor can increase functionality of conventional CAR T cells while protecting the T cell from leukemia-mediated inhibition. Anti-CD19 CAR T cells with PD-1/CD28 fusion receptors were generated and showed strong CD19-dependent cytotoxicity, proliferation, activation and cytokine release. No unspecific cytokine release mediated by the fusion receptor in absence of CD19 was detected. In presence of PD-L1, fusion receptor CAR T cells out-competed conventional 1^st and 2^nd generation anti-CD19 CAR T cells and released significantly higher levels of Th1 cytokines IFN-γ, IL-2 and TNF-α. PD-1/CD28 anti-CD19 CAR T cells were able to persist after >4-fold stimulation with leukemic cells and showed significantly increased long-term killing capacity and cytokine release compared to conventional CAR T cells after multiple stimulations. Superiority of CAR T cells with PD-1/CD28 fusion receptor was confirmed in an anti-CD22 CAR T cell model.

Conclusions: Anti-CD19 and anti-CD22 CAR T cells with PD-1/CD28 fusion receptor can increase functionality of conventional CAR T cells by circumventing leukemia-induced T-cell inhibition pre allo-SCT.

Disclosure: Nothing to declare.

P106 Allogeneic Chimeric Antigen receptor-invariant Natural Killer T Cells Exert Both Direct and Indirect Antitumor Effects through Host Cd8 T Cell cross-priming

Federico Simonetta ^1,2, Toshihito Hirai¹, Juliane K. Lohmeyer¹, Kristina Maas-Bauer¹, Maite Alvarez¹, Arielle S. Wenokur¹, Jeanette Baker¹, Amin Aalipour¹, Samuel Haile³, Crystal L. Mackall³, Robert S. Negrin¹

¹Stanford University, Stanford, CA, United States, ²Geneva University Hospitals, Geneva University, Geneva, Switzerland, ³Stanford Cancer Institute, Stanford, CA, United States

Background: Chimeric antigen receptor (CAR) T cells have shown impressive results in B-cell malignancies but, unfortunately, their widespread use is still limited by the logistical and financial burdens related to the need of generating autologous cell products. The development of universal allogeneic CAR T cells to be used off-the-shelf has faced major limitations, namely the risk of Graft-versus-Host-Disease (GvHD) induction and the rejection of the cells by the host immune system. Invariant Natural Killer-T (iNKT) cells are innate lymphocytes deprived of GvHD induction potential and displaying antitumor effects, both directly and indirectly, through enhancement of CD8 T cell responses. Preclinical studies in xenogeneic mouse models demonstrated the feasibility of using iNKT cells as a platform for CAR-based therapies, and two clinical trials are currently ongoing. In this work, we assessed the immunoadjuvant effect of allogeneic CD19-specific iNKT CAR on the host immune system.

Methods: We transduced murine iNKT cells from FVB/N (H-2K^q) mice with a CD19-specific CD28/CD3ζ CAR and assessed their antitumor effect in vitro and in vivo.

Results: CD19-iNKT CAR had a direct cytotoxic effect in vitro against the CD19+ A20 lymphoma cells and significantly improved survival of mice after administration to major histocompatibility complex (MHC)-mismatched, immunodeficient BALB/c (H-2K^d) Rag2^-/- gamma-chain^-/- mice receiving A20 lymphoma cells (2x10e4; Figure 1A) without inducing any signs of GvHD. To test the efficacy of iNKT CAR cells in the presence of host immune cells, we employed BALB/c mice receiving sublethal irradiation (4.4 Gy), resulting in only a partial and transient lymphopenia. The antitumor effect of allogeneic iNKT CAR cells was greatly enhanced suggesting the participation of host cells in the antitumor effect. Interestingly, the iNKT CAR effect was partially abrogated when we employed as recipients BALB/c BATF3^-/- mice, in which CD8 T cell cross-priming is impaired as a result of the absence of BATF3-dependent CD103+ CD8a+ dendritic cells known to play a role in iNKT cell interactions with other immune effector cells. Moreover, co-administration of allogeneic FVB/N iNKT CAR with autologous BALB/c CD8 T cells at the time of transfer of T-cell-depleted autologous bone marrow cells and A20 cells into lethally irradiated BALB/c recipients resulted in a synergistic effect. To prove the induction of tumor specific CD8 T cell responses, host CD8 T cells were isolated at day 60 from sublethally irradiated BALB/c mice receiveing A20 cells and treated with iNKT CAR. CD8 T cells primed in the presence of iNKT CAR transferred into new lethally irradiated recipients receiving A20 cells and BM from syngeneic Rag2^-/- gamma-chain^-/- mice significantly increased survival. Due to their immuno-adjuvant effect on host CD8 T cells, low numbers of allogeneic iNKT CAR outperformed allogeneic conventional CAR T (Tcon CAR) when administered to sublethally irradiated BALB/c mice receiving A20 cells.

Conclusions: Collectively, these results demonstrate the potent immunoadjuvant effect exerted by allogeneic iNKT CAR cells toward the host immune system suggesting that iNKT CAR cells are an attractive off the shelf product for adoptive immunotherapy.

Clinical Trial Registry: N/A

Disclosure: Nothing to disclose

P107 NKG2D Chimeric Antigen receptor-expressing Lymphocytes Target Acute Myeloid Leukemia Cells

Alejandra Leivas ¹, Laura Córdoba¹, Antonio Valeri¹, Mari Liz Paciello², Paula Rio³, Daniel Primo⁴, Joan Ballesteros⁴, Lucía Fernández⁵, Antonio Pérez-Martínez⁶, Dean A. Lee⁷, Daniel J. Powell Jr.⁸, Joaquin Martinez-Lopez¹

¹Hospital Universitario 12 de Octubre, Spanish National Cancer Center, Madrid, Spain, ²Hospital Universitario 12 de Octubre, Madrid, Spain, ³Research Center for Energy, Environment and Technology, Madrid, Spain, ⁴Vivia Biotech, Madrid, Spain, ⁵Spanish National Cancer Center, Madrid, Spain, ⁶Hospital Universitario La Paz, Madrid, Spain, ⁷The Research Institute At Nationwide Children’s Hospital, Columbus, OH, United States, ⁸University of Pennsylvania, Philadelphia, PA, United States

Background: Chimeric antigen receptor (CAR) therapy is showing promising results in hematological malignancies. Since AML exhibits high heterogeneity and does not have specific differential antigens of the hematopoietic stem cell, using NKG2D-CAR cells could be an appropriate therapeutic strategy against AML. NKG2D receptor has a wide range of specific tumor cell ligands expressed in more than 80% of all tumors. Here we evaluate the anti-tumor activity of activated and expanded natural killer cells (NKAE) and T cells expressing an NKG2D CAR.

Methods: T cells and NK cells were isolated from the healthy donor´s PBMCs (n=5). NKAE cells were obtained by co-culture with subletally irradiated CSTX002 cells. Then, NKAEs and T cells were transduced with an NKG2D CAR. The efficiency of transduction was evaluated by flow cytometry. The cytotoxicity and toxicity on healthy tissues was evaluated by 4 hour europium release assay. The safety of NKG2D-CAR transduced cells was evaluated using CGH arrays.

Results: Both the AML cell lines and primary blasts from AML patients showed expression of the MICA/B and ULBPs-1 to 3 ligands (high expression of at least 3 of the 5 analyzed ligands). Four hour europium release assays revealed that untransduced T cells had higher cytotoxicity than untransduced NKAE cells at the same ratio (32:1) against both OCI-AML-3 cytarabine-resistant cell line (52.7% ± 14.2% vs. 32.5% ± 7.2%) as to the cytarabine-sensitive cell line (56.42% ± 5.6% vs. 50.14 % ± 5.9%). T cells showed a better transduction efficiency than NKAE cells at a multiplicity of infection (MOI) of 5. It was observed that both the CAR-NKAE cells and the CAR-T cells had higher cytotoxicity against these two lines (OCI-AML-3R and OCI-AML-3S) after being transduced with our NKG2D-CAR. However, the antitumor activity of CAR-T cells always remained superior to that of the CAR-NKAE for both OCI-AML-3R (54.26% ± 3.8% vs. 35.3% ± 6.7%) and for OCI-AML-3S (63.36% ± 3.5% vs. 54.3% ± 3.7%) cell lines, with a greater difference compared to drug resistant cells. The antitumor activity of CAR-T cells and CAR-NKAE cells was always superior on the sensitive cell line. The antitumor activity of NKG2D CAR-T cells was evaluated against primary blasts from AML patients (n = 4), observing a nearly complete destruction of the blasts after 24 hours, at low target: effector ratio (4:1). CAR-T cells were highly positive to CD45RO and showed reduced expression of CD45RA. They showed high IL-2 production exhibiting a central memory phenotype. CAR-T cells exhibited some toxicity on third party PBMCs being null in the case of CAR-NKAE. CGH arrays studies showed no variation in the copy number, resulting from the introduction of the CAR. In vivo studies are ongoing.

Conclusions: AML cells could be target with an NKG2D-CAR. Primary NKAE cells and T cells can be transduced with an NKG2D-CAR at a very low MOI to enhance their antileukemic activity. CAR-T cells were able to completely destroy AML blasts. Although further studies are needed, these results show the potential of NKG2D-CAR T and NK cell therapy in AML.

Disclosure: Dean A. Lee declare.s an equity interest, advisory role, and intellectual property licensing to CytoSen Therapeutics and Kiadis Pharma, and advisory role with Caribou BioSciences and Courier Biosciences. Daniel J. Powell Jr. hold patents in the area of CAR T cell therapy. Rest of the authors have nothing to declare.

P108 Clinical-grade Manufacturing of ROR1 CAR T-cells using a Novel virus-free Protocol

Katrin Mestermann ¹, Marie Eichler², Markus Machwirth¹, Kati Kebbel², Ulrike Köhl², Hermann Einsele¹, Claudia Müller², Jörg Lehmann², Tamás Raskó³, Felix Lundberg³, Zsuzsanna Izsvák³, Gerno Schmiedeknecht², Michael Hudecek¹

¹Universitätsklinikum Würzburg, Würzburg, Germany, ²Fraunhofer-Institut für Zelltherapie und Immunologie, Leipzig, Germany, ³Max-Delbrück-Centrum für Molekulare Medizin, Helmholtz Gemeinschaft, Berlin, Germany

Background: Immunotherapy with T-cells that were modified to express a ROR1-specific chimeric antigen receptor (ROR1 CAR-T) has therapeutic potential in ROR1⁺ malignancies in hematology and oncology. In toxicology studies in non-human primates, the adoptive transfer of ROR1 CAR-T did not disclose relevant clinical toxicity, encouraging the initiation of clinical trials to assess the safety and efficacy of ROR1 CAR-T therapy in patients with advanced ROR1⁺ malignancies. In this study, we sought to establish and validate clinical-grade manufacturing of ROR1 CAR-T to enable a Phase I/IIa clinical trial. In particular, we sought to integrate virus-free gene-transfer based on Sleeping Beauty transposition into this manufacturing protocol to easily permit scale-up, and to reduce the regulatory burden associated with conventional viral gene-transfer.

Methods: Buffy coats or leukaphereses were obtained from healthy donors to perform protocol optimization (n=7) and scale-up runs (n=1). CD4⁺ and CD8⁺ T cells were isolated separately and stimulated with CD3/CD28 TransACT reagent (Miltenyi). T cells were transfected with mRNA encoding hyperactive Sleeping Beauty transposase (SB100X) and minicircle DNA encoding a pT2 transposon comprising the ROR1 CAR and an EGFRt marker gene using the MaxCyte GTx electroporation platform. Following transfection, T cells were expanded for 10-13 days in G-REX bioreactors and then harvested and formulated into the drug product at a 1:1 ratio of CAR-expressing CD4:CD8 T-cells. The drug product underwent comprehensive phenotypic, functional and genomic analyses as part of product qualification.

Results: The set of protocol optimization runs provided insights into the optimal timing between T-cell activation and transfection, as well as the amount of SB100X mRNA and ROR1 CAR minicircle DNA for transfection into the T-cells. On average, the stable gene-transfer rate at the end of the manufacturing process was 71% in CD4⁺ (n=5) and 54% in CD8⁺ T-cells (n=7). The average yield of CAR-expressing T-cells relative to the number of input T-cells was 12.6-fold for CD4⁺ and 9.4-fold for CD8⁺ after 12-15 days of expansion, with an average viability of 84% for CD4⁺ and 82% of CD8⁺ T-cells. The set of scale-up runs was performed with leukapheresis product from which 70x10^6 CD4⁺ T-cells and 130x10^6 CD8⁺ T-cells were further processed. At the end of the manufacturing process on day 12, there were 844x10^6 CAR-expressing CD4⁺ and 857x10^6 CAR-expressing CD8⁺ T-cells, which equals a 16-fold and 7.9 fold expansion relative to the input T-cell number, respectively. Overall, ROR1 CAR-T showed specific recognition and potent elimination of ROR1⁺ target cells, as well as antigen-dependent cytokine production and productive proliferation. Experiments to determine the anti-tumor potency of the drug product in vivo and detailed genomic analyses are ongoing.

Conclusions: With this novel protocol, we aim to obtain the first manufacturing license for CAR-T in Europe that integrates our optimized approach with SB100X mRNA and transposon minicircle DNA for CAR gene-transfer on the MaxCyte transfection platform. The quality and yield of the drug product support the design and dose escalation of the proposed clinical trial with ROR1 CAR-T, and will serve as a blueprint for other CAR-T products from our pipeline.

Disclosure: Nothing to declare.

P109 Lentivirally and Alpharetrovirally Engineered CD19-specific Chimeric Antigen Receptor Natural Killer Cells are Highly Cytotoxic against Acute Lymphoblastic Leukemia

Tobias Bexte^1,2,3, Stephan Müller^1,2,3, Veronika Gebel^1,2, Franziska Kalensee^1,2, Eva Stolzenberg¹, Jessica Hartmann⁴, Ulrike Koehl^5,6,7, Axel Schambach^8,9, Wels Winfried S.^3,10,11, Ute Modlich¹², Evelyn Ullrich ^1,2,3

¹University Hospital Frankfurt, Goethe University, Frankfurt, Germany, ²University Hospital Frankfurt, Goethe University, Frankfurt, Germany, ³German Cancer Consortium (DKTK) partner site Frankfurt/Mainz, Frankfurt, Germany, ⁴Paul-Ehrlich-Institut, Langen, Germany, ⁵Fraunhofer Institute for Cell Therapy and Immunology (IZI), Leipzig, Germany, ⁶Hannover Medical School, Hannover, Germany, ⁷University Leipzig, Leipzig, Germany, ⁸Hannover Medical School, Hannover, Germany, ⁹Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States, ¹⁰Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, Frankfurt, Germany, ¹¹Frankfurt Cancer Institute, Goethe University, Frankfurt, Germany, ¹²Paul-Ehrlich Institut, Langen, Germany

Background: Autologous chimeric antigen receptor-modified (CAR) T cells with specificity for CD19 showed potent antitumor efficacy in clinical trials regarding relapsed and refractory acute lymphoblastic leukemia (ALL). Natural killer (NK) cells are cytotoxic lymphocytes that are capable to kill their targets in a non-specific manner and additionally do not cause GvHD. Therefore, using CD19-CAR-NK cells exhibits several advantages, such as safety in clinical use, possible allogenic settings and the potential to also attack heterologous leukemia cells which lost CD19. Here, we focused on the optimization of generating CD19-CAR-NK cells by viral transduction under feeder-cell free conditions.

Methods: Human NK cells were isolated from healthy donor peripheral blood mononuclear cells via CD56 negative selection. After a feeder-cell free expansion phase with interleukin 15 (IL-15), transductions were performed with a CD19-CAR encoding vector at different multiplicities of infection (MOI). To optimize gene modification different viral vector systems were compared using lentivirus and alpharetrovirus, pseudotyped with either VSV-G or RD114-TR. Finally, generated CD19-CAR-NK cells were tested in their ability to kill CD19-positive and CD19-negative cell lines.

Results: Transduction efficiencies of NK cells transduced with the RD114-TR pseudotyped alpharetroviral or lentiviral CD19-CAR vectors outperformed transduction with VSV-G pseudotyped lentiviral vector (lentiviral/RD114-TR: MOI 1: 10,9%, MOI 5: 24.0%, MOI 10: 27.3%; alpharetroviral/RD114-TR: MOI 1: 14.7%, MOI 5: 28.5%, MOI 10: 37.4%; lentiviral/VSV-G: MOI 1: 0.9%, MOI 5: 4.4%, MOI 10: 8.2%). As possible mechanism, dependent on IL-15, we observed a significant upregulation of the surface expression of ASCT-2 on the primary NK cells that is an entry receptor for RD114-pseudotyped vectors.

Remarkably, CD19-CAR-NK cells generated by RD114-TR pseudotyped retroviral vectors showed stable transgene expression and were able to expand almost as good as non-transduced (NT) NK cells over a time period of 14 days.

Independent of the transduction method, engineered CD19-CAR-NK cells showed an impressively high cytotoxic capacity against CD19-positive ALL cells compared to NT-NK cells; alpharetroviral/RD114-TR CD19-CAR-NK inducing 73.1% vs. lentiviral/RD114-TR CD19-CAR-NK cells inducing 74.7% vs NT- NK cells inducing 35.9% of cell death; E:T ratio 1:1 in 4 hours).

Conclusions: CD19-CAR-NK cells can be successfully generated under feeder-cell free conditions using different transduction enhancers and viral vector systems. Our data suggest the usage of Vectofusin-1 in combination with RD114-TR pseudotyped retroviral vectors to genetically modify NK cells to achieve sufficient amounts of highly cytotoxic transduced cells. These CD19-CAR-NK cells mediate high cytotoxicity and therefore may offer a new therapeutic option in the treatment of ALL. These insights will be transferable in CAR-NK-cell engineering to target different other malignancies.

Disclosure: Axel Schambach is an inventor on a patent describing alpharetroviral SIN vectors. Winfried S. Wels is an inventor on a patent describing chimeric antigen receptors with an optimized hinge region. The remaining authors have nothing to disclose.

P110 Novel Strategies to Enhance the safety of CAR T-cell Immunotherapy: The Imsavar Project

Miriam Alb ¹, Jonathan Moggs², Lars Wallstabe¹, Benedikte Hatz¹, Hermann Einsele¹, Peter Loskill³, Andries van der Meer⁴, Scott Wagers⁵, Ulrike Köhl⁶, Michael Hudecek¹

¹imSAVAR Consortium, Würzburg, Germany, ²imSAVAR Consortium, Basel, Switzerland, ³imSAVAR Consortium, Stuttgart, Germany, ⁴imSAVAR Consortium, Enschede, Netherlands, ⁵imSAVAR Consortium, Maasmechelen, Belgium, ⁶imSAVAR Consortium, Leipzig, Germany

Background: Adoptive immunotherapy with gene-engineered CAR-T-cells is a transformative treatment in hematology but can be associated with significant toxicity from e.g. cytokine release syndrome (CRS). Preclinical testing to assess CRS is not standardized and there is a strong medical need and desire to establish algorithms to assess the propensity of novel CAR-T-cell products and technologies to induce CRS and other toxicity. imSAVAR - immune safety avatar - is an EU Innovative Medicines Initiative (IMI) project that tackles this challenge in a joint academia-industry consortium and seeks to establish a framework and platform for assessing the utility of innovative non-clinical models and endpoints for enhancing the safety assessment of e.g. CAR-T cells.

Methods: imSAVAR is pursuing a 4-step approach: Step 1 comprises a systematic literature review on pathophysiology and clinical occurrence of CRS after CAR-T-cell therapy. Step 2 comprises a survey amongst academia and industry stakeholders to identify current gaps of existing and emerging preclinical test systems that are used to assess CRS. Step 3 is an open multi-stakeholder workshop that also engages EU and US regulators and patients to determine a roadmap for studies that establish a new set of non-clinical assays and endpoints that will subsequently be validated for their ability to enhance hazard identification, provide mechanistic insight, and help mitigate clinical safety concerns in Step 4.

Results: In Step 1 imSAVAR established a new conceptual map of CRS pathogenesis as an immune-related adverse outcome pathway (irAOP) comprising key molecular events (CAR target antigen engagement, signaling and T-cell activation) and cellular events (CAR-T-cell migration to tumor site, engagement with tumor cells in an immune synapse, secretion of pro-inflammatory mediators, activation of tissue resident and endothelial cells, and systemic inflammation). To each of these events, existing and emerging pre-clinical assays were allocated. In Step 2, a pilot survey was conducted with n=3 CAR-T-cell products from within the consortium. Encouragingly, the repertoire of novel test systems available in imSAVAR for evaluating CAR-T mediated cytokine release include in vitro co-culture assays of CAR-T with tumor cells, single-cell resolution molecular endpoints, in vivo humanized mouse models (e.g. NSG-3G) as well as microphysiologic organ-on-a-chip models. imSAVAR is preparing an open survey to collect data from n≥10 CAR-T and n≥10 other immune-oncology products to inform the research roadmap. All data will then be normalized and correlated with clinical data to identify optimal pre-clinical assays for enhancing the assessment and prediction of CRS.

Conclusions: imSAVAR has established an irAOP that will enable the development and validation of novel non-clinical assays that aim to enhance the characterization of CAR-T-cell associated cytokine release during pre-clinical development. This effort is ultimately anticipated to enhance the safety assessment of therapeutic CAR-T products, thus potentially accelerating patient access to CAR-T products with an enhanced therapeutic index. This CAR-T irAOP strategy forms part of imSAVAR’s broader efforts to enhanced non-clinical safety assessment algorithms for additional immunomodulatory therapeutic modes-of-action (e.g. TCR-transgeneic T cells, bi-specific T-cell engaging antibodies; checkpoint inhibitor antibody combinations; Treg modulators), and a range of immune system-related toxicities (e.g. ICANS, infections).

Disclosure: Nothing to declare. This project receives funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 853988.

P111 Adult Peripheral Blood and Umbilical Cord Blood NK Cells Are Good Sources for Effective Car Therapy Against CD19 Positive Leukemic Cells

Lara Herrera ^1,2, Silvia Santos^1,2, Miguel Ángel Vesga^1,2, Juan Anguita^3,4, Itziar Martin-Ruiz³, Tomás Carrascosa^2,5, Manel Juan⁶, Cristina Eguizabal^1,2

¹Basque Center for Blood Transfusion and Human Tissues, Galdakao, Spain, ²Biocruces Bizkaia Health Research Institute, Barakaldo, Spain, ³CIC bioGUNE, Derio, Spain, ⁴Ikerbasque, Basque Foundation for Science, Bilbao, Spain, ⁵Hospital Galdakao-Usansolo, Galdakao, Spain, ⁶Hospital Clínic de Barcelona, Hospital Sant Joan de Déu, Institut d’Investigacions Biomèdiques August Pi i Sunyer Hospital, Universitat de Barcelona, Barcelona, Spain

Background: Among hematological cancers, Acute Lymphoblastic Leukemia (ALL) and Chronic Lymphocytic Leukemia (CLL) are the most common leukemia in children and elderly people respectively. Chimeric antigen receptor (CAR) therapy is one of the newest and more effective treatments against these cancers. CAR T cell therapy presents still some risks for the patients, including cytokine release syndrome (CRS) and neurotoxicity. We proposed NK cells from different cell sources for allogeneic CAR therapy.

Methods: 1. Enrichment and culture of NK cells from AB and CB. NK cells were isolated from AB or CB PBMCs by negative selection after magnetic cell isolation. Then, the NK cells were cultured with IL-2 and IL-15 for 8 days.

2. CD19-CAR lentiviral transduction to AB and CB NK cells

3. Functional assays facing CD19-CAR transduced and non-transduced AB and CB NK cells against CD19 expressing target cells. We measure CD107a marker in degranulation assays; and Calcein-AM released by target cells in cytotoxicity assays.

Results: 1. Percentage of the purity of the CD56+ NK cell population was 92.68±2.90 in AB and 91.46±5.14 in CB. NKp46 levels during the culture increase significantly from day 0 to day 7 in both cell sources. In fact, CB NK cells were significantly more stimulated than AB NK cells. We obtained more cells from the isolation from CB than from AB. During the first week, both sources expanded similarly; however, slightly higher fold expansion was observed after two weeks in CB NK cells

2. The mean AB CAR-NK transduction efficiency was 47.46 (range 62.6-20.2%; n=12) while CB CAR-NK transduction efficiency was 46.8 (range 79.7-18.1%; n=12). Seven days post-transduction the viability of AB and CB NK cells remained at 78.85% ± 10.18% and 76.2% ± 5.3%, respectively. In both cases, viability decreased over time until day 28. CAR expression shows a stable decrease of transduction from 40% to 20% with time as determined by flow cytometry every 7 days.

3. On one hand, when exposed to CD19 positive cells, AB CD19-CAR NK cells showed a significantly higher degranulation than non-transduced AB NK cells. On the other hand, when exposed to CD19 positive cells, CB CD19-CAR NK cells showed a significantly higher degranulation than non-transduced CB NK cells. We observed the same results when performing a cytotoxicity assay. AB CD19-CAR NK cells kill slightly better than CB CD19-CAR NK cells.

Conclusions: - CB NK cells present a more stable number of cells per unit than AB NK cells, and they can be stimulated with different interleukins in order to enhance the in vitro expansion, their killing activity and survival.

- Despite the difficulty of infecting NK cells, in our hands we obtain around 40-50% of infection with AB and CB NK cells with CD19-CAR.

- CD19 expressing target cells are killed more efficiently by AB and CB NK cells transduced with CD19-CAR than by non-transduced AB and CB NK cells.

CD19-CAR infected NK cells from AB and CB kill similarly CD19 expressing target cells. However, we observe a higher degranulation of the AB NK cells.

Disclosure: Nothing to declare.

P112 Tyrosine Kinase Inhibitor Followed by Cart Therapy for the Treatment of Relapsed Philadelphia chromosome-positive B-cell Acute Lymphoblastic Leukemia after Allogeneic Hematopoietic Stem Cell Transplantation

YUEHUI LIN, Biping Deng, Zhichao Yin, Lihong An, Defeng Zhao, DAN LIU

Beijing Boren Hospital, Beijing, China

Background:

Philadephia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) is a distinct type of ALL, which has a high incidence of adult patients and a dismal poor prognosis. Resistance/relapse(r/r) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remain a significant challenge. Once relapsed, almost patients are resistant to the TKI because T315I mutation of ABL-kinase domain mution(AKDM).

Chimeric antigen receptor T-cells (CART) has shown a higher complete remission(CR)rate in r/r B-ALL patients and has a good security.

So we sequentially applied CART and TKI therapy to treat the Ph+ALL patients relapsed after allo-HSCT and observed the effect.

Methods: From January 1,2018 to June 31,2019, fourteen adult Ph+ALL patients relapsed after allo-HSCT were enrolled. CD19 and/or CD22 expression on blasts and AKDM were detected by flow cytometry(FCM) and polymerase chain reaction(PCR), respectively.

Recipient-derived donor T cells were collected and cultured CART cells, which were transfected by lentiviral vectors encoding the CAR composed of CD3zeta-4-1BB.

ALL patients received fludarabine with or without cyclophosphamide before CART cell infusion, some patients received othder chemotherapy or TKI based on the precondition because high disease burden or extramedullary disease (EMD). CART cell dose was 0.5-2×105/kg (CD19-CART) and 1-2.8×105/kg (CD22-CART). After CART cell

infusion, CART cell, cytokines were measured on D7, D9, D11 etc. and other days depending on the patient’s condition. We evaluated Bone marrow(BM) and cerebrospinal fluid (CSF)morphology, minimal residual disease(MRD)by FCM and BM BCR-ABL1fusion transcripts by real-time quantitative PCR(QPCR) on D30, EMD was examined by imaging examination and once every month later.

Once these patients acquired CR, TKI treatment was followed according to the AKDM and followed up to November 26,2019(6-22 months).

Results: Fourteen patients were aged 17 to 55 years(medium 29), including ten P190, three P210, one special BCR-ABL1 and nine hematological relapse, two FCM-MRD+, two BCR-ABL1+:one with multiple EMD, one only central nervous system leukemia(CNSL). After HSCT, twelve patients relapsed within 12 months(1.5-12 months), two patients relapsed in the 28th and 48th month. Twelve patients had received chemotherapy, TKI, donor lymphocyte infusion (DLI), murinized CD19-CART, radiotherapy before, but all failed;Two patients didn’t received any therapy.

Thirteen patients were detected AKDM:five T315I, one T315I and Y253H, one T315L, one Y317L, five no mutation(one T315I before HSCT). One patient didn’t detect AKDM because blast cells was not enough.

After first CART therapy, two patients had no effect and died, one patient gave up and died. Another 11(100%) patients all achieved CR and MRD negative(CRMRD-) with incomplete blood count recovery(CRiMRD-), and 10/11(90.91%)patients achieved molecular complete response (CRmi) and all of them hadn’t CNSL. ALL these patients received other therapies:three patients received second CART and one then received DLI, TKI was used in eleven patiets based on their AKDM results. To the present, eleven patients remained CRm:two patients stoped use TKI in February and July 2019, one patient received second HSCT in May 2019.

Cytokine release syndrome(CRS) occurred 9/14(64.29%)patients after the first CART:8 grade I, 1 grade III. Only one patient exhibited CAR T-cell-related encephalopathy syndrome (CRES) who had CNSL before CART, and no fetal graft-versus-host disease(GVHD)occurred.

Conclusions: CART therapy for Ph+ALL patients relapsed after HSCT is efficacy

and secure, once they achieved CR after CART therapy, sequencial TKI therapy may prolong the overall survival, leukemia free survival.

Disclosure: Nothing to declare.

Cellular Therapies other than CARs

P113

Abstract already published.

P114 Adoptive Immunotherapy of Refractory Viral Infections after Allogeneic HSCT: An Academic Network Framing the use of an Atmp under Hospital Exemption

Yingying WANG^1,2, Marcelo DE CARVALHO^1,2, Typhaine PIERRE¹, Mélanie GAUTHIER^1,2, Véronique DECOT^1,2, Laurence CLEMENT^3,4, Cécile POCHON^1,2,4, Karin BILGER^4,5, Jérôme LARGHERO^4,6, Hélène ROUARD^4,7, Anne FIALAIRE LEGENDRE^4,8, Nadine PETITPAIN^1,4, Jean Hugues DALLE^4,9, Danièle BENSOUSSAN ^1,2,4

¹CHRU de Nancy, Vandoeuvre les nancy, France, ²Université de Lorraine, UMR CNRS 7365, Vandoeuvre les Nancy, France, ³CHU de Bordeaux, Bordeaux, France, ⁴SFGM-TC, Lyon, France, ⁵CHRU de Strasbourg, Strasbourg, France, ⁶Hôpital Saint-Louis, Paris, France, ⁷EFS, Créteil, France, ⁸EFS, Saint Denis, France, ⁹Hôpital Robert Debré, Paris, France

Background: Viral infections are major complications of Hematopoietic Stem Cell Transplantation (HSCT). As efficacy of anti-viral drugs is limited in absence of immune reconstitution and often associated with severe side effects, infusion of Virus-Specific T cells (VSTs) becomes a promising alternative treatment for viral infections and diseases after HSCT. We previously performed a successful phase I/II clinical trial and secondarily obtained an ATMP under hospital exemption authorization from the French regulatory agency for the preparation of VSTs (especially ADV-STs) for all the clinical centers in need. A national group was created under the aegis of the Francophone Society of Bone Marrow transplantation and Cell Therapy (SFGM-TC) to analyze, validate and follow the different requests. We present here the results that have been collected until 2016.

Methods: We previously demonstrated the feasibility of isolating ADV-STs from donors using the IFNg-capture system from Miltenyi biotec followed by immunomagnetic selection on the CliniMACS device (Aissi-Rothé et al, 2010; Qian et al, 2017). Since we obtained the ATMP authorization, we have treated patients with an infusion of polyclonal ADV-STs (n=8) or CMV-STs (n=4) or EBV-STs (n=2) generated by a 6-hour ex vivo stimulation with an appropriate peptide pool (PepT-ADV5 Hexon, PepT-CMV pp65, PepT EBV Select, respectively, Miltenyi Biotec) of leukapheresis collected from their original stem cell donor or more often from third party haploidentical donors, followed by isolation of IFNg producing cells.

Results: We report more than 40 requests to the group, 75% of them in 2019, from different French and Belgium centers followed by 8 refusals, the generation of 14 VST preparations and the infusion of patients (4 months-65 years) with viral infection disease. They received a mean of 0.96 10⁴ CD3-IFNg+ cells/kg (range: 0,042 to 1.436 10⁴). In vivo expansion of transferred VSTs was observed from day 15 to 60 following adoptive transfer infusion associated with viral load decrease or clearance in more than half of the patients. During the 3 month-follow-up, 4 patients experienced failure of the treatment with a persistent increase of viral load. Neither de novo GVHD, nor side effects were observed. Reactivation of grade I aGVHD occurred in 2 patients in the month following infusion and in 3 patients after D45 (grade II and IV). Unfortunately, eight patients died, 4 related to persistent viral infection or disease. However, none of the responders experienced a viral-associated mortality.

Conclusions: Adoptive transfer of VSTs is a feasible and well-tolerated therapeutic option, representing a fast and efficient procedure to achieve reconstitution of antiviral T-cell and decrease or clearance of viral load. However, today this is a last chance therapy and viral load is often over 6.5 log (4 patients) when infusion is performed, not giving VST time to expand and be efficient. The French organization, under the aegis of SFGM-TC, is very secure and reactive and contributes to encourage clinical centers to initiate their request earlier.

Disclosure: Danièle Bensoussan, start up StemInov, CSO

P115 How to Benefit from Exhaustion: patient-derived Inhibited T Cells as a Novel Source of tumor-reactive T Cell Clones

Francesco Manfredi ¹, Lorena Stasi¹, Danilo Abbati¹, Sara Mastaglio², Fabio Ciceri², Eliana Ruggiero¹, Chiara Bonini^1,2

¹Università San Raffaele, Milan, Italy, ²IRCSS San Raffaele Hospital, Milan, Italy

Background: A notable percentage of blood cancer patients who undergo Allogeneic Hematopoietic Stem Cell Transplantation (alloHSCT) still suffers a dismal prognosis; this therapeutic gap could be filled by Adoptive T cell therapy, but its exploitation is still limited by the incomplete knowledge of tumor-specific T cells dynamics in vivo and by the difficulty to isolate such T cell specificities for therapeutic purposes.

Methods: To visualise and purify tumor-specific T cells ex vivo, we screened circulating cells at 30,60,90,120,180 and 365 days after alloHSCT in N=35 patients affected by blood malignancies with a 18-colour Flow Cytometry panel including fluorescent MHC-I complexes loaded with Tumor-Associated Antigen (TAA) peptides or with a viral peptide. Together, we followed T-Cell Receptor (TCR) clonal dynamics by cell sorting and sequencing.

Results: TAA-Specific T cells were found circulating in the patients’ peripheral blood, as soon as 30 days after alloHSCT. By exploiting high-dimensionality un-biased analytical tools we dissected their phenotype, showing that they express multiple inhibitory receptors at higher levels if compared with either the total CD8 T cell population or viral-specific T cells, independently from major clinical variables (disease status at transplant, disease type, GvHD incidence). The inhibitory signature was the most pronounced 4 months after alloHSCT, and was followed by a substantial contraction of the pool of TAA-specific memory T cells.

We also took advantage of cell sorting to isolate and expand TAA-specific T cells. We established a rapid, highly specific protocol that isolated 24 tumor-specific T cell colonies from n=13/20 screened patients, each one enriched for a single TCR clonotype identified by RNA sequencing. When challenged with peptide-pulsed targets, such ex vivo clones were poorly responsive but when the TCR sequences were cloned into lentiviral vectors and transferred in T cells after Crispr/Cas9 disruption of the endogenous TCR (TCR-edited lymphocytes), cells proved highly efficient and specific in lysing matched pulsed targets (fig.1A). This observation, linked with the previous phenotypic analysis, suggests that TAA-specific T cells are circulating in vivo but are exhausted. We thus tried to broaden the search of Tumor-reactive T cell clones by exploiting the exhaustion signature to purify a T cell subset enriched with anti-tumour reactivities. We sorted T cells from 3 patients affected by Acute Myeloid Leukemia (AML) on the basis of the inhibitory receptors (IR) expression and stimulated both IR+ and IR- cells with matched Leukemic Dendritic Cells (LDC). Serial LDC stimulations promoted the expansion of dominant clones over time in the IR+ but not in the IR- fraction and IR+ T cells proved superior in killing autologous AML blasts in vitro. Again, dominant TCRs were identified in IR+ cultures from the first patient, and TCR-edited lymphocytes efficiently and selectively recognized autologous blasts (fig.1B).

Conclusions: Our findings shed some light on the in vivo dynamics of tumor-specific T cells and introduce two models for the isolation of tumor-specific TCRs, one requiring the knowledge of the target peptide, the other exploiting the IR signature to discover novel tumor specificities.

Disclosure:

Chiara Bonini recieves Resarch funds from Intellia Therapeutics and Immudex, and she´s consultant for Intella Therapeutics, Novartis and Molmed.

The other authors declare. no relevant conflict of interest

P116 Efficient Crispr/Cas9-mediated Inactivation of the Glucocorticoid Receptor for antigen-specific T-cell Immunotherapy

Maria Alvanou^1,2, Anastasios Kouimtzidis^1,3, Kyriakos Koukoulias^1,3, Chrysoula Pantazi^1,3, Nikoletta Psatha⁴, Giorgios Tsiolas⁵, Alexandros Spyridonidis², Kostas Stamatopoulos⁵, Antonios Makris⁵, Achilles Anagnostopoulos¹, Evangelia Yannaki¹, Anastasia Papadopoulou ¹

¹George Papanikolaou Hospital, Thessaloniki, Greece, ²University General Hospital of Patras, Patras, Greece, ³Aristotle University of Thessaloniki, Thessaloniki, Greece, ⁴Altius Institute for Biomedical Sciences, Seattle, WA, United States, ⁵Centre for Research and Technology Hellas (CERTH), Thessaloniki, Greece

Background: Adoptive immunotherapy (AI) with pathogen-specific T cells (pSTs) is a promising alternative to pharmacotherapy for the treatment of opportunistic infections after allogeneic hematopoietic stem cell (allo-HSCT) or solid organ transplantation. However, clinical implementation of AI is limited to patients receiving either low dose or no steroids, a prerequisite for optimal T-cell function, practically excluding the most susceptible to infections patients from the benefits of AI. Aims. We evaluated the impact of dexamethasone (DEX) on primary T cells and developed a CRISPR/Cas9 system to genetically disrupt the glucocorticoid receptor (GR) in lymphocytes and confer resistance to steroids, in order to ultimately develop steroid-resistant pSTs.

Methods: The impact of DEX on T cell proliferation, phenotype and apoptosis was evaluated in human OKT3 blasts generated by stimulating peripheral blood mononuclear cells through CD3 and CD80 ligation. To inactivate the GR gene, 10 guide RNAs (gRNAs) were prepared to target different genomic sequences corresponding to various domains of the GR (a transcription start site, and exons 2, 3, 4 and 5) and delivered separately into the T2 lymphoblastic cell line using lentiviral vectors. Cells transduced with an “empty” viral vector expressing Cas9 but no gRNA were used as negative control. The resistance of T2 cell line to glucocorticoids was assessed as cell viability by trypan blue exclusion. The on-target inactivation of the GR in T2 cell line was measured by western blot and T7 assay.

Results: A 3-day exposure of OKT3 blasts to DEX negatively impaired the proliferation of stimulated primary T cells and induced early apoptosis over the “no DEX” condition (p=0.001, p=0.01 respectively). These effects correlated with a DEX-induced upregulation of T regulatory cells (p=0.0002). DEX also upregulated PD-1 and CTLA-4, the major coinhibitory molecules in antigen-specific immune responses, over the “no DEX” condition (p< 0.05). Then, in order to render cells steroid-resistant, T2 cells were transduced with lentiviral vectors encoding Cas9 and 10 different gRNAs targeting GR and subsequently incubated in the presence or absence of DEX. T2 cells edited with 7/10 single gRNAs, presented normal proliferation on DEX treatment as contrasted to their untreated counterparts and the empty vector-transduced cells, suggesting functional DEX-resistance. The on-target GR inactivation in T2 cells was confirmed by both western blot and T7 assay. Among tested functional gRNAs, the optimal gRNA was selected for further studies, on the basis of high GR disruption efficiency and low off-target activity.

Conclusions: Overall, we provide a series of gRNAs to CRISPR/Cas9-disrupt the GR and ultimately generate steroid-resistant pSTs in order to offer the benefits of AI to the most vulnerable to infections patients, as those with graft-versus-host-disease receiving high-dose steroids post allo-HSCT.

Disclosure: Funding for this project was provided in part by an EHA Research Grant award granted by the European Hematology Association and in part by the State Scholarships Foundation (I.K.Y.).

P117 Comparison of Outcome post-second Allogeneic Hematopoietic Cell Transplantation Versus Donor Lymphocyte Infusion in Allogeneic Hematopoietic Cell Transplant Patients

Eshrak Al-Shaibani ^1,2, Jeffrey H. Lipton^1,2, Dennis D. Kim^1,2, Auro Viswabandya^1,2, Rajat Kumar^1,2, Wilson Lam^1,2, Arjun Law^1,2, Zeyad Al-Shaibani^1,2, Armin Gerbitz^1,2, Ivan Pasic^1,2, Jonas Mattsson^1,2, Fotios V. Michelis^1,2

¹Princess Margaret Cancer Centre, Toronto, Canada, ²University of Toronto, Toronto, Canada

Background: Allogeneic hematopoietic cell transplantation (HCT) is potentially curative for a variety of benign and malignant hematological disease, however may be complicated by disease relapse or graft loss/poor graft function. Both second allogeneic HCT and donor lymphocyte infusions are utilized in the management of both complications. The purpose of the present study is to compare outcomes following both interventions in a single center cohort of patients transplanted over the last five years.

Methods: We retrospectively investigated 65 patients in total, 34 (52%) underwent second allogeneic HCT and 31 (48%) received donor lymphocyte infusions (DLI), from June 2011 to November 2018.

Results: Median patient age at the time of the post-transplant intervention was 51 years (range 19-72). Second HCT was performed for disease relapse in 11 patients (5 of which were transplanted for AML) and for graft failure (GF) in 23 patients (primary in 6 and secondary in 17 patients). Donors for second HCT were related (n=10), unrelated (n=18) and haploidentical (n=6), the same donor was used in 20 (59%) patients. At second HCT, the HCT-CI was 0-2 for 22 patients (65%) and ≥3 for 12 patients (35%). Concerning DLI patients, this was performed for relapse for 17 patients (8 of which were transplanted for AML) and for secondary GF or chimerism loss in 14 patients. Donors for DLI were related for 13 patients, unrelated for 16 patients and haploidentical for 2 patients. KPS at first DLI was 90-100% for 20 patients (65%) and 70-80% for 11 patients (35%). Median number of DLI administered was 2 (range 1-11).

[Figure 1: Overall survival with second transplant vs donor lymphocyte infusion for relapsed patients]

Median follow-up of survivors following intervention was 18 months (range 3-66 months). Univariate analysis demonstrated 2-year overall survival (OS) of 50% (95%CI 37-62%) for the entire cohort, while 2 year OS was identical between all second transplant patients and DLI patients (50% for both groups, p=0.9%). For second HCT patients, 2-year OS was 82% (95%CI 45-95%) and 35% (95%CI 17-54%) for relapse as an indication versus GF respectively (p=0.01). For the DLI patients, 2-year OS was 44% (95%CI 20-66%) and 56% (95%CI 27-78%) for relapse as an indication versus GF/loss of chimerism respectively (p=0.64). For disease relapse as an indication, second HCT was significantly superior to DLI (p=0.03, Figure 1). Multivariable analysis for second HCT patients demonstrated age (HR 1.04, 95%CI 1.00-1.07, p= 0.03) and donor type (HR 0.17 for related donor, 95%CI 0.04-0.75, p=0.02) to independently predict OS. For DLI, multivariable analysis demonstrates KPS at the time of the first dose of DLI as the predominant predictor of survival (HR 0.89, 95%CI 0.82-0.96, p=0.002).

Conclusions: Second allogeneic HCT demonstrates superior survival when performed for disease relapse post-transplant compared to DLI. In contrast, second HCT for graft failure results in poor long-term survival. Second allogeneic HCT should be preferred as a reasonable treatment option for patients that relapse post-transplant and achieve pre-second HCT remission.

Disclosure: Nothing to declare.

P118 Automated Application for Depletion of Tcrab⁺, CD19⁺ and CD45RA⁺ Cells from Apheresis Products using the Clinimacs Prodigy®

Julia Dzionek ¹, Carina Thießen¹, Felix Hebbeker¹, Stephanie Soltenborn¹, Joanna Justyna Stenzel¹, Burgund Kauling¹, René Meißner¹, Nikolas Kaltz¹, Kirsten Langeveld¹, Michaela Malchow¹, Mario Assenmacher¹, Andreas Bosio¹, Eleni Papanikolaou^1,2

¹Miltenyi Biotec B.V. & Co. KG, Bergisch Gladbach, Germany, ²National and Kapodistrian University of Athens, Athens, Greece

Background: Major complications of allogeneic stem cell transplantation are GvHD and infections. Ex-vivo T cell depletion (TCD) can effectively prevent GvHD, however it may prolong immune reconstitution and increase the risk of infections. Depletion of TCRab⁺ T cells combined with the transfer of CD45RA^- donor memory T cells may ameliorate the infection risk and simultaneously decrease the risk of GvHD. Here, we report the development of a single, automated manufacturing process on the CliniMACS Prodigy^® to generate personalized grafts providing a TCRab-depleted stem cell product and a memory T cell product.

Methods: Currently, the combined depletion of TCRab⁺/CD19⁺ cells and the depletion of CD45RA⁺ cells exist as two separate applications on the CliniMACS Prodigy. The novel integrated CliniMACS Prodigy LP-TCRab-19-45RA depletion process merges these two strategies in one application performed in one tubing set, namely CliniMACS Prodigy TS 320. Depending on the desired cell composition of the graft, the user can choose to perform either:

· sequential depletion of CD45RA⁺ and TCRab⁺ cells with or without simultaneous depletion of CD19⁺ cells,

· a depletion of TCRab⁺ cells with or without simultaneous CD19⁺ cells or

· a CD45RA⁺ cell depletion only.

All TCRab depletion cases (with or without simultaneous depletion of CD19⁺ cells) can be performed in normal or large scale, depending on the number of total WBC, TCRab⁺ and CD19⁺ cells. The memory T cell product and the stem cell product are collected in separate bags and can be combined to a single cell product, according to each patient’s need (personalized graft).

The new application software effectively depletes 2.4x10⁹ CD45RA⁺ cells from up to 6x10⁹ total WBC, and 48x10⁹ total TCRab⁺ cells plus 15x10⁹ total CD19⁺ cells from up to 120x10⁹ total WBC.

Results: In-house evaluation runs (total n = 41, 10 mobilized and 31 non-mobilized apheresis products) resulted in comparable values for depletion, yield, recovery, and WBC viability of the target products regardless of the application case performed. The mean log depletion achieved for the TCRab±CD19-depleted products (n = 41) was 4.5 (range 3.5-5.2) for TCRab⁺/CD45RA⁺ cells and 3.4 (range 2.6-4.3) for CD19⁺ cells with a stem cell viability over 90% and mean yield of 81%. In the CD45RA-depleted products (n=31) a mean log depletion of 5.4 (range 3.8-6.4) for TCRab⁺/CD45RA⁺ cells was obtained.

The duration of CD45RA depletion takes between 1.5-1.7 hours, while the duration of TCRab±CD19 depletion ranges between 5.1-8.3 hours. Finally, the combined TCRab±CD19/45RA depletion needs 6.7-10.3 hours to complete, depending on total cell numbers. Importantly, input of a defined process end time is possible.

Effective quality control panels and express modes for MACSQuant^® Flow Cytometers enable easy and accurate monitoring of the entire cell manufacturing process.

Conclusions: In summary, the novel automated CliniMACS Prodigy LP-TCRαβ-19-45RA depletion process is capable to deplete CD45RA⁺, TCRab⁺ and CD19⁺ cells efficiently from apheresis products with a mean yield of 81% for CD34⁺ cells. The performance verification and submission to an European notified body for CE marking as medical device application are the important next steps.

Clinical Trial Registry: n/a

Disclosure: n/a

P119

Abstract already published.

P120 Good Response Rates of WJ-MSC, Comparable to BM-MSC, in the Treatment of Refractory GVHD

Sílvia Torrents ¹, Laura Alonso², Joaquim Vives¹, Luciano Rodríguez¹, Georgina Morón-Cazalilla³, Izaskun Elorza⁴, Maria Luz Uria², Maria Isabel Benítez², Rocío Parody⁵, Guillermo Ortí², Maria Trabazo³, Jesús Fernandez-Sojo¹, Margarita Codinach¹, Laura Medina¹, Isabel Badell⁴, Cristina Diaz de Heredia², Sergi Querol¹

¹Banc de Sang i Teixits, Barcelona, Spain, ²Hospital Vall d´Hebron, Barcelona, Spain, ³Santa Creu i Sant Pau Hospital, Barcelona, Spain, ⁴Hospital Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain, ⁵ICO - Hospital Duran i Reynals, Barcelona, Spain

Background: Acute graft-versus-host-disease (aGVHD) is one of the main complications derived from an allogeneic hematopoietic progenitor cell transplant (HPCT). First line therapy is based on the use of steroids but many patients are refractory. Due to the immunomodulatory characteristics of multipotent mesenchymal stromal cells (MSC) this cell type have been used with success in the treatment of refractory aGVHD. Wharton Jelly’s (WJ) is a new source of MSC with advantages for large-scale production and standardization. The aim of this study is to evaluate the ability of WJ MSC’s to improve refractory aGVHD compared to MSC’s obtained from Bone Marrow (BM).

Methods: Retrospective study of patients with refractory aGVHD treated with MSC produced at Banc de Sang I Teixits between (2017-2019). All patients received at least two doses of MSC (1E6 MSC/kg of patient body weight per dose). To obtain and process the cells, an approved IND was followed in our production facilities using BM-MSC’s (PEI 13-081) or WJ-MSC’s (PEI 16-017). Patients were treated in 4 hospitals of Barcelona area, after receiving corticosteroids and second or further lines of alternative drugs. Upon request by transplant center, MSC samples were released for a therapy scheduled for infusion on days 1, 4, 11 and 18 using a compassionate schema.

Results: Eighteen patients (12 pediatric and 6 adults) have been treated during this period. Table 1 shows diagnosis, graft source, GVHD grade and organ involvement and MSC source. The first MSC infusion was performed on median 5 months after the onset of the GVHD (range 0.6 to 46). There were no adverse reactions related to the MSC infusions. Two patients died before day 7 due to sepsis and viral infection not related to the procedure. They received only 2 doses of therapy and were not included in the survival analysis. Over 16 patients, five patients died due to GVHD progression, relapse or infection. Remarkably, ten patients (63%) have responded to treatment, and five (31%) achieved complete response. Responders achieved high overall survival. The median response time was 14 days after the first MSC infusion (range, 7-28 days). Evaluating performance status (Karnofsky/Lansky scale) median improvement was in day 21 (range, 7-49 days). One responder died later on time, due to sepsis after achieving CR. According to the source of MSC, 7 of 12 evaluable patients that were treated with WJ-MSC responded to treatment (58%), comparable to 3 of 4 from BM-MSC (75%).

Conclusions:

MSC treatment resulted in a safe procedure with a response rate of 63% of heavily pretreated patients. WJ-MSC showed similar results than BM-MSC. These results show the feasibility and support the proposal of a prospective trial in order to demonstrate efficacy in this setting.

Diagnosis	Acute leukaemia (12) Non malignant diseases (6)
Graft source	Related (5) Unrelated (9) Cord blood (4)
GVHD grade	I (2) II (1) III (8) IV (7)
Organs Involved	Skin (9) Gut (15) Liver (7)
MSC source	Wharton Jelly (12) Bone Marrow (6)

[Table 1]

Disclosure: Nothing to declare.

P121 An “all in one” T-cell Product from non-transplantable Cord Blood Units for Virus- and leukemia-specific T-cell Immunotherapy

Kyriakos Koukoulias^1,2, Anastasia Papadopoulou ¹, Anastasios Kouimtzidis^1,2, Damianos Sotiropoulos¹, Minas Yiangou², Achilles Anagnostopoulos¹, Evangelia Yannaki¹, Panayotis Kaloyannidis³

¹George Papanikolaou Hospital, Thessaloniki, Greece, ²Aristotle University of Thessaloniki, Thessaloniki, Greece, ³King Fahad Specialist Hospital Dammam, Dammam, Saudi Arabia

Background: Leukemic relapse and opportunistic viral infections represent the major causes of morbidity and mortality post allogeneic hematopoietic cell transplantation (allo-HCT). T-cell immunotherapy with chimeric antigen receptor T-cells (CAR-Ts) is currently the spearhead of research in refractory hematological malignancies, however, CAR-Ts for myeloid leukemias lag well behind CAR-Ts for B-cell lymphoid malignancies, mainly due to the lack of an appropriate, targetable antigen. On the other hand, while immunotherapy with non-genetically engineered virus-specific T cells has been shown to successfully control viral infections post-allo-HCT, single-epitope leukemia-specific T-cells (Leuk-STs) targeting the less immunogenic leukemia-associated antigens (LAAs) have met limited clinical success. Aim. By adapting our previously developed protocol of generating multivalent Leuk-STs, targeting multiple epitopes of various leukemic antigens by stimulation with overlapping peptides spanning the whole proteins, we here aimed to generate a non-engineered, “all-in-one”, T-cell product from Non-Transplantable Umbilical Cord Blood Units (NT-UCBUs), called LEukemia-VIrus-specific T-cells (LEVIS), which simultaneously targets four viruses and two common LAAs.

Methods: Matured CD34+-derived dendritic cells from NT-UCBUs were stimulated with both leukemic [Wilms tumor protein (WT1) and Preferentially Expressed Antigen in Melanoma (PRAME)] and viral [EBNA1, LMP2 and BZLF1 (EBV); IE1 and pp65 (CMV); Hexon and Penton (AdV) and Large-T and VP1 (BKV)] pepmixes and used to “educate” autologous, naive T-cells.

Results: By reclaiming disqualified for allo-HCT NT-UCBUs and using our approach, we have been consistently obtaining clinical doses of LEVIS (CD3+ cells: 1.01±0.2x10⁸). The resultant T-cell products are polyclonal, containing both CD4+ and CD8+ T-cell subsets (39±2% and 50±2%, respectively), expressing effector memory (CD45RA-/CD62L-: 47.36±5%) and effector memory RA markers (CD45RA+/CD62L-: 48.50±4%), while containing insignificant amount of naïve and regulatory (CD4⁺/CD25^high) T cells. LEVIS demonstrated high specificity against all targeted antigens [spot-forming units (SFC)/2x10⁵ cells: CMV: 311±149, EBV: 319±111, BKV: 245±122, AdV: 432±32, Leuk: 553±257], similar to that conferred by Leuk-STs alone, suggesting successful “training” of naïve T cells and lack of antigen competition by the addition of immunodominant viral antigens. Importantly, LEVIS demonstrated low expression levels of Programmed cell Death protein-1 (PD-1) and barely detectable Cytotoxic T-Lymphocyte Associated Protein-4+ (CTLA-4), which remained stable throughout the culture, suggesting that persistent antigen exposure did not impair their Th-1-polarized function in vitro, an effect that could be translated into anti-leukemic and antiviral response after infusion.

Conclusions: Overall, by “recycling” NT-UCBUs, we provide the potential for future banking of LEVIS, to serve as third-party, “off-the-shelf”, multipotent T-cell products, thus further optimizing adoptive immunotherapy and improving the outcome of allo-HCT.

Disclosure: Nothing to declare.

P122 Clinical Success of Granulocyte Transfusions in Adult Neutropenic Patients after Chemotherapy and/or Allogeneic Transplantation - Time Matters!

Kira Inkari Thies, Michael Kramer, Friedrich Stölzel, Martin Bornhäuser, Johannes Schetelig, Simone von Bonin, Ralph Schneider, Kristina Hölig

Technische Universität Dresden, Dresden, Germany

Background: For decades, granulocyte transfusions (GTX) have been performed to treat neutropenic haematological patients with infectious complications. Nevertheless, the clinical efficacy of this cellular therapy is remaining controversial.

Methods: We performed a risk factor analysis in a large cohort of patients who received GTX between 2004 and 2014 at the University Hospital Dresden. Demographical data, diagnosis and outcome of the patients were registered. Among other parameters, type and state of the infection, dosage of the transfused granulocyte concentrates, and adverse effects had been recorded during each GTX cycle. GTX during an active infection were considered as “therapeutically” and GTX in patients who previously had survived life-threatening infections were considered as “prophylactically”. We evaluated overall survival and day-30-mortality from infection according to several risk factors. Treatment-cycle- or product-related variables were modeled as time-dependent variables and analyzed with Cox regression with time-dependent covariate. Cumulative incidences of infection related deaths were estimated according to the methodology of Gray. Competing risk was death from other causes than infection. The cause specific hazard for death due to infection was estimated with Cox regression.

Results: A total of 187 patients received 886 transfusions within 232 treatment cycles. The mean dose was 8.05 ∙ 10¹⁰ neutrophil cells (SD =2.5) per transfusion. In 194 of 232 cycles (84 %) granulocytes were transfused therapeutically, in 37 cycles (16 %) prophylactically.

Patient-related factors had impact on clinical outcome. State of the infection appeared to be the most important factor: Patients with septicemia had significantly lower treatment success than patients with localized infections with a significantly lower Overall survival (HR 2.4; CI: 1.68 - 3.52; p < .001) and a 4.8-fold higher cause specific hazard for infection-related death within 30 days after the first GTX (CI: 2.48 - 9.32; p < .001). Analysis of surrogate parameters for the severity of infections supported these findings (e.g. patients in ICU, patients requiring ventilation support, bacterial versus mycotic infections or a combination of both).

Among transfusion-related factors, early administration of GTX was favorable for therapeutic success. Patients with prophylactic GTX had a significantly lower 30-day-infection-mortality than patients with therapeutic GTX (HR 0.14; CI: 0.02 - 0.94; p = .044) and a slightly better overall survival (HR 0.71; CI: 0.38 - 1.27; p = .238). Patients who received ≥ 4∙10¹⁰ granulocytes per transfusion had a significant lower 30-days-infection-related mortality (HR 0.76; CI: 0.63 - 0.92; p = .005). Transfusion reactions were seen in 60 out of 886 (7 %) transfusions. Our analysis revealed no difference in the frequency of side effects with respect to the amount of granulocytes per transfusion (HR 0.95; CI: 0.67 - 1.34; p = .756).

Conclusions: Our data indicate that patients receiving GTX at an early stage of their infection seem to particularly benefit from this treatment. High dose GTX seem to be advantageous, In our cohort, GTX proved to be a safe approach without any severe side effects.

Nevertheless, these retrospective data are limited and should be validated in further prospective controlled studies.

Disclosure: Nothing to declare.

P123 Impact of long-term Cryopreservation of Autologous Hematopoietic Stem Cells Products

Judith Desoutter, Aline Regnier, Christèle Ossart, Alexis Caulier, Véronique Harrivel, Marie Noelle Lacassagne, Jean Pierre Marolleau

CHU Amiens Picardie, Amiens Cedex, France

Background: Freezing and storage of hematopoietic stem cells (HSC) graft are keys steps of therapeutic intensification process by autograft. No maximum storage period is defined in literature and less data are available concerning the quality of graft cryoconserved for a long duration. Now a day, only the notion that storage duration more than 15 years may be potentially harmful was advanced by 2014 SFGM-TC guidelines. (Calmels and al, Pathologie biologie 2014; 62: 221-225)

Methods: Fifty seven autologous grafts with long term storage (more than 5 years) were thawing in our study and were:

- evaluated by a quality control using Stem-Kit (Beckman Coulter, France) by flow cytometer including: viability/total nucleated cells count (TNC), viability/number of CD34+ cells, hematopoietic reconstitution evaluation (CFU-GM)

- compared with 60 short-term storage autologous grafts (less than 2 years) thawing routinely in laboratory.

Results: By comparison with routinely thawing graft quality criteria, we observed that CD34+ yield (p< 0.0001), TNC yield (p = 0.037) and number of CFU-GM/kg (p< 0.0001) were negatively impacted, based on lengthening of storage period. Moreover, we highlighted a significatively decreased of clonogenicity linked with increase graft storage duration (p=0.02).

Conclusions: Autologous graft long-term cryopreservation has a clear impact on product quality, in view of decreased CD34+ cells as well as CSH functionality in vitro. No national consensus defining cryopreservation modality and grafts storage, capable of influencing positively or negatively grafts quality, notably during long term conservation.

Disclosure: Nothing to declare.

P124 Optimizing Lentiviral Vector Transduction to Gene Modify Cord Blood CD8⁺ T Cells for off-the-shelf Adoptive Cell Therapy to Treat Cancer

Vania Lo Presti ¹, Ester Dunnebach¹, Maud Plantinga¹, Annelisa Cornel¹, Jurgen Kuball¹, Jaap Jan Boelens², Niek van Til *^1,3, Stefan Nierkens *^1,4

¹UMC-Utrecht, Utrecht, Netherlands, ²MSKCC, New York, NY, United States, ³AVROBIO Inc, Cambridge, MA, United States, ⁴Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands

Background: Adoptive T cell therapy utilizing autologous T cells has shown promising results for cancer treatment. However, the limited numbers of tumor associated antigen (TAA)-specific T cells and the functional aberrancies due to disease progression or treatment remain factors that may significantly limit the success of the therapy. The use of allogeneic T cells as an off-the-shelf therapy overcomes these issues, but requires gene-modification to induce a robust and specific anti-tumor effect. Umbilical cord blood (CB) might be particularly suited for this purpose; CB T cells are readily available in cord blood banks, show low toxicity, high proliferation rates and increased anti-leukemic effect upon transfer. Moreover, CB T cells can be used as combinational therapy in the hematopoietic cell transplantation setting to prevent minimal residual disease, relapses, and completely eradicate all tumor cells. However, combining anti-tumor gene modification and preserving advantageous immunological traits of CB T cells represents a major challenge for the harmonized production of T cell therapy products.

Methods: CB CD8⁺ T cells were isolated from fresh CB donors, subsequently expanded and activated. CB CD8⁺ T cells were transduced with lentiviral vectors (LV) expressing GFP and WT1-TCR, in order to compare methods, culture media, promoter strength and use of transduction enhancers. Analysis of immune-phenotype was performed in CB CD8⁺ T cells and PB CD8⁺ cells after isolation, expansion and transduction.

Results: In this manuscript we describe an efficient protocol to expand and transduce CB CD8⁺ T cells using LV, achieving an efficiency up to 83% of transduced cells. The protocol was established by optimizing the timing of LV treatment, selection of culture media, and application of different promoters. We confirmed LentiBOOST as a non-toxic transduction enhancer, however its use decreased the proliferation capacity of the T cells. Finally, we show that CB CD8⁺ T cells were more amenable to LV transduction than PB CD8⁺ T cells, and that the immune phenotype of the two cell sources were remarkably different with respect to the expression of inhibitory receptors and maturation markers.

Conclusions: We show an efficient method of gene modification of CB CD8⁺ T cells using LV, which is especially useful for off-the-shelf adoptive cell therapy products for cancer treatment, especially in post hematopoietic cell transplantation setting.

Disclosure: Nothing to declare.

P125 Donor Lymphocyte Infusion after Allogeneic Hematopoietic Stem Cell Transplantation. Single Centre Experience

Isabel Iturrate, Analys Ruiz, Sara Martínez, Natalia García-León, Mercedes Royg, Ángela Figuera, Adrián Alegre, Beatriz Aguado

Hospital Universitario La Princesa, Madrid, Spain

Background: Donor Lymphocyte Infusion (DLI) is often used to treat relapsed haematological malignancies after allogeneic stem cell transplantation. DLI is an immune-mediated therapy, mainly driven by the antitumor effect of donor T cells which can, in part, augment the graft-versus-tumor effect. However it can sometimes induce fatal adverse events such as severe graft-versus-host-disease (GVHD) and infectious complications.

Methods: We retrospectively analyzed 72 patients who received DLI for treatment of relapsed haematological malignancies, who had been allotransplantated in our centre between 1994 and 2018. Median age of 43 years old (range 16-70) at the time of DLI. Underlying diseases treated with DLI included chronic myeloid leukemia (CML) (n=20), acute myeloid leukemia (AML) (n=20), acute lymphocytic leukemia (ALL) (n=11), Hodgkin lymphoma (HL) (n=8), non Hodgkin lymphoma (NHL) (n=7), myelodysplastic syndrome (MDS) (n=5) and multiple myeloma (MM) (n=1). Fifty-nine patients received HLA-matched sibling donor, 2 haploidentical related donor and 11 matched unrelated donor transplant. Conditioning regimen was mieloablative in fifty-three patients, and reduced intensity conditioning in nineteen patients. All patients received DLI as treatment for relapsed disease after allogenic transplantation. In the present study we analyse response rate, graft-versus-host-disease (GVHD), progression free survival (PFS) and overall survival (OS).

Results: Our patients received a median of 3 infusions (range 1-5). The median number of infused CD3+ cells was 0.5x10⁸/kg (range 0.1x10⁸/kg to 2.84x10⁸/kg). Sixty-eight percent of patients received dose-escalation DLI. Patients with low disease burden only received DLI. Thirty-nine percent received DLI-associated therapy (chemotherapy, radiotherapy, tyrosine-kinase inhibitors).

From the sixty-three patients eligible for evaluation, 35 (56%) got clinical benefit (CML n=14, ALL n=6, AML n=6, HL n=5, MDS n=2 NHL n=2). Progression free survival was higher in CML, with a median of 132 months, followed by NHL (84 months). Acute graft-versus-host-disease developed in 15% of the patients (5 patients grades I-II, the other 5 grades III-IV). Two patients died from acute hepatic GVHD. Chronic GVHD developed in 22% (6 cases limited, 9 extend). One patient died from chronic pulmonary GVHD.

With a median follow up of 16 years, median progression-free survival was 120 months [IC 95% 84.51-155.49] for the whole series. There are substantial survival differences according to underlying diseases, with a better survival rates for CML and LH.

Conclusions: Inmunotherapy with DLI is an attractive strategy for relapsed patients after allogeneic transplantation. In our experience, patients with CML have more clinical benefit, with a response rate of 70%, similar to published. DLI response in other pathologies is lower, although it can be useful in association with other therapies. However, further studies are needed to develop strategies to reduce toxicity and enhance anti-tumor activity.

Disclosure: Nothing to declare.

P126 Case Report: Chronic Active epstein-barr Virus Infection (CAEBV) Controlled by Allogeneic Hematopoietic Stem Cell Transplantation (alloHSCT) and Transfusion of EBV-specific T-cells

Elisabeth Meedt ¹, Daniela Weber¹, Britta Eiz-Vesper², Britta Maecker-Kolhoff³, Agnes Bonifacius², Klaus Schwarz^4,5, Myriam Lorenz⁴, Susanne Delecluse^6,7, Henri-Jacques Delecluse^6,7, Ernst Holler¹, Wolfgang Herr¹, Matthias Edinger¹, Daniel Wolff¹

¹University Medical Center Regensburg, Regensburg, Germany, ²Hannover Medical School, Hannover, Germany, ³Hannover Medical School, Hannover, Germany, ⁴University of Ulm, Ulm, Germany, ⁵German Red Cross Blood Service, Baden-Wuerttemberg-Hessen, Ulm, Germany, ⁶German Cancer Research Center (DKFZ), Heidelberg, Germany, ⁷German Center for Infection Research (DZIF), Braunschweig, Germany

Background: Chronic active Epstein-Barr virus infection (CAEBV) is one of the Epstein-Barr virus (EBV)-positive lymphoproliferative diseases. It is a rare and often fatal complication of EBV infection. In CAEBV, EBV-infected B-, T- or NK-cells clonally proliferate and infiltrate multiple organs, leading to their failure. At present, allogeneic hematopoietic stem cell transplantation (alloHSCT) is the only curative therapy. Other treatments such as high-dose systemic corticosteroids or ganciclovir combined with either histone deacetylase inhibitors or proteasome inhibitors (e. g. bortezomib) may temporarily reduce systemic toxicity and allow the patient time to receive a transplant.

Methods: We report a case of T-cell-type CAEBV in a 27-year-old female caucasian patient with severe skin, neurological, hepatic and pulmonary involvement.

Results: After several therapeutic approaches including high-dose systemic steroids, ganciclovir combined with bortezomib and rituximab had failed with EBV encephalitis requiring mechanical ventilation, third-party EBV-specific T-cells were administered and clinical symptoms resolved, while EBV viremia persisted. Subsequently, alloHSCT was performed from an HLA-matched unrelated donor after conditioning with antithymocyte globulin (ATG), fludarabine and treosulfan followed by an alpha-beta T-cell depleted and EBV-specifc T-cell enriched peripheral stem cell graft and GvHD prophylaxis with everolimus. Intriguingly, the viremia cleared after administration of ATG in alloHSCT setting. When the virus reactivated again in persisting host T-cells everolimus was tapered and viremia could again be controlled by transfusion of donor derived EBV-specific T-cells. Until now, no underlying immunodeficiency was found in the patient while complete host genome DNA and EBV genome sequencing is pending.

Conclusions: Treatment with EBV-specific T-cells from a third party donor followed by alloHSCT from an EBV seropositive donor is an effective therapeutic approach in CAEBV. As EBV-viremia was cleared after the administration of ATG in the alloHSCT setting for the first time in the patient, ATG might be further analysed as a potential treatment option in T-cell-type CAEBV due to its depletive activity on T-cells.

Disclosure: Nothing to declare.

Chronic leukaemia and other myeloproliferative disorders

P127 Incidence of late Relapse after Allogeneic Stem Cell Transplantation for Myelofibrosis

Isik Kaygusuz Atagunduz, Anita Badbaran, Gaby Zeck, Christine Wolschke, Francis Ayuk, Maximilian Christopeit, Nicolaus Kröger

University Hospital Eppendorf, Hamburg, Germany

Background: Despite advances in transplantation procedures and significant prolongation in survival, relapse following allogeneic hematopoietic stem cell transplantation (SCT) for myelofibrosis (MF) remains a significant issue. Most relapse occurs during the early period of allogeneic SCT. We aimed to analyze the clinical characteristics of the patients with late relapse following allogeneic SCT.

Methods: In this cross-sectional study we retrospectively evaluated the files of 259 patients with myelofibrosis transplanted between 1994 and 2015 for late relapses. Late relapse was defined as the relapses later than first five years of stem cell transplantation (SCT). Study patients were grouped according to their relapse status under follow-up after five years. Group A consisted of patients with a late relapse. Patients under long term follow-up after five years with no relapse consisted Group B. Clinical and laboratory parameters of late relapse were investigated.

Results: A total of 94 patients (M/F=55/39, 58.5 vs. 41.4%, respectively) out of 259 MF transplant patients were identified with a median follow-up of 9.15 years (range, 5.12-19.61). Median age at transplantation of the whole study population was 56 (range;29-75). Sixty two patients (66%) had primary MF (PMF), 18 (19.1%) had post polycythemia vera (PV) and 14 (%14.9) had post essential thrombocythemia (ET) myelofibrosis. Thirteen patients (M/F=7/6) experienced (12%) late molecular (n=6) or hematological (n=6) relapses at a median of 7.1 years (range, 5.02-10.20). Eighty- one patients (M/F=48/33) with a median follow-up of 8.76 years (5.02-19.61) did not experienced relapse. Median age at transplant was similar in both groups (Group A vs Group B: 55 (36-73) vs. 57 (29-75)). Although, numerically smaller, median time from diagnosis to transplantation, 20 months (3-100) in Group A and 13 months (1-353) in Group B, had no effect on relapses. Other clinical and laboratory parameters analyzed were not associated with a significantly higher risk of late relapse. Relapse patients received either DLI (n=9) and/or second transplantation (n=4). Of those 61.5 % achieved again full donor cell chimerism and/or molecular remission. After a median follow up of 105 months (range,4-236) of the relapsed patients the 2 years PFS and overall survival is 92.3% and 84.6%, respectively.

Conclusions: In this large MF group we observed late molecular or hematological relapses. DLI and second SCT are effective to induce remission. Early detection of minimal residual disease (MRD) and therapy adjustment resulted in full chimerism and negative MRD status. Our results implicate the importance of close monitoring of MF patients even after 5 years post allograft.

Disclosure: Nothing to declare.

P128 Hematopoietic Stem Cell Transplantation in Myelofibrosis: The Experience of Three University Transplant Centres in Rome

Giulia Galassi ¹, Patrizia Chiusolo², Raffaella Cerretti³, Walter Barberi¹, Luisa Quattrocchi¹, Ursula La Rocca¹, Federica Sorà², Valentina Rossi³, Giovanni Manfredi Assanto¹, Mattia Brescini¹, Roberto Ricci¹, Roberto Latagliata¹, Massimo Breccia¹, William Arcese³, Andrea Bacigalupo², Simona Sica², Anna Paola Iori¹

¹Università Sapienza, Rome, Italy, ²Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy, ³Università Tor Vergata, Rome, Italy

Background: Myelofibrosis (MF) is a rare BCR-ABL negative myeloproliferative neoplasm, which can only be cured by Hematopoietic Stem Cell Transplantation (HSCT). Because of transplant related mortality (TRM) and morbidity, HSCT is reserved only to patients aged < 70 years with intermediate-2 or high risk MF, according to IPSS or DIPSS, or intermediate-1 with biological high-risk characteristics. Recently, Myelofibrosis Transplant Scoring System (MTSS) has been proposed in order to estimate the transplant risk. The aim of this analysis was to evaluate the outcomes of patients transplanted for MF in three University Transplant Centres in Rome and to verify the accuracy of MTSS in this population.

Methods: We retrospectively analysed 83 MF patients transplanted in Rome at Policlinico Umberto I (25 pts), Policlinico Tor Vergata (23 pts) and Policlinico Agostino Gemelli (35 pts), between 1986 and 2019 (75% of HSCT performed after 2012). Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method. The log-rank test was used to compare risk factors categories. Cumulative incidence (CI) was used to calculate TRM, Relapse Risk (RR), graft failure (GF) and GVHD. A modified MTSS not including ASXL1 mutation was used (ASXL1 mutation data available for only 2 patients).

Results: Median age was 54 years (range 21 - 72). 44%, 28% and 28% of patients received transplant from HLA-identical related, unrelated and haploidentical donors, respectively. Peripheral hematopoietic stem cells were used in 59% of patients. RIC regimens (mainly Thiotepa, Busulphan and Fludarabine-based) were employed in 70%. Forty patients had been previously treated with Ruxolitinib: 27 patients responded or showed disease stability; 13 patients progressed during treatment. Modified MTSS was evaluated in 47 patients, for whom driver mutation data was available. The risk was low in 12 (25%), intermediate in 21 (45%) and high in 14 (30%) patients. Five-year OS was 60%. Features associated to a better OS were: Karnofsky ≥90% (p=0.04), spleen< 22 cm (p=0.04) and cGVHD (p=0.013). A trend to a worse OS was observed in patients who had progressed while in treatment with Ruxolitinib. At 5 years, DFS and RR were 56% and 22%, respectively. CMV and EBV reactivations were associated to an increased RR. TRM was 12% at 100 days, 20% at 1 year and 28% at 5 years. CI of GF at 100 days was 6.5%, with a higher risk trend for HSCT performed before 2012 and donor/recipient sex mismatch (F/M). Acute GVHD CI was 38% (III-IV grade 11% of patients). Two-year CI of cGVHD was 45%; mild and moderate cGVHD was observed in 82% of cases. Transplant from sibling donor and MAC regimen were associated to an increased risk of cGVHD. The 2-year OS according to modified MTSS was: 100% for low, 85% for intermediate and 50% for high risk (p=0.01).

Conclusions: In our experience, better outcome was observed for patient < 57-year-old, with higher PS, not progressing during Ruxolitinib treatment before HSCT. Modified MTSS was a robust tool for the evaluation of transplant risk.

Disclosure: Nothing to declare.

P129

Abstract already published.

P130 CML Relapse after Allogeneic HSCT: Survival, Treatment Efficacy and Prognostic Factors for Outcome

Dunja Kampelmann, Dietrich W. Beelen, Rashit Bogdanov, Vesna Klisanin, Michael Koldehoff, Lambros Kordelas, Rudolf Trenschel, Markus Ditschkowski

University Hospital Essen, Essen, Germany

Background: Tyrosine kinase inhibitors (TKI) have fundamentally changed the therapeutic concept in CML leading to excellent outcome. Although allogeneic stem cell transplantation (HSCT) is currently only required for a limited number of patients (pts) post-transplant relapse remains a major challenge.

Methods: Retrospective single center long-term evaluation of overall survival (OS), relapse-free survival (RFS) and the incidence of CML relapse after allo-HSCT. Analysis of OS and leukemia-free survival (LFS) among relapsed transplant recipients compared to non-relapse pts, review for prognostic factors and evaluation of response to relapse treatment. Data on 488 eligible CML pts transplanted between January 1996 and September 2015 were analyzed. At time of transplant 80% of all pts were in chronic, 12% in accelerated and 8% in blast phase. For the comparison between OS in pts with and w/o relapse after HSCT only survival longer than 15 months post-transplant (n=352) was considered to minimize lead-time-bias by landmark analysis. Cox regression was used to ascertain influencing factors for RFS.

Results: Median follow-up in the cohort was 129 months, 25% (n=120) of all transplant recipients sustained relapse with a median onset of 15 months after HSCT. Cumulative incidences (CI) of relapse were 13%, 23%, 26%, 28% and 30% after 1, 3, 5, 10 and 15 years post-transplant. RFS was assessed 67%, 53% and 47% after 1, 5 and 10 years post-transplant. Multivariate analysis of RFS proved advanced disease stages (> 1. chronic phase) at time of HSCT to be an independent adverse prognostic factor (p=0,005) whereas chronic GvHD showed only significant impact in univariate analysis. Based on landmark analysis, OS could be demonstrated to be significantly higher in transplant recipients w/o relapse (p=0,042). Among relapsed pts OS was significantly worse in hematologic compared to molecular or cytogenetic relapse (p=0,018; p=0,012). In 72% of pts with CML-relapse long-term remission could be induced resulting in a median progression-free survival of 98 months. For molecular relapse 15-year OS was 92% after discontinuation of immunosuppression, 100%, 89% and 80% after treatment with DLI, IFN or TKI. For cytogenetic relapse 15-year OS was 56% after discontinuation of immunosuppression and 100% after treatment with DLI, IFN or TKI. Hematologic relapse resulted in a 10-year OS of 100% after treatment with IFN and 67% after TKI therapy.

Conclusions: To achieve favorable RFS in CML, allo-HSCT should be applied in non-advanced disease stages. However, even in case of relapse after HSCT remissions with favorable long-term survival can be induced in particular when relapse is diagnosed as molecular or cytogenetic CML recurrence.

Disclosure: Nothing to declare.

P131 Chronic Myeloid Leukemia: Allogeneic Hemopoietic Stem Cells Transplantation in the Era of Tyrosine Kinase Inhibitors

Elena Morozova, Yuliya Vlasova, Mariya Barabanshikova, Kseniya Afanasieva, Nikolay Mamaev, Ildar Barkhatov, Alexander Alyanski, Elena Darskaya, Mariya Vladovskaya, Sergey Bondarenko, Ivan Moiseev, Boris Afanasyev

Pavlov First Saint Petersburg State Medical University, Saint Petersburg, Russian Federation

Background: The overall therapeutic tactics strategy in CML patients has changed drastically after tyrosine kinase inhibitors (TKIs) were introduced. There is, however, a subgroup of advanced disease phase patients or patients with TKIs intolerance/ loss of response, in which the overall prognosis is dismal and allo-HSCT is the only curative option. As a large transplant center we have observed the overall treatment landscape change with new TKIs generations being introduced. This retrospective study summarizes our experiences in pre- and post-TKIs era.

Methods: Our retrospective cohort study includes allo-HSCT recipients with CML treated between 1995 and 2019 (n=114). The diagnosis was based on clinical and laboratory criteria. In all patients either Philadelphia (Ph) chromosome or chimeric BCR-ABL gene were found. Disease stage was determined according to WHO criteria. The chronic phase 1 (CP1) was confirmed in patients with no history of accelerated phase (AC) or blast crisis (BC), otherwise CP≥2 was confirmed. Pre allo-HSCT hematological, cytogenetic or molecular response was evaluated according to ELN criteria. The myeloablative conditioning regimen used consisted of 16 mg/kg of busulfan and 120 mg/kg of cyclophosphamide. However, 96% of patients received reduced intensity conditioning regimen with 180 mg/m² of fludarabine and 8-14 mg/kg of busulfan or 140 mg/m² of melphalan.

Results: The number of transplant-eligible CP1 patients decreased dramatically after TKIs introduction. While in 1995-2004 as much as 75% transplant recipients were in CP1 there were only 12% in 2017-2019. In recent years most CP1 patients scheduled for allo-HSCT (93%) have history of TKIs resistance, some also are transplanted after T315I mutation is found or due to treatment intolerance (7%). From 2008 on, there is also a concurrent trend for less CML patients receiving allo-HSCT in AP or BC (50% in 2008 and 21% in 2017-2019). Most of these patients reached CP≥2 on 1^st and 2^nd generation TKIs. Since 2004-2005 the CP≥2 patients’ proportion is consistently raising reaching as much as 65.6% in 2017-2019. Due to the targeted therapy improvement we are now able to achieve response even in BC patients. Therefore, the proportion of patients with BC history increased from 12% in 2004 to 60% in 2019, 20% of current allo-HSCT recipients having history of several BCs. The latter may point at a failure to refer a patient to allo-HSCT in time. Some recent years are marked by increase of 5-year overall survival (OS) from 25% to 58%, which may be explained by the fact that much less patients are now receiving allo-HSCT in AC or BC. A total of 46 patients in our cohort died, 29% of them (n=13) due to GVHD, 24% (n=11) of infectious complications, 39% (n=18) after disease relapse, 4% (n=2) due to heart attack, 4% (n=2) due to VOD.

Conclusions: The allo-HSCT belongs currently to 3^rd or 4^th line therapy for CP1 CML patients. It is also still a modality of choice if there is history of AC or BC. New generation TKIs are used to prepare patients for allo-HSCT thus raising significantly the CP≥2 allo-HSCT recipients proportion.

Clinical Trial Registry: NA

Disclosure: Nothing to declare.

P132 Reduced Intensity Allogeneic Stem Cell Transplant with Campath T-cell Depletion for Myelofibrosis in the Era of Jak Inhibitors- A Single Centre Experience

Claire Horgan, Shereef Elmoamly, Alex Kanellopoulos, Richard Lovell, Shankara Paneesha, Bhuvan Kishore, Mary Dillon, Katie O’Collins, Kathy Holder, Emmanouil Nikolousis

University Hospitals Birmingham NHS Foundation Trust, Birmingham, United Kingdom

Background: Despite recent advances in understanding the pathogenesis and molecular landscape of myelofibrosis over recent years, the condition continues to pose a number of challenges for the treating clinician. Allogeneic stem cell transplant remains the only potentially curative option, however, the heterogeneity in both clinical course and therapeutic response, as well as patients’ comorbidities, can make it difficult to weigh up the risks and benefits for individual patients. The advent of JAK inhibitors has revolutionized the treatment paradigm over the last decade with preliminary data suggesting positive impact on transplant outcomes. We conducted a retrospective review of patients undergoing a reduced-intensity Alemtuzumab- conditioned allogeneic stem cell transplant for myelofibrosis over a 9-year period, at Birmingham Heartlands Hospital, in order to provide real world data and identify any significant correlation between patient characteristics, JAK-2 inhibitor use, and outcomes.

Methods: We identified 27 patients (16 Male vs 11 Female, 8 sibling donor vs 15 matched-unrelated donor vs 4 mismatched-unrelated donor) who had undergone an allogeneic stem cell transplant for myelofibrosis at Heartlands Hospital between 16^th April 2010 and 7^th August 2019. 9 patients had received Ruxolitinib prior to allogeneic stem cell transplant. All patients were DIPS score intermediate 2/high. Data was obtained from transplant protocols, discharge letters and clinic letters accessed via the hospital online record system. The information was inputted onto an excel spreadsheet and statistical analysis was carried out using SPSS.

Results: Patients had a median age of 64.6 years and were followed up for a median of 23 months. Median overall survival for the cohort was 65.9%. (see figure 1)

25% patients developed acute graft versus host disease (GVHD) grade 3/4, including 2 patients who died of GVHD, and 14% patients developed chronic GVHD. Only 1 patient died of disease progression post transplant, a 2^nd patient progressed but regained remission with donor lymphocyte infusion (DLI) and ruxolitinib. Progression free survival was 62% at 23 months.

37% patients in total received DLI and 1 patient received a stem cell top up for secondary graft failure. 7.4% patients had a prior diagnosis of essential thrombocythemia, and 81% patients had neutrophil engrafted by day +28.

Sibling donors were associated with significantly better survival than matched unrelated donors (p=0.033). There was also a statistically significant improvement in survival in those patients who received DLI (p=0.037).

In our cohort, we did not identify any statistically significant correlation between prior ruxolitinib use and risk of death, progression, or acute and chronic GVHD.

Conclusions: Although patient numbers were small, our results highlight the curative potential of allogeneic stem cell transplantation in myelofibrosis using a reduced intensity approach with Alemtuzumab-based T-cell depletion. This approach is both safe and effective, even in a relatively older population, and the suggestion that post -transplant DLI may confer a survival benefit will need further evaluation in larger multicentre cohorts.

[Figure 1- overall survival]

Disclosure: Nothing to declare.

P133 Allogenic Stem Cell Transplantation in advanced Systemic Mastocytosis after Cytoreductive Treatment with Cladribine - A Single Center Experience on Two Patients

Christoph Buhl ¹, Emin Abdullayev¹, Johanna Kerschbaum¹, Herrad Baurmann¹, Andreas Reiter², Bertram Glaß¹

¹HELIOS Klinikum Berlin-Buch, Berlin, Germany, ²Universitätsmedizin Mannheim, Mannheim, Germany

Background: Systemic mastocytosis (SM) is characterized by proliferation and accumulation of clonal mast cells in bone marrow, skin and visceral organs. Bone marrow mast cell infiltration, elevated serum tryptase and a KIT D816V mutation (>90% of patients) are diagnostic hallmarks. The various subtypes of this rare haematological neoplasm are characterized by a more or less aggressive course. Targeted therapy against mutant-KIT with midostaurin has been approved, however, complete responses have not yet been reported and durable major response may only occur in 50-60% of patients. Cladribine has demonstrated efficacy in treatment of indolent SM and advanced SM (AdvSM) while allogeneic stem cell transplantation (ASCT) is a treatment option for eligible AdvSM patients with refractory or aggressive clinical course. In a retrospective study, response rates of 70% have been reported at day +100, followed by long term survival in 50-60% of patients.

Methods: We here report on ASCT in two patients (female, 70 years old; male, 50 years old) with aggressive SM and associated myelodysplastic/myeloproliferative neoplasm (ASM-MDS/MPN). The first patient presented with a bone marrow infiltration of 5%, a serum tryptase of 320 µg/l (normal value < 11.4), massive splenomegaly and multiple additional somatic mutations in ASXL1, SETBP1 and CSF3R in addition to KIT D816V. The second patient presented with a bone marrow mast cell infiltration of 80%, a serum tryptase of 540µg/l and only mild splenomegaly. Somatic mutations were identified in KIT D816V, NRAS and TET2. Both patients were resistant to midostaurin but achieved a stable partial remission on one and seven cycles cladribine, respectively. Bone marrow biopsy revealed residual mast cells of < 5% and serum tryptase was decreased to 52µg/l and 102µg/l when conditioning therapy with fludarabine (150mg/m2), treosulfan (36g/m2) and ATG Neovii® (45mg/kgBW) was initiated. Peripheral stem cells from unrelated 10/10 donors were used as stem cell source. While one patient had negligible skin reactions associated to the central line, the second patient presented with high fever and rash one week after transplantation mimicking hyperacute GvHD, which was, however, most likely an associated with mediator release/allergic reaction upon antimycotic treatment with an echinocandin.

Results: Both patients show complete chimerism on day +100, tryptase is normal in the first patient and near normal (35µg/l) in the second patient. The first patient shows mild mucocutaneous chronic GvHD.

Conclusions: Our experience shows feasibility and short-term efficacy of ASCT in ASM-AHN after induction of best possible remission with several cycles of cladribine and treosulfan-based conditioning. Mediator release may remain an important issue during and after transplantation and its differentiation from GvHD may be difficult.

Disclosure: Nothing to declare.

P134 Allogeneic Stem Cell Transplantation for Idiopatic Myelofibrosis: A Single Centre Experience

Matteo Parma ¹, Elena Elli¹, Elisa Diral², Elisabetta Terruzzi¹, Marilena Fedele¹, Rossella Renso¹, Andrea Aroldi², Giovanni Zambrotta², Pietro Pioltelli¹, Carlo Gambacorti Passerini^1,2

¹San Gerardo Hospital, Monza, Italy, ²University of Milano-Bicocca, Monza, Italy

Background: Allogeneic Stem Cell Transplantation (ASCT) is the only curative option for Myelofibrosis (MF). Development of reduced intensity conditioning (RIC) regimens and introduction of Ruxolitinib (Rux) have improved the outcome of ASCT. However, this procedure is still burdened by substantial morbidity and high transplant-related mortality (TRM). Here we report our experience with ASCT in MF setting, in order to evaluate the factors influencing post-transplant outcome, in term of overall survival (OS) and Progression-free survival (PFS).

Methods: In the last 10 years we performed 30 ASCT on 27 MF patients (pts); 3 pts of them received a second ASCT for MF relapse. The median age was 51 (range: 25-68) years. Driver mutations were found in 23 pts and were: JAK2V617F in 16 (59%), MPL in 3(11%) and CALR mutations in 4 (15%) pts; 4 (15%) pts were defined as “triple-negative”. According to Dynamic International Prognostic Scoring System (DIPSS) at transplant, pts were stratified into high, intermediate-2 and intermediate-1 risk in 11 (41%), 12 (44%) and 4 (15%) cases, respectively. Considering the first ASCT, donors were matched related (MRD), matched unrelated (MUD) and haploidentical in 18 (67%), 7 (26%), and 2 (7%) of cases, respectively. Conditioning regimen (CR) was RIC in 11 pts (41%) or myeloablative in 16 pts (59%); all CR were Busulfan and Fludarabine-based, in 48% of cases (n=13) associated with Tiothepa. Conventional GVHD prophylaxis regimens were used according to type of ASCT. Splenectomy or spleen irradiation were performed before ASCT in 2 and 6 pts in pre-Rux era; 16 pts (59%) received Rux before ASCT. Source of stem cells were bone marrow in 15 (56%) or peripheral blood stem cells in 12 (44%) pts. OS and PFS have been evaluated by Kaplan-Meier analysis.

Results: Aafter a median follow-up of 18.5 (range: 0.5 - 175) months from first ASCT, 4/27 pts (15%) died for early TRM, 6 (22%) pts for MF relapse (4) or leukemic evolution (2). 17 (63%) pts were alive, 15 of them with full chimerism and complete remission (one after the second ASCT); 2 pts were alive in MF relapse. Chronic GVHD occurred in 6 (22%) pts.

The probability of OS for the entire cohort at 2 and 5 years was respectively 75% and 60% and the 2 and 5 year PFS was 75% and 55% respectively. In statistical analysis, significant predictive factors of good outcome were: intermediate-1 DIPSS score at transplant, Rux-exposition pre-transplant and development of chronic GVHD. There was no correlation between clinical outcome and type of driver mutations, age at transplant, donor type, CR, source of stem cells.

Conclusions: ASCT in MF is actually a valid therapeutic option for pts eligible to the procedure also in the Rux era. In our experience, earlier stage of MF at time of transplant and Rux exposition before transplant seem to have a favourable impact on the outcome post-ASCT; also a chronic GVHD seems to play a protective role for reducing relapse risk post-ASCT.

Disclosure: Nothing to disclose

P135 A case of Successful Second Haploidentical Bone Marrow Transplantation after Secondary Graft Failure in a Patient with Refractory Chronic Myeloid Leukemia

Nadezhda Shnalieva, Anna Melikhova, Iurii Osipov, Galina Salogub, Vladimir Ivanov, Elza Lomaia

Almazov National Medical Research Centre, Saint-Petersburg, Russian Federation

Background: Allogeneic hematopoietic stem cell transplantation (alloHSCT) is currently considered a mandatory therapy option in patients with refractory to at least two of tyrosine kinase inhibitors (TKI). Haploidentical alloHST are becoming increasingly important in this cohort of patients.

Methods: 33 years old, male. History of CML: blast crisis as a debut; the disease was characterized by primary cytogenetic resistance to imatinib and bozutinib. In the study of BCR-ABL mutations during bozutinib therapy, the T315I mutation was detected. The loss of complete hematological response (CHR) was stated with the preservation of the chronic phase (CP) of CML; cytoreductive therapy with hydroxyurea 3000 mg/day was added to bozutinib. Patient only had one haploidentical donor (mother).

When CHR was achieved, alloHSCT was performed (period from disease debut to alloHSCT is 58 months). Conditioning regimen (CR):fludarabine 150 mg/m2, busulfan 8 mg/ kg; prophylaxis of the graft-versus-host disease (GVHD): high-dose (50 mg/kg DD3,4) cyclophosphamide was administered, tacrolimus and mycophenolate mofetil therapy was initiated at D5. To D+30 the patient had 100% donor chimerism, Ph-chromosome in cytogenetic studies of bone marrow was not determined, but minimal residual disease (MRD) remained-0,210% BCR-ABL p210 (15349 ABL copies). Prophylactic therapy with TKI- dasatinib 50 mg/day was initiated at D+58. From D+62, there was a decrease in donor chimerism: 93.8% (D+62) => 91.5% (D+82) => 91.6% (D+118), MRD by these terms decreased by 1 log. By D+128 immunosuppressive therapy (IST) was withdrawn. From D+148: deepening profundity of persistent cytopenia, decreasing of donor chimerism to 82%. Infusion of donor lymphocytes (DLI) - 1*10^6 CD3+CD45+/kg was performed on D+152. Total bone marrow hypoplasia, decreasing of donor chimerism to 33.5% were detected on D+158. The secondary graft failure was stated.

Results: Second alloHSCT from the same donor was performed within 7 days after the diagnosis of secondary graft failure. CR: fludarabine 150 mg/m2, melphalan 140 mg/m2; prophylaxis of GVHD was the same. On D+29 100% donor chimerism was detected, BCR-ABL p210-0% (11212 ABL copies). By D+63 decreasing of donor chimerism to 93,3% was stated, on D+63 IST was completely withdrawn. On D+78, donor chimerism increased up to 98%. On D+83, due to high risk of secondary graft failure, DLI was performed (5*10^5 CD3+CD45+/kg). On DD+110, +137 full donor chimerism was defined. MRD was not detected during the entire post-transplant period, and therefore prophylactic administration of TKI was not resumed. To date, chronic multilocus GVHD (skin, mucosa, liver) has occurred, which was successfully treated with ruxolitinib and extracorporeal photopheresis.

Conclusions: Allogeneic (haploidentical) HSCT in patients with refractory CML may be a successful alternative to a fully HLA-compatible SCT. Second allogenic (haploidentical) HSCT from the same donor with the change of CR in our patient was effective. As a stimulation of the graft-versus-leukemia (GVL) effect, "earlier” withdrawal of IST and DLI may be successfully performed. “Deep molecular response” in post-transplant period can be achieved without administration of TKI due to satisfactory graft function. Ruxolitinib is actively used in GVHD treatment, and can also stimulate an antitumor response.

Earlier alloHSCT can contribute to reduce incidence of complications.

Disclosure: Nothing to declare.

Conditioning regimens

P136 Combining Clofarabine and Fludarabine with Exposure Targeted Busulfan for Pediatric Leukemia: An Effective, Low Toxic, TBI-free Conditioning Regimen

Anne Birgitta Versluys ^1,2, Coco de Koning², Marc Bierings^1,2, Stefan Nierkens^1,2, Caroline Lindemans^1,2, Dorine Bresters^1,3, Wouter Kollen^1,3, Arjan Lankester³, Jaap Jan Boelens^2,4

¹Prinses Maxima Centre for Pediatric Oncology, Utrecht, Netherlands, ²University Medical Center Utrecht, Utrecht, Netherlands, ³Leiden University Medical Center, Leiden, Netherlands, ⁴Memorial Sloan Kettering Cancer Center, New York, NY, United States

Background: The combination of Clofarabine + Fludarabine + Busulfan (CloFluBu) was found to have synergistic anti-leukemic activity against ALL and AML blasts in vitro (Andersson et al: BBMT 2011). As TBI induces significant late effects in childhood ALL, and AML patients have high relapse rates, we hypothesized that CloFluBu may be a potential alternative to TBI in ALL, and could add anti-leukemic activity in AML. Within the “Dutch COG HCT Working Group” we prospectively studied the outcomes of a CloFluBu-conditioning regimen for lymphoblastic and myeloid malignancies.

Methods: Patients from the 2 pediatric HCT programs (LUMC and UMC Utrecht/Princess Máxima Center for Pediatric Oncology) in the Netherlands with a lymphoblastic or myeloid malignancy receiving their first HCT, between August 2011 and April 2019, were included. Over 4 days, Clofarabine 30mg/m2 was given in 1 hour, followed by Fludarabine 10mg/m2 in 1 hour, followed by a 3-hour infusion of once-daily targeted Busulfan (weight-based dosing + therapeutic drug monitoring to a total Bu-exposure of 90mg*h/L). Thymoglobulin was added in unrelated donors (except in AML patients receiving cord blood). GvHD-prophylaxis was according to standard protocols. Minimal Residual Disease (MRD) negative was defined as < 10e-4. Primary endpoints were Overall Survival (OS) and Leukemia Free Survival (LFS). Secondary endpoints were Non Relapse Mortality (NRM), Relapse, acute and chronic Graft-versus-Host Disease (GvHD), and VOD/SOS. Cox Proportional Hazard and fine and gray competing risk models were used for data analysis.

Results: 155 children were included; 66 ALL (38 in CR1, 28 ³ CR2), 69 AML (28 in CR1, 40 in CR2, 1 in active disease) and 20 other malignancies (mostly MDS-EB). Median age was 9.7 (0.5-18.6) years. Most donors were unrelated (119 vs 36 related); 79 Bone Marrow (BM), 66 Cord Blood (CB) and 10 Peripheral Blood Stem Cells. Median follow up was 964 (19-2994) days. Overall the 3-yr estimated OS and LFS was 72 ± 4.5% and 65 ± 5% respectively. Estimated 3-yr LFS for MRD-neg ALL, MRD-pos ALL, AML CR1 and AML CR2 was 74 ± 7%, 40 ± 12%, 64 ± 10%, 65 ± 9% respectively). NRM in whole cohort was 10.3 ± 3.0% (with 25 ± 4.3% for AML CR1 (n=28), and 5.8 ± 2.3% in the rest). Other endpoints: only 2 graft-failures were noted, incidence of aGvHD III-IV at 6 months was 11 ± 3%, extensive chronic GvHD at 3-yr was 5.2 ± 2.2%. Relapse at 3-yr was 25 ± 4.3% (MRD-neg ALL 16.2 ± 3.7%, versus 60 ± 4.9% in MRD-pos ALL, in AML 22.5 ± 4.2%) and no VOD/SOS was noted.

Conclusions: CloFluBu in myeloid- and lymphoblastic malignancies, showed very limited toxicity and encouraging LFS in all groups, in particular for MRD negative ALL. More studies, preferably in randomized controlled clinical trials, are needed to draw firm conclusion with regards to the anti-leukemic effect and late effects.

Clinical Trial Registry: N/A

Disclosure: nothing to disclose

P137 Benda-beam High-dose Therapy Prior to auto-sct is Effective in Resistant/relapsed DLBCL: A Phase II Study

Giuseppe Visani ¹, Federica Loscocco¹, Stefano Guidi², Potito Scalzulli³, Attilio Olivieri⁴, Emanuele Angelucci⁵, Saveria Capria⁶, Francesca Patriarca⁷, Barbara Castagnari⁸, Francesco Angrilli⁹, Daniele Vallisa¹⁰, Gerardo Musuraca¹¹, Andrea Mengarelli¹², Piero Galieni¹³, Francesco Gaudio¹⁴, Patrizia Tosi¹⁵, Pierluigi Zinzani¹⁶, Alberto Bosi², Nicola Cascavilla³, Barbara Guiducci¹, Marco Rocchi¹⁷, Alessandro Isidori¹

¹Hematology and Stem Cell Transplant Center AORMN, Pesaro, Italy, ²Carreggi Hospital, Firenze, Italy, ³IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy, ⁴Ospedali Riuniti, Ancona, Italy, ⁵San Martino Hospital, Genova, Italy, ⁶La Sapienza University, Roma, Italy, ⁷AOU di Udine, Udine, Italy, ⁸Santa Maria delle Croci di Ravenna, Ravenna, Italy, ⁹Spirito Santo Hospital, Pescara, Italy, ¹⁰Piacenza Hospital, Piacenza, Italy, ¹¹IRST, Meldola, Italy, ¹²IRCCS Regina Elena Institution, Roma, Italy, ¹³Mazzoni Hospital, Ascoli Piceno, Italy, ¹⁴AOU Policlinico di Bari, Bari, Italy, ¹⁵Infermi Hospital, Rimini, Italy, ¹⁶Sant’Orsola Hospital, Bologna, Italy, ¹⁷Carlo Bo University, Urbino, Italy

Background: A major drawback affecting clinical trials of high-dose therapy (HDT) followed by autologous stem cell transplant (ASCT) in lymphomas is the high heterogeneity of histological entities. As a consequence, the statistical power is reduced when we focus on a specific histological subset, and data are often not conclusive. We designed a phase II study to evaluate the efficacy of the BeEAM conditioning (bendamustine 200 mg/m2 on days -7,6, cytarabine 400 mg/m2 days -5-4-3-2, etoposide 200 mg/m2 days -5-4-3-2, melphalan 140 mg/m2 day-1) in resistant/relapsed diffuse large B-cell non-Hodgkin lymphoma (DLBCL) patients.

Methods: The study was registered at European Union Drug Regulating Authorities Clinical Trials (EudraCT) N. 2011-001246-14. 64 patients (median age 54.5 years, range 19-70) with resistant/relapsed DLBCL or transformed follicular lymphoma were enrolled. The primary end-point of the study is to evaluate the 1-year complete remission rate.

Results: Briefly, 47/64 patients had advanced stage disease (III-IV); 21 were primary refractory and 43 had relapsed. 33/64 were in II or subsequent CR after salvage therapy, whereas 24 were in PR and 7 in progressive disease. A median number of 5.55x10⁶ CD34+/Kg cells (range 2.07-12.20) collected from peripheral blood was reinfused to patients. All patients engrafted, with a median time to ANC>0.5x10⁹/l of 10 days. Median times to achieve a platelet count >20x10⁹/l and >50x10⁹/l were 13 and 18 days respectively. Twenty-four out of 64 patients presented a FUO (37.5%). One patient died due to an incomplete hematological recovery after transplant and one patient died due to acute liver failure, producing an overall transplant related mortality of 3.1%. Sixty-two patients are evaluable for response: 51/62 (82%) obtained a CR, 4/62 (6%) a PR, whereas 7/62 (11%) did not respond to therapy. The median follow-up after transplant was 34 months (range 1-90).

Conclusions: The stringent inclusion criteria at enrollment allow to precisely evaluate the impact of HDT with Bendamustine followed by ASCT in a highly selected population of patients with DLBCL. The 1 year remission rate was superior to 55%, thus reaching the primary end-point. Accordingly, our data provide the evidence that the Benda-BEAM regimen is safe and has promising high efficacy in resistant-relapsed aggressive diffuse large B cell lymphoma.

Disclosure: Nothing to declare.

P138 Reduced-toxicity Conditioning with Fludarabine, Thiotepa and Melphalan in Allogeneic Hematopoietic Cell Transplantation for Patients with Impaired Lung Function

Jesus Duque-Afonso, Gabriele Ihorst, Miguel Waterhouse, Robert Zeiser, Ralph Wäsch, Hartmut Bertz¹, Mehtap Yücel, Thomas Köhler, Joachim Müller-Quernheim, Reinhard Marks, Jürgen Finke

University of Freiburg Medical Center, Freiburg, Germany

Background: The age of patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) has increased during the last decades, mainly due to improved reduced intensity/toxicity conditioning protocols. A reduced-intensity conditioning based on fludarabin, carmustin/BCNU and melphalan (FBM) has been previously developed at our institution. Since we observed detrimental effects in patients with compromised lung function prior allo-HCT and conditioned with FBM, efforts have been made in order to replace BCNU by thiotepa (FTM) to reduce toxicity.

Methods: In this study, we retrospectively analyzed the outcome, Graft-versus-Host (GvHD) incidence, lung function and organ toxicity of patients transplanted at our institution after conditioning with the reduced intensity/toxicity protocols FBM (n=122) and FTM (n=73) between January 1^st 2013 and December 31^st 2017. Patients were stratified by caring physicians to receive conditioning according to FBM protocol (fludarabine 4x30mg/m², BCNU/carmustine 2x150mg/m² and melphalan by patients >55 years:1x110mg/m² or < 55 years:1x140mg/m²) or FTM (fludarabine 4x30mg/m², thiotepa 2x5 mg/kg and melphalan for patients >55 years:1x110mg/m² or < 55 years:1x140mg/m²). We included in the analysis all patients at first allo-HCT and surviving at least 100 days after allo-HCT. During the observation period, continuously increasing number of patients were treated with FTM. Therefore, patients treated with FBM had a longer median follow-up of 957 (range 104 -2337) vs. 801 days (range 124 -1667) of FTM-treated patients.

The Cox proportional hazards regression model was used to estimate hazard ratios (HR) and confidence intervals (CI) for overall survival and progression-free survival. We applied the Fine and Gray model to compare cumulative incidence rates in the presence of competing risks and presented as subdistribution hazard ratios for relapse incidence, non-relapse mortality, aGvHD and cGvHD incidence. Pearson’s chi-square and Fisher’s exact tests were used to compare categorical variables as appropriate and Student’s T-test to compare continuous variables.

Results: Compared to patients conditioned with FBM, FTM-treated patients were younger and received less frequently GvHD prophylaxis with alemtuzumab. Patients treated with FTM suffered more frequently lymphoid malignancies and received more chemotherapy cycles. As expected, there were more patients with a HCT-CI score ≥ 4 and with impaired lung function allocated in the FTM group, due to the patient selection by caring physicians to the presumably less pulmonary toxic protocol.

Despite a higher comorbidity-index prior allo-HCT, patients conditioned with the FTM protocol show similar overall survival and relapse incidence. Hence, patients with impaired lung function prior allo-HCT, as defined by FEV1< 80% of predicted or DLCOcSB< 80% of predicted, and conditioned with FTM had a 2-year overall survival of 83.0% compared to 71.1% of FBM-treated patients (p=0.11). FTM-treated patients had less pulmonary cause of death compared to patients treated with FBM. In contrast, gastrointestinal complications were more frequently observed in patients conditioned with FTM. No differences were observed in incidence and severity of acute and chronic GvHD. Lung function was reduced in FTM-treated patients prior allo-HCT and 1 year after allo-HCT compared to FBM-treated patients.

Conclusions: In summary, the FTM protocol has reduced toxicity but sufficient anti-neoplastic effect and is suitable for patients with impaired lung function prior allo-HCT.

Disclosure: Nothing to declare.

P139 Allogeneic Stem Cell Transplant with minimal-intensity Conditioning in Patients with Cutaneous T-cell Lymphoma. A Single Centre Retrospective Review

Marianne Gallanagh ¹, Amy Brown¹, Angharad Pryce¹, Richard Szydlo², Stephen Morris³, Renuka Palanicawandar¹, Edward Kanfer¹

¹Imperial Healthcare Trust, London, United Kingdom, ²Imperial College London, London, United Kingdom, ³Guy’s and St. Thomas’ NHS Foundation Trust, London, United Kingdom

Background: Haematopoietic stem cell transplantation (HSCT) in advanced cutaneous T-cell lymphomas (CTCL), of which mycosis fungoides (MF) and Sezary syndrome (SS) are the most common subtypes, is increasingly practiced as a curative therapy. Minimal-intensity conditioning, using a protocol established in Stanford using anti-thymocyte globulin (ATG) and total nodal lymphoid irradiation (TNLI), is an option for CTCL patients, particularly those of older age, and those with chronic colonisation of skin lesions by potentially multi-resistant organisms which would render myeloablative conditioning regimens higher risk. The conditioning protocol comprises initial total skin electron beam therapy (TSEB) (4-8 week course) pre-transplant, followed by TNLI (day -11 to day 0), 10 x in 80cGy fractions of 4 radiation fields (2 anterior and 2 posterior including all major lymphoid areas) and ATG (day -11 through day -7, 1.5mg/kg/day). Ciclosporin was given from day -3 onwards, MMF was given from day +1 onwards. The benefits of this protocol include reduced incidence of acute GvHD and prompt multi-lineage engraftment, with evident graft vs tumour effect.

Methods: This is retrospective case series of 32 CTCL patients who underwent allogeneic transplant for advanced CTCL using the TSEB/ATG/TNLI protocol at a single centre after failure of standard therapy between 2012 and 2019. Of the 32 patients, 3 had SS and 29 of had MF. The number of prior treatments ranged from 3-8. 11 patients had matched sibling allografts, 2 patients had haploidentical sibling allografts and 19 patients had grafts from matched unrelated donors. We used the patients’ transplant protocols and hospital electronic records to retrieve information. We collected data for DFS and OS analyses as well as transplant-related mortality, and the doses and responses to donor lymphocyte infusions (DLI).

Results: We used the Kaplan Meier method to generate survival curves looking at time to two events; disease-free survival (DFS) and overall survival (OS). Of the 32 patients who were transplanted, 14 patients relapsed, of which 4 then died due to the disease progression. 7 patients received at least one DLI post-transplant, either for relapsed disease or falling chimerism, and 4 were successfully salvaged with DLI and chemotherapy/radiotherapy. An additional 5 patients died due to sepsis/GvHD. 13 patients remain in remission. The Kaplan Meier estimates of 5-year OS and 5-year DFS in this study were 63% and 45%, respectively.

Conclusions: Use of this minimally intensive protocol resulted in a predicted OS of 2/3 of patients at 5 years with approximately half of the patients being disease free, suggesting promising long-term outcomes in a disease with otherwise poor overall survival. This study has shown successful engraftment can be achieved with this minimally-invasive protocol and suggests reducing the risk of non-relapse related mortality can be achieved without increasing risk of relapse or progression. For those who relapse DLI may be of benefit and further study of its use in this setting is recommended.

[Kaplan Meier Survival Curves]

Disclosure: Nothing to declare.

P140 Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Acute Lymphoblastic Leukemia and Karnofsky Performance Status Score Equal or Lower Than 80%. A Study from the ALWP-EBMT

Francesco Saraceni ¹, Myriam Labopin², Riitta Niittyvuopio³, Gerard Socié⁴, Nicolaus Kröger⁵, Edouard Forcade⁶, Paul Browne⁷, Péter Reményi⁸, Jan Cornelissen⁹, Stephen Robinson¹⁰, Ibrahim Yakoub-Agha¹¹, Thierry Lamy¹², Eolia Brissot², Bipin Savani¹³, Arnon Nagler¹⁴, Mohamad Mohty²

¹Ancona University Hospital, Ancona, Italy, ²Saint Antoine Hospital, Paris, France, ³HUCH Comprehensive Cancer Center, Stem Cell Transplantation Unit, Helsinki, Finland, Helsinki, Finland, ⁴Hopital St. Louis, Paris, France, ⁵University Hospital Eppendorf, Hamburg, Germany, Hamburg, Germany, ⁶CHU Bordeaux, Hôpital Haut-leveque, Bordeaux, France, ⁷St. James`s Hospital, Dublin, Ireland, ⁸Dél-pesti Centrumkórház - OrszágosHematológiaiésInfektológiaiIntézet, Budapest, Hungary, ⁹Erasmus MC Cancer Institute, University Medical Center Rotterdam, Rotterdam, The Netherlands, Rotterdam, Netherlands, ¹⁰Bristol Royal Hospital for Children, Bristol, United Kingdom, ¹¹CHU de Lille, LIRIC, INSERM U995, Université de Lille, Lille, France, ¹²Centre Hospitalier Universitaire de Rennes, Rennes, France, ¹³Vanderbilt University Medical Center, Nashville, TN, United States, ¹⁴Chaim Sheba Medical Center, Tel-Hashomer, Israel

Background: We report here the results of a retrospective study designed to evaluate outcome of ALL patients undergoing allo-HCT with KPS score ≤80%.

Methods: The analysis included ALL patients aged ≥18 years, undergoing allo-HCT in first remission between 2000 and 2018, with a KPS score of 50% to 80% at the time of transplant. Patients who received manipulated grafts or had incomplete data about cytogenetics were excluded. Conditioning intensity was defined according to EBMT definitions (Aoudjhane M. et al, Leukemia 2005; 19: pp. 2304-2312).

Results: A total of 1,010 patients were identified. Median age at transplant was 43 years (18-76 years). Median year of transplant was 2011. The KPS score was =80% in 83% of the patients and < 80% in 17% of the patients. Diagnosis was Philadelphia chromosome (Ph) negative B-ALL, Ph positive B-ALL or T-ALL in 34%, 44% and 22% of the patients, respectively. Donor type was MSD or 10/10 UD in 60% and 40% of the patients, respectively. Conditioning was myeloablative (MAC) or reduced-intensity (RIC) in 78% and 22% of the patients, respectively, and it was TBI-based in 79% of the patients. Stem cell source was PBSC in 76% and BM in 24% of the patients, respectively. Anti-thymocyte globulin (ATG) was administered to 21% of the patients receiving MSD and 68% of the patients receiving 10/10 UD as donor type. Cumulative incidence of grade II-IV and III-IV aGVHD was 32% and 9%, respectively. The 2-year cumulative incidence of chronic GVHD (cGvHD) and severe cGVHD was 43% and 18%, respectively. Non relapse mortality (NRM) and relapse incidence (RI) at 2 years were 18% and 28%, respectively. At 2 years, leukemia-free survival (LFS), overall survival (OS) and GVHD-free, relapse-free survival (GRFS) rates were 54%, 64% and 41%, respectively.

On multivariate analysis, transplant from 10/10 UD was associated with higher incidence of aGVHD (HR 1.8, p< 0.0001) and higher risk of NRM (HR 1.7, p< 0.01) as compared to MSD. RIC conditioning was associated with higher risk of relapse (HR 1.2, p=0.02), lower LFS (HR 1.3, p=0.03) and lower GRFS (HR 1.3 p=0.02) as compared to MAC. NRM was not significantly different between MAC and RIC. Factors independently associated with improved OS were younger age at transplant, female sex, more recent year of transplant and Ph+ B ALL phenotype. Administration of ATG was associated with reduced risk of developing grade II-IV aGVHD (HR 0.6, p< 0.001), cGVHD (HR 0.5, p< 10^-4) and severe cGVHD (HR 0.4, p< 10^-4).

Conclusions: In conclusion, allo-HCT is feasible in patients with acute lymphoblastic leukemia in first remission and KPS score ≤80%, with acceptable NRM and survival rates. Transplant from a sibling donor was associated with reduced risk of NRM and aGVHD as compared to matched unrelated donor. Interestingly, despite the poor KPS score of the patients included in the analysis, a MAC protocol was associated with similar NRM, lower relapse and better LFS and GRFS as compared to RIC in the selected population. Finally, administration of ATG was associated with reduced acute and chronic GVHD rates.

Disclosure: Nothing to declare.

P141 A Prospective Cohort Study Comparing long-term Outcomes with and without Palifermin in Patients Receiving Hematopoietic Cell Transplantation for Hematologic Malignancies

Wael Saber ¹, Patricia Steinert¹, Mei-Jie Zhang^1,2, Min Chen¹, Andrea Pope¹, Armand Keating³, John Wingard⁴, Karen Ballen⁵, Patrick Stiff⁶, Miguel-Angel Perales⁷, Stephen Forman⁸, Richard Champlin⁹, Amelia Langston¹⁰, Torbjörn Kullenberg¹¹, Mattias Rudebeck¹¹, Mary Horowitz¹

¹CIBMTR (Center for International Blood and Marrow Transplant Research), Medical College of Wisconsin, Milwaukee, WI, United States, ²Medical College of Wisconsin, Milwaukee, WI, United States, ³Princess Margaret Cancer Center, Toronto, Canada, ⁴University of Florida, Gainesville, FL, United States, ⁵University of Virginia Health System, Charlottesville, VA, United States, ⁶Loyola University Medical Center, Maywood, IL, United States, ⁷Memorial Sloan Kettering Cancer Center, New York, NY, United States, ⁸City of Hope, Duarte, CA, United States, ⁹University of Texas MD Anderson Cancer Center, Houston, TX, United States, ¹⁰Winship Cancer Institute of Emory University, Atlanta, GA, United States, ¹¹Swedish Orphan Biovitrum (Sobi), Stockholm, Sweden

Background: Incidence of debilitating oral mucositis (OM) can be as high as 99% after myeloablative conditioning regimens preparing patients with hematologic malignancies for hematopoietic cell transplant (HCT). Palifermin is a recombinant human keratinocyte growth factor that stimulates proliferation and differentiation of epithelial cells. In randomized controlled trials, palifermin reduced incidence and duration of severe OM in patients with hematologic malignancies receiving myelotoxic therapy in the setting of autologous hematopoietic cell support. Long-term safety of palifermin or the potential risk of stimulation of new malignancies (NM), however, has not been well established.

Methods: In this long-term, prospective, matched cohort study, patients who received palifermin and underwent autologous or allogeneic HCT for hematologic malignancies from 2006-2013 were 1:1 matched to patients who did not receive palifermin. Subjects were matched on age, HCT type, donor type, HCT date, disease type, disease status, region, and whether TBI was included in the conditioning regimen. Primary outcomes were overall survival (OS), relapse, and NM.

We adjusted for imbalances with a propensity score, modeled by logistic regression. The following covariates were used to identify factors associated with treatment assignment: age, race, disease, disease status, time from diagnosis to HCT, prior radiotherapy, type of HCT, growth factors use, graft source, donor age, donor-recipient sex and cytomegalovirus (CMV) serostatus match, conditioning regimen, graft-vs-host disease (GVHD) prophylaxis, year of HCT, and region. Equal propensity scores in both groups predicted they were equally likely to be treated with palifermin. Relative risks were estimated using Cox proportional hazards regression analysis, stratifying on the matched pair and considering the propensity score as a continuous covariate.

[Figure 1 overall survival; Figure2 New Malignancy]

Results: The analysis population consisted of 2191 matched pairs. The median follow-up was 8 years (range, 1-12.5 y), with excellent completeness of data across both arms (93% at 8 y). Overall, the median age was 51 y (range, < 1-80 y). HCT for acute leukemia was the most common indication (40%), followed by plasma cell disorder (28%), and non-Hodgkin lymphoma (13%). TBI was used in 41% of conditioning regimens. Fifty percent of the matched pairs underwent allogeneic HCT, and the two most common donor types were identical siblings (37%) and well-matched unrelated donors (35%). Among allogeneic HCT recipients, the majority (88.5%) received myeloablative regimens. In multivariate analyses, the relative risks of OS, relapse, and NM were not statistically significantly different between those who received palifermin and those who did not (relative risk [RR] for OS 1.01 (95% confidence intervals [CI] 0.91-1.12); RR for relapse 1.06 (95% CI 0.94-1.18); RR for NM 0.89 (95% CI 0.67-1.18)) (Figures 1, 2). The potential interactions between receiving palifermin and propensity score were tested, and no interactions were detected.

Conclusions: Long-term safety of palifermin was confirmed with no increased risk of overall mortality, relapse or NM.

Clinical Trial Registry: Not applicable

Disclosure: Swedish Orphan Biovitrum (Sobi) contracted with CIBMTR for services associated with fulfillment of the LTFU study. CIBMTR aligns all activities through the lens of its research mission and utilizes funding sources only to expand research infrastructure and to facilitate a broad research portfolio. It contractually maintains independent review and publication rights and, as such, does not consider the services provided to be a conflict of interest.

Kullenberg and Rudebeck are employees and shareholders of Sobi.

Dr. Perales reports honoraria from Abbvie, Bellicum, Celgene, Bristol-Myers Squibb, Incyte, Merck, Novartis, Nektar Therapeutics, Omeros, and Takeda. He serves on DSMBs for Cidara Therapeutics, Servier and Medigene, and the scientific advisory boards of MolMed and NexImmune. He has received research support for clinical trials from Incyte, Kite/Gilead and Miltenyi Biotec. He serves in a volunteer capacity as a member of the Board of Directors of American Society for Transplantation and Cellular Therapy (ASTCT) and Be The Match (National Marrow Donor Program, NMDP), as well as on the CIBMTR Cellular Immunotherapy Data Resource (CIDR) Committee.

P142 Pharmacokinetics of Melphalan in Lymphoma Patients undergoing Beam and Autologous Hematopoietic Stem Cell Transplant

Parastoo Dahi ^1,2, Andew Lin¹, Jessica Flynn¹, Christian Uruburo¹, Ian Mcgeary¹, Ryan Schofield¹, Valkal Bhatt¹, Lauren Derespiris¹, Bradley Figgins¹, Meagan Griffin¹, Carmen Lau¹, Anthony Proli¹, Dean Carlow¹, Christina Cho^1,2, Oscar Lahoud^1,2, Miguel Perales^1,2, Craig Sauter^1,2, Michael Scordo^1,2, Gunjan Shah^1,2

¹Memorial Sloan Kettering Cancer Center, New York, NY, United States, ²Weill Cornell Medical College, Cornell University, New York, NY, United States

Background: High dose chemotherapy with BEAM (Carmustine, etoposide, cytarabine and melphalan) is a standard regimen for autologous hematopoietic cell transplantation (AHCT) in lymphoma patients. Multiple myeloma studies have shown that dosing melphalan as a fixed dose based on body surface area leads to inter-patient differences with a 5-fold variability in area under the curve (AUC), with higher AUCs associated with improved outcomes but increased toxicity. In this study, the pharmacokinetics (PK) of Evomela® (propylene glycol free melphalan, PGF-MEL) in BEAM, and its associations with outcome and toxicity were evaluated.

Methods: On D-1 prior to AHCT, 140 mg/m2 of PGF-MEL was given over 30 minutes and serum sample were drawn serially at 5, 15, 30, 40, 75, and 150 minutes after the dose. AUC PK modeling was done with Cetara Phoenix WinNonlin, Princeton, NJ. Toxicity collection is ongoing using CTCAE v4 through D+100 after AHCT.

Results: Eighty-seven patients that received BEAM conditioning between 08/2016 and 09/2019 had melphalan PK analysis. The median age was 51 (range, 19-74), 62% were male, and 53% had aggressive B-cell lymphoma. The median PK parameters were as follows: AUC 8.1 mg*h/L (range, 3.8-18.8); clearance 31.8 L/h (range 16.4-79.1); volume of distribution 33.2 L (range, 19.7-70.1); and half-life of elimination 0.7 hours (range, 0.5-1.7). The median dose of melphalan given was similar between patients ≤ median AUC and those above (260 mg [range, 200-340 mg) and 270 mg [range, 210-340 mg], respectively.) With a median follow up of 8.94 months (range 0.72-32.91) in survivors, univariate analysis showed no difference in 1-year overall survival (OS) (95.5% [84-100%] vs. 87.4% [76.5-100%], p=0.2) or progression-free survival (PFS) (78.4% [63.6-96.6%] vs. 78% [63.7-95.5%], p>0.99) when evaluating patients ≤ or above median melphalan AUC, respectively. Patients with a melphalan AUC ≤ the median had an average length of stay of 19 days (range, 5-27) vs. 21 days (range, 7-38) for those above the median exposure (OR 1.19 [1.05-1.38], p = 0.004). Toxicity data collection is ongoing.

Conclusions: Melphalan exposure ≤ 8.1 mg*h/L resulted in a shorter length of hospitalization likely driven by less toxicities, that will be reported upon completion of toxicity collection. Despite early results showing no difference in OS and PFS, the 5-fold variability seen with PGF-MEL AUC suggests that a sweet spot to optimize outcomes and minimize toxicities is needed.7

Characteristic	≤ Median AUC (N = 45)	> Median AUC (N = 42)	OR (95% CI)	P-value
Age - yr (median, range)	40 (19-74)	62 (30-74)	1.09 (1.05-1.14)	< 0.001
Sex - N (%) Male	28 (62)	26 (62)	1.02 (0.43-2.45)	> 0.9
Disease- N (%)				< 0.001
B-cell lymphoma (aggressive)	15 (33)	31 (74)	-
B-cell lymphoma (indolent)	3 (7)	3 (7)	0.73 (0.11-5.95)
Hodgkin lymphoma	16 (36)	3 (7)	3 (7)
T-cell lymphoma	11 (24)	5 (12)	0.22 (0.06-0.72)
Length of stay - days (median, range)	19 (5-27)	21 (7-38)	1.19 (1.05-1.38)	0.004

[Table 1. Baseline Characteristics]

Clinical Trial Registry: n/a

Disclosure: Valkal Bhatt (Incyte)

Miguel Perales (MolMed, NexImmune, Abbvie, Bellicum, Bristol-Myers Squibb, Incyte, Nektar Therapeutics, Novartis, Omeros, Takeda, Kite, Merck, Servier, Medigene)

Craig S. Sauter (Juno Therapuetics, Sanofi-Genzyme, Celgene, Spectrum Pharmaceuticals, Novartis, Genmab, Precision Biosciences, Kite, a Gilead Company, Gamida Cell, Pfizer, GSK)

Gunjan L. Shah (Janssen, Amgen)

P143 Comparison of Total Body Irradiation- vs chemotherapy-based Conditionings for Early Complications of Allogeneic Hematopoietic Stem Cell Transplantation in Children with All

Koray Yalcin ¹, Berrin Pehlivan², Gulsun Karasu¹, Vedat Uygun³, Seda Ozturkmen³, Hayriye Daloglu³, Suna Celen¹, Dayanat Pashayev¹, Elif Gulsah Bas², Canan Kabakci², Fugen Pekun¹, Volkan Hazar¹, Akif Yesilipek¹

¹MedicalPark Göztepe Hospital, İstanbul, Turkey, ²Bahcesehir University, İstanbul, Turkey, ³MedicalPark Antalya Hospital, Antalya, Turkey

Background: Pediatric patients with acute lymphoid leukemia (ALL) mainly receive myeloablative conditioning regimens based on total body irradiation (TBI) or chemotherapy (CHT) including busulfan before allogeneic hematopoietic cell transplantation (allo-HSCT). Due to severe long term complications of TBI, CHT-based conditioning has been preferred in many centers for pediatric patients. But there is lack of data about the early complications of allo-HSCT comparing TBI vs CHT.

Methods: To compare early complications of TBI and CHT consisting of busulfan, fludarabine and thiotepa conditioning regimens, we performed a retrospective analysis of single center registry data collected between 1^st of January, 2015 and 30^th of June, 2019 to assess the outcomes of patients receiving these regimens before an allo-HSCT. Variables associated with early complications of allo-HSCT (only in the first 100 days after transplant) and hence included into the analysis were: engraftment time, engraftment syndrome, acute graft versus host disease (aGVHD) grade 2-4, veno-occlusive disease (VOD), capillary leakage syndrome (CLS), thrombotic microangiopathy (TMA), cytomegalovirus (CMV) reactivation, bloodstream infection (BSI), hemorrhagic cystitis and posterior reversible encephalopathy syndrome (PRES).

Results: The characteristics of 72 patients was revealed in Table 1. These two conditioning regimens (CHT, n: 50; TBI, n: 22) were compared in pediatric ALL patients aged 18 years or younger at the time of transplantation in complete morphological remission (CR) (CR1, n: 40/CR2, n: 30/>CR2, n: 2). The incidences of aGVHD grade 2-4, VOD, CLS, TMA, BSI, hemorrhagic cystitis and PRES before day 100 were similar for both conditioning regimens; however, patients received TBI-based conditioning had significantly longer neutrophil engraftment time (17.5 vs 13 days, p: 0.001) and tended to have more engraftment syndrome (45.5% for TBI vs 24.0% for CHT, p: 0.069). Multivariate analysis showed that TBI-based conditioning was associated with a longer neutrophil engraftment time (HR: 1.20, p: 0.006), more CMV reactivation (HR: 3.65, p: 0.038) and more engraftment syndrome (HR: 3.18, p: 0.078). At the time of last follow-up, 59 patients were alive. Four patients died of disease progression and infection (n: 4) was the most common cause of non-relapse mortality (NRM). With a median follow-up of 25 months (2-45 months), 3 year-overall survival (OS) and -event-free survival (EFS) were 79.1% (95% CI 68.9-89.4). There was no survival advantage between two conditioning regimens [84.2% (95% CI 67.7-100.0) for TBI and 77.0% (95% CI 64.2-89.7) for CHT, p: 0.538]. Cumulative incidence of relapse (CIR) and NRM were 11.9% (95% CI 6.2-22.4) and 14.0% (95% CI 7.6-26.0), respectively, for all patients. Both groups showed a similar CIR and NRM [CIR, 5.0% (95% CI 0.7-37.1) for TBI and 6.6% (95% CI 2.2-19.7) for CHT, p: 0.844; NRM, 10.2% (95% CI 2.7-38.3) and 15.7% (95% I 7.9-31.5), respectively, p: 0.588].

Conclusions: Although this retrospective registry-based analysis has several limitations, both conditioning regimens showed a similar early complications profile. Conditioning by TBI demonstrated longer neutrophil engrafment time and more CMV reactivation in comparison to CHT and also there is a tendency for engraftment syndrome with TBI based conditioning. Comparison of these conditioning regimens warrant further evaluation in a prospective manner.

Disclosure: Nothing to declare.

P144 Differential Alemtuzumab Dosages in T-cell Deplete Allogeneic Haematopoietic Stem Cell Transplants for Myeloid Malignancies

Varun Mehra ¹, Daniele Avenoso¹, Ximena C Castellano¹, Adrian Choy¹, Stefani Widya², Mili Shah¹, Shafqat Inam¹, Shreyans Gandhi¹, Austin Kulasekararaj¹, Pramila Krishnamurthy¹, Francesco Dazzi¹, Hugues de Lavallade¹, Victoria Potter¹, Ghulam J Mufti¹, Tony Pagliuca¹

¹King’s College Hospital, London, United Kingdom, ²King’s College London, London, United Kingdom

Background: Alemtuzumab is a monoclonal anti-CD52 antibody, a pan-lymphodepleting immunosuppressive agent in common use as part of conditioning for allogeneic stem cell transplantation (Allo-HSCT) in United Kingdom and many other centres across the globe, with benefits related to reduced graft versus Host disease (GVHD) and lower non-relapse mortality (NRM). However, evidence for effective dose schedule in Allo-HSCT remains debatable with some concerns related to delayed immune reconstitution, increased relapses with higher doses; but increased risk of acute and chronic GVHD with lower doses.

Methods: We retrospectively evaluated 391 patients undergoing Allo-HSCTs for myeloid malignancies(AML/MDS/MPNs) during 12-year period (Jan 2008 to April 2019) at Kings College Hospital, London. Two dosage schedules of Alemtuzumab based T-cell deplete conditioning with FluBu and Bu-Cy regimens using standard 100mg dose (n-158; 40.4%) were compared to those (n-233; 59.6%) receiving a lower < 100mg dose, with respect to HSCT outcomes. Close monitoring for infections, GVHD, chimerism (included fractionated lymphoid/myeloid) and disease assessments post HSCT were undertaken as per institutional policy.

Results: Baseline characteristics were broadly similar between the 2 groups in terms of conditioning intensity, patient age, underlying disease, disease risk index and donor HLA matching. Median follow up of survivors was 38 months (range 01-136months) with significantly longer follow up available for 100mg group (median 102 months vs 28 months;p< 0.001). Standard Alemtuzumab dose (100mg) was associated with a significant improvement in composite GRFS (54% vs 24% at 60 months; p< 0.001; Fig 1a) and significantly lower incidence of both grade 3-4 acute (18% vs 42% at D100; p-< 0.003; Fig 1b) and chronic GVHD (all grades)(19% vs 42% at 12 months; p< 0.001; Fig 1c) compared to < 100mg dose. No differences in OS (45% vs 45% at 60 months; p-0.55; Fig 1d), NRM (28% vs 23% at 60 months; p-0.32; Fig 1e) and relapse incidences (29% vs 30% at 60 months; p-0.75; Fig 1f) were observed along with no impact on rates of CMV, Adenoviraemia or invasive fungal disease(IFD) between the 2 cohorts, except lower EBV viraemia incidence was noted in 100mg dose group(49% vs 66%; p< 0.001).

Multivariate adjusted cox analysis (MVA) confirmed older age>60 years, mismatched unrelated donor, absence of chronic GVHD, disease relapse, ITU admission event, CMV reactivation and absence of any EBV reactivation post HSCT as significant predictive factors for poor OS, but this not affected by different Alemtuzumab doses, disease risk index or type of disease. Similarly NRM was not affected by differential alemtuzumab doses, while GRFS was positively influenced by standard 100mg dose on MVA

Conclusions: Despite concerns of relapses and delayed immune reconstitution, this report on a homogenous cohort of allo-HSCTs in myeloid malignancies confirms the contrary with no impact on OS, NRM or relapses and no significant increase in opportunistic infections with 100mg dose. With improved supportive care, effective infection management and pre-emptive cellular therapy approaches available in current era, standard dose (100mg) of alemtuzumab can be considered safe and effective in both RIC and myeloablative allo-HSCTs for myeloid malignancies, with significantly lower GVHD related morbidity and overall better GFRS.

Disclosure: No disclosures or conflict of interest to declare.

P145 Novel Reduced Intensity Conditioning (RIC) Approach to Allogeneic Hematopoietic Cell Transplantation (HCT) in Patients with Benign and Malignant Disorders of T Cell Proliferation or Dysregulation

Dimana Dimitrova ¹, Gulbu Uzel², Luigi D. Notarangelo², Amanda K. Ombrello³, Deborah Stone³, Mark Parta⁴, Ellen Carroll¹, Jennifer Wilder⁴, Stephanie N. Hicks¹, Jennifer L. Sadler¹, Daniel H. Fowler¹, Ronald E. Gress¹, Christopher G. Kanakry¹, Jennifer A. Kanakry¹

¹National Institutes of Health, National Cancer Institute, Bethesda, MD, United States, ²National Institutes of Health, National Institute of Allergy and Infectious Disease, Bethesda, MD, United States, ³National Institutes of Health, National Human Genome Research Institute, Bethesda, MD, United States, ⁴Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, MD, United States

Background: HCT has been used for decades as a definitive therapy in both primary immunodeficiency (PID) and hematological malignancy. A subset of these patients have a dysregulated T cell compartment either due to underlying PID or peripheral T cell lymphoma (PTCL) and are at particularly high risk of graft failure and/or relapse but may also enter HCT with significant comorbidities necessitating a low toxicity approach.

Methods: Twelve patients with PID (n=7) or PTCL (n=5; relapsed, n=3 and primary refractory, n=2), median age 22 years (range 7-64) received a serotherapy-based, radiation-free RIC platform designed with the goals of enhancing host T cell depletion pre-HCT to reduce graft failure risk and provide disease control, while also optimizing immune reconstitution, minimizing toxicities and complications such as graft-versus-host disease (GVHD), and permitting use of alternative donors via a posttransplantation cyclophosphamide-based approach. This was a high-risk cohort with median HCT comorbidity index score of 3 (range 0-7), and active disease in 2 PTCL patients at time of HCT. Alternative donors were commonly used: 5 patients received mismatched grafts (4 haploidentical, 1 mismatched unrelated) and 5 matched unrelated grafts. Patient and donor characteristics are detailed in Figure 1b.

Results: Neutrophil recovery occurred at median day +16 (range 13-25). With median follow up of 6 months (range 2-14), graft-failure-free survival was estimated at 81% at 6 months, with no deaths. There were 2 graft failures (1 primary, in context of rising donor-specific HLA antibodies despite desensitization, and 1 secondary), both now with full donor chimerism after retransplantation. GVHD rates have been low, with grade 1 skin only acute GVHD, not requiring systemic therapy (n=1), grade 2 steroid-responsive acute GVHD of the skin and gut (n=1), and mild chronic GVHD (n=1). Bacterial infectious complications included sepsis/pneumonia (n=2), bacteremia (n=2), and furunculosis (n=1). While BK virus-associated hemorrhagic cystitis occurred at high rates (58%), severe viral complications were infrequent. CMV reactivation occurred in 29% of known at-risk patients (n=2 of 7), with no CMV disease. RSV, asymptomatic adenoviruria, and anemia due to parvovirus B19 occurred in 1 patient each, none requiring inpatient management. At last follow up, some degree of phenotype reversal is evident in all PID patients, and all PTCL patients are either in confirmed complete remission (n=2) or show no clinical signs of disease (n=3).

Conclusions: Based on promising early outcomes, this novel platform offers a safe and effective HCT approach to diseases with historically poor survival or high risk of graft failure, while enabling use of alternative donors. Longer term follow up is needed to better characterize phenotype reversal in PID patients, incidence of relapse in PTCL patients, graft durability, immune reconstitution and late toxicities of the platform.

Clinical Trial Registry: NCT03663933

NCT03922724

Disclosure: None

P146 Profound Lymphopenia at the time of anti-thymocyte Globulin Administration is not Predictive of Survivals after allo-transplantation

Maxime Jullien ¹, Thierry Guillaume¹, Pierre Peterlin¹, Alice Garnier¹, Amandine Le Bourgeois¹, Camille Debord¹, Beatrice Mahe¹, Viviane Dubruille¹, Soraya Wuilleme¹, Nicolas Blin¹, Cyrille Touzeau¹, Thomas Gastinne¹, Benoit Tessoulin¹, Yannick Le Bris¹, Marion Eveillard¹, Alix Duquesne², Philippe Moreau¹, Steven Le Gouill¹, Marie C Bene¹, Patrice Chevallier¹

¹Nantes University Hospital, Nantes, France, ²EFS, Nantes, France

Background: Prophylactic T cell depletion via anti-thymocyte globulin (ATG) during ASCT conditioning is a standard of care for GVHD prophylaxis, although the optimal dosing strategy is still unknown. Recent studies have reported that absolute lymphocyte counts at the time of ATG administration (ALC/ATG) may predict survivals in ASCT with unrelated donors, suggesting that the dose (especially at the cut-off of < 0.1x10⁹/L) and timing of ATG administration must be taken into account (Soiffer et al, JCO 2017; Kennedy et al, BBMT 2018).

Methods: To examine this issue, the outcome of ASCT was evaluated in all consecutive patients transplanted between 2009 and 2019 for a hematologic malignancy in our department. Conditioning regimen were purine analogue/busulfan/ATG-based. The reduced-intensity conditioning (RIC) regimen consisted of fludarabine 30mg/m²/day (d) from d-6 to d-2, busulfan 3,4 mg/kg/d from d-4 to d-3 and ATG (Thymoglobuline, Sanofi, Lyon, France) 2,5 mg/kg/d, d-2 and d-1 (FB2A2) or the same but with clofarabine 30mg/m²/d in replacement of fludarabine with 1 or 2 d of ATG (CloB2A2/CloB2A1). Reduced-toxicity myeloablative conditioning regimens (RTMAC) consisted of the same as FB2A2 but with 3 or 4 d of busulfan instead of 2 (FB3A2/FB4A2). Peripheral blood stem cells were used as source of graft from matched or 9/10 mismatched unrelated donors or siblings. We exhaustively looked at patients for whom a blood differential was available in order to evaluate the impact of lymphocyte counts at the time of ATG administration (ALC/ATG) in terms of overall, disease-free and GVHD-free/relapse-free survival.

Results: Of 395 eligible patients, 116 had a documented differential on the day of ATG administration. The median follow-up for alive patients was 49 months. RIC was administered in 80 (69%) of the patients as follows: 39 FB2A2, 12 CLOB2A2 and 29 CLOB2A1. The 36 other patients received RT-MAC: FB3A2 for 27 and FB4A2 for 9 respectively. Four-year OS, DFS and GRFS were 56.2% (47-66), 40.9% (32-51) and 34.5% (26-45), respectively for the whole cohort.

ROC curve analysis failed to identify a cut-off allowing to predict better survivals according to ALC/ATG. The median ALC/ATG was 0.070x10⁹/L (range: 0-2.300). No difference in terms of survivals was observed when considering patients under this threshold vs others (Fig A). The same was true when considering 0.100x10⁹/L as ALC/ATG cut-off. Regarding MAC, the median ALC/ATG was 0.100x10⁹/L with no difference in survivals between patients under or above this value. The same was true for RIC with ALC/ATG cut-offs below the median (0.055x10⁹/L) or below 0.100 x10⁹/L. Interestingly, considering patients with ALC/ATG below 0.100 x10⁹/L within the RIC setting, survivals were similar between patients who received 1d (n=25) or 2d (n=29) of ATG (Fig B).

Conclusions: This study indicates that ATG can be administered to ASCT recipients whatever the conditioning regimen and the lymphocyte count.

[Survivals according to (A) ALC/ATG (B) number of ATG administration in lymphopenic patients]

Clinical Trial Registry: Non applicable

Disclosure: Nothing to declare.

P147 Lipid Core Nanoparticles as Vehicle for Etoposide in the Conditioning Regimen of Marrow Transplantation in Acute Myeloid Leukemia not Responding to Induction Therapy: Pilot Study

Sandra Serson Rohr ^1,2, Raul Cavalcante Maranhao^3,4, Thauany Martins Tavoni³, Aleksandra Tiemi Morikawa³, Debora Fernandes Deus³, Jose Salvador Rodrigues Oliveira^1,2

¹Unifesp, Sao Paulo, Brazil, ²Santa Marcelina, Sao Paulo, Brazil, ³INCOR, Sao Paulo, Brazil, ⁴USP, Sao Paulo, Brazil

Background: Myeloablative conditioning regimens for HSCT elicits high toxicity

Maranhao (1994, 2003) have already showed that lipid core nanoparticles (LDE), as carrier of anti-cancer drugs reduces drug toxicity. We tested LDE-etoposide in the myeloablative conditioning regimen of HSCT of AML patients not responding to induction therapy.

Methods: A prospective pilot study with 15 patients from 2 academic hospitals in São Paulo, Brazil

Inclusion criteria: primary AML not responding to the induction therapy, 18 - 70yr, HLA-matched related or unrelated donor, ECOG ≤ 2, Karnofsky ≥ 80, and comorbidity score ≤ 2. Exclusion criteria: haploidentical donor or umbilical cord blood.

Conditioning regimen: LDE-etoposide from 20mg/kg/BW until 60mg/kg/BW on D-7 and D- 6 and TBI 1200cGy on D-3, D-2 and D-1. D0: day of stem cells infusion. For unrelated donors, thymoglobulin was added. Graft-vs-host disease (GVHD) prophylaxis: cyclosporine and methotrexate.

Results: 15 AML patients (8 males, 7 females), aged 22-66 yrs (median 47 yrs), 10 x 10 HLA-matched stem cells (9 related, 6 unrelated donors) were enrolled. Peripheral stem cell donors were mobilized with GCSF. CD34+ average infused cells were 7.6±1.6 x 10⁶ /kg/BW. Two patients received peripheral and marrow stem cells: CD34+ (9.0±1.0 x 10⁶ cells/kg/BW) and TNC (3.5±0.5 x 10⁸ cells/kg/ BW). Neutrophil engraftment occurred on day 20 ± 5 and platelet 16 ± 4. All patients engrafted. There were no episodes of hypotension, anaphylaxis, or other adverse effects during LDE-etoposide infusion. There was no grade 4 or higher toxicities. Grade 3 toxicity: mucositis (6 patients), diarrhea (3) and elevation of total bilirubin (1), all before D+30. SOS was observed in 1 patient based on the Seattle criteria, which did not fulfill the Baltimore criteria.

Acute GVHD: skin grade 1 in 4 patients and grade 2 in 1. One patient had skin and GI grade 1 aGVHD. The rate of systemic aGVHD was 33,7% (26.7% grade 1, 6.7% grade 2). Chronic GVHD: 8 patients (57,1%): 4 moderate global cGVHD (28.6%) and 4 severe global cGVHD (28.6%). No fatal GVHD events occurred.

CMV reactivation: 5 patients before D+100 and 1 patient after D+100. Bacterial infection: 7 patients before D+ 100 (3 by multiresistant bacteria) and in 7 patients after D+100 (2 by multiresistant bacteria). One patient had disruption of the pulmonary aspergilloma on D+41 after engraftment and one reactivated Aspergilosis sp infection after D+60.

Five patients died, one before D+100 (aspegilloma disruption), 3 patients of refractory relapse on D+174; D+207, and D+285; and 1 patient during re-induction therapy on D+181. Seven patients are in complete response with 100% chimerism.

The median follow-up time of patients was 17.4 months (41 - 836days). Cumulative incidences of overall survival, event-free survival, relapse and non-relapse mortality at 27 months were 66.7%, 46.7%, 46.7% and 6.7% respectively.

Conclusions: LDE-etoposide based conditioning regimen of HSCT for AML has a clear-cut potential for being advantageously introduced in the clinical practice.

Disclosure: Nothing to declare.

P148 A Phase II Study to Investigate the Efficacy of short-term Everolimus in Addition to post-transplant Cyclophosphamide as graft-versus-host-prophylaxis after Allogeneic Stem Cell Transplantation (Octet-ever)

Udo Holtick ¹, Marco Herling¹, Lukas P Frenzel¹, Carmen Herling¹, Joanna Schiller¹, Marta Rebecca Cruz Aguilar¹, Sebastian Theurich², Michael Hallek¹, Christof Scheid¹

¹Universität Köln, Köln, Germany, ²Universitätsklinikum Großhadern, Ludwig-Maximilians-Universität, München, Germany

Background: Conditioning regimens and the choice of immunosuppression have substantial impact on immune reconstitution after allogeneic hematopoietic stem cell transplantation (aHSCT). The pivotal mechanism to achieve and maintain remission in patients undergoing allogeneic transplantation is the induction of the graft-versus-tumor effect (GvT). Such GvT effects are not achieved in all patients transplanted and relapse is a common event. Moreover, graft versus host disease (GvHD) attacking the recipients’ healthy tissues often preceeds the development of the GvT effect and requires prolonged immunosuppressive therapy hereby abolishing the desired GvT effect. Classic immunosuppressive strategies implementing calcineurin inhibitors (CNI) hamper the immune recovery and built-up of the anti-cancer immune response.

Methods: We designed a phase II clinical study for patients with high-risk hematological malignancies using a CNI-free approach consisting of post-transplant cyclophosphamide and short-term everolimus, an immunosuppressant with anti-proliferative properties given from d+5 to d+100, after reduced-intensity conditioning and matched peripheral blood stem cell transplantation. Results after recruitment of all 19 patients planned will be presented.

Results: Nineteen patients with relapsed or refractory lymphoma and myeloma at high-risk for relapse underwent allogeneic peripheral blood stem cell transplantation with a matched related or unrelated donor after conditioning with fludarabine and busulfan. After application of post-transplant cyclophosphamide on d+3 and +4 after transplant, short-term everolimus was given from d+5 to d+100. Primary endpoint is the cumulative incidence and severity of acute GvHD. All patients presented a complete donor chimerism by d+30 and d+100. Engraftment was delayed with 17, 29 and 27 days for neutrophils, hemoglobin and platelets, respectively. The overall incidence of acute GvHD was 53%. Grade II aGvHD was found in 36% while none of the patients experienced grade III or IV aGvHD. In most cases aGvHD presented as cutaneous manifestation shortly after engraftment. The overall incidence of chronic GvHD was 21%, which was mild in all cases. Two patients died due to sepsis 18 and 20 days after transplant. One patient died due to secondary AML/ MDS three years after transplant. The cumulative incidence of non-relapse mortality on d+100 and d+365 was 11% with a median follow-up of 628 days (18-1152 days). There was one secondary graft failure. The cumulative incidence of relapse was 32% and 37% at one and two years after transplant, respectively. Relapse-free survival was 58% and 52% after one and two years. The overall survival was 73% and 64% after one and two years. All surviving patients are currently without cGvHD and immunsuppressive medication.

Conclusions: The use of post-transplant cyclophosphamide and short-term everolimus is safe with low rates of aGvHD, no severe aGvHD and a low incidence of mild cGvHD translating into a low rate of early non-relapse mortality. The relapse rates in this difficult to treat patient population are encouraging and warrant further studies using the combination of post-transplant cyclophosphamide and everolimus.

Clinical Trial Registry: Study protocol code: Uni-Koeln-1717 EudraCT number: 2013-005507-14

Disclosure: The study was supported by a research grant from Novartis to CS/UH. The other authors have no conflicts of interest to disclose.

P149 Allogeneic Stem Cell Transplantation in Patients ≥ 65 Years with Hematological Malignancies after Myeloablative treosulfan-based Conditioning: Results in 118 Patients

Simona Piemontese ¹, Lorenzo Lazzari¹, Magda Marcatti¹, Fabio Giglio¹, Raffaella Greco¹, Daniela Clerici¹, Maria Teresa Lupo Stanghellini¹, Andrea Assanelli¹, Francesca Farina¹, Francesca Lorentino¹, Sara Mastaglio¹, Sarah Marktel¹, Matteo Carrabba¹, Consuelo Corti¹, Massimo Bernardi¹, Jacopo Peccatori¹, Fabio Ciceri^1,2

¹IRCCS San Raffaele Scientific Institute, Milan, Italy, ²University Vita-Salute San Raffaele, Milan, Italy

Background: Allogeneic hematopoietic stem cell transplantation (allo-SCT) remains the only potentially curative treatment for many hematological malignancies. For most of these, median age of occurrence is 60 years and even more. Nevertheless, the use of allo-SCT had been usually limited to a younger population because of concern related to non-relapse mortality (NRM) of older patients. We here report our large experience in allo-HSCT in patients diagnosed with hematological malignancies and older than 64 yrs.

Methods: From 2005 to 2019, 118pts older than 64yrs received a T-replete allo-SCT for acute leukemias (88pts, 75%), myelodysplastic syndromes (21pts, 18%) or others hematological malignancies (9pts, 7%) at our center. Donors were matched siblings in 19pts (16%), unrelated in 39pts (33%), haploidentical in 57pts (48%) and single cord blood unit in 3pts (3%). Median age at transplant was 67y (65-76). Seventy-seven patients (65%) were transplanted in early disease status (complete remission, CR, or upfront) while 41pts in active disease (35%). One-hundred and six patients out of 118 (90%) received a myeloablative treosulfan-fludarabine based conditioning regimen. Graft-versus-host-disease prophylaxis was sirolimus-based in 91 out of 118 pts (77%), cyclosporine-based in 27pts (23%). Post-transplant Cyclophosphamide was used in 68pts (58%), antithymocyte globulin in 41pts (35%).

Results: Median follow-up among survivors (63pts) was 35 months (3-104). All but two patients engrafted. Median time from transplant to engraftment was 21 days for neutrophils (11-50) and 24 days for platelets (9-632).

Overall survival (OS) at 1 and 3 years was 67+/-4% and 56+/-5%, respectively. Disease free survival (DFS) at 1 and 3 years was 62+/-5% and 46+/-5%, respectively. Day-100 NRM was 18+/-4%. The 1 and 3-year NRM was 26+/-4% and 36+/-5%, respectively. The 1 and 3-year cumulative incidence (CI) of relapse was 16+/-4% and 27+/-5%. Day-100 CI of acute GvHD grade II-IV was 41+/-5%, of grade III-IV was 15+/-3%. CI of overall cGvHD at 1 year was 30+/-5%, of extensive cGvHD was 19+/-4%. No differences in transplant outcomes were found in patients younger or older than 70yrs.

In multivariate analysis early disease status at transplant was the only risk factor associated to OS (HR 0.478; p=0.007. CI: 0.279-0.818), DFS (HR 0.435; p=0.001. CI: 0.262-0.722) and NRM (HR 0.433; p=0.011. CI: 0.227-0.823). The 3-year OS, DFS and NRM for patients transplanted in early disease status were as follows: 70+/-5%, 58+/-6% and 13+/-4%, respectively. Matched sibling donors were associated to lower CI of day-100 aGvHD in multivariate analysis (HR 0.538; p=0.023. CI: 0.316-0.918). Diagnosis of acute leukemia was the only risk factor associated to lower CI of cGvHD (HR 0.311; p=0.00044. CI: 0.162-0.597).

Conclusions: Based on our results we can conclude that age alone should not limit allo-SCT eligibility of patients with hematological malignancies, above all in early disease status. The use in the majority of our patients of treosulfan, an alkylating agent with a low toxic profile, could have contributed to the low incidence of NRM without negatively affecting long-term disease control.

Disclosure: Nothing to declare.

P150

Abstract already published.

P151 Fludarabine-melphalan Conditioning Results in Favorable leukemia-free Survival after Allogeneic Transplantation in Patients with Active or Measurable Residual AML

Kathryn Bower ¹, Madiha Siraj², Jongphil Kim¹, Biwei Cao¹, Hany Elmariah¹, Lia Perez¹, Asmita Mishra¹, Taiga Nishihori¹, Farhad Khimani¹, Rawan Faramand¹, Aleksandr Lazaryan¹, Hugo Fernandez³, Michael Nieder¹, Dan Sullivan¹, Joseph Pidala¹, Claudio Anasetti¹, Nelli Bejanyan¹

¹H Lee Moffitt Cancer Center and Research Institution, Tampa, FL, United States, ²University of South Florida, Tampa, FL, United States, ³Memorial Healthcare System, Pembroke Pines, FL, United States

Background: A recent large CIBMTR study demonstrated no survival benefit with use of myeloablative (MAC) compared to reduced-intensity conditioning (RIC) in patients receiving allogeneic hematopoietic cell transplant (alloHCT) for acute myeloid leukemia (AML) or myelodysplastic syndrome with high-risk disease risk index (DRI) (Bejanyan, ASH 2019). While commonly used MAC fludarabine-busulfan (FluBu) and RIC fludarabine-melphalan (FluMel) result in similar outcomes after alloHCT for AML in remission (Eapen, Blood Adv 2018), the preferred conditioning regimen for active or detectable residual (MRD+) AML at alloHCT remains unknown.

Methods: We analyzed outcomes of 125 patients with active (n=62) or MRD+ (n=63) AML who received alloHCT (2005-2017) with either MAC FluBu4 (72%) with PK-targeted IV daily average Bu AUC of 5300 or RIC FluMel (28%) with total Mel dose of 140 mg/m2.

Results: The group receiving FluMel had a higher proportion of >60-year-old patients (74% vs 21%, p< 0.001), adverse genetic risk AML by ELN 2017 (63 % vs. 51%, p=0.015), alloHCT performed from 2015-2017 (83% vs. 33%, p< 0.001) and Tacrolimus/ Sirolimus-based GVHD prophylaxis (86% vs. 50%, p=0.001). The rest of the characteristics were similar between FluBu and FluMel recipients, including the disease status at HCT (active AML, 54% vs. 37%, p=0.14). Probabilities of 2-year non-relapse mortality (NRM), relapse, leukemia-free survival (LFS) and overall survival (OS) are shown in the Figure. In multiple regression analysis after adjusting for disease status at alloHCT (active vs. MRD+) and DRI, the FluMel regimen compared to FluBu resulted in significantly lower risk of relapse (HR=0.26, 95% CI 0.11-0.63; p=0.003) and higher LFS (HR=0.49, 95% CI 0.28-0.86; p=0.014), but there was only a statistically non-significant trend of better OS (HR=0.57, 95% CI 0.32-1.02; p=0.06) (Table). NRM was similar between the two conditioning groups.

Conclusions: In conclusion, our data support the use of the RIC FluMel regimen for alloHCT in patients with MRD+ or active AML as it results in lower risk of relapse and better LFS compared to MAC FluBu. This study´s findings require confirmation in a larger cohort of patients with MRD+ and active AML.

	NRM		Relapse		LFS		OS
Variables	HR (95% CI)	p value	HR (95% CI)	p value	HR (95% CI)	p value	HR (95% CI)	p value
FluMel vs FluBu	1.50 (0.71-3.17)	0.29	0.26 (0.11-0.63)	0.003	0.49 (0.28-0.86)	0.014	0.57 (0.32-1.02)	0.06
Active Disease vs MRD+	2.18 (0.81-5.92)	0.12	1.07 (0.44-2.60)	0.89	1.40 (0.69-2.84)	0.35	1.72 (0.84-3.52)	0.14
High/Very High DRI vs Low/Intermediate DRI	1.79 (0.68-4.71)	0.24	3.11 (1.11-8.68)	0.03	3.01 (1.40-6.51)	0.005	3.61 (1.64-7.95)	0.0015

[Multivariate Analysis of Clinical Outcomes]

[Clinical outcomes of active or MRD+ AML patients by conditioning regimen]

Disclosure: Aleksandr Lazaryan- Eusa Pharma LLC scientific advisory board

The rest of the authors have nothing to declare.

P152 Sequential Conditioning: Flamsa-TBI versus flamsa-treo in High Risk Acute Myeloid Leukemia (AML) in First Complete Remission and High Risk Myelodysplastic Syndrome (MDS)

Elisa Sala, Verena Wais, Mai Thanh Nguyen, Adela Neagoie, Marie-Luise Hütter-Krönke, Andrea Gantner, Hartmut Döhner, Donald Bunjes

Ulm University Medical Center, Ulm, Germany

Background: Reduced Intensity Conditioning (RIC) regimens allowed allogeneic stem cell transplantation (allo-SCT) for patients with high risk hematological malignancies at advanced age and/or with comorbidities. In aggressive leukemia, RIC regimens may not be sufficient to control the disease, resulting in high relapse rates. The FLAMSA RIC regimen, that associates a short course of chemotherapy with a RIC backbone including TBI 4Gy, reported encouraging results in the treatment of high risk AML and MDS. Still the original protocol is associated with acute toxicity, mainly due to TBI. In this context Treosulfan is being investigated at different dosages as an attractive alternative in order to ameliorate the toxicity profile, preserving the anti-leukemic activity in a high risk population.

Methods: We substituted in the FLAMSA protocol (Schmid, JCO 2005) the TBI with Treosulfan 12g/m2/d from day -6 to -4 (FLAMSA-Treo). A retrospective comparison was then performed between FLAMSA-TBI and FLAMSA-Treo considering patients with high risk AML in first Complete Remission (CR1) and high-risk MDS. The high risk status was defined according to molecular markers, karyotype, delayed response to induction chemotherapy, and AML secondary to MDS or previous chemotherapy. Standard risk AML patients in molecular relapse after standard treatment were also considered “high risk”. The decision to treat patients with FLAMSA-Treo instead of FLAMSA-TBI conditioning was at the physician’s board discretion according to TBI availability, patient age and/or presence of comorbidities.

Results: Between 01/2006 and 06/2019 a total of 59 patients with high risk AML in CR1 (n=53) and high risk MDS (n=6) received allo-SCT after a FLAMSA conditioning. Out of 59 patients, in 45 (76%) a FLAMSA-TBI protocol was administered, while in the remaining 14 (24%) Treosulfan replaced TBI. All the patients, except three, received PBSC as source of transplantation. The GvHD Prophylaxis was based on a combination between CyclosporinA and Mycophenolate Mofetil. Further Patients’ characteristics are listed in Figure 1a. Comparing the outcome of the two subpopulations (TBI vs Treo), no significant differences were observed in terms of OS (1yOS 73% vs 90% respectively, p=0.15), TRM (1yTRM, 45% vs 7%, p=0.3) and relapse incidence (1yRI 22% vs 20%, p=0.4). Considering that we introduced the FLAMSA-Treo platform mostly in the last two years (13/14 pts) and in order to minimize potential biases related to the year of transplantation, we performed a time driven sub-analysis, including only patients transplanted since 01/2017 in both cohorts (n=23, TBI n=10, Treo n=13). In this context, Treosulfan proved to confer a survival advantage to TBI-based conditioning (1yOS 92% vs 50%, p=0.05), manly due to a reduction in the transplant related mortality (1yTRM 8% vs 40%, p=0.09).

Conclusions: In our analysis the Treosulfan-based FLAMSA protocol demonstrated a favorable toxicity profile, at least not inferior to the standard platform including TBI, for the treatment of high risk AML/MDS older patients and/or with comorbidities. The reduced toxicity profile of Treosulfan could favor especially AML patients in first complete remission. A larger prospective series of patients is needed in order to confirm these promising preliminary findings.

Disclosure: Sala E: Honoraria with Gilead.

P153 Increased non-relapse Mortality and Poor Overall Survival in Elderly Patients Treated with Fludarabine and Myeloablative Dose of Busulfan: Transplant Complications Working Group of the JSHCT

Akihito Shinohara ¹, Michiho Ebihara¹, Nobuaki Nakano², Emiko Sakaida³, Naoyuki Uchida⁴, Kentaro Fukushima⁵, Hitoshi Sakai⁶, Takashi Ashida⁷, Yoshinobu Kanda⁸, Junji Tanaka¹, Takahiro Fukuda⁹, Yoshiko Atsuta^10,11, Hideki Nakasone⁸

¹Tokyo Women’s Medical University, Tokyo, Japan, ²Imamura General Hospital, Kagoshima, Japan, ³Chiba University Hospital, Chiba, Japan, ⁴Federation of National Public Service Personnel Mutual Aid Associations, Toranomon Hospital, Tokyo, Japan, ⁵Osaka University Hospital, Osaka, Japan, ⁶Shinshu University, Nagano, Japan, ⁷Kindai University Hospital, Osaka, Japan, ⁸Jichi Medical University Saitama Medical Center, Saitama, Japan, ⁹National Cancer Center Hospital, Tokyo, Japan, ¹⁰Japanese Data Center for Hematopoietic Cell Transplantation, Aichi, Japan, ¹¹Nagoya University, Aichi, Japan

Background: Fludarabine and a myeloablative dose of intravenous busulfan (Flu/Bu4) are widely used together in allogeneic hematopoietic stem cell transplantation (alloHSCT) as a reduced-toxicity conditioning regimen. Although Flu/Bu4 has been applied to a wide range of age groups, the increasing number of transplant-related complications observed among elderly patients remains a major concern.

Methods: We conducted a retrospective survey of alloHSCT in Japan, using the transplant outcomes registry database maintained by the Transplant Registry Unified Management Program. The following inclusion criteria were applied: patients >15 years old with hematological malignancies who had received their first alloHSCT between 2006 and 2017, and who were treated with Flu/Bu4 (total intravenous busulfan dose of 11.2-16 mg/kg or equivalent). Patients who received total body irradiation (TBI) or other chemotherapeutic drugs were also included. Patients who received alloHSCT from cord-blood donors were excluded.

Results: The median age of patients was 58 years (range 16-80), and 43.4% of patients were 60 years or older. Of 1,443 patients, 62.6% were male. Patients were diagnosed with myeloid malignancies (87.1%), lymphoid malignancies (9.1%), and other malignancies (3.0%). Approximately two-third of the patients (66.4%) received bone marrow transplantation, and 584 (25.5%) and 830 (36.3%) patients received alloHSCT from matched related donors and 8/8 matched unrelated donors. The 5-year overall survival (OS) rate after alloHSCT was 45.5% (95% confidence interval [CI]: 42.3.5%-48.6%) for the young group (< 60 years) and 34.8% (95% CI: 31.2%-38.5%) for the elderly group (≥60 years). Although the 5-year cumulative incidence of relapse was equivalent between the two groups (P = 0.67, 32.7% and 33.8%, respectively), the 5-year non-relapse mortality (NRM) was significantly higher for the elderly group (34.0%) than for the young group (25.0%) (P < 0.01). According to the multivariate analysis, increased patient age (≥60 years) was associated with an increased risk of poor OS (hazard ratio [HR] 1.33, 95% CI: 1.19-1.49, P < 0.01) and poor NRM (HR 1.40, 95% CI: 1.19-1.65, P < 0.01). In the subgroup analysis of the elderly group, advanced diseases, administration of chemotherapeutic drugs in addition to Flu/Bu4, and poor performance status (>0) were significant risk factors for poor OS. Those patients who received chemotherapeutic drugs in addition to Flu/Bu4 experienced thrombotic microangiopathy and bleeding complications more frequently than those who did not (P < 0.01 for both comparisons); however, no significant differences were observed for primary causes of death. Nearly half of the elderly patients received TBI with Flu/Bu4. No significant difference in the OS was observed between patients treated with and without TBI; however, TBI resulted in significantly increased NRM (P < 0.01). Elderly patients treated with TBI experienced sinusoidal obstruction syndrome (P < 0.01) and bleeding complications (P = 0.04) more frequently than those treated without TBI.

Conclusions: Flu/Bu4 for elderly patients was associated with increased NRM, resulting in poor OS. In particular, the administration of additional chemotherapeutic drugs or TBI in combination with Flu/Bu4 in elderly patients increased the incidence of certain complications, which might be associated with poor NRM. Therefore, Flu/Bu4 should be used with caution in elderly patients.

Clinical Trial Registry: Not applicable

Disclosure: The authors declare. no conflict of interest. This work was supported in part by the Practical Research Project for Allergic Diseases and Immunology (Research Technology of Medical Transplantation) from Japan Agency for Medical Research and Development, AMED.

P154 Total Marrow and Lymphoid Irradiation (TMLI) in Combination with Cyclophosphamide and Etoposide improves the Outcome of Patients with poor-risk Acute Leukemia

Anthony Stein, Ni-Chun Tsai, Joycelynne Palmer, Ibrahim Aldoss, Haris Ali, Ahmed Aribi, Len Farol, Chatchada Karanes, Samer Khaled, An Liu, Guido Marcucci, Ryotaro Nakamura, Vinod Pullarkat, Eric Radany, Joseph Rosenthal, Amandeep Salhotra, Ricardo Spielberger, David S Snyder, Stephen J Forman, Monzr M Al Malki, Jeffrey Wong

City of Hope, Duarte, CA, United States

Background: Total marrow and lymphoid irradiation (TMLI) delivers augmented doses of radiation to the bone marrow while maintaining low doses to vital organs. We have conducted a phase II study in which we combined TMLI with cyclophosphamide (Cy) and etoposide (VP16) as a conditioning regimen to evaluate its anti-leukemia activity and safety/tolerability in patients with relapsed/refractory acute leukemia. We report here on 57 patients with a median of more than one year of follow-up.

Methods: TMLI (2000cGy to targets, 1200cGy to liver/brain) was administered on days -9 to -5, VP16 60mg/kg (adjusted body weight) on day -4, and Cy 100mg/kg (ideal body weight) on day -2. Bone marrow (n=6) or peripheral blood stem cells (n=51) were given on day 0. Graft versus host disease (GVHD) prophylaxis used was tacrolimus and sirolimus. The primary endpoint was progression free survival (PFS), and secondary endpoints included overall survival (OS), non-relapse mortality (NRM), and toxicity.

Results: Of the 57 patients (Table) with a median of at least 1 year of follow up, the median follow up was 12.5 months (range 1.1-48.3). Engraftment was noted for all patients. The CR/CRi rate at day +30 was 100% for the 56 patients with available data. Disease relapse/progression at 1 year was 47% (95%CI: 35-62). The estimates of NRM at 100 days and 1 year were 4% (95%CI: 1-14) and 6% (95%CI: 2-17), respectively. Relapsed disease after transplant occurred in 34 patients (60%). Four patients died in remission because of infections (n=2), West Nile encephalitis, and cGVHD.

One-year estimates of OS and PFS were 67% (95%CI: 53-78) and 48% (95%CI: 34-60), respectively. The OS/PFS of patients with a Duval score of ≥2 (i.e., high risk) was not statistically significantly different than those associated with a score < 2.

Grade ≥2 Bearman toxicities were bladder (Gr2 n=2), central nervous system (Gr2 n=1), gastrointestinal (Gr2 n=4), hepatic (Gr2 n=1, Gr3 n=1), pulmonary (Gr2 n=1), and renal (Gr2 n=2, Gr3 n=2). Grade 2 and 3 stomatitis occurred in 12 and 2 patients, respectively. There were no grade 4 toxicities or toxicity-related deaths. Acute GVHD was manageable and consistent with previous experience with the regimen.

Conclusions: 1) TMLI can be safely delivered in combination with VP16 and Cy, with NRM rates < 10%; 2) The regimen is effective for patients with relapsed/refractory acute leukemia; 3) Patient outcomes are superior over traditional rates as reported by Duval et al (Duval et al., J Clin Oncol 2010, pp.3730-9).

Variable	Median(range) or N(%)
Age at transplant (yrs)	40(16-59)
Prior regimens	3(1-7)
Disease diagnosis: AML, ALL	43(75), 14(25)
Disease status at alloHCT: 1RL, 2RL, IF	18(32), 4(7), 35(61)
Donor source: Sibling	26(46)
Matched unrelated, mismatched (9/10) unrelated	5(9), 26(45)
% Blasts in bone marrow, blood* at baseline	25(0**-95), 17.5(1-83)
Cytogenetics at baseline: ALL: Intermediate, Adverse, Unknown	7(12), 6(11), 1(2)
AML: Favorable, Intermediate, Adverse	1(2), 16(28), 26(45)

[Patient characteristics. *28 patients had 0% and were excluded. **5 patients had extramedullary disease.]

Clinical Trial Registry: NCT02094794

Disclosure: Anthony Stein: Stemline: Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Celgene: Speakers Bureau.

Joycelynne Palmer: Gilead Sciences: Consultancy.

Haris Ali: Incyte: Consultancy, Speakers Bureau.

Ibrahim Aldoss: Jazz Pharmaceuticals: Honoraria, Other: travel/accommodation/expenses, Speakers Bureau; Agios: Consultancy, Honoraria; Helocyte: Consultancy, Honoraria, Other: travel/accommodation/expenses; AUTO1: Consultancy.

Ryotaro Nakamura: Kirin Kyowa: Other: support for an academic seminar in a university in Japan; Merck: Membership on an entity´s Board of Directors or advisory committees; Celgene: Other: support for an academic seminar in a university in Japan; Alexion: Other: support to a lecture at a Japan Society of Transfusion/Cellular Therapy meeting

Amandeep Salhotra: Celgene: Other: Research Support; Kadmon Corporation: Other: Non paid consultant. Ali: Incyte: Consultancy, Speakers Bureau.

P155 A CD45-targeted Antibody Drug Conjugate Enables Allogeneic Hematopoietic Stem Cell Transplantation as a Single Agent in Mice

Sharon Hyzy ¹, Rahul Palchaudhuri¹, Jennifer Proctor¹, Bradley Pearse¹, Ganapathy Sarma¹, Geoff Gillard¹, Asim Saha², Tahirih Lamothe¹, Melissa Brooks¹, Katelyn Hammond¹, Anjali Bhat¹, Charlotte McDonagh¹, Hans-Peter Kiem³, John Wagner², Bruce Blazar², Anthony Boitano¹, Michael Cooke¹

¹Magenta Therapeutics, Cambridge, MA, United States, ²University of Minnesota, Minneapolis, MN, United States, ³Fred Hutchinson Cancer Research Center, Seattle, WA, United States

Background: Allogeneic hematopoietic stem cell transplant (Allo-HSCT) is a potentially curative treatment for malignant and non-malignant blood disorders. However, current conditioning regimens limit the use of this curative procedure due to conditioning-related mortality and morbidities. As a result, many patients are not able do not undergo this potentially curative therapy. We developed a novel antibody drug conjugate (ADCs) to provide a readily translatable approach that is fully myeloablative as a single agent while reducing the toxicity associated with current conditioning agents. We have generated an anti-mouse CD45 ADC to model this approach for conditioning recipients for minor mismatch and fully allogeneic HSCT.

Methods: Our tool CD45 ADC is engineered for rapid clearance (T1/2=1.7hr) to enable HSCT after conditioning, and a single dose of 3 mg/kg is fully myeloablative. To determine if the tool CD45-ADC could successfully condition recipients for minor histocompatibility antigen mismatched allo-HSCT, we used a single dose of the tool CD45-ADC to condition DBA/2 hosts (H-2d, CD45.2+) for transplant with CByJ.SJL(B6) mice (H-2d, CD45.1+). A matched dose of non-targeted isotype ADC (Iso-ADC) was used as a negative control, while 9 Gy TBI was used as the conventional conditioning positive control. To determine if the tool CD45 CD45-ADC could successfully condition recipients for fully mismatched allo-HSCT, we compared the ability of a single dose of the tool CD45-ADC, alone or supplemented with various levels of TBI, to condition C57BL/6 hosts (H-2b, CD45.2+) for transplant with cells from CByJ.SJL(B6) mice. We used matched doses of Iso-ADC with and without supplemental TBI and 9 Gy TBI as controls. In both studies, conditioned mice were transplanted with 2x107 whole BM cells, and peripheral chimerism was monitored over 16 weeks.

Results: In the minor mismatch (Balb/c CD45.1+→DBA/2 CD45.2+) model of allogeneic HSCT, a single dose of the tool CD45-ADC enabled full donor chimerism through 12 weeks as a single agent (Figure 1A); >90% donor chimerism was observed in T-, B-, and myeloid lineages, comparable to 9 Gy TBI conditioning. Treatment with a matched dose Iso-ADC was not effective. In the fully mismatched Balb/c → C57Bl/6 allo-HSCT model, CD45-ADC as a single agent enabled partial, transient chimerism at 3 weeks post-transplant; an iso-ADC did not. With CD45-ADC as the primary agent, supplementation with TBI doses as low as 0.5 Gy enabled durable full donor chimerism (Figure 1B), comparable to 9 Gy TBI alone. Iso-ADC required a minimum supplementation of 4 Gy TBI to enable donor chimerism.

Conclusions: Conditioning with CD45-ADC is fully myeloablative and enables complete chimerism in a minor mismatch allo-HSCT model as a single agent and enables complete chimerism in the full mismatch allo-HSCT model when supplemented with low dose (0.5 Gy) TBI. This targeted, readily translatable approach for safer conditioning could improve the risk-benefit profile for allogenic and haploidentical HSCT and may extend the curative potential of HSCT to more patients suffering from blood cancers and other diseases that may benefit from HSCT.

[Figure 1]

Disclosure: Sharon Hyzy- Ownership Interest and Salary, Magenta Therapeutics

Rahul Palchaudhuri- Ownership Interest and Salary, Magenta Therapeutics

Jennifer Proctor- Ownership Interest and Salary, Magenta Therapeutics

Bradley Pearse- Ownership Interest and Salary, Magenta Therapeutics

Ganapathy Sarma- Ownership Interest and Salary, Magenta Therapeutics

Geoff Gillard- Ownership Interest and Salary, Magenta Therapeutics

Asim Saha- Nothing to declare.

Tahirih Lamothe- Ownership Interest and Salary, Magenta Therapeutics

Melissa Brooks- Ownership Interest and Salary, Magenta Therapeutics

Katelyn Hammond- Ownership Interest and Salary, Magenta Therapeutics

Anjali Bhat- Ownership Interest and Salary, Magenta Therapeutics

Nicholas Clark- Ownership Interest and Salary, Magenta Therapeutics

Charlotte McDonagh-- Ownership Interest and Salary, Magenta Therapeutics

Hans-Peter Kiem- Nothing to declare.

John Wagner- Consultant, PI (Magenta Therapeutics); Board Member (Gadeta); PI (BlueRock); Consultant (Rocket Pharma); PI (Novartis)

Bruce Blazar- Advisory Board Member (Kamon Pharmaceuticals, Five Prime Therapeutics, Regeneron Pharmaceuticals, Magenta Therapeutics, BlueRock Therapeutics); Research support (Fate Therapeutics, RXi Pharmaceuticals, Alpine Immune Sciences, Abbvie, BlueRock Therapeutics, Leukemia and Lymphoma Society, Childrens´ Cancer Research Fund, KidsFirst Fund); Co-Founder (Tmunity)

Anthony Boitano- Ownership Interest, Royalty and Salary (Magenta Therapeutics)

Michael Cooke- Ownership Interest and Salary (Magenta Therapeutics)

P156 Final Results of a Prospective, Multicenter, non-interventional Study on thiotepa-based Autologous Hematopoietic Cell Transplantation (ASCT) for CNS or non-CNS Lymphoma

Herbert Gottfried Sayer ¹, Mathias Witzens-Harig², Mohammad Wattad³, Agnieszka Korfel⁴, Inken Hilgendorf⁵, Georg-Nikolaus Franke⁶, Gerald Illerhaus⁷, Michael Heinsch⁸, Bernd Metzner⁹, Eva Bettina Zinngrebe¹⁰, Nadezda Basara¹¹, Mascha Binder¹², Mark Ringhoffer¹³, Alexander Röth¹⁴, Thomas Geer¹⁵, Volker Schmidt¹, Peter Dreger²

¹Helios Klinikum Erfurt, Erfurt, Germany, ²Universitätsklinik Heidelberg, Heidelberg, Germany, ³Klinikum Essen Süd, Essen-Werden, Germany, ⁴Universitätsmedizin Berlin, Berlin, Germany, ⁵Universitätsklinikum Jena, Jena, Germany, ⁶Universitätsklinikum Leipzig, Leipzig, Germany, ⁷Klinikum Stuttgart, Stuttgart, Germany, ⁸Helios Klinikum Duisburg, Duisburg, Germany, ⁹Klinikum Oldenburg, Oldenburg, Germany, ¹⁰Evangelisches Krankenhaus Bielefeld, Bielefeld, Germany, ¹¹Malteser Krankenhaus Flensburg, Flensburg, Germany, ¹²Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany, ¹³Städtisches Klinikum Karlsruhe, Karlsruhe, Germany, ¹⁴Universitätsklinikum Essen-Duisburg, Essen, Germany, ¹⁵Diakonissen-Klinik Schwäbisch-Hall, Schwäbisch-Hall, Germany

Background: Thiotepa-containing high-dose chemotherapy (HDCT) followed by ASCT is considered as standard of care in the treatment of primary or secondary central nervous system lymphoma (PCNSL/SCNSL) based on its capacity to penetrate the blood-brain barrier. In order to collect data in daily practice, this prospective, multicenter, non-interventional study was initiated to evaluate thiotepa-based HDCT prior to ASCT in patients with PCNSL or SCNSL, or non-CNS lymphoma: non-Hodgkin or Hodgkin lymphoma (NHL, HL). Primary aims of this study were assessment of safety and efficacy of thiotepa-based high-dose regimens in ASCT for lymphoma.

Methods: Eligible patients were 18 years of age or older and were assigned to undergo ASCT after HDCT either with thiotepa 20 mg/kg, BCNU 400 mg/m² +/- etoposide 450 mg/m² (TT+BCNU) for PCNSL/SCNSL; or thiotepa 10 mg/kg, etoposide 800 mg/m², araC 1600 mg/m², melphalan 140 mg/m² (TEAM) for non-CNS lymphoma (B-/T-NHL, HL). Primary endpoints were toxicity and efficacy. Data were documented at 4 time-points: before therapy, at day 30, day 100 and 1 year post ASCT.

Results: From Oct 2013 to Apr 2017, 83 patients were registered by 16 centers, of whom 80 [51 male,] had a complete dataset available and were included in this analysis. Median age was 59 years (range: 22-78), with 12 patients being older than 65 years. T+BCNU and TEAM were used in 44 (55%) and 33 (41%) patients, respectively, and other combinations in the 3 remaining patients. Diagnosis was PCNSL in 32 (40%) patients, SCNSL in 13 (16%) patients, and NHL/HL) without CNS involvement in 35 (44%) patients. Main non-hematological grade 3-4 organ toxicities up to day +30 were mucositis, diarrhea, infection, and fever, occurring in 67%, 21%, 47%, and 16%, respectively, of all 80 patients. Neutrophil recovery (>500/µl) occurred at a median of 10 days (4-21), and platelet recovery (>20.000/µl) at a median of 13 days after transplantation. Non-relapse mortality at day +100 and 1 year was 8.8% corresponding to non-adjusted 7 fatalities, all infection related with no impact of underlying disease, thiotepa regimen used, and age. On day 100, 72 patients were evaluable for response, here 42 (53%) achieved complete response, 20 (25%) partial response and 3 (4%) patients stable disease. Nineteen (24%) patients experienced relapse/progression, translating into a progression-free survival at one year of 68% (PCNSL: 78%; SCNSL: 54%; B-/T-NHL, HL: 63%), and an overall survival of 78% (PCNSL: 81%; SCNSL: 69% and B-/T-NHL, HL: 77%). No difference of therapy outcome could be detected in patients being < or > 60 years, but a worse PFS and OS for patients older than 65 years.

Conclusions: The results of this prospective study suggest that thiotepa-based high-dose chemotherapy for ASCT for both CNS and non-CNS lymphoma is effective and does not raise safety concerns compared to other HDCT regimens commonly used for ASCT of lymphoma across all age groups.

Clinical Trial Registry: CTU82G

Disclosure: Herbert G. Sayer: Honoria from RIEMSER Pharma GmbH

P157 Post-Transplant Cyclophosphamide (PT-CY), Cyclosporin (CSA) and Mycophenolate (MMF) for Patients Grafted from HLA Identical Siblings or Matched Unrelated Donors

Andrea Bacigalupo¹, Patrizia Chiusolo¹, Federica Sora¹, Luca Laurenti¹, Sabrina Giammarco ², Elisabetta Metafuni², Idanna Innocenti², Francesco Autore², Alessia Di Giovanni², Eleonora Alma², Silvia Bellesi², Simona Sica¹

¹Universitá Cattolica del Sacro Cuore, Roma, Italy, ²Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy

Background: GvHD remain a significant complication in HLA matched grafts, receiving prophylaxis with cyclosporin (CSA), methotrexate (MTX), also when combined with anti-thymocyte globulin (ATG). In a prospective study the triple combination of post-transplant cyclophosphamide (PT-CY), CSA and mycophenolate (MMF), has shown to provide the best protection against GvHD in HLA matched transplants (Bolanos, Lancet Haematol, 2019)

Methods: To assess the outcome of HLA matched grafts receiving GvHD prophylaxis with PTCY+CSA+MMF or ATG+CSA+MTX, we retrospectively analyzed the outcome of 113 HLA identical transplants grafted from identical siblings (SIBS) (n=58) or 8/8 allelic matched unrelated donors (MUD) (n=55). GvHD prophylaxis was PTCY based in 28 and ATG based in 85.

The median age was borderline lower in the PTCY arm (48 vs 53 years, p=0.08). The conditioning regimen for 82% of patients in both arms, was thiotepa (10 mg/kg), busulfan 9.6 mg/kg and fludarabine 150 mg/m^2 (TBF); full dose TBI (12 Gy) was given to 4% of the ATG based patients and 14% of the PTCY based patients (p=ns). The disease phase was equally distributed in the two groups. Acute leukemia was the most frequent diagnosis in 48% and 46% of patients respectively, followed by MDS in 19% and 16% and myelofibrosis in 14% and 17%. Peripheral blood was the graft source for all patients.

Results: Median time to neutrophils 0.5x10^9/l was day 16 vs 18 days in the ATG vs PTCY patients (p=0.01). The proportion of patients with grade 0 acute GvHD was 25% for ATG and 94% for PTCY (p=0.00001); GvHD grade II developed in 19% vs 5% respectively an grade III-IV in 2% vs 0% (p=0.002). Chronic GvHD was absent in 54% vs 96% of ATG vs PTCY patients, and moderate severe cGvHD was diagnosed in 27% vs 0% (p=0.0008). TRM was documented in 22% vs 7% of ATG vs PTCY patients (p=0.07). Follow up is too short to analyzed relapse and survival. We compared matched grafts receiving the triple PTCY based GvHD prophylaxis, with a large concurrent group of HAPLO mismatched family grafts receiving the same prophylaxis (n=105): the incidence of GvHD grade II-IV was 21% in the HAPLO grafts and 3% in the matched grafts (p=0.01), given the same GvHD prophylaxis. Similarly cGvHD (moderate severe) was diagnosed in 19% of HAPLO grafts vs 0% of matched grafts (p=0.0009).

Conclusions: Data suggest that for HLA matched transplants, a triple PTCY based -GvHD prophylaxis is significantly superior to a triple ATG based -GvHD prophylaxis, in protecting patients from acute and chronic GvHD and results in a low TRM. It also suggests that, given the same PTCY based prophylaxis, GvHD is less frequent in matched related and unrelated grafts as compared to HAPLO mismatched grafts, reassessing the role of HLA matching in allogeneic transplants. We need to determine whether relapse is not increased given the extremely low incidence of GvHD, with the triple PTCY based GvHD prophylaxis in matched grafts. However, if these results can be reproduced, we may find out that HLA matching returns as a major predictor of GvHD.

Disclosure: No disclosures

P158 Conditioning Regimen Comparison for Allogeneic Stem Cell Transplantation in non-hodgkin Lymphoma

Kristen Peterson, Andrew Lin, Josel Ruiz, Junting Zheng, Sean Devlin, Gunjan Shah, Michael Scordo, Craig Sauter, Miguel Perales, Sergio Giralt, Larry Buie, Parastoo Dahi

Memorial Sloan Kettering Cancer Center, New York, NY, United States

Background: Allogeneic hematopoietic cell transplantation (allo-HCT) allows for the possibility of cure for patients (pts) with non-Hodgkin Lymphoma (NHL) as it provides an immunologic graft-versus-lymphoma effect. Non-relapse mortality (NRM) was felt to be prohibitive with myeloablative regimens, but technical advances with the advent of reduced-intensity conditioning (RIC) or nonmyeloablative (NMA) regimens have decreased these rates. RIC regimens are generally associated with more toxicity and higher NRM than NMA regimens. Though studies showed both approaches are safe and effective, there is lack of direct comparison between these different intensities of in NHL.

Methods: This retrospective study identified patients aged ≥ 18 years who underwent allo-HCT for relapsed/refractory NHL between 3/2008-6/2017 at our center. Outcomes were compared between pts who received NMA and RIC conditioning, with intensity delineated per CIBMTR definitions. Progression-free survival (PFS) was the primary outcome. Secondary outcomes included overall survival (OS) and non-relapse mortality (NRM). Additional outcomes included rates of acute GVHD at Day 100, chronic GVHD, and CMV reactivation at Day 100. Regimen intensity and other variables significant by univariate analysis were included in the multivariate analysis.

Results: For the 144 patients identified, the median age was 56 years (range, 19-79). More pts received NMA regimens (n=80, 56%) and most did not undergo prior autologous HCT (n=103, 72%). NMA regimens were given more frequently to pts with indolent B-cell lymphoma and were more likely to receive ATG and/or rituximab (p = 0.008, p < 0.001, and p < 0.001, respectively). At a median overall follow-up of 57.8 months (range 49 - 75.1) neither median PFS or OS were reached. In univariate analysis, NMA conditioning was associated with a longer PFS than RIC [HR 1.9 (1.11-3.24), p = 0.019). No difference in OS when comparing NMA and RIC regimens [HR 1.56 (0.85-2.85), p = 0.15). There was an increase in all grades of aGVHD [HR 3.68 (2.16, 6.28), p < 0.001)] with RIC regimens, but only 12 events of grade III/IV aGVHD overall.

In multivariate analyses (with histology and ATG as covariates) NMA with rituximab had improved PFS compared to RIC without rituximab [HR 0.43 (95% CI 0.22, 0.81; p=0.009)]. However, PFS was similar comparing NMA and RIC groups [HR 0.72 (95% CI 0.37, 1.41; p=0.3)]. Similarly, aGVHD (any grade) risk was lower in NMA pts receiving rituximab compared to RIC pts who did not [HR 0.15 (0.07-0.32), p < 0.001). No significant differences were noted in NRM or CMV reactivation between groups.

Conclusions: Our study suggests that there are comparable and favorable outcomes between RIC and NMA conditioned allo-HCT for NHL with careful patient and regimen selection. Further studies are needed to better define specific criteria in choosing between NMA and RIC allo-HCT conditioning regimens for pts with NHL.

Disclosure: Gunjan Shah- Investigator + Research Funding for Janssen and Amgen

Michael Scordo- Consultancy: McKinsey & Company + Angiocrine Bioscience

Craig Sauter- Advisory Board, Honoraria and Research Funding: Juno + Sanofi-Genzyme + Celgene + Precision Biosciences. Advisory Board and Honoraria: Spectrum Pharmaceuticals + Novartis + Genmab + Kite + Gamida + Pfizer + GSK

Miguel Perales- MolMed: Advisory Board and Honoraria + NexImmune: Advisory Board and Honoraria + Abbvie: Advisory Board and Honoraria + Bellicum: Advisory Board and Honoraria + Bristol-Myers Squibb: Advisory Board and Honoraria + Incyte: Advisory Board, Honoraria and Research Funding + Nektar Therapeutics: Advisory Board and Honoraria + Novartis: Advisory Board and Honoraria + Omeros: Advisory Board and Honoraria + Takeda: Advisory Board and Honoraria + Kite: Research Funding + Merck: Consultancy and Honoraria + Servier: DSMB Honoraria + Medigene: DSMB Honoraria

Sergio Giralt - Amgen: Consultant and Investigator, Research Funding + Actinium: Consultant and Investigator, Research Funding + Celgene: Consultant and Investigator, Research Funding + Johnson & Johnson: Consultant and Investigator, Research Funding + Miltenyi: Investigator, Research Funding + Takeda: Consultant and Investigator, Research Funding + Consultant for Kite + Spectrum Pharmaceuticals + Jazz Pharmaceuticals + Novartis

P159 A Thiotepa Based Intensified Reduced Intensity Conditioning Regime in Adult Cord Blood Transplant is a Promising Alternative in Patients Unable to Receive Myeloablative Conditioning

Ian Wu ¹, Tangia Muquith¹, Yeh Ching Linn², Michelle Poon¹, Lip Kun Tan¹, Belinda Tan¹, Yelly Yelly¹, Teck Guan Soh¹, Davanaliz Gonzales Ramos¹, William Hwang², Liang-Piu Koh¹

¹National University Cancer Institute, National University Health System, Singapore, Singapore, ²Singapore General Hospital, Singapore, Singapore

Background: High relapse and graft failure rates have been seen with the Minnesota reduced-intensity conditioning (RIC) for umbilical cord blood transplantation (UCBT) regimen consisting of fludarabine (Flu) 200mg/m², cyclophosphamide (Cy) 50mg/kg and 2 Gy of total body irradiation (TBI). We evaluated a new thiotepa-based intensified RIC regimen consisting of Flu 150mg/m2, Cy 50mg/kg, thiotepa 10mg/kg, and 4Gy TBI, which has shown promising results with sustained engraftment and acceptable toxicity.

Methods: We performed a retrospective analysis of 90 adult patients in 2 institutions in Singapore receiving 4/6-6/6 HLA matched UCBT for various haematological malignancies between Aug 2006 and May 2019. Patients received 1 of 3 conditioning regimens - myeloablative Conditioning (MAC, n=56) regimen of Flu 90mg/m², Cy 120mg/kg and 12 Gy TBI, standard reduced intensity conditioning (s-RIC, n=20) and thiotepa-based intensified reduced intensity conditioning (i-RIC, N=14) regimen.

Results: There was no significant difference in the median day to neutrophil engraftment among the 3 groups (p=0.18). The cumulative incidence (CI) of relapse-related mortality (RRM) was the highest in patients receiving s-RIC (HR 5.35, 95% CI 2.35-12.18; p=0.003) compared to the MAC and i-RIC (Figure 1). This difference remained statistically significant in multivariate analysis (p=0.004).

5-year overall survival was lowest amongst patients receiving s-RIC (MAC 46%; s-RIC 20 %; i-RIC 43%; p=0.165). CI of transplant related mortality (TRM) was comparable among the 3 groups (MAC 36%; s-RIC 15 %; i-RIC 29%; p=0.245). There was no statistically significant difference in CI of grade 2-4 acute graft-vs-host disease (GVHD) or chronic GVHD among the 3 groups.

Conclusions: The results of this retrospective analysis show improvements in OS and decrease in RRM without an increase in TRM in patients receiving thiotepa-based intensified RIC as compared with standard RIC. CI of RRM was comparable between patients receiving MAC and i-RIC, which were both significantly lower compared with patients receiving s-RIC. A thiotepa based intensified reduced intensity conditioning regimen provides an alternative option that may improve outcomes in patients not fit to receive MAC for UCB transplantation.

[Figure 1: Cumulative Incidence of Relapse Related Mortality MAC, S-RIC and I-RIC]

Disclosure: Nothing to declare.

P160 Haploidentical Stem Cell Transplantation with post-transplant Cyclophosphamide using as Conditioning Fludarabine Melphalan plus low Doses of Total Body Irradiation. Long term follow-up of 60 Patients

Amado Jose Karduss, Rosendo Perez, Giovanni Ruiz, Angelica Cardona, Juan Alejo Jimenez, Luis Rodolfo Gomez, Pedro Reyes

Instituto de Cancerología, Clínica las Américas, Medellín, Colombia

Background: The use of Haploidentical Transplantation (haploSCT) with pos-transplantation cyclophosphamide (PTCy) is a valid alternative for patients without a matched donor, however it is not clear what is the "best" conditioning regimen in this setting. With the scope of increasing the anti tumor effect and also improve the engraftment rate, we added to, the well- known fludarabine- melphalan conditioning, a dose of 200-400 cGy of total body irradiation (TBI). We present the long-term results obtained with the use of this combination in a group of 60 patients with leukemia and lymphoma

Methods: The cellular source in all cases was PBSC. The conditioning consisted of melphalan 100-120 mgs/m2, on day -7, fludarabine 40 mgs/m2 from day -6 to -3 and TBI 200-400 cGy on day -2. PTCy 50 mg/kg/day was administered on D+3 and D+4, the cyclosporine and mycophenolate were initiated on day + 5 in 28 patients and, after an amendment, on days 0 and + 1, in 32

After a signed informed consent, 60 patients underwent to transplant; median age was 35 years (19-65), the diagnoses were: acute lymphoblastic leukemia 27, acute myeloid leukemia or myelodysplasia 21, lymphoma 6, and 3 with other diseases. 44% of the patients were beyond CR1, the disease risk index (DRI) was low in 28%, intermediate in 37% and high in 30%, three cases were not classified.

Results: 80% of patients received flu-mel +TBI 200-300 cGy, while in 20% the dose was 400 cGy. A mean of 10 million of PBSC/kg was infused. The neutrophil engraftment rate was 98%, median time to achieve 500 or more was 15 days (range 13-29), 4 patients died before d+ 100 without platelet recovery, the remaining had a self- sustained platelet count of 20.000 or more at an average of 16 days (range 12-50). Chimerism was done in all cases that survived beyond day + 100 and all of them had full donor hematopoiesis.

The main toxicity was gastrointestinal; diarrhea 70%, mucositis G II-III 30%. With a median follow-up for surviving patients of 22 months, the incidence of GVHD acute (GII-IV) and chronic extensive was 41 and 16% respectively. The transplantation related mortality was 21% while the rate of relapse was 15%. Causes of non-relapse mortality were infections associated to GVHD 11.5%, without GVHD 8.3%, and hemorrhagic cystitis one case

Event was defined as death for any cause or relapse, the event free survival (Kaplan Meier) at 36 months for the whole group was 55% (CI 0.37-0.69), and 70%, 55% and 44% for patients with DRI low, intermediate and high (fig 1)

Conclusions: The long-term follow-up of 60 patients transplanted using flu-mel-low TBI as a preparative regimen in the haplo PBSC setting showed a fast and almost universal engraftment, acceptable toxicity and favourable disease free survival. A good balance between tolerance and anti tumor activity. The incidence of aGVHD was high, with the scope to decrease it, we are working in a modification of the time of starting the immunosuppression and in decreasing the number of CD34 and CD3 infused

Disclosure: Nothing to declare.

P161 Comparison of Beam and Team as Conditioning Regimen for Lymphoma Patients undergoing Autologous Stem Cell Transplantation

Elif Birtas Atesoglu ¹, Burak Deveci², Imran Dora¹, Cigdem Eren¹, Suat Celik¹, Gokhan Kusdemir¹, Esra Bayrak¹, Ihsan Karadogan², Zafer Gulbas¹

¹Anadolu Medical Center Hospital, Kocaeli, Turkey, ²Medistar Antalya Hospital, Antalya, Turkey

Background: Autologous stem cell transplantation with high-dose therapy is frequently used in lymphoma patients for consolidation of first complete response or after salvage chemotherapy after relapse. BEAM (carmustine-etoposide-cytosine arabinoside-melphalan) is the most commonly used conditioning regimen. TEAM (thiotepa- etoposide-cytosine arabinoside-melphalan) is becoming a more frequently used regimen in recent years. In this study, we aimed to compare the results of these two regimens.

Methods: We retrospectively analysed the results of 225 lymphoma patients from 2 different centers who had been transplanted with conditioning regimens BEAM and TEAM between January 2015 and July 2019.

Results: There were 167 lymphoma patients who had received BEAM conditioning regimen and 58 lymphoma patients who had received TEAM conditioning regimen. Patients with primary central nervous system lymphoma were excluded from the analysis. 34,2 % of the patients had Hodgkin Lymphoma, 31,6% of the patients had Diffuse Large B cell Lymphoma, 12,9% of the patients had Mantle Cell Lymphoma, 10,7% of the patients had Peripheral T cell Lymphoma and the rest 10,6% had varying types of Non-Hodgkin Lymphoma. Neutrophil engraftment time and thrombocyte engraftment time did not differ between 2 groups. Hospitalization duration was statistically shorter in patients who received BEAM conditioning regimen (p=0,04). Although the differences were not statistically different, rates of documented bacterial, viral and fungal infections were higher in patients who received TEAM conditioning regimen. Clinical results of patients receiving BEAM or TEAM conditioning regimen are shown in Table 1. The PFS and OS were not different between groups (p=0,37, p=0,61, respectively).

Conclusions: According to our results BEAM and TEAM conditioning regimens seem equally effective in terms of survival end-points. But hospitalization period of patients who received TEAM was longer than patients who received BEAM conditioning regimen. This can be explained by higher infection rates observed in patients who received TEAM, even though statistically significant difference could not be demonstrated.

	BEAM	TEAM	p
Neutrophil engraftment time	9,5(8-16)	10(8-23)	0,89
Thrombocyte engraftment time	11(8-23)	12(7-28)	0,06
Hospitalization duration	22(12-35)	23(14-57)	0,04
Documented bacterial infection	26,3%	37,9%	0,09
Documented viral infection	4,2%	8,6%	0,19
Documented fungal infection	1,8%	3,4%	0,6

[Table 1: Clinical results of lymphoma patients who had received BEAM or TEAM conditioning regimen for autologous stem cell transplantation]

Disclosure: Nothing to declare.

P162 Assessment of the Safety and Efficacy of the Conditioning Regimen Beeac before auto-hsct for the Treatment of primary-refractory and Relapsed forms of Malignant Lymphomas

Anastasiia Samoylova, Vladislav Sarzhevsky, Vladimir Melnichenko, Nikita Mochkin, Julia Dubinina, Elena Smirnova, Anna Bannikova, Vladimir Bogatyrev

National Medical and Surgical Center named after N.I. Pirogov of the Ministry of Healthcare of the Russian Federation, Moscow, Russian Federation

Background: There are several most commonly used conditioning regimens for high-dose chemotherapy (HDCT)followed by autologous transplantation of hematopoietic stem cells(auto-HSCT)to patients with malignant lymphomas(ML). However, there are currently no data on the conduct of randomized studies that would compare the effectiveness of different regimens and their toxicity.

Methods: Assessment of the safety and efficacy of the BeEAC regimen as a conditioning regimen before auto-HSCT for the treatment of primary-refractory and relapsed ML

Materials and Methods From January 2016 to June 2018 the study included 113 patients:72 with Hodgkins lymphoma,41 with non-Hodgkins lymphomas;55 women and 58 men. The median age was 33 years. Tumor status before auto-HSCT:complete remission - 58 patients, partial remission and stabilization - 52 and 3 patients, respectively. Median follow-up was 26 months. BeEAC conditioning regimen: increasing doses of bendamustine 160-200 mg/m², administered on D-6 and D-5, combined with fixed doses:cytarabine 200 mg/m² every 12 hours on D-4 - D -1, etoposide 200 mg/m² on D-4 - D-1, cyclophosphamide 140 mg/kg on D-4 - D-1.

Results: In Phase I of the study(3 cohorts of 3 patients each), when the dose of bendamustine was increasing from 160 to 200 mg/m², no manifestations of dose-limiting toxicity were identified. Subsequently, patients received bendamustine at a dose of 200 mg/m².

Hematologic toxicity of BeEAC presented in table 1.

Characteristic	Result (Median)
Day (after transplantation) of maximum neutrophil reduction	D+5
Duration of agranulocytosis (days)	8
Maximum platelet reduction	5x10 9/L
Duration of thrombocytopenia (days)	11
Day of maximum hemoglobin reduction	D+9
Maximum decrease in hemoglobin	82 g/l

[Table 1. Hematologic toxicity of BeEAC]

According to WHO criteria for oral mucositis, grade II mucositis was diagnosed in 27 patients(42.2%), grade III and IV - in 14 patients(21.9%).

According to NCI-CTC criteria, grade III and IV enteropathy was diagnosed in 17 patients (37.0%).

Cardiotoxic effects were detected in 10 patients(8.9%)and manifested as hydropericardium, dry pericarditis, paroxysmal atrial flutter, acute biventricular insufficiency and acute post-cytostatic cardiomyopathy.

Pulmonary toxicity occurred in 2 patients(1.8%)-post-cytostatic pulmonitis.

[Table 2. Comparison of tumor status before and after auto-HSCT]

Hepatic toxicity occurred in 34 patients (30.1%), mainly grade I.

Assessing the tumor status after auto-HSCT (after 2-3 months), the following results were obtained:complete remission - 62,9%(71 patients), partial remission - 16,8%(19 patients), stabilization - 0,9%(1 patient), progression - 15,0%(17 patients). In 5 patients, the effect was not evaluated (Table 2.)

Transplant-related mortality(until D + 30)was 3,6%(4 patients;causes:2-complications of sepsis,2-acute cardiotoxicity). The total mortality over the observation period(median-26months)was 23%(26 patients).

The overall survival rates(OS)for the entire cohort of patients at 12,18,24 and 36 months were 88%,82%,78% and 64%, respectively, and the progression-free survival rates(PFS)were 61%,57%,54 % and 40%, respectively.

Conclusions: BeEAC has demonstrated relative safety when used as conditioning regimen in ML. It is necessary to obtain further data to evaluate the effectiveness of the regimen and conduct a retrospective comparative analysis with other conditioning regimes for ML.

Clinical Trial Registry: ClinicalTrials.gov NCT03315520

Disclosure: None Declared

P163 Allogeneic Stem Cell Transplantation after total-body Irradiation using Helical Tomotherapy - A Single Center Experience

Thomas Heinicke, Ana-Maria Waldleben, Denise Wolleschak, Thomas Brunner, Günther Gademann, Thomas Fischer, Hans-Joachim Ochel

Otto-von-Guericke University, Magdeburg, Germany

Background: The role of helical tomotherapy (HT) as radiation technique for total body irradiation (TBI) prior to allogeneic stem cell transplantation (alloSCT) has yet to be defined. We report our initial experience using HT in patients with hematological diseases that had received their first allogeneic stem cell transplantation at our institution.

Methods: All consecutive patients who were treated with HT-TBI-based conditioning and transplanted from a sibling or unrelated donor for various hematological diseases between 1/2015 and 4/2019 were included. TBI was applied with 6 MV photons using helical tomotherapy (Accuray). After obtaining informed consent treatment planning was performed using computed tomography (Aquilion, Toshiba, 3 mm slices) with patients placed in a vacuum bag. Delineation of organs at risk was performed and a treatment plan including dose-volume histograms was generated. This plan was dosimetrically verified using a phantom (Alderson). Irradiation dose deviations of up to 3 percent were deemed acceptable. Since the tomotherapy device has a longitudinal treatment limit of 160 cm patients with a body length exceeding this were irradiated caudally as far as possible and then turned around by 180 degrees to treat the remainder of the body. Primary endpoint of the study was leukemia-free survival (LFS). The study was approved by the local institutional review board.

Results: Twenty-six patients were included, 15 males and 11 females. Median age at time of alloSCT was 43 years (range 16 to 60 years). Indications for alloSCT were acute myeloid leukemia (AML) (n= 10), myelodysplastic syndrome (MDS) (n=5), acute lymphoblastic leukemia (ALL) (n=7), bi-phenotypic acute leukemia (n= 2), chronic myeloid leukemia in blastic phase (n=1) and paroxysmal nocturnal hematuria (n=1). Donors were matched related (n=4), matched unrelated (n=18) and mismatched unrelated (n=4). Conditioning regimens used were TBI/cyclophosphamide (n=12), TBI/VP16 (n=2), TBI/fludarabine (n=3) and FLAMSA-RIC (n=9). TBI doses ranged from 4 Gy given at a single fraction (n=9) to 8 Gy given at 4 fractions of 2 Gy over two days (n=3) to 12 Gy given as six fractions of 2 Gy over three days (n=14). Neutrophil engraftment was achieved after a median of 18 days (range 15 to 26 days). One patient experienced secondary poor graft function. Fifteen patients developed mukositis III-IV. Seven patients experienced a hematologic or molecular relapses at a median of 0.7 y (range 0.5 to 3y). Six patients developed an acute GVHD which was of grade I in all cases. Five patients developed moderate chronic GVHD, two of them after treatment of relapse using donor lymphocyte infusions in combination with sorafenib. After a median follow up of living patients of 2.6 y (range 0.6 to 4.8 y) three patients have died, one after 16 days due to sepsis, two others due to relapse, resulting in an estimated LFS at 2 y of 71%.

Conclusions: Our retrospective data show that using HT for TBI-based conditioning prior to alloSCT is feasible. Initial survival outcomes are encouraging. Longer follow-up is needed to assess late effects and define the role of HT in the context of TBI-based conditioning further.

Disclosure: Nothing to declare.

P164 Feasibility of CLAMSA-RIC as an Alternative Conditioning Regimen Compared to FLAMSA-RIC in Heavily Pretreated Refractory AML Patients - A Retrospective Single Center Analysis

Krischan Braitsch, Alix Pianka, Kathrin Holzhauser, Katharina Götze, Florian Bassermann, Peter Herhaus, Mareike Verbeek

Technical University of Munich, Munich, Germany

Background: The outcome of patients with relapsed/refractory acute myeloid leukemia (r/r AML) remains very poor even after undergoing allogeneic hematopoietic stem cell transplantation (alloSCT). In patients with very high relapse risk the conditioning regimen with fludarabine/amsacrine/cytarabine (FLAMSA) followed by reduced-intensity conditioning (RIC) has emerged as a very promising therapeutic concept. The second-generation purine analogue clofarabine has been reported to have a higher anti-leukemic activity compared to fludarabine, and promising results when incorporated in conditioning regimens for AML patients have been reported. As comparative data of the FLAMSA-RIC regimen with the clofarabine/amsacrine/cytarabine (CLAMSA) -RIC regimen are missing, we conducted a retrospective single center analysis.

Methods: In this retrospective, single center analysis 44 consecutive patients with r/r AML (median age 58 years, range 37-71) treated at our center between 2009 and 2019 were included. Per definition patients presented with primary induction failure to standard therapy (n=21), early refractory relapse (n=10), or had active AML with myelodysplasia-related changes and history of myelodysplastic syndrome (n=13). Patients either received fludarabine (30 mg/m2/day) (n=27) or clofarabine (50mg/day) (n=17) in combination with cytarabine (2 g/m2/day) and amsacrine (100 mg/m2/day) for 4 days. The RIC part consisted of busulfan (4x 0,8 mg/kg) and cyclophosphamide (60 mg/kg). Per institutional guidelines immunosuppression consisted of antithymocyte globulin, mycophenolatmotefil and a calcineurininhibitor. The primary endpoint of this study was overall survival (OS). Secondary endpoints were the rate of complete remission (CR), the rate of relapse-free survival (RFS) and cumulative incidence of acute graft-versus-host disease (GvHD) II-IV°.

Results: The median follow-up time was 53 months. The median OS (CLAMSA-RIC vs. FLAMSA-RIC) was 5.4 vs. 11.4 (p=0.10) months. The median RFS was 4.4 vs. 13.1 (p=0.01) months in comparison. Out of 17 CLAMSA-RIC treated patients, 10 (58%) achieved a CR, 2 were refractory and 5 died before response evaluation. In comparison 88% achieved a CR in the FLAMSA-RIC cohort and 3 had died before response evaluation. Cumulative incidence of acute GvHD II-IV° was 41% vs. 52% respectively. On average, patients in the CLAMSA-RIC cohort had received twice the amount of previous therapies compared to the FLAMSA cohort (3.2 vs 1.8). All patients within the CLAMSA-RIC group were either primary refractory or had refractory relapse and 58% had never achieved a CR. In comparison 13 (48%) patients in the FLAMSA-RIC group had undergone alloSCT without any previous chemotherapy.

Conclusions: Our study demonstrates that the incorpororation of clofarabin into conditioning prior to alloSCT in patients with r/r AML is feasible. Compared to the FLAMSA-RIC regimen the CLAMSA-RIC group showed inferior results in RFS. There was no significant difference in OS, however a clear trend towards the FLAMSA cohort. Comparison of the groups may be difficult as the 17 patients in the CLAMSA had higher disease activity and received more intense previous treatment regimens. However for extensively pretreated r/r AML patients with very poor prognosis, CLAMSA-RIC may be feasible as alternative conditioning regimen. Further prospective clinical trials are urgently required.

[Figure 1: Comparison of the conditioning regimens CLAMSA-RIC and FLAMSA-RIC]

Disclosure: Nothing to declare.

P165 Flamsa-based High-dose Sequential Conditioning Regimen followed by Allogeneic Hematopoietic Stem Cell Transplantation(ALLO-HSCT): Is It Effective in Patients with Primary Refractory or Relapsed Acute Leukemia?

Guldane Cengiz Seval, Ekin Kircali, Sinem Civriz Bozdag, Selami Kocak Toprak, Meltem Kurt Yuksel, Onder Arslan, Muhit Ozcan, Taner Demirer, Gunhan Gurman, Osman Ilhan, Hamdi Akan, Meral Beksac, Pervin Topcuoglu

Ankara University, Ankara, Turkey

Background: Advances in chemotherapy have improved the prognosis of patients with acute leukemia. However, patients with refractory disease or early relapsed still have a poor outcome. Allo-HSCT is the most effective anti-leukemic treatment. Nevertheless because of relapse and treatment-related complications, long- term survival is rare in advanced disease. Kolb and colleagues developed fludarabine/cytarabine/amsacrine (FLAMSA) regimen and reported the promising results in patients with acute myeloid leukemia. This reports describes our experience with the 45 patients who had high risk, primary refractory or relapsed acute leukemia and received FLAMSA-based high dose sequential conditioning regimen followed by allo-HSCT.

Methods: Patient characteristics are summarized in Table 1. We analyzed 45 consecutive patients (16 females, 29 males) with a median age of 39 years (range 19-62) transplanted after FLAMSA-based high-dose sequential conditioning regimen (36 RIC and 9 MAC) in our institution from October 2007 to November 2018. Six out of 45 patients received FLANG (fludarabine, cytarabine, mitoxantrone) instead of FLAMSA. In our cohort, five patients underwent the second allo-HSCT due to relapse of acute myeloid leukemia. Donors were HLA-identical siblings in 23 (51.1%) and unrelated donors in 22 patients (48.9%). The allograft source was peripheral blood stem cells in 42 patients (93.3%); two patient () received cord blood and one patient (2.2%) received bone marrow.

Results: There were 42 (93.3%) patients who were transplanted in the setting of active disease and 3 MRD⁺ patients in this retrospective analysis. Twenty-eight (62.2%) patients achieved complete remission (CR). Of these fourteen patients relapsed, but CR was re-achieved all patients after chemotherapy and donor-lymphocyte infusions. After a median follow up of 12.4 months (range: 3.1-92.8 months), the incidence of non-relapse mortality was 30% (n=). Median time from diagnosis to alloHSCT was 18.2 months (range: 8.0-24.3 months). The median number of transplanted cells was 5,67±1,9x10⁶CD34+ cells/kg (range 1.3-9.9 x10⁶). Nineteen patients (42.2%) died from reasons not related to leukemia before day +100 (Table 1). Acute GvHD occurred in nineteen patients, reaching grade I in 3, grade II in 5, and grade III and IV in 11 cases. Of the 30 patients who survived more than day 100 chronic GvHD developed in 11 patients. The estimated 1-year progression free survival (PFS) and overall survival (OS) from the transplantation was %47,4±10,5 (median: 11.4 months, 95%CI 7.8-15.0) and %21.6±6.3 (median: 4.1 ay; %95 CI 3.1-5.1).

Conclusions: Although 62% of CR rate makes this approach attractive, high rates of relapse and transplant related mortality needs to be improved new transplant modalites.

Disclosure: Nothing to declare.

P166 Increasing in Serum total Amylase Levels After Total Body Irradiation Conditioning Regimen as a Predictive Marker of transplant-related Mortality in Pediatric Hematopoietic Stem Cell Recipients

Antonio Grasso ¹, Rossella Vidimari², Francesca Ciriello², Roberto Simenone³, Fabrizio Cupardo², Natalia Maximova⁴

¹University of Trieste, Trieste, Italy, ²Ospedale Maggiore, Trieste, Italy, ³ASUITS, Trieste, Italy, ⁴IRCCS Burlo Garofolo, Trieste, Italy

Background: Total Body Irradiation (TBI) represent one of the most used conditioning regimens for hematopoietic stem cell transplantation (HSCT) especially for malignant haematological disease. However, radiation susceptibility differs greatly among individuals and a biological dosimeter is warranted to predict individual risk of radiation exposure.

We have observed a variable increase in serum total amylase (TA) during TBI-based conditioning regimen. This study aims to determine a cut-off value of the TBI-related total amylase increase that might be a specific prognostic marker for transplant outcomes in the pediatric population.

Methods: The study included 78 pediatric patients with acute lymphoblastic leukemia (ALL) who received TBI-based standard myeloablative conditioning in preparation for an allogeneic HSCT between 2000 and 2018. We defined two TBI protocol groups: the first one was of total 12 Gy, delivered in 6 fractions; the second one was of 7.5 Gy in a single dose. A linear, accelerator-based, L-L irradiation was used. The lung was shielded with upper limbs in lateral position. In vivo dosimetry was performed using TLD only until 2003. Serum TA and pancreatic amylase were evaluated before and after the TBI, on a daily basis, until their normalization.

Results: TBI total dose was 12 Gy for 57 (73.1%) patients, and 7.5 Gy for 21 (26.9%) patients. Mean dose-rate ±SD was 14.0 ±2.0 cGy/min and 18.7 ±1.7 cGy/min respectively. The mean percent variation ±SD in dosimetry was -0.9 ±1.9% in 12 Gy group and 1.5 ±1.0% in 7.5 Gy group, under the acceptable 10% range. 71 (91.0%) patients had abnormal levels of TA values during TBI treatment. The mean ±SD of peak TA values was 368.4 ±348.2 U/L (n.r. 28-100 U/L). The difference in the maximum TA values between the two TBI groups was not significant (P = 0,2111). Maximum TA values were excellent in predicting the transplant outcomes as overall survival (OS) and disease recurrence. TA values >374 U/L had the best performance in predicting OS with AUC =0.773 and 95% CI = 0.66 - 0.86 (P < 0.0001), sensitivity 58.6% and specificity 95.9%. Diagnostic performance of maximum TA values >374 U/L in predicting the disease recurrence-related death was even better with AUC = 0.865 and 95% CI = 0.77 - 0. 93 (P < 0.0001), sensitivity 80.0% and specificity 88.9%. Kaplan-Meier curve analysis confirmed the statistically higher survival probability in patients with maximum TA values < 375 U/L (P < 0.0001).

Conclusions: Human population heterogeneity in radiosensitivity has been demonstrated in many studies due to polymorphic genetic variations. So far, the TBI protocols have not considered individual radiation susceptibility. In the era of precision medicine, the dosage of TA can be an useful tool to assessing the individual risk of radiation exposure.

Disclosure:

The authors declare. no conflict of interest.

P167 Evolution of Donor Chimerism after Haploidentical Stem Cell Transplant - Clinical Correlations

Carla Alves, Nuno Miranda, Pedro Sousa, Isabelina Ferreira, Gilda Teixeira, Ana Sofia Jorge, Maria Joao Gutierrez, Fernando Leal-da-Costa, Manuel Abecasis

Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal

Background: Donor Chimerism has been used in the post-hematopoietic stem cell transplant (HSCT) setting for monitoring graft and disease state.

Methods: Data from patients who underwent an haploidentical HSCT at our institution, between May 2014 and October 2019 was retrospectively collected from clinical files. The data regarding the evolution of lymphoid and myeloid lineage (CD3+ and CD33+, respectively) donor chimerism was then plotted on a dispersion chart. The patients were compared accordingly to type of conditioning, time to engraftment, and disease relapse to verify the presence of any correlation with chimerism state.

Results: We identified 29 patients; median age of 33 years (8-67) and follow-up of 32,8 months. A total of 19 patients had Hodgkin’s Lymphoma (HL) and were conditioned with a reduced-intensity conditioning (RIC). Patients with acute leukemia or myelodysplastic syndrome (11 patients) were mostly conditioned with a myeloablative conditioning (MAC); only one AML patient was conditioned with RIC. A calcineurin inhibitor plus mycophenolate mofetil and post-transplant cyclophosphamide were used for graft-versus-host disease prophylaxis. The median time to neutrophil and platelet engraftment was 16 and 20 days in the MAC patients and 19 and 21 in the RIC patients.

A total of 27 patients achieved CD3+ full donor chimerism during follow-up; 4 patients lost CD3+ full donor chimerism but only 1 didn’t re-achieve it during follow-up. The same 27 patients also achieved CD33+ full donor chimerism; 7 patients lost CD33+ full donor chimerism and 3 regained it during follow-up. Only 2 patients didn’t ever achieve CD3+ and/or CD33+ full donor chimerism; one of them had primary graft rejection.

At day +30, average CD3+ chimerism was 84.5% vs 100% and average CD33+ chimerism was 91% vs 99.9% for RIC and MAC patients, respectively. At day +100 the same trend occurred, with average CD3+ chimerism 87.5% vs 99.6% and average CD33+ chimerism 87% vs 100% for RIC and MAC patients.

Of the 8 relapsing patients (6 HL, 1 AML, 1 ALL), 4 maintained CD3+ and CD33+ full donor chimerism, 2 lost only CD33+, 1 lost both CD3+ and CD33+ and 1 patient didn’t achieve either. The occurrence of relapse wasn’t related to the state of CD3+ chimerism and it wasn´t possible to find a correlation between time to engraftment and CD3+/CD33+ chimerism at D+30.

Conclusions: Haploidentical full donor chimerism established rapidly, earlier in the patients conditioned with MAC. Notwithstanding, most of the RIC patients also achieved full donor chimerism. There wasn’t a correlation between loss of CD3+ chimerism and disease relapse. This suggest that other mechanisms may be underlying this phenomenon, although loss of graft-versus-disease effect may still be important. Diminished lymphocyte effector activity or loss of HLA haplotypes by the neoplastic cells are both possible avenues of study.

Disclosure: No conflitos of interest to declare.

P168 Thiotepa-busulfan-fludarbine as Conditioning Regimen for Patients with Myelofibrosis undergoing Allogeneic Hematopoietic Stem Cell Transplantation: A Single Center Experience

Mara Memoli ^1,2, Annalisa Paviglianiti¹, Florent Malard^1,3,4, Giorgia Battipaglia^1,4, Eolia Brissot^1,3,4, Clémence Médiavilla^1,4, Antonio Bianchessi^1,5, Anne Banet¹, Zoé Van de Wyngaert¹, Tounes Ledraa¹, Ramdane Belhocine¹, Simona Sestili¹, Simona Lapusan¹, Agnès Bonnin¹, Anne Vekhoff¹, Ollivier Legrand^1,3,4, Mohamad Mohty^1,3,4, Rémy Duléry^1,3,4

¹Saint Antoine Hospital, AP-HP, Paris, France, ²Federico II University, Naples, Italy, ³INSERM, Paris, France, ⁴Sorbonne University, Paris, France, ⁵University of Pavia, Pavia, Italy

Background: Allogeneic hematopoietic cell transplantation (HCT) is the only curative therapy for myelofibrosis (MF), nevertheless the optimal conditioning regimen has not yet been defined. Thiotepa-Busulfan-Fludarabine (TBF) is a promising regimen. However, only a small series of 12 patients receiving this conditioning regimen for MF with a short follow-up of 1 year has been reported, thus far. We therefore aimed to improve the assessment of outcomes associated to TBF in patients undergoing HCT for MF.

Methods: We report a single-center, retrospective analysis of adult patients with MF undergoing HCT, with TBF as part of the conditioning regimen, between October 2013 and January 2019.

Results: Twenty-nine patients were included. The median age was 56 (range 41-71) years. Fourteen patients had primary and 15 patients had secondary MF. Thirteen patients (45%) were female and 8 patients (28%) had received 2 or more previous lines of treatment. Eighteen patients had a JAK2 mutation (including 2 with an associated CALR mutation), 6 had single CALR mutation, 1 had MPL mutation and 4 patients were triple negative. According to the refined Dynamic International Prognostic Scoring System (DIPSS-plus) for primary myelofibrosis, patients were stratified as intermediate-1 (n=2), intermediate-2 (n=10), and high (n=15) risk. The majority (n=21) of patients were in progressive disease at the time of HCT, including two patients with blast transformation. Ruxolitinib was given to 16 patients prior to HCT. The median time from diagnosis to HCT was 11 (range 1-249) months. Graft source was peripheral blood stem cells in 27 patients and bone marrow in 2 patients. Donor type was HLA-matched related (n=5), matched unrelated (n=16), mismatched unrelated (n=1), and haploidentical (n=7). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and ATG for all patients, combined with mycophenolate mofetil in 25 patients. High dose post-transplant cyclophosphamide was added in haploidentical HCT. All patients engrafted except 2, who died during aplasia. The median time to neutrophil recovery was 14 days (range, 9-34). The median times to achieve platelet engraftment, >20 G/L and >50G/L, was 18 (range 1-387) and 20 (range 8-497) days, respectively. Six patients (21%) experienced grade II-IV acute GVHD. Among these, 4 had grade IV acute GVHD. Chronic GVHD occurred in 9 patients (31%). Only one severe form of chronic GVHD (pulmonary) was observed. The median follow-up was 35 (range, 10-57) months. Overall survival (OS) was 69 ± 9% at 2 years. Nine patients died: 5 of infection, 2 of GVHD and 2 due to multi-organ failure. No relapse was observed. OS was significantly lower among patients who had Ruxolitinib before HCT compared to patients who had not (50% versus 92%, p=0.02), respectively. A trend towards better OS was observed for patients who underwent HCT before the median time period of 11 months (86% versus 53%, p=0.05).

Conclusions: Our findings confirm that TBF is a valid conditioning strategy in patients with MF, and allows for a high incidence of engraftment, good disease control and promising OS. Previous use of Ruxolitinib and delay from diagnosis to HCT seem to negatively influence survival.

Disclosure: Nothing to declare.

P169 The Results of Allogeneic Hematopoietic Stem Cell Transplantation from HLA-haploidentical Donor with post-transplant Cyclophosphamide Regimen in Children

Alexandra Burya ¹, Kirill Kirgizov², Yulia Nikolaeva¹, Veronica Konstantinova¹, Ekaterina Pristanskova¹, Natalia Sidorova¹, Anastasia Mezenceva¹, Ludmila Olhova¹, Oxana Blagonravova¹, Olga Filina¹, Larisa Petrova¹, Elena Skorobogatova¹

¹Russian Children’s Research Hospital of Pirogov Russian National Research Medical University, Moscow, Russian Federation, ²N.N. Blokhin National Medical Research Center of Oncology, Moscow, Russian Federation

Background: Hematopoietic stem cell transplantation is a commonly accepted treatment option for high-risk hematological and immunological patients. The strategy of using stem cells of a HLA-haploidentical related donor combined with using post-transplant cyclophosphamide provided good control of the graft versus host reaction while maintaining the efficacy of HSCT

Methods: Between 2013 and 2019, 44 haplo-HSCTs with post-transplant cyclophosphamide regimen were performed in 40 patients, of which: acute lyphoblastic leukemia (n = 13), acute myeloid leukemia (n = 16), juvenile myelomonocytic leukemia (n = 7), severe combined immunodeficiency (SCID) (n = 3), aplastic anemia (n = 1). The average age of the patients was 3.6 years (6 month - 15 years). Stem cell sources were bone marrow (BM) (n = 39) and peripheral blood stem cells (PBSC) (n =5). Patients received regimen: busulfan-based (n = 13), threosulfan-based (n = 21), full-dose total body irradiation TBI 12 Gray (n = 5), non-myeloablative TOT and cyclophosphamide (n=1). In case of primary graft rejection second HSCT was performed for 4 patient with threosulfan and melphalan conditioning (n=2) and melphalan only conditioning (n=2). Post-trasplant cyclophosphamide was administered for all patients +3 and +4 days in 50 mg/kg dosage.

Results: The median day for neutrophil engraftment was 22 days for BM HSCT and 19 days for PBSC. The following complications occurred: oral mucositis: grade 1 (n=9), grade 2 (n=30), grade 3 (n=5); neutropenic enterocolitis: grade 1 (n=8), grade 2 (n=27), grade 3 (n=7), grade 4 (n=2); toxic hepatitis (n=22), hemorrhagic cystitis (n=6), systemic inflammatory syndrome (n=15), polyneuropathy (n=2), TMA-HUS (n=2). Viremia: cytomegalovirus (n=15), herpes virus type 6 (n=6), adenovirus (n=4) - with negation in the short term. Acute GVHD with skin rash symptoms of grade 1 (n=5), grade 2 (n=25), grade 3 (n=5), grade 4 (n=2); GVHD with gastrointestinal manifestation of grade 1 (n=7), grade 2 (n=15), grade 3 (n =7), grade 4 (n = 2); hepatic GVHD (n=5) of degree 3 of severity; chronical form (n=9). The transplant-related mortality occurred in a patient with TMA (n=1).

Complete +30 day donor chimerism was achieved in 80% patients (35/44). The risk of primary graft failure was 13.6% and was higher in 5/13 patients (38%) treated with busulfan, compared with 1/21 patients within threosulfan group (4.8%). Also the relapses occurred more frequently among busulfan treated patients (30%) than among threosulfan treated (19%).

Patients with SCID who had respiratory insufficiency of a 2-3 degree before conditioning had improved and resolved complications up to 45-60 days after HSCT. The 5 out of 6 patients with primary graft failure had HLA-C mismatched transplant. Of 40 patients 31 is currently alive (79%). Median follow-up has been 2 years (range 3 months - 6 years).

Conclusions: Our experience shows that haplo-HSCT with post-transplant cyclophosphamide regimen is effective treatment for high-risk patients with acceptable toxicity and low transplant associated mortality rate. Early control of infection and anti-virus immune response stimulation are the issues to be resolved. It is still disputable whether threosulfan-based regimen is beneficial for engraftment. High incidence of GVHD requires administration of adaptive supportive care.

Disclosure: Nothing to declare.

P170 Analysis of Differences in Preventive Measures after high-dose Cyclophosphamide Among Belgian Stem Cell Transplant Centres

Eva De Backer, Dries Deeren

AZ Delta, Roeselare, Belgium

Background: Cyclophosphamide is used in high dose in the conditioning regimen of allogeneic and autologous stem cell transplantation and early post-transplant as prophylaxis of graft-versus-host disease (GVHD). The risk of bladder toxicity and hemorrhagic cystitis is well established. However, preventive measures differ depending on local protocol.

Methods: We conducted a survey among Belgian transplant centres to identify differences in preventive measures after high dose cyclophosphamide. All 15 JACIE accredited Belgian transplant centres were asked to complete a short questionnaire. Centres who did not use high dose cyclophosphamide (n=2) were excluded from the analysis.

Results: A total of 13 centres were included in the analysis. High dose cyclophosphamide was used in conditioning regimen pre-allogeneic stem cell transplantation in 11 centres (84,6%) and pre-autologous stem cell transplantation in 5 centres (38,5%). In 11 centres (84,6%) high dose cyclophosphamide was used as GVHD prophylaxis.

Preventive measures included hyperhydration and forced diuresis, administration of mesna and insertion of a bladder catheter. Hyperhydration with or without forced diuresis was reported in all centres (100%). Mesna was used in all centres (100%), however dosing depended on local protocol ranging from 500mg/m2 in bolus injections (each 3 hours) to a daily total dose of mesna estimated equal to 80% to 160% of the total dose of cyclophosphamide either administered in bolus injection or continuous infusion.

Three centres (23,1%) reported insertion of a bladder catheter as a standard precaution in all patients. Motivation included either historical reasons or previous cases of severe hemorrhagic cystitis. No centres reported continuous bladder irrigation as a standard practice, but one centre (7,7%) used continuous irrigation in high risk patients with contraindication for hyperhydration.

In three centres (23,1%) a standard interval for diuresis was defined (with waking patients up at night). In most centres (92,3%) urine output was monitored with a specific target urine output defined in 4 centres (30,8%).

Conclusions: Major differences in preventive measures after high dose cyclophosphamide could be found between the Belgian transplant centres. In particular, the use of bladder catheters and the dosing of mesna vary depending on local protocol. Bladder catheters may cause discomfort and are not without complications. As the majority of Belgian centres do not use this as standard procedure, this study can serve as a benchmark and may encourage to question the systematic use of bladder catheters in this setting. More evidence is needed to identify best practice and obtain a more uniform and standardised approach.

Clinical Trial Registry: not applicable

Disclosure: Nothing to declare.

P171 Irradiation-free Re-conditioning for T-cell Depleted haplo-identical Stem Cell Transplantation

Susanne Aydin, Ingo Müller

Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany

Background: Haplo-identical stem cell transplantation (hHSCT) is an option for patients requiring stem cell transplantation who lack an HLA-matched donor. We focus on transplantation of T-cell depleted HLA-haploidentical stem cells (TCD hHSCT) from a parent to their child, which is associated with a risk of graft rejection in 10%. We identified 9 patients who rejected a first TCD hHSCT and received a salvage TCD hHSCT from the other parent following a irradiation-free lymphodepleting reconditioning regimen.

Methods: Our cohort of 9 patients (7 female, 2 male, 4 with an initial indication of malignancy, 5 for non-malignant diseases) received their second TCD hHSCT either due to graft-rejection (5/9), or due to non-engraftment (4/9) after their first TCD hHSCT, conducted from 2011 to 2018. No acute GvHD was observed. Their median age was 2.3 years (3 months - 10 years).

In all cases, one parent donated with peripheral stem cells for the first transplantation, the other for the re-transplantation. The conditioning for the first, failed haplo-transplantation was fludarabine and thiotepa for all patients, 7 also received anti-thymocyte globulin, 2 thymoglobulin or alemtuzumab. The final conditioning components were treosulfan and melphalan in 4, and TDM busulfan in 1 patient.

The second transplantation was 6 to 26 days (median: 16 days) after the first. All patients were conditioned with fludarabine, thymoglobulin, and thiotepa. No radiation was administered. T-cell depletion of PBSC was employed in 6 patients by CD34⁺ selection and in 3 patients with CD3/CD19 depletions. The median of transplanted stem cells was higher than in the first transplantation.

Results: Leucocyte engraftment was achieved in all patients 9 to 15 days post-transplantation (median: day 12). 5 of the 9 patients exhibited no symptoms of GvHD, 2 had grade I aGvHD, and 2 had grade II aGvHD limited to the skin. By day 100 the aGvHD had resolved in all 4 affected patients.

The follow-up times ranged from 4 months to 7 years (median: 11 months). 8 of the 9 patients were alive at last follow-up. All of these patients showed a sustained engraftment and complete donor chimerism. At last follow-up no patient showed symptoms of a cGvHD.

One patient died due to a leukemia relapse and multi-organ failure. Of the 8 surviving patients, 4 had a CMV reactivation, 1 suffered from a transfusion related acute lung injury shortly after transfusion, and 1 from a BK-virus-associated hemorrhagic cystitis.

Of the 8 surviving patients, all but one received no transplantation related medication and were in good health. The most recent patient is at day 218 in stable health after a severe episode of autoimmune hemolytic anemia (AIHA). The Lansky Scores for all patients reached 80% to 100% at day 100.

Conclusions: With a median follow-up of 11 months, the overall outcome after irradiation-free re-conditioning is promising. Omitting irradiation spares side effects and reduces the infection risk. With all patients showing a robust engraftment and only few complications post-transplantation, this conditioning seems to be a promising regimen, notwithstanding the relatively small cohort size of 9 patients.

Disclosure: Nothing to declare.

P172 Low Graft CD4 Cell Dose Predicts Relapse in the Atg‐based Myeloablative Conditioning Regimen

Nabil Yafour ^1,2, Faiza Serradj¹, Soufi Osmani¹, Mohamed Brahimi^1,2, Sihem Bekadja¹, Amel Mihoubi¹, Rachid Bouhass^1,2, Abdessamad Arabi^1,2, Mohamed Amine Bekadja^1,2

¹EHU 1er Novembre 1954 d’Oran, Oran, Algeria, ²Université d’Oran 1, Oran, Algeria

Background: T cells, on the peripheral blood stem cell (PBSC) allogeneic allogeneic hematopoietic stem-cell transplantation (HSCT) play a crucial role of the immunologic effect of graft-versus-host disease (GVHD) and graft-versus-tumor (GVL). However, the exact doses of subsets of lymphocytes CD4, and CD8, and that effect on outcome is not well characterized, and may changes between different types of conditioning and GVHD prophylaxis.T

To determine the impact of graft T-cell doses on incidence of disease relapse, acute and chronic GVHD after allogeneic HSCT with ATG-based myaloablative conditioning regimen, in adult patients with hematological malignancies.

Methods: this is a prospective, single-institution cohort (N=32) of patients with hematological malignancies (28 AML, 2 ALL, 2CML), who received allogeneic HSCT from February 2013 to February 2019. At time of transplant, all AML and ALL patients were in CR. Myeloablative conditioning regimen consisted to intravenous Busulfan (Bu) - Fludarabine (Fu) for AML and CML, and Bu- Melphalan for ALL patients. GVHD prophylaxis included ATG (thymoglobulin) 2.5 mg/kg on D-2 and D-1, ciclosporin and methotrexate. All patients received PBSC from an identical HLA-related donor. Analysis of Graft subsets lymphocytes by flow cytometry (BD CANTO cytometer, II 8 colors). None of patients received prophylactic DLI.

Results: median age at transplant was 32 years (18-62), including 19 men and 13 women. Median CD34+/ kg cells and CD3 + lymphocytes infused were 4.5 x 10⁶ (2.24-7) and 2.32 x 10⁸ (0.72-6.24) respectively. Median time for absolute nuclear cells > 0.5 × 10⁹/L was 13 days (6-25), and unsupported platelet counts of at least 20 x 10⁹/L was14 days (10-43). Median CD4 and CD8 cells infused were 0.84 x10⁸(0.09-2.88), and 1.13x10⁸(0.08 -4.14). There were no significant correlations between the CD8 graft content and risk of relapse (P=0.09), however higher CD4 cell doses (cutoff >0.81x10⁸) were associated with trend lower risk for disease relapse 11% vs 43% (p= 0.05), without a significant increase risk acute or chronic GVHD 36% vs 33% (p=0.89), and 21% vs 39% (p=0.32) respectively.

Conclusions: A potential strategy for optimizing graft T-cell doses, apear to be useful to improve outcome in patients received allogeneic HSCT with ATG based myeloablative conditioning regimen.

Disclosure: No conflict of interest

P173

Abstract already published.

P174 Haplo-identical Hematopoietic Stem Cell Transplantation (HSCT) in high-risk Hematological Malignancies, Algerian Experience

Dina Ait Ouali, Malek Benakli, Farih Mehdid, Sabrina Akhrouf, Nadia Rahmoune, Mounira Baazizi, Hanane Bouarab, Sara Zerkout, Imene Abderrahim, Farida Harieche, Rose-Marie Hamladji, Redhouane Ahmed Nacer

Pierre and Marie Curie Center, Alger, Algeria

Background: The haplo-identical HSCT is currently a rescue procedure in patients (pts) with high risk hematological malignancies when identical HLA donor is not available. We propose a retrospective study of 71 pts who benefited from this procedure.

Methods: From May 2013 to May 2019, 71 haplo-identical HSCT were used in 71 pts with hematological malignancies (15 AML, 39 ALL, 10 CML, 1 lymphoblastic NHL, 4 AL biphenotypic, 2 MDS). Median age was 26 years (4-61) and sex-ratio (M/F):2.7. At the time of the transplant, 15 pts were in first complete remission (CR), 48 pts in second CR and 8 pts in active disease. The donors used were parent (35), siblings (29) or offsprings (7). The degree of compatibility (HLA A, B and DR) is 3/6 (50 cases), 4/6 (15) and 5/6 (6). Two successive conditioning regimens were used; the first was inspired to Pekin (HP) associated: Busilvex 9.6mg/kg, Aracytine 8g/m², Cyclophosphamide 3.6g/m² for 36 pts in HEPA filtered rooms; the GVHD prophylaxis included the combination Ciclosporin-Methotrexate- Mycophenolate-Thymoglobulin (10mg/kg) and received an unmanipulated bone marrow (BM) transplant and Peripheral blood stem cells (PBSC). The second one (TBF) associated Fludarabine (150mg/m²)-Thiotepa (10 mg/kg)-Busilvex (9,6mg/kg) for 35 pts in rooms without HEPA filters; the GVHD prophylaxis included the association Ciclosporin-MMF-Endoxan 50mg/kg day3-5 and received PBSC. Median dose infused CD34+ cells: 8.15.10⁶/kg (1.43-32) and nuclear cells: 4,89.10⁷/kg (0.59-7,44). At September 2019, the minimal follow-up delay was 4 months and maximal 76 months.

Results: Aplasia was observed in all pts with median duration of 18 days (10-38). The median day of neutrophils engraftment was 13 days (11-27). Two cases of VOD were observed. Four pts presented Thrombotic Micro-angiopathy (TMA). Four pts (5%) presented an early rejection. Acute GVHD occurred in 32 pts (48%) including 30 (93%) grade II-IV. Chronic GVHD was seen in 19 pts (43%) with extensive form in 9 pts (47%). twenty eight pts (42%) showed CMV reactivation. Forteen cases (21%) of haemorrhagic cystitis (HC) are observed. Thirteen pts (18%) relapsed, of which 5 pts were blast crisis at the time of the transplant. After a median follow-up of 32 months (4-76), 29 pts (40,8%) are alive and 42 pts (59,2%) died within 30 pts (42%) from TRM (GVHD:10, severe infection:10, HC: 1, TRALI syndrome: 1, TMA :1, V0D :2, early rejection :3, multi-visceral failure: 1, cerebral hemorrhage :1) and 12 pts (17%) after relapse, There was no significant difference between the two conditioning regimens (HP Vs TBF) in terms of aGVHD (48%Vs48%; p= 0.87), cGVHD (34%Vs55%; p= 0.13), CMV (48%Vs36%; p= 0.32), HC (21%Vs21%) and relapse (33%Vs12%; p= 0.13) except for TRM (27%Vs57%; p=0.02). The overall survival and disease free survival at 76 months are 37% (at 36 months: 46%Vs29,5%; p=0.5) and 37,2% (at 36 months: 44,15%Vs30,17%; p=0.9) respectively without significant difference.

Conclusions: Haplo-identical HSCT is, currently, a well-validated procedure in pts with high-risk haematological malignancies who do not have sibling HLA donor. However TRM is relatively high essentially in TBF procedure may be explained by the different conditions of realization (absence of laminar flow).

Disclosure: Nothing to declare.

P175 Interruption of Conditioning for allo-HCT does not affect Clinical Outcomes other than Chronic GVHD

Satoru Matsushima ¹, Ryoji Kobayashi¹, Daiki Hori¹, Masato Yanagi¹, Koya Kodama¹, Daisuke Suzuki¹, Atsushi Manabe², Kunihiko Kobayashi¹

¹Sapporo Hokuyo Hospital, Sapporo, Japan, ²Hokkaido University, Sapporo, Japan

Background: Conditioning regimens for hematopoietic cell transplantation (HCT) should be performed according to usual standards and timescales. However, an interval of one or two days is occasionally required during the conditioning because of hospital closure, predetermined HCT dates or simultaneous HCTs for multiple patients. This interrupted conditioning may have negative effects on the clinical outcomes of the HCT, and we tested this hypothesis in patients who had undergone HCT in our hospitals.

Methods: We retrospectively evaluated 83 pediatric patients (median age 9.7 years; range 1.5-19.9 years) with a malignant disease who had received 12 Gy or 13.2 Gy total body irradiation (TBI) as part of their conditioning regimen before allo-HCT at Sapporo Hokuyu Hospital or Hokkaido University Hospital. Among these patients, 19 patients had experienced interrupted conditioning and the remaining 64 patients received conventional uninterrupted regimens. The five-year overall survival (OS), event free survival (EFS), the median number of days of neutrophil engraftment and the incidence of acute and chronic graft versus host disease (GVHD) were compared between the two groups. The interrupted group had a mean interval duration of 1.4 days (range 1-2 days), and the interval during TBI was set in 8 of the 19 patients (42%). Most of the patients were diagnosed as hematologic malignancies (92%). Patient characteristics were compared between the conventional and the interrupted conditioning groups in terms of age, sex, diagnosis, disease status at HCT, graft source, related or unrelated donor, drugs used for GVHD prophylaxis and conditioning regimen; these were almost consistent across the two groups except for the type of calcineurin inhibitor administered.

Results: The differences in five-year OS and EFS were not statistically significant between the group without interval and the group with interval (OS: 50% vs 47%, p=0.925, and EFS: 43% vs 40%, p=0.892). Moreover, the median number of days of neutrophil engraftment was not significantly different in patients who had received uninterrupted regimens or those who experienced treatment intervals (median 18 days, range 11−46 days vs median 19 days, range 14−26 days, p=0.976). However, the interrupted conditioning group showed a marginally significant tendency toward the higher incidence of chronic GVHD than the conventional conditioning group. (19% vs 42%, p=0.063). Consequently, the association between an interrupted conditioning regimen and chronic GVHD was investigated through logistic regression analysis with clinical variables that were significant in the univariate analysis (p< 0.1). In the multivariate analysis, an interval during conditioning for allo-HCT was significantly associated with chronic GVHD (odds ratio, 3.72, 95%CI, 1.04-13.3, p=0.043). (Table 1)

Conclusions: Our study of patients with malignant diseases who had undergone allo-HCT with 12 Gy or 13.2 Gy TBI indicates that an interval during HCT conditioning does not affect clinical outcomes such as OS or EFS. However, interrupted conditioning can affect the occurrence of chronic GHVD, and this association requires further investigation.

Disclosure: Nothing to declare.

P176 Reduced Intensity Conditioning followed by Haploidentical Hematopoietic Cell Transplantation (Ric-haploHCT) and post-transplant Cyclophosphamide as Graft versus Host Disease Prophylaxis, for Hematological Disorders: Single Centre Experience

Vinod Patil, Reghu Sukumaran, Mita Roychowdhury, Sayak Chaudhuri, Jeevan Kumar, Saurabh Bhave, Rizwan Javed, Niharendu Ghara, Reena Nair, Vivek Radhakrishnan, Mammen Chandy

Tata Medical Center, Kolkata, India

Background: Haplo-HCT has emerged as a viable option for patients without matched sibling donors. With the use of Reduced intensity conditioning(RIC) and post-transplant cyclophosphamide (PTCy), the outcomes of haplo-HCT are improving steadily. We conducted a retrospective audit of our experience to assess real world transplant outcomes in the Indian scenario.

Methods: This is a retrospective chart review of patients with hematologic disorders who underwent RIC-HaploHCT and PTCy at our centre between August 2012 and September 2019. Demographic data, clinical features and outcomes were analyzed using standard descriptive statistical methods and survival analysis.

Results: Of a total of 64 HaploHCT done in the study period, 21 patients underwent RIC-HaploHCT, of which 17 were malignancies [AML(5), Acute Lymphoblastic Leukemia (2), Hodgkin lymphoma (5), NHL(2), MDS (2), CML (1), Aplastic Anemia (3), Fanconi anemia (1)]. The median age was 34 years (range: 10-60 years) and 55.5% (n=15) patients were males. 3 patients were in first complete remission (CR1), 11 were in CR2 or CR3, and 7 patients had active disease[Aplastic anemia - 3, MDS - 2, Fanconi anemia-1, CML-1] at the time of transplantation. The most common conditioning regimen used was fludarabine and melphalan (n=14). Donor types were sibling (n=13), parent (n=4), cousin (n=1) and child (n=3). Stem cell source was peripheral blood stem cell graft in all patients. The median CD34 cell dose infused was 5 x 10⁶ cells/ kg. 76.2% (n=16) patients achieved >95% chimerism at D+28. D+100 survival was 58% (n=12)[5 patients (23.8%) died pre-engraftment (neutropenic sepsis - 4, grade 4 VoD - 1) and 4 (19%) died post-engraftment (bacterial sepsis - 2, relapse - 1, graft rejection - 1)]. Acute GVHD was seen in 38% (n=8) patients with grade III/IV acute GVHD in 19% (n=4). Steroid refractory persistent GVHD was seen in 2 patients. Chronic GVHD developed in 14.2% (n=3) patients. One patient with MDS had disease relapse. In the entire cohort, median survival was 4.8 months while the estimated 3 year survival was 40%. 80.9% (n=17) patients had surveillance cultures (Faecal or throat) positive for 1 or more multi-drug resistant organisms (MDRO). All of them were gram negative bacilli (GNB) and included 38% carbapenem resistant organisms. During the peri-transplant period, 9 cultures were positive: gram negative bacilli in 6 and gram positive cocci, Fusarium and Aspergillus in 1 culture each.

Conclusions: RIC-HaploHCT for hematological disorders is associated with modest overall outcomes in our study with early mortality affecting the survival. Higher non-relapse mortality due to MDRO infections is of urgent concern. Relapse rates were however low.

Number of patients	n= 21
Participating center	1
Median age and range	34 years(10 to 64 years)
Male :Female	15:6
Malignancies (AML, ALL, MDS, NHL, Hodgkin Lymphoma, CML)	17
Other hematological disorders (Aplastic anemia/marrow failure)	4
Patients in Complete remission at transplant	14
Patients with Active disease at transplant	7

[Patient Characteristics]

Disclosure: Nothing to declare.

P177 Describe and Explore a Patients´ Outlook on Dental Care in the Context of their Medical Diagnosis and Treatment Prior to and following Allogeneic HSCT

Charlotte Wilson-Dewhurst ^1,2, Amit Patel³, Shelagh Thompson²

¹Royal Liverpool and Broadgreen University Trust, Liverpool, United Kingdom, ²Liverpool University, Liverpool, United Kingdom, ³Clatterbridge Cancer Centre NHS Foundation Trust, Liverpool, United Kingdom

Background: Within the United Kingdom, national guidance recommends patients receive a dental assessment, and necessary treatment prior to haematopoietic stem cell transplant, due to the resulting immunosuppression and increased risk of sepsis. It is uncertain from the current literature what benefits pre-HSCT dental interventions have on patients’ outcome post-HSCT.

Methods: This study involved a qualitative approach with the use of face-to-face semi-structured interviews. A topic guide was used to facilitate the discussion in the interview. Areas of interest such as diagnosis and medical background, views on the care pathway and dental service, impact and feelings around dental treatment and advice provided, oral complications and future views on dental care were explored.

Patients were recruited from a late effects clinic >100days following allogeneic HSCT. All potential participants were given the opportunity to discuss the study and completed a consent form if they wished to proceed to interview. Ethical approval was granted for this study.

Results: From a potential 12 participants, 7 completed the face-to-face semi-structured interview. The interviews ranged from 15 minutes to 45 minutes in duration. The recorded interviews were transcribed verbatim by the researcher. Thematic analysis was used to analyse the results.

From the results, 4 main themes emerged:

• 1. Preventing transplant related complications: Overall particiants understood the need for a dental assessment prior to HSCT, and that improved oral hygiene could improve post-HSCT oral complications. However they highlighted the diffculties in completing oral hygiene practices whilst being an in patient due to their levels of fatigue and medical complications.

• 2. Patient experience of the care recieved: Generally participants were reassured by seeing a specialist dental unit prior to HSCT however there was differing expectations as to the treatment available and follow up process. Participants suggested having further information regarding the dental service so that they could tailor their expectations.

• 3. Consequences of medical management: Participants discussed both oral and medical complications of their transplant including GvHD, sepsis along with mucositis, xerostomia and dysguesia.

• 4. Psychological impact of treatment: Participants highlighted anxiety regarding their medical treatment but also a number of them experienced dental anxiety. The participants appeared pragmatic with regards to their dental anxiety with many of them stating their anxieties around dental treatment had reduced following the expereince of HSCT.

Conclusions: To conclude, completion of this study will enable changes to the current care pathway for patients including provision of more written information as to the reason for dental assessment, importance of continued oral hygiene and follow up dental care post-HSCT. It also provides a base for future research to build upon with regards to improving the oral health care for this patient group.

Clinical Trial Registry: N/A

Disclosure: Nothing to declare.

P178 Safety and Efficacy of low-dose Benda-EAM as Compared to Beam Conditioning for Autologous Transplantation of Refractory/relapsed Lymphoma Patients

Naif I. AlJohani, Momen Nasani, Azhar Nawaz, Hosam Eldin Ali, Jalil Ur Rehman Khan

King Faisal Specialist Hospital & Research Center, Jeddah, Saudi Arabia

Background: The standard of care in relapsed/refractory lymphoma is consolidation with high dose chemotherapy and autologous stem cell transplantation (ASCT). BEAM has been widely used as a conditioning regimen for ASCT since 1990. However, issues such as pulmonary toxicity and scarcity of carmustine (BCNU) have led centers to seek alternative agents such as bendamustine. The optimum dose of bendamustine is not well defined, with total doses reported in the literature ranging from 100mg/m² to 400mg/m². Higher doses have been associated with increased renal toxicity. At our institution, we used BEAM from 2008 until 2017 at which point we made Benda-EAM our standard. After reviewing the experience of other centers, we chose a total dose of Bendamustine 320 mg/m² to minimize side-effects. The objective of this study is to compare the two conditioning regimens in terms of overall survival (OS), relapse free survival (RFS), and adverse events

Methods: Global summary and bivariate analyses of patients comparing Bend-EAM vs BEAM type of conditioning was made to describe the baseline and post-ASCT events characteristics.

Overall survival and relapse-free survival (defined as the first event between relapse and death) since ASCT were illustrated with the Kaplan-Meier method and curves were compared thanks to the log-rank test. Hazard-Ratios of univariate and multivariate analyses (incorporating baseline variables that was significantly different between conditionings and significant on univariate analyses as adjustment co-variables) were estimated with Cox regressions.

Results: A total of 71 patients were evaluated (BEAM n= 54, Benda-EAM n=17). There were no significant differences in the baseline characteristics of the two groups, with the following notable exceptions: pre-transplant status with less complete response [1/17 (5.88%) vs 7/53 (13.21%) (p=0.016)] and more ICE salvages [(14/17 (82.35%) vs 27/54 (50.00%), p=0.023)]in Benda-EAM versus BEAM respectively.

In terms of non-hematological toxicity, there was a higher incidence of significant mucositis (≥Grade 3) in the Benda-EAM group [82.3% vs 48% (p=0.02)]. There were no significant differences in pulmonary adverse events (n=2 and n=6 (p=0.82) or in renal toxicity [11.4 % vs 7.5 % (p=0.75)] between Benda-EAM and BEAM respectively. No severe cases of renal toxicity (≥Grade 3) were observed. Transplant related mortality (TRM) was 5.9% (1/17) in the Benda-EAM group and 3.7% (2/54) in the BEAM group (p=1.0).

Neutrophil and platelet engraftment favored Benda-EAM over BEAM, (10 vs 14 days (p= < 0.001) and 16 vs 27 days (p= < 0.001) respectively. The cumulative incidence of relapse 15 months after ASCT was 36% in Bend-EAM and 24% in the BEAM group (p=0.369).

Median OS was not reached in either group. The probability of OS at 18 months for the Benda-EAM and BEAM groups was 94.12 % and 91.89% respectively (p=0.66).

Conclusions: Benda-EAM utilizing a total bendamustine dose of 320mg/m² is a safe and efficacious conditioning regimen. Renal toxicity utilizing this dose is minimal. BendaEAM is associated with more GI & mucosal toxicity even with reduced dose. TRM and other adverse effects were not significantly different as compared to BEAM. Benda-EAM is non-inferior to BEAM conditioning in terms of RFS and OS.

Disclosure: Nothing to declare.

P179 Conditioning Regimen with Fludarabin/treosulfan Compared to Busulfan/cyclophosphamid Prior to Allogeneic Stem Cell Transplantation in Younger Patients with AML And MDS: A Single Center Retrospective Analysis

Alix Pianka, Peter Herhaus, Krischan Braitsch, Katrin Holzhauser, Katharina Götze, Florian Bassermann, Mareike Verbeek

Technical University of Munich, Munich, Germany

Background: Non-myeloablative conditioning regimens such as Fludarabin/Treosulfan (Flu/Treo) enable allogeneic stem cell transplantation (alloSCT) for a broad range of patients with hematologic malignancies due to reduced toxicity rates and transplant related mortality. Beelen et al. showed, that conditioning with Flu/Treo provides excellent disease control and low rates of treatment related mortality in older and comorbid patients.[1] Nevertheless, myeloablative conditioning regimens (MAC) such as Busulfan/Cyclophosphamide (Bu/Cy), which are associated with higher toxicities, are often conducted in younger patients, because it is thought that those regimens lead to a better disease control[2]. Yet it is still of debate if younger patients could profit from a less toxic MAC regimen. This retrospective, single center analysis compares conditioning with Flu/Treo to Bu/Cy prior to alloSCT in younger patients with myeloid malignancies concerning outcome, toxicity and Graft-versus-Host-Disease (GvHD).

[1] Beelen, D. W., R. Trenschel, M. Stelljes, et al. Treosulfan or busulfan plus fludarabine as conditioning treatment before allogeneic haemopoietic stem cell transplantation for older patients with acute myeloid leukaemia or myelodysplastic syndrome (MC-FludT.14/L): a randomised, non-inferiority, phase 3 trial. The Lancet/Haematology 2019, published online October 9, https://doi.org/10.1016/S2352-3026(19)30157-7.

[2] Scott BL, Pasquini MC, Logan BR, et al. Myeloablative versus reduced-intensity hematopoietic cell transplantation for acute myeloid leukemia and myelodysplastic syndromes. J Clin Oncol 2017; 35: 1154-61.

Methods: In this single center, retrospective study 44 patients aged between 25-55 with hematologic malignancies (AML (34), sAML (2), tAML (2), MDS (5), tMDS (1)) receiving either Flu/Treo (20 patients, 9 female, average age 48,9 years, 15 patients in complete remission before alloSCT) or Bu/Cy (24 patients, 19 female, average age 40,4 years, 23 patients in complete remission before alloSCT) conditioning before alloSCT at our institution between 1998 - 2019 were analyzed. Data concerning outcome, toxicity and GvHD were evaluated retrospectively. Patients were eligible for allogeneic transplantation based on their underlying malignancy and to institutional guidelines. All patients received either anti-thymocyte globuline and cyclosporine in combination with mycophenolatmofetil or Methotrexat short.

Results: Median overall survival (Bu/Cy vs. Flu/Treo, median (days): 1293 vs. 452, p=0,25) and progression free survival (Bu/Cy vs. Flu/Treo, median (days): 1201 vs. 331, p=0,15) did not differ between the two groups (Figure A, B). Non-relapse mortality was 33% in both groups. The rate of acute GvHD (only Grade 3 and 4 considered) did not differ significantly between both groups (25% in the Bu/Cy, 35% in the Flu/Treo group, p=0,59, Figure 1C). The rate of chronic GvHD (only extensive considered) did neither differ significantly between the two groups (12% in the Bu/Cy, 32% in the Flu/Treo group, p=0,93, Figure 1D).

Conclusions: This retrospective analysis reveals that the conditioning regimen Flu/Treo has comparable outcomes concerning overall survival, progression-free survival and rates of acute and chronic GvHD to Bu/Cy. The tendency to a more favorable overall survival within the Bu/Cy group might partially be explained by the higher rate of active disease and older patients within the Flu/Treo group. Therefore the comparison of the Flu/Treo conditioning regimen with MAC should be studied in a randomized, prospective trial.

[Figure 1. Comparison of the conditioning regimens Bu/Cy and Flu/Treo, p-values using log-rank-test.]

Disclosure: Nothing to declare.

P180 Atg in Conditioning for Sibling Allogeneic Stem Cell Transplantation; Single Center Experience

Lazar Chadievski, Aleksandra Pivkova Veljanovska, Irina Panovska Stavridis, Zlate Stojanoski, Lidija Cevreska, Nevenka Ridova, Marija Popova Labacevska, Zaklina Ancevska, Gabriela Trajkovska, Borce Georgievski

University Clinic for Hematology, Skopje, North Macedonia, the Republic of

Background: The majority of hematologic diseases, especially the malignant group, are attributed with low survival rates. The modern medicine copes with finding the optimal treatment protocol. Allogeneic stem cell transplantation holds the biggest curative potential for this group of diseases. But still acute and chronic graft versus host disease (GvHD) represents a major problem to solve.

Methods: Our goal was to present our experience in conditioning candidates for sibling allogeneic stem cell transplantations by adding ATG balancing between GvHD prevention, infectious complications and survival.

We have made a 5 year retrospective analysis of 29 patients where sibling allogeneic stem cell transplantation was done in our transplant center. We have included not only malignant hematological diseases, but also patients with aplastic anemia. We did not detail the patients in terms of previous treatment intensity, and made a more general analysis of outcome in patients where ATG was used in conditioning and where it wasn`t the case. We administered mainly anti-human T-lymphocyte immunoglobulin (Grafalon) 8-10 mg/kgTT.

Results: We have included 29 patients. 16 were male (55%), and 13 females (45%). The mean age was 39.7 years. The majority of patients, 15 (51%) were diagnosed with AML, 6 (20.6%) with MDS, 3 (10.3%) with ALL, 2 (6.8%) with myelofibrosis, 2 (6.8%) with CML, 1 (3.4%) with AA. As sibling donors we used 12 females (41.3%) and 17 (58.7%) males. ATG was applied in the conditioning of 12 patients (41%). The median number of cells, mainly mononuclear cells, used in the graft in the ATG group was 3.3, while in the non ATG group 3.8. There was no significant difference in days to engraftmen, 13.7 in the ATG group, compared to 12.9 in the non ATG group. We used standard MTX+CsA immunosuppression posttransplant. In the majority of patients Bu-Cy-ATG was used as conditioning protocol. In the ATG group, in 35% of the patients some kind of infectious complication was confirmed, even with some multiresistant strains like E.Coli ESBL+ or Vanvomicin resistant Enterococcus (VRE), while in the non ATG group, only 11% had infectious complications, mainly catheter associated. But, if we analyze the GvHD, in the ATG group, acute GvHD it was diagnosed in 22% of the patients, while in the non ATG group it doubled the incidence of acute GvHD, and it was near 42%, gr III-IV was most prevalent and it could be related to 40% of the deaths in the non ATG group. The relapse rate in the ATG group was 10%, ehile in the non ATG group, around 12%, but we must emphasize that the risk profile of the patients was much worse, and nearly all of them were transplanted in nearly active disease.

Conclusions: ATG should be recommended in conditioning for sibling allogeneic stem cell transplantation in hematological diseases. More rigorous control and treatment of infectious complications must be and can be provided with adequate use of antibiotics. The higher rate of infections does not outweigh the benefit of lower rate for GvHD, predominantly acute GvHD making allogeneic HSCT safer and more applicable.

Clinical Trial Registry: Not aplicable

Disclosure: Nothing to declare.

Experimental stem cell transplantation

P181 2^nd allo-hsct for Patients who Diagnosed Recurrence all after the 1^st allo-hsct

Li Nan-nan¹, Zhang Jian-ping ¹, Lu Pei-hua¹, Lu Yue¹, Zhao Yan-li¹, Zhou Jia-rui¹, He Jun-bao², Yang Jun-fang¹, Fan Li-jun¹, Yin Dong-xu¹, Gao Xin-xia¹, Lu Dao-pei²

¹Hebei Yanda Lu Daopei Hospital, Lang fang, China, ²Beijing Lu Daopei Hospital, Beijing, China

Background: Recurence of ALL after Allo-HSCT is described with poor prognosis and very low long-time survival rate. At present, there are no definite effective treatment measures for these patients. The results of 2^nd Allo-HSCT in patients with this group leukemia in our center was analyzed in order to understand whether the therapeutic effect can improve prognosis on the patients.

Methods: Retrospective analysis, from July 1st, 2015 to November 1st,2019, all patients undergo 2^nd Allo-HSCT who diagnosed as R/R ALL after Allo-HSCT. Total 28 cases. Male 16/ Female 12; 27 cases diagnosed as B-ALL (10 cases with BCR/ABL1, 1 with IKZF1 mutate, 1 with IKZF1 and ETV6 mutate; 1 with Ph-like; 2 cases with E2A/PBX1) and 1 diagnosed as T-ALL. Conditioning regimen in 1^st Allo-HSCT 5 cases are TBI/CY/ATG/Me-CCNU and 23 cases are BU/CY/ATG/Me-CCNU. In contrast Conditioning regimen in 2^nd Allo-HSCT conditioning regimen, 23 cases are TBI/CY/ATG/Me-CCNU and 5 cases are BU/CY/ATG/Me-CCNU. 22 cases accepted CART before 2^nd Allo-HSCT.

Results: Recurrence time had significant effect on overall survival(OS) and leukeamia free survival(LFS). recurrence time more than 6months vs less than 6 months: 1-year OS 58.4% vs. 33.3%, p=0.029; 2-year OS 58.4% vs. 33.3%, p=0.029; 1-year LFS 53.3% vs. 33.3%, 2-year LFS 42.7% vs. 33.3%; incidence of viral disease 67.9% (19/28), CMV46.4%(13/28), EBV-PTLD 10.7%(3/28), others 10.7%(3/28); Cause of mortality: total 11cases, viral disease 8cases (including 2cases PTLD), septic shock 1case, TMA1case, GI-GVHD 1case.

Conclusions: 1. 2^nd Allo-HSC can improve the prognosis of Recurrence ALL after 1^st Allo-HSCT who reached CR. 2. Recurrence time less than 6months had significant effect on OS and LFS; 3. Another CR even FCM-MRD negative could be reached who undergone CART therapy, access to 2^nd Allo-HSCT; 4. The main early complications of 2^nd Allo-HSCT were viral disease; 5. The main causes of death after 2^nd Allo-HSCT were none relapse mortality, mainly viral diseases.

Disclosure: Nothing to declare.

P182 Establishing a Transplant Sharing Program

Iryna Luts ¹, Maria Calbacho², Ana Lerma¹, Juan Churruca³, Maria Dolores Martínez¹, Jose Maria Sanchez-Pina², Maria Isabel Ustariz¹, Maria Jesus García¹, Ana Jiménez-Ubieto², Sonia del Valle¹, José Ángel Hernández-Rivas³, Joaquín Martínez-Lopez², Fernando Solano¹, Juan José Lahuerta²

¹Nuestra Señora del Prado Hospital, Talavera de la Reina, Spain, ²12 de Octubre University Hospital, Madrid, Spain, ³Infanta Leonor Hospital, Madrid, Spain

Background: Autologous stem-cell transplantation (ASCT) is a prevalent therapy with firmly established efficacy and safety indices. However, to perform this procedure is necessary to transfer patients to referral centers with obvious implications for patients and their relatives. Besides, the increasing demand of autologous and allogeneic transplants may cause transplant delays.

Based on previous studies carried out in Canadian centers (Crump. Bone Marrow Transplant. 1992), an autologous transplant sharing program has been set between 3 centers in Spain to increase the availability of ASCT, avoid transplant delays and improve patient and family comfort.

Methods: Retrospective, observational and analytical study of the ASCT enrolled in this program between July 2017 and October 2019.

Selected ASCT candidates for multiple myeloma (MM), lymphoma and acute myeloid leukemia (AML) from Infanta Leonor (ILH) and Nuestra Señora del Prado Hospitals (NSPH) were included after signing the informed consent.

Uniform clinical protocols were used between the 3 hospitals. A clinical transplant update program for nurses and physicians was set up before the program started.

The program is divided into 2 stages: First stage: Pre-transplant patient evaluation, stem-cell apheresis collection and cryopreservation as well as administration of high-dose therapy and hematopoietic stem-cell infusion were performed at 12 de Octubre hospital (H12O). Second stage: in absence of significant clinical events patients were transferred to the referring center (NSPH and ILH) on day +1 for supportive care.

Results: Results:

- Population: 12 patients (4 female, 8 male). Median age: 58 years (23-71). Diagnosis: multiple myeloma (MM): 9, acute promyelocytic leukemia (APL): 1, follicular lymphoma: 2. Conditioning regimens: Melfalan 200 (75%), CyBU (8%), BEAM (17%) All patients received standard prophylaxis with acyclovir, fluconazole and cotrimoxazole. G-CSF was allowed from day +5.

- HSCT and engraftment: no patient needed an additional bridge therapy because of transplant delay. All 12 patients were transferred on day +1. Median time to neutrophil (> 0.5x10⁹/l) and platelets (> 20x10⁹/l) engraftment was 11 days (10-14) and 12 days (11-20) respectively. Secondary graft failure: 1/12 patients.

- Adverse events: Febrile neutropenia was observed in all patients with microbiological documentation in 42%. Documented pathogens: bloodstream infections due to Pseudomonas Aeruginosa, Enterobacter cloacae and Streptococcus gallolyticus. Urinary tract infection: Klebsiella pneumoniae. 1 infectious colitis caused by Campylobacter jejuni. Engraftment syndrome was observed in 2 patients (17%) and grade ≥ 3 mucositis in 6 patients (50%). 7 patients (58%) required parenteral nutrition.

- Results: 11 patients were successfully discharged. 1 patient died due to secondary graft failure. Follow up was provided as needed in the referring center. Patients were reviewed in H12O on day +100 and annually therafter.

Conclusions: The sharing transplant program is a feasible and safe network that eases the access of patients to this therapy avoiding delays and prolonged stays in reference centers, with the consequent psychological and social benefit for patients and their families. Outcome and adverse events were according to literature. This is a pilot study that aims to extend to other centers within the PETHEMA group.

Clinical Trial Registry: No applicable

Disclosure: Nothing to declare.

Experimental transplantation

P183 Impact of Gut Fungal Composition on Outcome after Allogeneic Hematopoietic Cell Transplantation

Florent Malard ¹, Aonghus Lavelle², Giorgia Battipaglia¹, Béatrice Gaugler², Rémy Dulery¹, Eolia Brissot¹, Tounes Ledraa¹, Razan Mohty¹, Harry Sokol², Mohamad Mohty¹

¹Hôpital Saint-Antoine, Paris, France, ²INSERM, UMR-S 938, Centre de Recherche Saint-Antoine, Paris, France

Background: Alterations of gut bacterial microbiota composition have been shown to impact outcome after allogeneic hematopoietic cell transplantation (alloHCT), including overall survival (OS), graft versus host disease (GVHD) and relapse incidence (RI). Furthermore, the role of eukaryotic gut virome in GVHD was recently shown (Legoff et al., Nature Medicine, 2017). In contrast, the impact of gut fungal microbiota is still unknown in the alloHCT setting. Earlier studies in patients with inflammatory bowel diseases or primary sclerosing cholangitis, suggested that gut fungal microbiota dysbiosis and composition contribute to disease severity.

Methods: With this background, we examined the role of fungal microbiota in patients undergoing alloHCT. Our goal was to attempt to correlate the fungal microbial shifts and changes with patients’ outcome. Fecal specimens were collected at day 0 of alloHCT (before graft infusion). The gut intestinal microbiota was characterized by 454 pyrosequencing of the ITS2 genes [ITS2 (sense) 5’-GTGARTCATCGAATCTTT-3′ and (antisense) 5′-GAT ATGCTTAAGTTCAGCGGGT-3′ and the optimized and standardized ITS2-amplicon-library preparation protocol (Metabiote, GenoScreen)]. Phylogeneic classification was obtained using the UNITE ITS database (version 12_11). Association of fungal microbiota with clinical predictors and outcomes were evaluated.

Results: In all, we analyzed 68 patients (34 males and 34 females). Median age was 60 (range, 22-74) years. Disease risk index was low-intermediate in 38 patients, high-very high in 27 patients (not assessed in 3 patients with aplastic anemia). 49 patients received a myeloablative reduced toxicity conditioning regimen, while 19 patients received a reduced intensity conditioning regimen. 16 patients received their graft from a matched sibling donor, 18 from a haploidentical donor, and 34 from an unrelated donor. 97% of patients received antithymocyte globulin as part of their conditioning regimen, and patients undergoing alloHCT from a haploidentical donor also received post-transplant cyclophosphamide.

Overall we found a low fungal diversity score of the fungal microbiota at day 0 in all patients from this cohort, with little variations. Therefore, it proved difficult to establish any statistically significant correlations between fungal diversity and patients’ outcome. Nevertheless, we observed a dominance by Candida albicans in alloHCT patients, and patients with higher number of Candida albicans at day 0 of alloHCT have a significantly lower overall survival and GVHD-free, relapse-free survival (p=0.026 and p=0.013 respectively. In multivariate Cox hazard analysis including the most important parameters associated with patients’ outcome, higher number of enterococcus, enterobacteria and Candida albicans was associated with a lower OS and GRFS, while bacteria belonging to the clostridiales were associated with a higher OS and GRFS.

Conclusions: In conclusion, we find an important disruption of gut fungal microbiota in patients undergoing alloHCT, as evidenced by the very low fungal diversity observed at day 0. Furthermore, increased numbers of Candida Albicans species at time of alloHCT were predictors of mortality and GVHD-free, relapse free survival, independently of clinical parameters and bacterial microbiota composition.

These results indicate that in addition to bacterial and viral microbiota, fungal microbiota is another important factor influencing outcome after alloHCT. Validation studies and exploration of the link between fungal and bacterial microbiota are warranted.

Disclosure: FM reports lecture honoraria from Therakos/Mallinckrodt, Janssen, Keocyte, Sanofi, JAZZ pharmaceutical and Astellas, all outside the submitted work. MM reports grants and lecture honoraria from Janssen, Sanofi, and JAZZ pharmaceutical, lecture honoraria from Celgene, Amgen, BMS, Takeda, and Pfizer, grants from Roche, all outside the submitted work.

The other authors declare. no competing financial interests.

P184 Monitoring Hematopoietic Cell Microparticles in Allografts and Transplant Recipients

Angeliki Xagorari, Michail Iskas, Christos Demosthenous, Dimitris Bougiouklis, Despoina Papadopoulou, Ioanna Sakellari, Achilles Anagnostopoulos, Damianos Sotiropoulos

G.Papanicolaou Hospital, Thessaloniki, Greece

Background: Peripheral blood microparticles (MPs) are released from plasma membrane of activated or apoptotic cells and carry cell surface markers of the mother cells. Platelet- and endothelial-derived MPs have been detected in a wide variety of clinical conditions as well as in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the role of MPs during and after allo-HSCT and their possible immunomodulatory effects is under investigation. The objective of this project was to study the role of MPs isolated from lymphocyte and stem cell populations of patients undergoing allo-HSCT.

Methods: Samples were collected from the grafts and the peripheral blood of 19 patients who underwent allo-HSCT in our department. Nine patients were diagnosed with acute myeloid leukemia (AML), 9 with acute lymphoblastic leukemia (ALL) and 1 with myelodysplastic syndrome (MDS). Informed consent was obtained from all patients. Eighteen patients received peripheral blood stem cell transplant from sibling donors and 1 from a matched unrelated donor (MUD). All patients were at complete remission before allo-HSCT. Conditioning regimen administered to 4 AML patients was myeloablative (BuCy), whereas 5 received reduced-intensity (RIC) regimens, ie Flu/Treo in 3, Flu/Bu in 2 and FluCy in 1 patient. Six ALL patients ie 1 received myeloablative condiotioning, received BuCY, 5 TBI/Cy, and 2 received RIC, ie Flu/MEL. The MDS patient received RIC conditioning, ie Flu/Treo. residual

MPs were isolated from plasma centrifugation and their number was determined by flow cytometry after incubation with Annexin V and CD34, CD3 or CD56. The number of MPs has been estimated in the graft as well as in the peripheral blood of the patients at days 0, 4 and 14 (day0, +4d, +14d) post allo-HSCT. Statistical analysis was performed using t-test, Pearson´s and Spearman´s depending on the normality of the distribution of variables.

Results: MPs were detected in the graft and in the peripheral blood of the recipients after allo-HSCT. MPs can also be detected in grafts. The number of total measured patient AnnV+ CD34+, CD56+, CD3+MPs on +14d was decreased compared to day0 and +4d. CD34+MPs of the graft were significantly associated with patient CD34+MPs on +14d after allo-HSCT (r=0.643, p=0.003). The median time to CD34+cell engraftment was 13 days after HSCT and was not correlated to patients and graft CD34+MPs. The number of CD3+MPs were low on days 0, 4 and 14 post-HSCT. The number of CD3+MPs on +4d was positively correlated to the CD3+MPs of the graft (r=0.579, p=0.009). Although CD3+MPs were not significantly associated to relapse, CD3+MPS were positively correlated with CD3+cell engraftment (r=0.622, p=0.008). CD56-derived MPs were positively correlated with CD3 cell engraftment (r=0.501, p=0.015). CD56+MPs on day 0 and those of the graft were positively correlated (r=0.517, p=0.23). CD34+, CD56+ and CD3+MPs were not significantly associated with chimerism on day 30 and 90.

Conclusions: Stem cell derived and T-lymphocyte and NK-derived MPs were detected in the graft and in patients undergoing allogeneic-HSCT. The number of MPs derived from T lymphocyte (CD3+MPs) and NK cells (CD56+MPs) were related to the T cell reconstitution. Therefore MPs may represent a valuable marker after allogeneic-HSCT

Disclosure: Nothing to declare.

Gene Therapy

P185 Ex-vivo Autologous Haematopoietic Stem Cell Gene Therapy in Mucopolysaccharidosis Type IIIA

Jane Kinsella ¹, Simon Jones², Heather Church³, Ceri Jones³, Stuart Ellison⁴, Claire Booth⁵, Karen Buckland⁵, Diego Leon Rico⁵, Brian Bigger⁴, Adrian J Thrasher⁵, Robert Wynn¹

¹Royal Manchester Children’s Hospital, MFT, Manchester, United Kingdom, ²Manchester Centre for Genomic Medicine, MFT, Manchester, United Kingdom, ³Manchester Centre for Genomic Medicine, MFT, Manchester, United Kingdom, ⁴University of Manchester, Manchester, United Kingdom, ⁵Great Ormond Street Institute of Child Health, University College, London, United Kingdom

Background: Mucopolysaccharidosis type IIIA (MPSIIIA) is progressive lysosomal storage disorder (LSD) caused by a mutation in the SGSH gene. A deficiency of the enzyme N-sulfoglucosamine sulfohydrolase prevents the degradation of heparan sulfate(HS), and substrate accumulation causes a predominantly neurological phenotype that result in early death. Allogeneic HSCT does not modify the disease phenotype even when performed early and with fully donor engraftment.

Preclinical data from our group has demonstrated correction of the disease phenotype with engraftment of gene-modified cells, with enzyme over-expression, including in the brain. Here we report the findings of a first-in-man, autologous, ex-vivo modified, haematopoietic stem cell gene therapy transplant for MPSIIIA from a first patient and discuss our open clinical trial for this disease.

Methods: A 2 years old patient underwent collection of autologous, mobilised, peripheral blood stem cell cells using G-CSF and plerixafor. The cells were transduced using a lentiviral vector incorporating the SGSH gene with the CD11b, myeloid specific promoter. The patient received myeloablative busulfan only conditioning and infusion of the cryopreserved gene modified stem cell product.

Results: The patient had neutrophil engraftment (ANC >0.5x10⁹/L) on day +16 and platelet engraftment (>20x10⁹/L) by day +39. The patient was discharged from hospital on day +33.

Enzyme analysis, substrate reduction and engraftment have been monitored following the transplant.

Enzyme levels are very significantly greater than normal in leucocytes, all leucocyte fractions and plasma and these supra-physiological enzyme levels are sustained. Substrate analysis shows reduction of HS to normal in urine (never achieved in allogeneic transplant) (Fig 1a), and plasma, and substantial reduction in CSF HS at an early time point. There is sustained, multilineage engraftment of gene-modified cells, and the incorporated VCN in engrafted cells in shown in Fig 1b.

Conclusions: We report the first patient to be treated with autologous ex-vivo haematopoietic stem cell transplant for MPSIIIA and demonstrates successful engraftment with sustained, supraphysiological high enzyme levels expressed with little toxicity. We report early neurodevelopmental data in this otherwise rapidly progressive, ultimately fatal neurological disease. A phase I/II trial of this approach is open and recruiting patients.

Disclosure: Nothing to diclare

Graft-versus-host disease – clinical

P186 Identification of Predictive Models Including Polymorphisms in Cytokines Genes Associated with Acute Graft versus Host Disease and overall Survival after Identical HLA-allogeneic Stem-cell Transplantation

Paula Muñiz ^1,2, Mi Kwon^1,2, Rebeca Bailén^1,2, Nieves Dorado^1,2, Laura Solán^1,2, Diego Carbonell^1,2, Julia Suárez-González^1,2, María Chicano^1,2, Cristina Andrés-Zayas^1,2, José María Bellón², Juan Carlos Triviño³, Javier Anguita^1,2, José Luis Díez-Martín^1,2,4, Carolina Martínez-Laperche^1,2, Ismael Buño^1,2,4

¹Gregorio Marañón General University Hospital, Madrid, Spain, ²Gregorio Marañón Health Research Institute (IiSGM), Madrid, Spain, ³Sistemas Genómicos, Valencia, Spain, ⁴Complutense University of Madrid, Madrid, Spain

Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for patients with hematologic malignances. However, 40% of patients develop post-transplantation complications such as acute graft versus host disease (aGVHD). Immune system genes like cytokines play a role in inflammatory process that occur during aGVHD. The aim of this study was to select polymorphisms in interleukins and chemokines genes to build models to predict the development of aGVHD and overall survival after allo-HSCT from an HLA-identical sibling donor.

Methods: We retrospectively selected 90 patients with hematological malignancies who received an allo-HSCT from an HLA-identical sibling donor from 2000 to 2015. At aGVHD analysis we did not include two patients due to early death. The genotyping was performed using an NGS panel (include 73 interleukins and 59 chemokines genes) in a HiSeq platform (Illumina, USA). The bioinformatics analysis was carried out with the GeneSystems software (Sistemas Genómicos, Spain). We analyzed variants located in coding regions, splicing sites, UTR, and 5´upstream and 3´downstream zones (+/- 200pb). The SNPs selected corresponding to non-synonymous variants, with read depth ≥30X in the canonical isoform with an allele frequency ≥0.4 and represented in at least 5% in our cohort. To compare the differences among groups we used fisher test for aGVHD and Kaplan-Meier for OS. Multiple logistic regression models were performed using combination of polymorphisms selected previously that could be applied to clinical practice to predict aGVHD. The models with the highest AUC value, sensitivity and specificity value and the lowest number of genetic variants used were selected. Statistical Package for the Social Sciences (SPSS, Chicago, USA) was used for statistical test.

Results: The cumulative incidence rates for aGVHD of grades II-IV and III-IV at 100 days after transplantation were 48.93% and 18.08%, respectively. And OS at 2 years was 60%. The clinical variables (age, gender, pathology, stem cell source and previous transplantation) were not correlated with aGVHD nor OS, except conditioning regimen that was significant at III-IV aGVHD (p= 0.041) and OS (p=0.034). Using filters defined previously, we detected 820 polymorphisms. Specifically, 14 SNPs were correlated with II-IV aGVHD, 13 SNPs with III-IV aGVHD and 47 SNPs with OS.

We developed multiple logistic regression models for II-IV, III-IV aGVHD and OS in interleukins and chemokines genes. According to predictive models, we classified patients at risk and low risk based on cut-point by ROC curve. Based on predictive scores the 80% of high-risk patients vs 12% of low-risk patients developed grades II-IV aGVHD and the 60% of high-risk patients vs 3% of low-risk patients developed grades III-IV aGVHD at 150 days after allo-HSCT. In the case of OS, the 7% of high-risk patients vs 94% of low-risk patients at five years after allo-HSCT were alive.

Conclusions: These predictive models allows the classification of patients at low and high risk of developing aGVHD, who could benefit from personalized management through immunosuppression and other drugs. However we must validated these polymorphisms in a prospective cohort and in others types of allo-HSCT.

Disclosure: The authors have nothing to disclose

P187 Search for Circulating Endothelial Cells of Donor Origin after Allo-HSCT: Potential Clinically Relevant Implications in the Context of graft-versus-host Disease

Camillo Almici ¹, Francesca Fontana², Giovanna Piovani³, Piera Balzarini³, Arabella Neva¹, Benedetto Bruno⁴, Cristina Skert³, Gianluca Rotta⁵, Simona Fisogni³, Rosanna Verardi¹, Andrea Bianchetti¹, Simona Braga¹, Michele Malagola³, Nicolò Manaresi², Fabio Facchetti³, Domenico Russo³, Mirella Marini¹

¹ASST Spedali Civili di Brescia, Brescia, Italy, ²Menarini Silicom Biosystems, Bologna, Italy, ³University of Brescia, Brescia, Italy, ⁴AOU Città della Salute e della Scienza, University of Torino, Torino, Italy, ⁵Becton Dickinson Biosciences, Milano, Italy

Background: We have confirmed that Circulating Endothelial Cell (CEC) count changes represent a valuable marker to monitor endothelial damage in patients undergoing allogeneic hematopoietic stem cell transplant (allo-HSCT) and hold the potential to enter clinical routine as a suitable tool to assist clinicians in GVHD diagnosis. At the same time, we have repeatedly documented that statistically significant higher CEC counts (P>0.003) are scored at engraftment in patients who will not manifest GVHD versus those who will develop GVHD (Transplantation 2014; Bone Marrow Transplantation 2017; Scientific Reports 2019). By considering the organ transplant setting, it has been recently reported that endothelial cells from the grafted organ, besides being a continuous source of alloantigens, can downregulate alloreactivity exerting tolerogenic responses. Therefore, by inference to the allo-HSCT field, the presence of donor CEC might result in a putative protective effect against GVHD presentation.

Methods: With the aim to test the hypothesis that at time of engraftment CEC present in peripheral blood (PB), besides coming from cells shedding from patient vasculature, could partly belong to donor, originating from the cellular graft, we conducted a two step study: 1) an exploratory set, and 2) a confirmatory set. In the exploratory set, we performed FISH analysis on flowcytometry-sorted CEC (CD45^neg/CD34^bright/CD146^pos, Lyotube #623920, BD Biosciences) (n=3) and on whole PB derived culture-expanded CEC (n=3) (EGM-2 BulletKit, Lonza), obtained at engraftment in sex-mismatched allo-HSCT. In the confirmatory set (n=15), single CEC were recovered from PB, at engraftment (T1) and at 90 days (T2) after allo-HSCT, through the DEPArray^TM technology (Menarini Silicon Biosystems), after preliminary bulk separation step carried out with the CellSearch^® System. Single recovered CEC was whole genome amplified (Ampli1™ WGA Kit) and short tandem repeat (STR) profile determined (Ampli 1^TM STR kit) on each single CEC. To confirm host/donor origin, single CEC STR profile was compared to that determined on patient and donor cells before allo-HSCT. Moreover, donor CEC presence was evaluated by CISH analysis on formaline fixed and paraffin-embedded biopsy sections obtained at least three months after sex mismatched allo-HSCT.

Results: By positive findings of the exploratory set, we proved, at the single cell level in the confirmatory set, the presence of donor CEC at engraftment (T1) in 4 out of 15 patients (see Table). Of them, 2 did not manifested GVHD, despite a GVHD risk score of 2, and the other 2 presented GVHD grade I. On the contrary, among the 10 patients in whom no donor CEC were detected, 6 experienced GVHD grade II-III, while 4 did not manifested GVHD, despite a 1-3 GVHD risk score.

Conclusions: Our results represent the proof of principle that D-CEC may flow in host PB early on from hematopoietic recovery and seldom persist thereafter at steady-state conditions. These puzzling findings will require in depth investigations with the aim to shed brighter light on tissue tolerance in the context of GVHD, opening up unexpected scenarios on the protective role potentially played by donor CEC.

Clinical Trial Registry: NCT04038827

Disclosure: Francesca Fontana and Nicolò Manaresi are employee of Menarini Silicom Biosystem; Gianluca Rotta is employee of Becton Dickinson Biosciences Italia.

P188 Double Lung Transplantation in Adults for Chronic Pulmonary Graft versus Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

Ram Vasudevan Nampoothiri ¹, Peter Riddell², Susan Chernenko², Matthew Binnie², Lianne Singer², Stephen Juvet², Jeffrey Howard Lipton¹

¹Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada, ²Toronto General Hospital, University of Toronto, Toronto, Canada

Background: Severe pulmonary chronic graft versus host disease (cGVHD) is a life-threatening complication that may occur following allogeneic hematopoietic stem cell transplantation (HSCT). Lung transplantation (LTx) is a potential therapeutic modality in this setting but evidence of tolerability and efficacy is restricted to case reports and small series. We aim to report our experience of double lung transplants in adults with severe pulmonary cGVHD after allogeneic HSCT.

Methods: We retrospectively reviewed all adult patients who underwent LTx for pulmonary cGVHD after allogeneic HSCT at our centre. Medical health care records were analysed for patient demographics, indication for allogeneic HSCT, induction and consolidation treatment received, HSCT details (including donor details, conditioning regimens, GVHD prophylaxis), post-HSCT complications (occurrence and severity of acute and chronic GVHD, pulmonary infections), details of LTx and post-transplant outcomes (including infections, acute rejection, chronic lung allograft rejection (CLAD)), survival after HSCT and after LTx. Survival outcomes were compared by Kaplan-Meier analysis.

Results: A total of 18 patients underwent bilateral LTx for chronic pulmonary GVHD between 2003 and 2019. The median(range) age at time of LTx was 38(19-55) years. Chronic myeloid leukemia (33%;n=6) was the most common indication for HSCT followed by Acute Lymphoblastic Leukemia (22.2%;n=4) and Acute Myeloid Leukemia (16.7%;n=3). Stem cell donors were matched related, matched unrelated, and haplo-identical in 80%, 13.3%, and 6.7% cases, respectively. All patients received myeloablative conditioning regimens with 84.6% (n=11) receiving total body irradiation at a median dose of 1200cGy. Acute GVHD of any grade was seen in 70% patients. Skin (66.7%) was the most common site of extra-pulmonary cGVHD followed by mouth (50%) and eyes (41.7%). Bronchiolitis obliterans (83.3%;n=15) was the most common pathological diagnosis of pulmonary cGVHD followed by pleuro-parenchymal fibro-elastosis (16.7%;n=3). The median(range) time to LTx following HSCT was 9.9 (1.2-19.2) years.

Post Lung transplant immunosuppressive therapy included a calcineurin-inhibitor (Cyclosporine or Tacrolimus), a cell-cycle inhibitor (Azathioprine or Mycophenolate) and Prednisone. In the first 2 years following LTx, four patients (22.2%) developed acute-cellular rejection, necessitating augmented immunosuppression (IV methylprednisolone in all patients plus Anti-Thymocyte globulin in 1 case). CLAD was observed in 44.4% patients (n=8), with the median time to developing CLAD being 5.1 years. After a median follow up of 31 months, 50%(n=9) patients died. Estimated survival at 5-years for patients undergoing LTx for pulmonary GVHD and LTx for other indications(during the same time period) were 48.1% and 59.4% respectively(p value-0.4). Sepsis (66%) was the most common cause of death followed by CLAD (33%). One patient suffered a relapse of their primary malignancy(CML) after lung transplant and is currently in remission.

Conclusions: Double lung transplant is a viable treatment modality for adults with severe pulmonary cGVHD after allogeneic HSCT with a satisfactory 5-year post lung transplant survival. When compared to lung transplants for other indications, there is a trend towards increased mortality associated with infection. Due to the rarity of this disease as a transplant indication, multicenter prospective studies are needed to accurately quantify the benefit of this approach, appropriate timing of lung transplant, and elucidate factors predicting favourable outcomes.

Disclosure: Nothing to declare.

P189 Reduced Inflammatory Tissue Infiltration during Intestinal steroid-refractory GVHD

Katarina Riesner ¹, Steffen Cordes², Maria Bartosova³, Martina Kalupa¹, Sarah Mertlitz¹, Lars Bullinger¹, Igor Wolfgang Blau¹, Claus Peter Schmitt³, Gernot Beutel⁴, Olaf Penack¹

¹Charité Universitätsmedizin Berlin, Berlin, Germany, ²Max Delbrück Center for Molecular Medicine, Berlin, Germany, ³University Hospital Heidelberg, Heidelberg, Germany, ⁴Hannover Medical School, Hannover, Germany

Background: Mortality in patients who fail initial steroid treatment (steroid-refractory GHVD; SR-GVHD) is very high because immunosuppressive treatments for SR-GVHD showed disappointing clinical results. SR-GVHD pathobiology is poorly understood and there were no experimental models of SR-GVHD, thereby hindering the development of novel therapeutic approaches. To shed light on SR-GVHD pathobiology we developed two murine SR-GVHD models and we analyzed intestinal patient biopsies from two independent alloSCT centres.

Methods: Murine models: To mimic SR-aGVHD, we used the chemotherapy based murine models 129→B6 (minor-mismatch) and B6→B6D2F1 (haploidentical) by administering i.p. 0.5 mg/kg/day dexamethasone upon clinical presentation of GVHD. Dexamethasone was used in mice instead of prednisolone due to practical reasons (longer lasting effects allowing once daily dosing). Intestinal tissues were harvested during non-treated GVHD versus SR-GVHD and were stained against CD4, CD8, CD11b and F4/80 as well as the endothelial marker CD31 and pericyte marker alpha smooth muscle actin (αSMA). Positive stained area in the intestinal mucosa was quantified by fluorescence microscopy and Image J.

Human data: Formalin fixed tissue sections from intestinal biopsies from independent patient cohorts with GVHD at diagnosis vs. SR-GVHD (Charité Berlin and Medical University Hannover) were stained against CD45, CD3 and Caspase 3. Cohort 1 included colon and duodenum biopsies from 6 and 5 patients at aGVHD onset vs. 6 and 5 patients during SR-GVHD, respectively. Cohort 2 included colon biopsies from 11 patients. In each of these patients two biopsies were taken: first at onset of aGVHD and second at diagnosis of SR-GVHD.

Results: In two independent clinical cohorts as well as in the experimental model we found considerably reduced inflammatory infiltration in intestinal biopsies in SR-GVHD compared with aGVHD at diagnosis (Fig 1). In mice, the predominant remaining cell populations in colon during SR-GVHD were CD4+ and CD8+ T cells, CD11b+ and F4/80+ myeloid cells; with significant lower levels of CD4+ and CD8+ T cells in SR-GVHD versus aGVHD without steroid treatment (Fig.1A-D). In patients, significant CD45+ leukocyte reduction (Fig.1F, G, H, I, J) was mainly mediated by significantly lower infiltration of CD3+ T cells (Fig.1K, L, M, N, O) in colon and duodenum biopsies during SR-GVHD vs. aGVHD at time of diagnosis. In H&E sections, we found massive tissue damage during SR-GVHD. Analyzing endothelial pathology in intestinal samples, we found endothelial damage as quantified by pericyte coverage (αSMA) reduction in colon vessels (CD31) was equally severe in SR-aGVHD and untreated aGVHD mice (Fig.1E). In line, Caspase 3 staining in patient intestinal biopsies demonstrated a high level of endothelial apoptosis during aGVHD both at diagnosis as well as during SR-GVHD (Fig.1P).

Conclusions: Our data indicates that despite severe tissue damage during SR-GVHD, the inflammatory activity in intestinal tissues is reduced after clinically unsuccessful steroid treatment. In the context of disappointing clinical results of SR-GVHD treatment by immunosuppressive agents, our current results provide a rationale for non-immunosuppressive therapies, e.g. tissue protection or regenerative approaches.

[Figure 1: Inflammatory infiltration and endothelial damage in experimental and human SR-aGVHD.]

Clinical Trial Registry: not applicable

Disclosure: Nothing to declare.

P190 Impact of Antithymocyte Globulin Dose for graft-versus-host Disease Prophylaxis in Stem Cell Tansplantation from Unrelated Donors

Sara Butera^1,2, Marco Cerrano¹, Lucia Brunello^1,2, Chiara Maria Dellacasa¹, Danilo Faraci^1,2, Sara Vassallo², Carolina Secreto^1,2, Nicola Mordini³, Roberto Sorasio³, Francesco Zallio⁴, Alessandro Busca¹, Benedetto Bruno^1,2, Luisa Giaccone ^1,2

¹AOU Città della Salute e della Scienza, University of Torino, Torino, Italy, ²University of Torino, Torino, Italy, ³AO Santi Croce e Carle, Cuneo, Italy, ⁴AO Santissimi Antonio e Biagio e Cesare Arrigo, Alessandria, Italy

Background: Despite the wide use of anti-thymocyte globulin (ATG) for GVHD prevention after allogeneic HCT convincing evidence about an optimal dose is lacking.

We assessed the impact of Thymoglobulin^® dose on main clinical outcomes in HCT from HLA-matched unrelated donors (MUD).

Methods: We report a retrospective analysis of 453 adult patients who received HCT for hematological malignancies at three Transplant Centers from January 2005 to December 2016. Primary endpoints included cumulative incidence of acute (aGVHD II-IV and III-V), and moderate/severe chronic GVHD, cumulative incidence of relapse (RI) and nonrelapse mortality (NRM). Secondary endpoints included Overall survival (OS), Event-free survival (EFS) and Refined GVHD/relapse-free survival (GRFS).

Results: Patients were divided into lower-ATG group (5mg/kg ATG, N= 213) and higher-ATG group (range 6-7.5 mg/kg ATG, N=240). Median age at transplant was 51 years, groups were balanced for major characteristics (EBMT risk score, disease type, female donor into male recipient, GVHD prophylaxis, graft source, active disease at transplantation) except for age (51.3 vs 50.7 years, p=0.035), higher proportion of HLA mismatched transplantations (56,7% vs. 31,6%, p< 0.001) and use of reduced intensity conditioning regimen (35% vs. 24,9% p=0.024) in the higher ATG group.

Median follow up was 83.7 months.

Cumulative incidence of grade II-IV aGVHD, grade III-IV aGvHD and moderate/severe cGVHD did not differ (6-month grade II-IV aGVHD 30.1% in the lower-ATG group vs 33.2% in the higher-ATG group, p=0.22; 6-month grade III-IV aGvHD 10.4% vs 12.5%, p=0.42; 3 years moderate-severe cGVHD 18,2% vs 21.8%, p=0.2; respectively) By multivariate analysis, HLA-mismatch regardless of ATG dose, significantly affected the cumulative incidence of II-IV aGVHD (HR 1.66, p=0.003) and III-IV aGVHD (HR 2.61, p=0.001). Conversely, only female donor into male recipient (HR 1.82, p=0.027) and reduced intensity conditioning (HR 0.54, p=0.021) affected moderate/severe cGVHD, while the risk was not significantly increased in patients with mismatched donors.

Likewise, cumulative incidence of relapse and NRM did not differ according to ATG dose (HR 1.03, p=0.8 and HR 1.29, p=0.18 respectively). By multivariate analysis, age and active disease had an impact on relapse incidence (HR 0.98, p=0.001 and HR 2.49, p< 0.001 respectively) and NRM (HR 1.03 p=0.001 and HR 1.52, p=0.03 respectively). Estimated median OS and RFS were 77.3 months and 20.8 months respectively though not different between groups (p=0.16 and p=0.17, respectively). By multivariate analysis, the only factors associated with OS were age (HR 1.01 p=0.041) and disease status at transplantation (HR 1.96, p< 0.001), while only the latter impacted on EFS (HR 2.2, p< 0.001). By univariate analysis, a trend for a higher probability of GRFS was observed in the lower-ATG group (2 years 47,5% vs 38,3% respectively, HR 1.2 p=0.069). (Figure 1). When adjusted by multivariate analysis, the only factor significantly associated with GRFS was disease status at transplantation (HR 1.84, p< 0.001)

Conclusions: In conclusion, in this analysis an ATG dose higher than 5mg/kg as GVHD prophylaxis showed no significant benefit in any of the outcomes analyzed, in particular it did not result in a significant improvement in GVHD control.

[Figure 1.]

Disclosure: Nothing to declare.

P191 Decreased Soluble HLA-e Levels in Patients after Allogeneic Stem Cell Transplantation are Associated with Severe Acute and Extended Chronic graft-versus-host Disease and Inferior overall Survival

Lambros Kordelas, Esther Schwich, Monika Lindemann, Falko M. Heinemann, Ulrike Buttkereit, Peter A. Horn, Dietrich W. Beelen, Vera Rebmann

University Hospital Essen, Essen, Germany

Background: HLA-E is a non-classical HLA molecule and by interaction with activating or inhibitory receptors of NK and T cells, HLA-E can lead to immune activation or suppression. Recently, the non-classical HLA molecules gained more attention in the setting of allogeneic hematopoietic stem cell transplantation (HSCT). Most studies so far have focused on the two most frequent genotypes (HLA-E*01:01, HLA-E*01:03) and investigated their potential association with clinical endpoints of HSCT, like graft-versus-host disease (GvHD), relapse, and overall survival (OS). However, these studies have produced inconsistent results. We therefore here investigate soluble HLA-E (sHLA-E) levels in patients following HSCT and relate this to clinical endpoints.

Methods: Plasma samples of 93 patients were procured 1, 2, 3, 4, 5, 6, 9 and 12 month(s) before and after transplantation. To capture sHLA-E the monoclonal antibody 3D12 (eBioscience, Frankfurt, Germany) was used. Recipients and donors were typed for HLA-E with a sequence-specific primer-PCR. Genomic DNA was isolated from buffy-coats using QIAamp® DNA Blood Mini Kit (QIAGEN GmbH, Hilden, Germany). HLA-E amplifications were performed in a Geneamp 9700 PCR thermal cycler (Applied Biosystems, Waltham, USA). Statistical analyses were performed by using SPSS 23.0 (SPSS Inc., Chicago, IL, USA) or GraphPad Prism V8.1.2 software (GraphPad Software, San Diego, CA, USA). Data are presented as mean ± standard error of mean (SEM). Continuous variables were compared by T-test, non-parametric Mann-Whitney test or two-way analysis of variance. For categorical data, 2-sided Fisher’s exact test was used.

Results: Patients with acute GvHD grade II-IV after HSCT displayed significantly (p=0.0004) reduced sHLA-E levels (mean +/-SEM) compared to patients with acute GvHD 0-I (Figure 1A). Similarly, sHLA-E levels were significantly (p=0.0007) diminished in patients with extended chronic GvHD compared to patients without or with limited chronic GvHD (Figure 1B). Furthermore, lower sHLA-E levels were significantly associated with mortality post HSCT (p=0.0056, Figure 1C). Using receiver operating characteristic analyses specific thresholds were identified being indicative for severe acute GvHD, extended chronic GvHD or inferior OS. We could not detect any association of the course of sHLA-E levels post HSCT with the three most frequent HLA-E genotypes (HLA-E*01:03/*01:03, HLA-E*01:01/*01:01, HLA-E*01:01/*01:03). However, there was an association of HLA-E*01:03 homozygosity with inferior 5-year-OS.

Conclusions: Our results indicate that clinical endpoints of HSCT like acute and chronic GvHD and OS have to be associated rather with sHLA-E than with HLA-E polymorphisms. These findings shed some light on the possible impact of reduced sHLA-E levels after HSCT on GvHD and OS. Thus, sHLA-E appears to be a novel promising candidate for the prediction of clinical HSCT outcome concerning extended cGvHD and OS.

[Figure 1]

Figure 1: Association of reduced sHLA-E levels with severe GvHD and inferior OS following HSCT. sHLA-E in patients with (A) aGvHD grade II-IV (red line) versus aGvHD grade 0-I (black line), (B) extended cGvHD (red line) versus no/limited cGvHD (black line) or (C) patients having died (red line) versus patients being alive (black line) during the follow-up time.

Disclosure: Nothing to declare.

P192 Effect of Extracorporeal Photopheresis on Production of Serum Soluble CD163: Relationship to Immunosuppression and Disease Activity in Chronic Graft Versus Host Disease

Nick C. Mattthews, Charlotte Burton, Arun Alfred

The Rotherham NHS Foundation Trust, Rotherham, United Kingdom

Background: Extracorporeal photopheresis (ECP) is a second line therapy for steroid refractory, dependent or intolerant chronic GVHD (cGVHD). In cGVHD, activated tissue macrophages contribute to fibrosis of the skin, lung and liver. CD163 is a scavenger receptor expressed by monocytes and macrophages, which is released as soluble CD163 (sCD163) following activation and is increased in the serum of patients with systemic scleroderma and pulmonary fibrosis (1). Plasma sCD163 is elevated in active cGVHD and de novo cGVHD patients compared to HSCT patients without cGVHD and healthy controls (2). We have previously shown in a pilot study that ECP reduced sCD163 levels in a subset of patients (3). Here, we have tested whether this holds in a larger sample and how sCD163 levels relate to immunosuppression and skin and liver disease activity.

Methods: Serum samples were collected from 72 cGVHD patients (39 male /33 female; age range: 25-74) and 17 age-matched healthy controls (10 male / 7 female) before ECP and at 3 month intervals up to 1 year. Patients had GVHD affecting skin (61/72), mucosal membranes (16/72), liver (14/72), joints (8/72), gut (17/72), eye (8/72), genital (4/72), and respiratory involvement (4/72). Serum sCD163 was assessed by ELISA (R&D Systems). Data were analysed using GraphPad Prism 6. Statistical tests performed include 2-tailed Mann-Whitney, Pearson’s correlation test, and 2-way ANOVA with repeat measures, as appropriate.

Results: Chronic GVHD patients had significantly elevated serum levels of sCD163 (P=0.0026; median of 723ng/ml, IQR 536-1101) compared to healthy controls (median of 466ng/ml, IQR 353-553). Stratification into sCD163 quartiles showed that ECP patients with an initial sCD163 level in the upper quartile (sCD163hi ; >1101 ng/ml) had significant reduction in sCD163 after 3 months of ECP (P< 0.05), but this was not sustained to the 6 month interval and remained substantially higher than in patients in the lower quartile (sCD163lo). Glucocorticoids and cyclosporine affect monocyte function, but there were no significant differences in prednisolone or cyclosporine dosages between the sCD163 quartiles at pre-ECP baseline or in the rate of steroid tapering. Where data were available, there was no significant relationship between Modified Rodnans skin scores and pre-ECP sCD163 levels. In measurements of liver inflammation, pre-ECP patients in the sCD163hi quartile had highly significantly increased levels of serum alanine amino-transferase (ALT) liver enzyme levels compared to sCD163lo patients (P< 0.0001), which was significantly reduced after 3 months of ECP (P< 0.003). Serum aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT), but not bilirubin, each had significant correlations with sCD163 (r=0.44: P< 0.0001, r=0.56;P< 0.0001and r=0.52;P< 0.0001 for ALT, AST and GGT, respectively), but only ALT and AST were reduced with ECP.

Conclusions: We confirm that sCD163 is significantly raised in a subset of cGVHD patients compared to healthy controls, which is reduced by ECP. Further, the data suggest that ECP therapy reduces hepatocellular injury as indicated by serum ALT and AST liver enzyme levels in sCD163hi patients.

Disclosure: NCM has received grant funding and attended advisory board for Mallinckrodt.CB has received grant funding from Mallinckrodt. AA has received speaker fees and grant funding from Mallinckrodt

P193 Post-transplant High-dose Cyclophosphamide Overcomes the Detrimental effect of a single-locus HLA Mismatched in Unrelated Donor Allogeneic Hematopoietic Stem Cell Transplantation

Alejandra Pedraza, Patricia Ferraz, Arturo Pereira, Ana Sofia Jorge, María Suárez-Lledó, Gonzalo Gutiérrez-García, Francesc Fernández-Avilés, Laura Rosinol, Teresa Solano, Noemí Llobet, Carla Ramos, Pedro Marín, Álvaro Urbano-Ispízua, Montserrat Rovira, Carmen Martinez

Hospital Clinic, Barcelona, Spain

Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) from mismatched unrelated donors (MMUD) at a single HLA locus -A, -B, -C, or -DR (7/8) are associated with worse survival outcomes compared to 8/8 matched unrelated (MUD). Despite that, 7/8 MMUD grafts remain a viable option for allo-HSCT, particularly in patients who lack suitable donors or in those with aggressive hematologic malignancies for whom the risks of disease progression due to delays in identifying optimal donors is offset in part by the benefits of earlier transplantation. We hypothesized that post-transplant high-dose cyclophosphamide (PTCy) could overcome the detrimental effect of a single-locus HLA MMUD.

Methods: We retrospectively analyzed 110 patients (median age 50y, range 42-62) who received 7/8 MMUD (n=56) or 8/8 MUD (n=54) allo-HSCT all of them with PTCy in our institution. Unrelated donor selection was performed according to standard criteria, including high resolution typing for alleles at HLA-A, -B, -Cw, DRB1 and DQB1.

Results: AML/ALL and MDS accounted for 66% of all diagnostics. Disease Risk Index (DRI) was low in 11%, intermediate in 47%, and high in 42%. Forty-nine percent of patients had a HCT-CI ≥3. All patients, except four received peripheral blood stem cells (PBSC). Conditioning regimens (most of them fludarabine plus busulfan or TBI) were myeloablative (MAC) in 50 patients (45%) and RIC in 60 (55%). GVHD prophylaxis consisted on PTCy 50mg/kg IV on days +3 and +4 followed by tacrolimus (n=99) or MMF (n=1) or tacrolimus plus MMF (n=10). All but one patient engrafted; the median time to neutrophil (>500/mL) and platelet (>20,000/mL) recovery was 19 days (IQR 16-22) and 14 days (IQR: 12-22), respectively. Eight patients (7%) developed an invasive pulmonary Aspergillosis, 25 (22%) had severe bacterial infection, 57 (52%) CMV reactivation, 10 (9%) cytomegalic disease and one EBV reactivation. The CI of 1-year TRM, 100-days acute grade II-IV, 100-days grade III-IV GHVD, and 1-year moderate-severe chronic GHVD were 14%, 12%, 5%, and 13%, respectively. The CI of 1 and 2-year relapse rate was 20% and 23%. After a median follow-up of 1 year (0.05-6.4), 5-year OS and DFS were 60% and 58%. 5-year survival free of relapse and free of moderate-severe chronic-GVHD was 48%. Patient’s age >50 years was associated to worse OS (HR 3.3, p=0.009), PFS (HR 2.2, p=0.03), and NRM (HR 3.5, p=0.05). Other variables such as HCT-CI (< vs. >3), DRI (low vs. intermediate vs. high), conditioning type (MAC vs. RIC), 1 vs. 2 immunosuppressors, and HLA matching (7/8 vs. 8/8) had not impact on post-transplant outcomes.

Conclusions: PTCy after unrelated PBSC allo-HCT results in low incidence of acute and chronic GVHD with no differences between 7/8 MMUD and 8/8 MUD in survival outcomes. An immunosuppressive schema of intermediate intensity such as PTCy followed by single-agent tacrolimus provide an adequate GVHD prophylaxis in both MMUD and MUD transplants. HLA 7/8 MMUD transplantation using this strategy is a suitable alternative to MUD.

Disclosure: Nothing to declare.

P194 Allogeneic Peripheral Blood Transplantation with post-transplant Cyclophosphamide and Sirolimus from Haploidentical and Matched Donors: “sir-PTCY” Results in 249 Patients

Raffaella Greco, Serena Albanese, Francesca Lorentino, Maria Teresa Lupo Stanghellini, Fabio Giglio, Simona Piemontese, Magda Marcatti, Daniela Clerici, Lorenzo Lazzari, Rosamaria Nitti, Carmine Liberatore, Sara Mastaglio, Andrea Assanelli, Luca Vago, Chiara Bonini, Consuelo Corti, Massimo Bernardi, Fabio Ciceri, Jacopo Peccatori

IRCCS San Raffaele Scientific Institute, Milano, Italy

Background: Post transplant cyclophosphamide (PT/Cy) has recently emerged as a very promising GVHD prophylaxis in the setting of allogeneic HSCT from haploidentical donors, and more recently in matched donor transplants. Herein, we compare long-term outcomes of allogeneic HSCT using GVHD prophylaxis with PT/Cy and sirolimus (“Sir-PTCy”), from haploidentical and matched related and unrelated donors.

Methods: Between 2013 and 2017, a total of 249 adult patients received either HLA-matched related (MRD), HLA-matched unrelated (MUD) or haploidentical donors for high-risk haematological malignancies in our center. According to Institutional algorithm, patients were assigned to haploidentical source if not available a matched donor > 9/10 in the due time for planned HSCT. Conditioning regimen was based on treosulfan and fludarabine; 86% received an intensified conditioning with the addition a 2nd alkylating agent (melphalan or thiotepa). Patients received unmanipulated PBSCs. Patients received PT/Cy on days 3 and 4, and sirolimus from day 5; mycophenolate mofetil (MMF) was added from day 5 to day 30, in MUD and haploidentical donors. All patients were treated according to current institutional programs upon written informed consent for transplant procedures and use of medical records for research.

Results: In the haploidentical donor group (n=151), we documented a cumulative incidence of grades II-IV and III-IV acute GVHD at 100 days of 35% and 20%, and a cumulative incidence of chronic GVHD of 42% at 3 years. The cumulative incidence of relapse and non-relapse mortality (NRM) was 35% and 27% at 3 years, respectively. The 3-year overall survival (OS) was 44%, while progression-free survival (PFS) was 38%; the composite end-point of GVHD/relapse-free survival (GRFS) was 24% at 3-years.

In the HLA-matched donor group (MRD, n=48, MUD, n=50), the cumulative incidence of grades II-IV and III-IV acute GVHD at 100-days was 23% and 9%, respectively. The cumulative incidence of chronic GVHD was 25% at 2 years. The cumulative incidences of relapse and NRM were 31% and 9% at 2 years, respectively. The 2-year OS was 72% and PFS 60%; GRFS was 52% at 2-years.

Comparing by multivariate analysis the main transplant outcomes across the different donor groups under study, we observed a higher risk of severe acute GVHD and chronic GVHD in the haploidentical setting. Moreover, haploidentical HSCT performs worse in terms of NRM, OS, PFS and GRFS at 2 years. However, more patients in the haploidentical group presented high/very high disease risk index (DRI; Armand et al), higher HCT-comorbidity index and more time elapsed from diagnosis to transplant. In patients presenting a low-intermediate DRI transplant outcomes were superimposable among the three donor groups. In this subgroup of patients GRFS at 2 years was 53% in MRD, 65% in MUD and 46% in haploidentical HSCT (p=0.33), respectively.

Conclusions: Sirolimus-PT/Cy platform is safe and offers a valid alternative to CNI-based GVHD prophylaxis for all donor, deserving further investigations and a formal prospective comparison with the other GVHD prophylaxis strategies currently in use. This strategy provide low mortality and superimposable severe GVHD in patients presenting a low-intermediate DRI, translating in a relevant long-term survival.

Clinical Trial Registry: NA

Disclosure: None

P195 A New Hope in the Treatment of steroid-refractory Graft Versus Host Disease (Sr-GVHD) after Allogeneic Hematopoetic Stem Cell Transplantation (AHSCT): Ruxolitinib

Osman Ilhan ¹, Guldane Cengiz Seval¹, Sinem Civriz Bozdag¹, Burak Deveci², Mustafa Pehlivan³, Leylagul Kaynar⁴, Irfan Yavasoglu⁵, Huseyin Bekoz⁶, Ipek Yonal Hindilerden⁷, Zeynep Arzu Yegin⁸, Simten Dagdas⁹, Ayse Avsar¹⁰, Atilla Hasan Ozkan¹¹, Tulin Firat Tuglular¹², Hakan Goker¹⁰, Zafer Golbas¹³

¹Ankara University, Ankara, Turkey, ²Antalya Medstar Hospital, Antalya, Turkey, ³Gaziantep University, Gaziantep, Turkey, ⁴Erciyes University, Kayseri, Turkey, ⁵Adnan Menderes University, Aydin, Turkey, ⁶Medipol University, Istanbul, Turkey, ⁷Istanbul University, Istanbul, Turkey, ⁸Gazi University, Ankara, Turkey, ⁹Bilkent City Hospital, Ankara, Turkey, ¹⁰Hacettepe Univesity, Ankara, Turkey, ¹¹Yeditepe University, Istanbul, Turkey, ¹²Marmara University, Istanbul, Turkey, ¹³Anadolu Medical Center Hospital, Kocaeli, Turkey

Background: Steroid refractory graft versus host disease(SR-GVHD) remains a clinical challenge and significantly contributes to nonrelapse morbidity and mortality after allogeneic hematopoetic stem cell transplantation(AHSCT). Recently, retrospective studies have reported that ruxolitinib, appears to be safe and effective in the both acute and chronic SR-GVHD, with upward of 80% of patients responding. Herein, we share a real-life experience using ruxolitinib in the treatment of SR-GVHD.

Methods: This multicenter retrospective study conducted in 13 different stem cell transplant centers included 77 adult patients diagnosed with acute or chronic SR-GVHD. We treated off-label these patients from June 2016 to November 2019 with ruxolitinib with a dose of 5 or 10 mg P.O. twice daily, depending on the hematological parameters. The physicians of the patients classified organ sites affected; acute GVHD(aGVHD) and chronic GVHD(cGVHD) grading before starting ruxolitinib according to Glucksberg staging system and the National Institues of Health(NIH) 2014 criteria. Steroid refractory chronic GVHD was defined as any disease that failed to respond to previous immunosuppressive therapy with steroids at least 4 weeks or inability to taper it w/wo additional immunosuppressive drugs.

Results: The baseline characteristics of the patients are listed in Table 1. Ruxolitinib was initiated for SR-aGVHD in 25 patients, whereas 52 patients received ruxolitinib for cGVHD. Patient characteristics are outlined in Table 1. Among patients treated for aGVHD; 4 patients(16%) had refractory skin GVHD, 2 patients(8%) had refractory gastrointestinal(GI) GVHD and remaining 19 patients(76%) had multisite refractory disease, involving the skin, GI tract and liver. A median of three(range; 1-6) prior therapies, including steroid administration, were administered before ruxolitinib. On initiation, 13 patients(52%) had grade II, 3 patients(12%) had grade III and 9 patients(36%) had grade IV GVHD. At day 28 after ruxolitinib initiation, 84% (21/25) of patients with aGVHD achieved CR or PR(CR, 15 patients; PR, 6 patients). Four non-responders (SD, 1 patients; PD, 3 patients) had grade IV GVHD at initiation of therapy.

As expected mouth(55.8%) and skin(78.8%) were the most frequently involved organs and 53.8 %(28/52) of patients showed evidence of cGVHD in more than two organs. A median of four prior treatment(range, 1-8) was administered before ruxolitinib. By 28days, 80.7% of patients(42/52) demonstrated evidence of response to therapy with 19(20.5%) patients in CR and 23(44.2%) patients experiencing improvement in at least one organ system. Three patients had stable disease under the ruxolitinib treatment and still continue receiving. Analysis by organ domain showed the best overall response in the GI tract 86.4%(19/22), lung 80%(12/15), skin 73.8%(31/42), and liver 72.7%(16/22). The four out of seven nonresponders had severe sclerodermatous skin GVHD. Ruxolitinib appeared to be well tolerated, and SR-cGVHD patients remained on therapy for median four months.

Conclusions: This retrospective, multicenter study of a limited patient number, treated with ruxolitinib due to SR GVHD, highlights the excellent results with good tolerance and minimal adverse effects, even in difficult cases such as lower GI tract involvement and lung disease. Further prospective studies would be appropriate to confirm our observations and to better define patients who would benefit from ruxolitinib treatment.

Disclosure: Nothing to declare.

P196

Abstract already published.

P197 Evaluation of the Prognostic Value of Histologic Assessment of Acute graft-versus-host-disease of the Upper Gastrointestinal Tract According to Lerner Early after Allogeneic Hematopoietic Cell Transplantation

Abed Alahad Sarraf ¹, Renate Schmelz¹, Henning Baldauf², Daniela Aust¹, Friedrich Stölzel^1,2, Jan Moritz Middeke¹, Katja Sockel¹, Raphael Teipel¹, Stefan Brückner¹, Marco Berning¹, Sebastian Zeissig¹, Jana Babatz¹, Christian Kirsch¹, Gustavo Baretton^1,3, Martin Bornhäuser^1,3, Jochen Hampe¹, Johannes Schetelig^1,2

¹University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany, ²DKMS Clinical Trials Unit, Dresden, Germany, ³National Center for Tumor Diseases (NCT), Dresden, Germany

Background: Acute graft-versus-host-disease (aGvHD) is a major cause of morbidity and mortality following allogeneic hematopoietic cell transplantation (alloHCT). Early after alloHCT, patients with persistent nausea, vomiting or anorexia represent a clinical challenge. Therefore, we set out to study the association between upper gastrointestinal tract (GIT) symptoms early after alloHCT, histological grade according to Lerner, overall clinical grade of aGvHD and mortality.

Methods: We performed a retrospective study on 174 patients, who received alloHCT between January 2007 and June 2018, presented with symptoms of aGvHD of the upper GIT within the first 42 days after alloHCT and underwent endoscopic examination.

Results: Indications for alloHCT were AML/MDS (66%, N=115), ALL (11%, N=19), Lymphoma/Myeloma (11%, N=20) and other diagnoses for the remaining 11% (N=20). The median age of patients was 56 years. Donors were HLA-identical siblings (15%, N=26), haploidentical relatives (6%, N=11), HLA-compatible (8/8) unrelated donors (57%, N=100), and partially matched (9/10) unrelated donors (21%, N=37). Conditioning regimens were myeloablative (36%, N=63), reduced-intensity (57%, N=99) or non-myeloablative (7%, N=12). GVHD-prophylaxis included a calcineurin-inhibitor for 94% (N=164) and ATG for 36% (N=63) of patients.

Abnormal macroscopic findings were reported for 86% of patients. Edema/erythema were seen in 59%, erosions/ulcers in 22% and an accompanying esophagitis in 23% of patients, respectively. Overall, histologic findings resulted in the pathological diagnosis of upper GIT aGvHD in 51% of patients. 43% of patients showed Lerner grade I, 4% grade II and 4% grade III-IV mucosal changes. The highest Lerner grade was found in biopsies taken from the duodenum in 82%, from the antrum in 41% and from the gastric corpus in 20% of patients.

Severity of overall aGvHD was rated grade II in 33%, III in 12% and IV in 13% of patients (N=100). Assessment of symptoms, macroscopic findings and histology resulted in subsequent systemic treatment in 91 patients (52%). Endoscopic and histologic evaluation resulted in a diagnosis other than aGvHD in 6 patients (3%): CMV infection (N=3), concomitant CMV/Giardia lamblia infection (N=1), esophageal stenosis (N=1) and suspected mycophenolate-induced gastropathy (N=1).

Eleven out of 14 patients who showed Lerner grade ≥II in the upper GIT had an overall severity of aGvHD grade III-IV. Hence, histological grade and the maximum overall grade of aGvHD correlated tightly (p < 0.001). The 1-year cumulative incidences of non-relapse mortality (NRM) of patients with upper GIT aGvHD Lerner grade I versus II-IV were 20% and 36%, respectively (Gray-Test, p=0.3). NRM was not statistically different for patients with aGvHD Lerner grade I versus 0. In landmark analyses from day +100, the 1-year NRM and relapse of patients with aGvHD overall clinical grade 0-I, II, and III-IV was 9%, 12% and 37% (Gray-Test, p=0.02) and 11%, 16% and 13% (Gray-Test, p=0.9), respectively.

Conclusions: Histologic grade of upper GIT aGvHD and overall clinical grade are tightly correlated. Histologic findings Lerner grade I in the upper GIT, themselves, were not associated with an increased risk of NRM. In contrast, Lerner grades >I in biopsies taken from the upper GIT often indicated life-threatening aGvHD.

Disclosure: Nothing to declare.

P198 Cyclosporine a Alone versus Mycophenolate Mofetil Plus Cyclosporine a Based GVHD Prophylaxis For Patients With AML undergoing Mud Transplantation. A Study from the ALWP

Annalisa Paviglianiti ¹, Myriam Labopin^1,2, Didier Blaise³, Gerard Socie⁴, Claude Eric Bulabois⁵, Bruno Lioure⁶, Nathalie Fegueux⁷, Arnim Gerbitz⁸, Gaelle Guillerm⁹, Johan Maertens¹⁰, Patrice Chevallier¹¹, Anne Huynh¹², Pascal Turlure¹³, Eric Deconinck¹⁴, Edouard Forcade¹⁵, Arnon Nagler^2,16, Mohamad Mohty^1,2,17

¹Hopital Saint Antoine, Paris, France, ²Acute Leukemia Working Party Office, Paris, France, ³Paoli-Calmettes Institute, INSERM CBT1409, Marseille, France, ⁴Hopital Saint Louis, Paris, France, ⁵Grenoble Alpes University Hospital, Grenoble, France, ⁶Nouvel Hopital Civil, Strasburg, France, ⁷CHU Lapeyronie, Montpellier, France, ⁸, Campus Virchow Klinikum, Berlin, Germany, ⁹Service Onco-Hematologie, Brest, France, ¹⁰University Hospital Gasthuisberg, Leuven, Belgium, ¹¹CHU Nantes, Nantes, France, ¹²Institut Universitaire du Cancer Toulouse, Toulouse, France, ¹³Limoges University Hospital, Limoges, France, ¹⁴Service d’Hématologie Besancon, Besancon, France, ¹⁵Service d’Hematologie et Thérapie Cellulaire, Bordeaux, France, ¹⁶Chaim Sheba Medical Center Tel-Hashomer, Tel-Aviv University, Tel Aviv, Israel, ¹⁷INSERM UMR 938, Sorbonne University, Paris, France

Background: Acute GVHD (aGVHD) remains an issue after allogeneic transplantation from matched unrelated donors (MUD). Since the introduction of mycophenolate mofetil (MMF) for GVHD prophylaxis, the association of Cyclosporine A (CsA) and MMF has rapidly increased in the setting of reduced intensity conditioning (RIC). Nevertheless, the use of CsA alone or in combination with MMF has not yet been reported in a large cohort of patients.

Methods: We retrospectively investigated the outcomes of 497 adult patients with AML in complete remission (CR) undergoing a MUD transplantation between 2007-2017 and receiving CsA+MMF or CsA alone as GvHD prophylaxis who were registered with the ALWP of the EBMT.

Results: GVHD prophylaxis consisted in CsA alone (n=183) or CsA+MMF (n=314). All patients underwent a RIC regimen with fludarabine 30mg/m² from day -6 to day -2 and busulfan 130mg/m² from day -5 to day -4 and received anti-thymocyte globulin as part of the conditioning. The median age at transplant was similar (59 and 60 years in the CsA and CsA+MMF group, respectively). The median follow-up was not significantly different between the two groups (CsA: 33 vs CsA+MMF: 34 months). Disease status at transplant was first complete remission (CR1) for 81% in CsA group and 86% in CsA+MMF group (p=NS). Peripheral blood stem cells (PBSC) was the graft source in 93% of patients receiving CsA alone and in 96% of patients who received CsA+MMF (p=0.17). All but 2 patients engrafted. The 100 day cumulative incidence (CI) of grade II-IV and grade III-IV acute GvHD were 30% and 10%, respectively. The 2-year CI of chronic GvHD was 35% (CI of extensive cGvHD was 15%). The 2-year CI of non-relapse mortality (NRM) and relapse were 19% and 25%, respectively. Disease recurrence (n=31), GvHD (n=20) and infection (n=17) were the most common causes of death in the CsA group. Relapse (n=53), GvHD (n=28) and infection (n=28) were the most frequent causes of death in the CsA+MMF group. The 2-year GVHD-free relapse-free survival (GRFS), leukemia- free survival (LFS), and overall survival (OS) were 45%, 56% and 60%, respectively. In multivariate analysis (MVA), no statistically significant differences were found among the two groups with respect to relapse, NRM, LFS, OS, acute and chronic GvHD. A positive cytomegalovirus serology of the donor was associated with higher NRM [HR=2.03, p< 0.001] and higher cGvHD [HR=1.44, p=0.03] and a lower OS [HR 1.66, p< 0.001], LFS [HR=1.69, p=0.001] and GRFS [HR=1.75, p< 0.001].

No differences were detected between the two groups for relapse, NRM, LFS, OS, or aGvHD when conducting a subgroup analysis in patients who received PBSC in CR1. Patients who received CsA alone tended to have a higher cGvHD (p=0.05). However, this finding was not statistically significant in MVA.

Conclusions: We observed comparable outcomes for patients with AML in CR1 who underwent MUD transplantation and RIC with CsA+MMF or CsA alone as GvHD prophylaxis. This suggests that both strategies may be considered valid approaches. Prospective randomized trials are needed to assess which patients could benefit from the addition of MMF as GvHD prophylaxis

Disclosure: No conflict of interests

P199 Transplant-associated Thrombotic Microangiopathy is Independently associated with Ruxolitinib Administration in Patients with graft-versus-host-disease

Eleni Gavriilaki, Ioanna Sakellari, Zoi Bousiou, Thomas Chatzikonstantinou, Despina Mallouri, Marianna Masmanidou, Anna Vardi, Eudoxia-Evangelia Koravou, Foteini Kika, Tasoula Touloumenidou, Apostolia Papalexandri, Evangelia Yannaki, Ioannis Batsis, Achilles Anagnostopoulos

G. Papanicolaou Hospital, Thessaloniki, Greece

Background: Recent data suggest that several novel biologic agents, such as imatinib, are associated with an increased risk of thrombotic microangiopathy (TMA). However, little is known about ruxolitinib, a JAK2 inhibitor. Given the latest approval of ruxolitinib administration in graft-versus-host-disease (GVHD), we aimed to investigate factors and outcomes associated with transplant-associated TMA (TA-TMA) in patients with GVHD.

Methods: We enrolled consecutive allogeneic hematopoietic cell transplantation (alloHCT) recipients followed-up for treatment of extensive overlap or chronic GVHD at our JACIE-accredited Unit (01/2016-06/2019). Ruxolitinib has been administered off-label in these patients since 2016. Patient data including details of transplantation procedure (donor, disease phase and type, conditioning, age, CD34+ cells infused), disease status, acute and chronic GVHD occurrence and treatment, Cytomegalovirus (CMV) or Epstein-Barr reactivation (EBV), disease-free (DFS) and overall survival (OS) were extracted from our prospectively acquired database. Charts from patients with TA-TMA were re-reviewed to identify diagnostic and therapeutic features. TA-TMA was diagnosed according to the International Working Group Criteria and treated according to our previously published protocol.

Results: Among 160 GVHD patients, 18 (11%) were diagnosed with TA-TMA. TA-TMA developed at a median of 150 post-transplant day (range 98-3013 days). Median ADAMTS13 activity was 62% (range 38-112%). Patients with TA-TMA had previously received GVHD treatment with: steroids (18/18), mycophenolate mofetil or cyclosporine inhibitor (18/18), extracorporeal photopheresis (ECP, 12/18), ruxolitinib (7/18), ibrutinib (2/18), and antithymocyte globulin (ATG, 3/18). TA-TMA management included: steroids (18/18), cyclosporine inhibitor cessation when applicable (9/18), plasma infusions (2/18), plasma exchange (8/18), and eculizumab (5/18).

Among studied pre- and post-transplant factors, diagnosis of TA-TMA was associated only with ruxolitinib administration (p< 0.001). With a follow-up of 38.4 months (4.6-83.9) in surviving patients, 5-year DFS was 48.4% and OS 52.9%. OS was independently predicted by TA-TMA (p=0.001), severe (grade 3-4) acute GVHD (p=0.002) and CD34+ cells infused (p=0.002). Ruxolitinib was not associated with survival rates in the whole population or in TA-TMA patients.

Conclusions: Our real-world data in a large cohort of GVHD patients suggest for the first time that ruxolitinib is associated with TA-TMA. Given the confounding comorbidities in these patients, increased awareness is needed by treating physicians to identify TA-TMA. Further studies are warranted to confirm these findings and unravel possible pathogenetic mechanisms.

Disclosure: Nothing to declare.

P200 Diagnostic Significance of Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) in Acute Intestinal graft-versus-host Disease (GVHD)

Georg Evers, Wolfgang Roll, Joern Christian Albring, Christian Reicherts, Rebecca Strotmann, Georg Lenz, Michael Schaefers, Matthias Stelljes

University Hospital Muenster, Muenster, Germany

Background: Allogeneic stem cell transplantation (alloSCT) is considered a potentially curative treatment for many refractory and high-risk hematologic malignancies that would otherwise be fatal, even with most of the current conventional therapies. Following alloSCT intestinal GvHD is a frequent complication, associated with a significant morbidity and mortality. Previously, we have shown, that FDG-PET can be used for diagnostic purposes and might have a prognostic value for patients suffering from intestinal GvHD. The objective of this retrospective study was to further elucidate diagnostic and prognostic value of FDG-PET in patients with intestinal GvHD.

Methods: Between 06/2011 and 02/2019, 101 patients with suspected acute intestinal GvHD underwent FDG-PET examination. Complete clinical and FDG-PET data sets were reviewed for presence of intestinal inflammation. 74 of the 101 patients had a clinically and/or histologically proven intestinal GvHD and signs of inflammation in FDG-PET. These patients were analyzed in detail regarding the response to GvHD therapy and survival. Different quantitative PET parameters, as well as clinical data, were compared between patients with fast and slow / no response to immunosuppressive treatment.

Results: For patients with suspected intestinal GvHD, sensitivity and specificity of FDG-PET for detection of intestinal GvHD was 92.8% (95% CI: 84.9 - 97.3) and 72.2% (95% CI: 46.5 - 90.3), respectively. Patients with subsequent rapid relief of GvHD symptoms had significantly higher standard uptake values for SUVmax (mean 13.5, 95% CI: 10.7 - 16.4) and SUV peak levels (mean 9.2, 95% CI: 7.3 - 11.1) compared to patients with slow or no response to immunosuppressive therapy (mean SUVmax: 7.7; 95% CI: 7.0 - 8.4; mean SUVpeak: 5.4, 95% CI: 4.9 - 5.8; p .005). Since immunosuppressive therapy with corticosteroids had already been initiated in 52 of 74 patients at the time of PET-CT examination, SUVmax/SUVpeak as prognostic parameters did not show significant influence on overall survival. However, overall survival at 12 month in patients with fast response to immunosuppressive therapy was significantly better than in patients with slow response (fast response: 66.7%; 95% CI: 44.5 - 88.9; slow/non-response: 33.2 %; 95% CI: 20.4 - 46.0; p .005).

Conclusions: This retrospective analysis indicates diagnostic value of FDG-PET in intestinal GvHD. Of further interest, our results suggest potential significance of FDG-PET in predicting treatment response following immunosuppressive therapy. Before implementation into clinical guidance of GvHD treatment and to strengthen these findings, prospective clinical trials are needed.

Disclosure: Nothing to declare.

P201 Long term Outcomes of Ruxolitinib Therapy in steroid-refractory graft-versus-host Disease in Children and Adults

Tatiana Bykova, Ivan Moiseev, Elena Morozova, Elena Darskaya, Olesya Paina, Anna Smirnova, Anna Dotcenko, Evgenia Borzenkova, Alexander Galimov, Yana Gudognikova, Kirill Ekushev, Polina Kozhokar, Anna Osipova, Olga Pirogova, Tatiana Rudakova, Olesya Shakeeva, Nikolay Tcvetkov, Egor Kulagin, Ludmila Zubarovskaya, Boris Afanasyev

Pavlov First State Medical University of St. Petersburg, Saint-Petersburg, Russian Federation

Background: Steroid-refractory graft-versus-host disease (srGVHD) is still one of the major causes of mortality after allogeneic stem cell transplantation (allo-HSCT). We conducted a prospective study of efficacy of ruxolitinib in both acute and chronic srGVHD in children and adults underwent allo-HSCT.

Methods: The study included 75 patients with srGVHD (32 acute, 43 chronic, 41 adults and 34 children). Indications for allo-HSCT were AML - 29%, ALL - 24%, MPD - 19%, LPD - 10%, non-malignant disorders - 18%. Severity of acute srGVHD was II gr. - 11 pts., III gr. - 10 pts., IV gr. - 11 pts. Skin was involved in 91%, gastrointestinal tract (GL) in 56% and liver in 37%. Among patients with chronic GVHD 14% had moderate disease and 86% - severe disease. Most commonly skin (91%), mouth mucosa (81%), GI (56%), liver (51%) and eyes (74%) were involved. Lung involvement was observed in 40% of patients with 13% of moderate and severe cases. Among patients with clinically significant chronic skin GVHD 39% had scleroderma.

Results: Median follow up was 28 months, range 23- 47 months. In patients with acute srGVHD overall response rate (ORR) was 75% (95%CI 57-89%), including 63% of patients with complete response (CR) cases (95%CI 44-79%) and 13% with partial response (PR) (95%CI 4-29%). Median time to PR in patients with acute GVHD was 20 days (range 1-112). Median time to CR was 53 days (range 9-255). Patients with grade III-IV GVHD (p=0.0292) and patients with grade IV gastrointestinal GVHD (p=0.0033) had significantly reduced ORR. Patients with chronic srGHVD had ORR of 81% (95%CI 67-92%), including 21% of CR (95%CI 10-36%) and 60% of PR (95%CI 44-75%). Median time to PR was 71 days (range 18-783) and median time to CR was 425 (27-635 days). Initial severity of organ involvement was not predictive for response except for lung GVHD severity (p= 0.0023). No differences in response was observed in adults and children (aGVHD - p=0.31, chGVHD - p=0.35). Hematological toxicity was the most common adverse event (Hb< 80/transfusion dependence - 86%/85%, thrombocytopenia 4 gr.- 77%/15%, neutropenia 4 gr.- 53%/5% in aGVHD and chGVHD respectively). After ruxolitinib initiation 59% had either persistence or de novo CMV reactivation. Seventy four percent received additional antibiotic treatment, 62% additional systemic antiviral treatment and 32% additional antifungal treatment. OS in acute GVHD group was 59% (95%CI 49-74%). OS In chronic GVHD group was 85% (95%CI 70-93%). The major factor predicting survival in acute GVHD group was grade III-IV GI involvement (29% vs 93%, p=0.0001). Neither overall severity of chronic GVHD, nor organ involvement, nor the age of patients were predictive for overall survival. No differences in survival was observed between adults and children (65% vs 53%, p=0.44).

Conclusions: The study demonstrated the high efficacy of ruxolinib for srGVHD in both adults and children with an acceptable toxicity profile.

Disclosure: Nothing to declare.

P202

Abstract already published.

P203 Efficacy and Toxicity of Ruxolitinib in Patients with steroid-resistant Acute and Chronic graft-versus-host Disease after Hematopoietic Cell Transplantation

ANNA PETROPOULOU, Mitja Nabergoj, Anne-Claire Mamez, Sarah Morin, Elif Mahne, Carmen De Ramon Ortiz, Caroline Stephan, Christian Ayer, Benjamin Bruno, Laura Bounaix, Maria Anastasiou, Maria Mappoura, Carole Dantin, Yan Beauverd, Federico Simonetta, Federica Giannotti, Stavroula Masouridi-Levrat, Yves Chalandon

Geneva University Hospital, Geneva, Switzerland

Background: Steroid-resistant (SR) acute and chronic graft-versus-host-disease (aGVHD - cGVHD) represent a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). Ruxolitinib is the first treatment having received FDA approval on May 2019 for SR-aGVHD.

Methods: We retrospectively evaluated the efficacy and toxicity of ruxolitinib in patients treated for SR- GVHD in our center. Primary objective was to evaluate the 28-day complete remission (CR) and partial remission (PR).

Results: Eighteen patients with aGVHD and 10 patients with cGVHD, and who had previously presented aGVHD, transplanted between 01.01.2015 and 31.10.2018 were included, 71.4% male and 28.6% female. Median age was 58 years (range, 21 to 73).

Among patients treated for grade II to IV SR-aGVHD, 11.1% had skin, 55.6% gastrointestinal, 11.1% liver and 22.2% multisite disease. A median of 3 prior therapies (range, 2 to 4), including steroids, were administered before ruxolitinib. Ruxolitinib was initiated at a median of 132 days (IQR: 44 to 248) post-transplant and 28 days (IQR: 12 to 71) after onset of aGVHD. At day 28 post-ruxolitinib initiation, 8 patients (44%) achieved CR and 4 patients PR (22%), maintained through day 56. Five out of six non-responders had grade IV GVHD and finally died because of GVHD. Median duration of treatment was 133 days (IQR: 58 to 443), with one patient remaining on ruxolitinib at last follow-up.

The median follow-up, for all alive, post-transplant and post-ruxolitinib initiation was 1206 (IQR: 1153 to 1234) and 445 days (IQR: 372 to 532) respectively. The estimated 6-month failure-free survival (FFS) was 44.4% and the estimated 6-month and 1-year overall survival (OS) 72.2% (standard error, SE=14.6%) and 50% (SE = 23.6%), respectively.

47%, 78% and 67% of patients presented grade III neutropenia, thrombocytopenia and anemia, respectively.

67%, 72% and 18% of patients presented at least one documented bacterial, viral and fungal infection respectively.

Among cGVHD patients treated with ruxolitinib, 40% had moderate cGVHD and 60% severe. Organ involvement included at least skin in 70% of patients. A median of 2.5 prior therapies (0 to 5) were administered before ruxolitinib. By day 28, nine patients (90%) obtained a CR or PR and only one patient failed and who finally died because of GVHD. The median duration of therapy was 269 days (IQR: 42 to 426). Ruxolitinib was withdrawn in one patient in CR. Concerning toxicities, one patient interrupted ruxolitinib because of hematologic toxicity, one because of relapse and seven patients are still under ruxolitinib at last follow-up.

The median follow-up, for all alive, post-transplant and post-ruxolitinib initiation was 1352 days (IQR: 990 to 1592) and 374 (IQR: 126 to 713), respectively. The estimated 6-month and 1-year FFS was 62.5% and the estimated 1-year and 3-year OS 90% (SE: 10.6%) and 77.1% (SE: 18.7%), respectively.

Anemia grade III was observed in only one patient.

Five patients presented documented bacterial and three viral infection; no fungal infection was observed.

Conclusions: Ruxolitinib represents a promising treatment for SR-GVHD, allowing satisfying response rates in patients having already received several lines of GVHD therapy. Careful infectious monitoring is nevertheless required.

[Overall Survival]

Disclosure: "Nothing to declare."

P204 Patient Characterization and Survival Outcomes in Paediatric Chronic Graft versus Host Disease Patients - A population-based Study in Sweden

Frida Schain ^1,2, Nurgul Batyrbekova^1,3, Annica Dominicus³, Simona Baculea⁴, Mats Remberger⁵, Jonas Mattsson^6,7, Jacek Toporski⁸

¹Karolinska Institutet, Stockholm, Sweden, ²Schain Research AB, Bromma, Sweden, ³Scandinavian Development Services AB, Danderyd, Sweden, ⁴Janssen Global Services, London, United Kingdom, ⁵Akademiska University Hospital, Uppsala, Sweden, ⁶Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden, ⁷University of Toronto, Princess Margaret Hospital, Gloria and Seymour Epstein Chair in Cell Therapy and Transplantation, Toronto, Canada, ⁸Skåne University Hospital, Lund, Sweden

Background: There is a scarcity of data describing incidence and real-world outcomes in paediatric chronic Graft versus Host Disease (cGVHD) patients.

Methods: Longitudinal population-based registries held by the National Board of Health and Welfare in Sweden were used to identify patients < 18 years of age that underwent allogeneic hematopoietic stem cell transplantation (HSCT) between 2006 and 2015. End of follow-up was 2017. Patients surviving ≥6 months post-HSCT were classified as having cGVHD by timing and extent of systemic immunosuppressive treatment. cGVHD was defined as those who received systemic corticosteroid treatment for ≥ 3 months alone (mild) or with extracorporeal phosphoresis (ECP) and/or other immunosuppressive treatment (moderate-severe) in children with malignancies, and systemic corticosteroid treatment for ≥ 3 months and/or ECP in children with non-malignant indications for HSCT. Our method may contrast with the standard NIH 2014 guidelines; i.e. the standard method for making decisions about treatment and enrollment in clinical trials. Crude survival rate (SR) and cause-specific mortality were evaluated by estimation of cumulative incidence. Morbidities were analyzed by multivariate negative binomial regression models to adjust for follow-up year and age. Median follow-up times were 5.8 (interquartile range [IQR] 2.8-8.7 [malignant]) and 6.2 (IQR 4.3-9.4 [benign]) years.

Results: Among patients surviving ≥6 months post-HSCT (n=327), 176 and 151 had underlying malignant and benign disease, respectively. The 1- and 5-year SRs were lower for patients with malignant [86.9, 95% CI 82.1-92.1 and 78.5, 95% CI 72.6-84.9] versus benign [98.7, 95% CI 96.9-100 and 95.2, 95% CI 91.8-98.7] disease. The incidence of cGVHD was higher in patients with malignancies (59.1%) versus for benign disorders (37.7%). For patients with malignancies, the 1-year SR from 6 months post HSCT increased with increasing cGVHD severity: 79.2 (95% CI 70.3-89.1) [non-cGVHD], 88.2 (95% CI 79.8-97.5) [mild cGVHD], 96.2 (95% CI 91.2-100) [moderate-severe cGVHD] (p=0.016), however this difference evened out at 5-years of follow-up (p=0.797). Similarly, he cumulative relapse-related mortality (RRM) after one year was higher in non-cGVHD [20.83, 95% CI 13.28-32.68] versus moderate-severe cGVHD [3.77, 95% CI 0.97-14.7] patients. Over the entire follow-up period, cGVHD status was not associated with survival in patients with benign disorders (p=0.14). Among patients with malignant and benign disorders, respectively, there were no differences in SR when comparing different stem cell sources, (p=0.38, p=0.076), donor relatedness (p=0.2, p=0.51), calendar periods [2006-2010, 2011-2016] (p=0.33, p=0.43) and age [≤11,≥12 years] at HSCT (p=0.56, p=0.64). When comparing morbidities among non- and moderate-severe cGVHD patients with malignancies, the most pronounced differences were observed for injury, poisoning and certain other consequences of external causes [IRR 0.03, 95% CI 0.02-0.05], diseases of the musculoskeletal system and connective tissue [IRR 0.16, 95% CI, 0.08-0.33] and diseases of the circulatory system [IRR 0.23, 95% CI 0.06-0.85].

Conclusions: The incidence of cGVHD was higher in patients with malignant versus benign disorders. Overall, the cGHVD incidence was higher compared to previous reports in Sweden, indicating that this diagnosis may be underreported in clinical practice. For patients with malignancies, increasing cGVHD severity was associated with higher survival rates the first follow-up year.

Disclosure: Dr Mattsson, Dr Remberger, Dr Toporski declare.s no conflict of interest. Dr Schain is owner of and employed by Schain Research AB and work as a consultant for Janssen and has previously been an employee of Janssen. Dr Baculea is employed by Janssen. Mrs Batyrkekova and Dr Dominicus are employed by Scandinavian Development Services AB and work as consultants for Janssen.

P205 Cytokine Levels following Allogeneic Hematopoietic Stem Cells Transplantation. A match-pair Analysis of Home Care Versus Hospital Care

Olle Ringden, Mats Remberger, Johan Torlen, Sigrun Finnbogadottir, Britt-Marie Svahn, Behnam Sadeghi

Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden

Background: During two decades more than 250 patients were treated at home as an alternative to isolation in the hospital during the neutrophenic phase after allogeneic hematopoietic stem cell transplantation. Home-care patients had less acute GVHD and improved survival compared to patients isolated in the hospital (Svahn et al. Blood 2002). Many days at home was correlated to a low risk of acute GVHD.

Methods: We analyzed cytokines, chemokines and growth factors during the first three weeks after HSCT and compared patients treated at home (n=42) with matched patients isolated in the hospital (n=37).

The patients in the hospital were matched with the home-care patients for age, diagnosis, remission status, timing, HLA-match and type of donor sibling or matched unrelated donor.

We used Laminex and analyzed; EGF, Eotaxin, G-CSF, GM-CSF, IFNγ, IL-10, IL-12 p40, IL-12 p70, IL-13, IL-15, IL-17A, IL-1RA, IL-1α, IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β, TNFα, TNFβ and VEGF.

Results: In multivariate analysis, patients treated at home had decreased GM-CSF, IFN-γ (p< 0.01), IL-13 and IL-5 (p< 0.05). GM-CSF, IFN-γ and IL-13 are associated with GVHD. Patients with blood stream infections had reduced eotaxim, G-CSF and IL-1a and increased IL-15 (p< 0.01). Patients who developed acute graft-versus-host disease had increased G-CSF and IP-10 and decreased IL-7 and IL-8 (p< 0.01). In addition, anti-thymocyte globulin, G-CSF treatment, immunosuppression, age, conditioning, related vs unrelated donors, graft source and total body irradiation affected various cytokine levels. Acute GVHD grades III-IV was 10% and 16% in the home-care and hospital-care patients, respectively. One year transplant-related mortality was 7% and 16% and overall survival at 5 years was 69% and 57% in the two groups, respectively.

The more similar outcome between home- and hospital-care in this analysis, may be due to that patients in more recent years spent a shorter time at home. Furthermore, several improvements in hospital-care were introduced to mimic home-care, such as better nutrition, more exercise and the possibility for walks outside the hospital.

Conclusions: Patients treated at home had decreased levels of GM-CSF, IFN-γ and IL-13, which may contribute to reduced acute GVHD.

Disclosure: Nothing to declare.

P206 Incidence of Chronic graft-versus-host Disease - Results from a Prospective Multicentre Analysis of 2 Cohorts

Antonela Lelas ¹, Ronja Langer², Michael Rittenschober³, Lana Desnica⁴, Hildegard Greinix⁵, Anne Dickinson⁶, Marit Inngjerdingen⁷, Anita Lawitschka^3,8, Radovan Vrhovac^1,4, Drazen Pulanic^1,4, Stefan Klein⁹, Jan Moritz Middeke¹⁰, Matthias Edinger¹¹, Daniel Wolff¹¹

¹University of Zagreb, Zagreb, Croatia, ²University of Regensburg, Regensurg, Germany, ³St. Anna Children’s Hospital, Medical University of Vienna, Vienna, Austria, ⁴University Hospital Centre Zagreb, Zagreb, Croatia, ⁵Medical University of Graz, Graz, Austria, ⁶Newcastle University, Newcastle upon Tyne, United Kingdom, ⁷University of Oslo, Oslo, Norway, ⁸Children’s Cancer Research Institute, Vienna, Austria, ⁹University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany, ¹⁰University Hospital Dresden, Dresden, Germany, ¹¹University Hospital Regensburg, Regensurg, Germany

Background: Incidence of chronic Graft-versus-Host Disease (cGvHD) is ~45%, but varies significantly depending on conditioning regimen, choice of donor, stem cell source, age and GvHD prophylaxis. In the past, increasing cGvHD incidence was reported due to accumulation of risk factors, but recent studies capturing the effect of new prophylaxis strategies are lacking.

Methods: This study was conducted as joint analysis of 308 patients from two cohorts - cohort 1 included patients (pts) transplanted 2017 at University Hospital Zagreb (Croatia), and St. Anna Children`s Hospital, Vienna (Austria), cohort 2 included consecutive pts documented in period from July 2015 to September 2018 within the German-Austrian-Swiss GvHD register.

Results: Cohort 1 consisted of 98 (55% male), mainly adult pts (70%), who underwent allogeneic hematopoietic stem cell transplantation (alloHSCT) at median age of 40 (range 0-66) years, and cohort 2 out of 210 (65% male) pts transplanted at median age of 56 (range 19-70) years. Most frequent indications for alloHSCT in both cohorts were acute leukaemia (51.9%), myelodysplastic/myeloproliferative diseases (19.2%), lymphoma (15.6%), plasma cell disorders (5.5%), non-malignant diseases (7.2%), and solid tumours (0.7%). 65% of all alloHSCT were performed from unrelated donors, 23% from matched related donors and 12% from haploidentical donors (25% in cohort 1 vs. 6% in cohort 2). Peripheral blood stem cells were applied in 73%, while 27% received bone marrow grafts. For both cohorts, at median follow-up of 333 (range 0-1149) days, the overall survival (OS) was 71% and cumulative incidence (CI) of treatment related mortality (TRM) 19%. CI of malignant disease relapse was 21%, and occurred at median of 154 (range 0-757) days after alloHSCT. Acute GvHD was reported with CI of 42% (6% for stage III/IV) in period of 100 days. For cohort 1 late acute GvHD had CI of 10% (1% for stage III/IV) and occurred at median time of 166 (range 110-424) days after alloHSCT and for cohort 2 CI was 11% (3% for stage III/IV) and occurred at median time of 217 (range 106-562) days.

In cohort 1 CI of cGvHD was 14% and all pts had NIH moderate/severe global score at onset which occurred at median of 197 (range 62-700) days with de novo, progressive and quiescent onset in 42%, 25% and 33%, respectively. In cohort 2 CI of cGvHD was 39% (19% moderate/severe) at onset at median of 197 (range 92-588) days with de novo, progressive and quiescent onset in 37%, 1% and 62%, respectively. Four pts of cohort 2 were diagnosed with cGvHD with other manifestations such as glomerulonephritis or cerebral vasculitis. Among cGvHD pts from cohort 1 most involved organs at onset were mouth (82%), skin (73%), and eyes (64%) followed by liver (55%), gastrointestinal tract and lung (each 27%) and genital tract (18%) with a median Karnofsky/Lansky score of 80% (range 50-100). In the joint analysis, 71% pts required second line treatment.

Conclusions: This study shows for the first time a decreasing incidence of cGvHD compared to previous publications which may reflect the change in practice pattern in prophylaxis and treatment of GvHD.

Disclosure: This work was supported by European Cooperation in Science and Technology (COST), through action number CA17138 - Integrated European Network on chronic Graft versus Host Disease.

A. Lelas - Work financed by Croatian Science Foundations` “Young researchers`career development project - training of doctoral students”

D. Wolff received research funds from Novartis and honoraria from Amgen, Neovii, Novartis, Mallinckrodt and Takeda.

P207 Early Introduction of Ruxolinitib for Children with Graft versus Host Disease - A Stitch in Time Saves Nine

Revathi Raj, Ramya Uppuluri, Venkateswaran vellaichamy, Nikila Ravichandran, Kesavan Iyer

Apollo Speciality Hospital, Chennai, India

Background: Algorithms for the management of graft versus host disease need to be revisited as the use of steroids and agents such as etarnacept and tociluzimab increases the risk of viral reactivation. Newer drugs such as ruxolinitib are oral JAK ½ inhibitors with little immunosuppressive effect making this an attractive option as the first line drug rather than salvage therapy for graft versus host disease in this setting. We describe our experience with early introduction of ruxolinitib in acute and chronic graft versus host disease and the outcomes in children.

Methods: A retrospective analysis of 50 children who had received Ruxolinitib between September 2017 and September 2019 on compassionate basis use was analysed. All children with acute graft versus host disease (GVHD) had Ruxolinitib introduced within 48 hours of commencing steroids and those with chronic graft versus host disease within four weeks. The grading of acute GVHD and the organ involved was documented as per Glucksberg grading and chronic GVHD the organ involved and if limited or extensive. Data analysed was regarding efficacy, toxicity and viral reactivation rates. Ruxolinitib was used at a dose of 2.5 mg twice a day in less than 20 kg and 5 mg twice a day in more than 20 kg children.

Results: The indication was acute GVHD in 18 children and chronic GVHD in 32 children. Gut was the most common organ affected in the acute group and skin and mouth in the chronic group. The response rate was high with resolution of symptoms over 5 to 7 days in 16 of 18 children with acute GVHD. Steroid taper was possible over 4 to 6 weeks and the viral reactivation was seen in 10 of 18 children. In the 32 children with chronic graft versus host disease, 30 had responded to the medication. Ruxolinitib was effective in limited rather than sclerosing chronic graft versus host disease and effective even in lung and eye graft versus host disease. There was no viral reactivation seen in this group and three children died due to leukaemia relapse. Thrombocytopenia was seen in over 65% of children in chronic graft versus host disease and over 90% in the acute GVHD group. In children less than 8 kg hypothermia was a peculiar side effect noted. There were no significant drug interactions.

Conclusions: Ruxolinitib offers a new avenue of care in children with graft versus host disease. The dramatic response rates of 88% in acute and 93% in chronic GVHD makes it an invaluable agent in this setting. Early introduction helps rapid taper of steroids and reduced rates of viral reactivation and mortality in acute GVHD. Morbidity due to steroids including hypertension, diabetes and avascular necrosis of the femoral head could be prevented in children with chronic GVHD if the drug is used early rather than as salvage therapy. The high cost of the medication is a challenge in developing countries and the Managed Access Patient (MAP) programme allows access to this medication on compassionate basis in children.

Disclosure: Twelve children obtained Ruxolinitib through the Novartis MAP programme on compassionate basis free of cost

P208 Post-transplant Cyclophosphamide as an Effective Strategy For GVHD Prevention in both HLA-matched and Mismatched Allogeneic Transplants

Irene García-Cadenas, Albert Esquirol, Rahinatu Awol, Silvana Saavedra, Silvana Novelli, Ana Garrido, Jordi López, Carol Moreno, Miquel Granell, Javier Briones, Salut Brunet, Jordi Sierra, Rodrigo Martino

Hospital de la Santa Creu i Sant Pau, Sant Pau, Jose Carreras Leukemia Research Institute, Autonomous University of Barcelona, Barcelona, Spain

Background: High-dose post-transplant cyclophosphamide (PTCy) has proven feasible and effective in overcoming the negative impact of HLA disparity on survival after haploidentical SCT. However, the optimal prophylaxis regimen for GvHD in the setting of matched or mismatched allogeneic transplants is not well-defined.

Methods: We retrospectively evaluated the combination of PTCy and a second immunosuppressive agent for GVHD prophylaxis in 64 consecutive adult patients diagnosed with high-risk haematological malignancies who received an allo-SCT in our institution between 2016 and 2019. Patient characteristics are shown in Table 1.

Results: At a median follow-up for survivors of 535 days (range: 30-1324), 44 patients (68%) were alive and in remission. The 1-year OS after identical sibling, MUD and MMUD allo-SCT was 82%, 86% and 66%, respectively (P = 0.1). Six patients had graft failure and 4 of them were successfully re-grafted using a different PTCy-based conditioning regimen. One patient died from severe bacterial infection before day +30. The median days to neutrophil (w/o G-CSF) and platelet recoveries were + 22 (range: 16-36) and +24 days (range: 10-249), respectively. The incidence (C.I.) of grade 2-4 aGVHD was 12% in sibling donor, 11% in MUD and 35% in MMUD donor groups (p=0.06), respectively, with 4 steroid-refractory cases (6%). Of the 52 evaluable patients, the 1yr. C.I. of moderate-severe chronic GVHD was 8.5% (95%C.I.: 4-14). The C.I. of relapse at 1 year was 31% in the MRD, 20% in the MUD group and 22% in the MMUD group (p=0.7), while NRM at 1-yr was 9.4%, 12% and 38%, respectively (p=0.06), with opportunistic infections being the most frequent cause of death (36% of 14 deaths), followed by relapse (28%) and GvHD (14%). Figure 1 shows the C.I of aGvHD and NRM according to donor type.

Conclusions: Our experience shows that single agent GvHD prophylaxis and PTCy can be combined outside the haploidentical setting with low incidence of both acute and chronic GvHD and acceptable relapse rates. There was a trend toward worse long-term outcomes after MMUD transplant which remains to be confirmed in future studies.

Age, median (range) ≥ 50 years	55 (19-72) 39 (61
Sex, male	34 (53)
Underlying disease AL and MDS NHL/Hodgkin Myelofibrosis or other MPN Others	33 (51) 15 (23) 9 (14) 7 (11)
Advanced disease at transplant	27 (42)
Sex mismatch: female to male	8 (12)
Donor type HLA Identical Sibling 10/10 matched URD / 1-allele mismatched URD	19 (30) 20/25(31/39)
Disease risk index: High/Very high	12 (41)
Conditioning Fludarabine-Busulphan (RIC) Fludarabine-Melphalan (RIC) MiniTiothepa-modified RICs Fludarabine- TBI or Busulphan (MAC)	11 (17) 13 (20) 23 (36) 17 (26)
Stem cell source (PBSC)	62 (97
Second immunosuppressive agent: Single-agent Tacrolimus/Sirolimus	61/3(95/5)

[Patient characteristics (N=64)]

Disclosure: Nothing to declare.

P209 Serum Autoantibodies in Allogeneic Hematopoietic Cell Transplantation (HCT) Patients: A Pilot Study

Ivan Pasic ¹, Ashley Di Meo², Ioannis Prassas², Ihor Batruch², Leeann Wilson¹, Eleftherios P. Diamandis², Fotios V. Michelis¹

¹Princess Margaret Cancer Centre, Toronto, Canada, ²Mount Sinai Hospital, Toronto, Canada

Background: Allogeneic hematopoietic cell transplantation (HCT) is the only curative option for several hematological malignancies including high-risk and relapsed/refractory acute myeloid leukaemia (AML). Allogeneic HCT is often associated with immune-mediated complications such as graft-vs-host disease (GVHD). As some of these complications are T cell-mediated, several anti-thymocyte therapies have been developed, including anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy). In contrast, less is known about the contribution of humoral immunity to GVHD. We sought to investigate the role of humoral immunity in the development GVHD through identification of novel autoantibodies in HCT patient serum.

Methods: In this pilot study, we investigated five patients who underwent HCT for de novo AML in first complete remission (CR1). Serum samples were collected on days -6, 0, +14, +30, +60 and up to day +150 post HCT. Autoantibodies were purified from serum by protein G magnetic beads and incubated with a pooled human tissue lysate containing >7,000 proteins, extracted from human liver, colon, skin and lung. After washing, antibody-bound protein antigens were trypsin-digested and positively identified on the Q-Exactive H-FX high-resolution mass spectrometer (MS) (Thermo Fisher Scientific, San Jose, California). Raw files were uploaded into Proteome Discoverer v.1.4 (Thermo) and searched against the Human Swiss-Prot database. A filtering algorithm was developed which excluded autoantibodies against highly abundant proteins, those present at baseline at high titers and those whose titers did not increase compared to baseline.

Results: Of the five patients, four were female. Median age was 45 (range 21-61). Three patients had a matched related donor, one had a haploidentical related donor and one had a matched unrelated donor. Two patients received myeloablative conditioning, while three received reduced intensity conditioning. GVHD prophylaxis consisted of ATG, PTCy, methotrexate (MTX) or cyclosporine A (CsA). Median follow up time among survivors was 141 days (range 130-157).

Of the five patients, three developed grade 1-4 acute GVHD. In two of these, we identified 19 autoantibodies which demonstrated a more than 2-fold increase in titer compared to baseline; no autoantibodies were detected in the third patient. Of the 19 autoantibodies, three were detected in both patients, including those against isoform 2 of clathrin heavy chain 1 (CLTC), isoform 4 of myosin-11 (MYH11), and talin-1 (TLN1). The titers of anti-MYH11, anti-TLN1, and anti-CLTC autoantibodies displayed a > 2-fold peptide count increase compared to baseline in patient 1 (peptide count correlates with protein abundance). In addition, titers of anti-MYH11, anti-TLN1, and anti-CLTC autoantibodies displayed a > 2-fold peptide count increase compared to baseline in patient 5. Two patients had no GVHD; no autoantibodies were discovered in these individuals.

Conclusions: Using immuno-mass spectrometry, we demonstrate that serum autoantibodies of potential clinical significance can be detected in patients at early time points post-HCT. Some of these autoantibodies, including those against CLTC, MYH11 and TLN1, are detected in patients with GVHD. Our finding of common autoantibodies in patients with GVHD suggests that these autoantibodies may potentially serve as biomarkers of GVHD and warrant further prospective studies to determine their role in the pathophysiology of GVHD.

Disclosure: Nothing to declare.

P210 Optimized Starting Dose of Cyclosporine Reduces Risk of Acute GVHD after Allogeneic Hematopoietic Cell Transplantation: A Single Center Experience

Jérémie Héritier, Michael Medinger, Dominik Heim, Helen Baldomero, Christian Arranto, Jörg Halter, Jakob R. Passweg, Martina Kleber

University Hospital Basel, Basel, Switzerland

Background: Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative option for many patients with hematologic malignancies. Acute (aGVHD) and chronic graft-versus-host disease (cGVHD) are the most common early and late complications after allo-HCT impacting outcome. Previous results have shown that close monitoring of cyclosporine A (CsA) dosing with active adjustments to maintain therapeutic levels above 195 µg/L in the first 10 days after allo-HCT, could significantly reduce aGVHD (Bianchi et al. Annals of Hematology; 2019; 98: 971-977).

Methods: In this retrospective analysis of patients undergoing allo-HCT, we correlate CsA levels on day 10 and its effect on the incidence of aGVHD vs. cGVHD and outcome [progression-free survival (PFS) and overall survival (OS)]. We hypothesized that with a higher starting dose, more patients will have levels higher than the desired minimum within the first 10 days as determined by ROC, and that consequently GVHD incidence would be lower.

Results: We evaluated 535 patients with primarily myeloid (65%) and lymphoid malignancies (32%). 160 (30%) patients received a CsA starting-dose of 5mg/kg (CsA5) and 375 (70%) patients a starting dose of 3mg/kg (CsA3). In patients with clinically relevant aGVHD grade ≥ 2, mean CsA level was lower on day 10 compared to patients without aGVHD (176µg/L ± 58 vs. 202µg/L ±64, respectively; p < 0.001). In our cohort, the optimal CsA cutoff was >193µg/L as suggested by receiver operating curve analysis and Youden’s index at day 10 to reduce aGVHD and was similar to published results. The CI of aGVHD grade ≥ 2 in patients with initial CsA level ≤193µg/L vs. >193µg/L was 49% (95% CI: 42%-55%) vs. 35% (95% CI: 28%-41%, p=0.0023), respectively. The frequency of patients achieving the desired CsA level of >193 µg/L at day 10 after HCT was significantly higher with CsA5 starting dose with 85/159 (54%) vs. 147/365 (40%) in patients with CsA3 starting dose, respectively (p=0.005). Correspondingly, the CI of aGVHD with grade ≥ 2 was significantly higher in patients within CsA3 (45%, 95%CI: 40%-51%) compared to patients with the CsA5 starting dose (36%; 95% CI: 28-44; p=0.024). Interestingly, in patients with CsA ≤193µg/L vs. >193µg/L on day 10 post allo-HCT, the 1-year CI of cGVHD was significantly decreased with 42% (95%CI: 36%-49%) vs. 53% (95%CI: 45-60%, p=0.038), respectively.

In addition, the 1-year PFS in the CsA5 group was significantly higher with 69% (95% CI: 60%-76%) compared to the CsA3 group with 59% (95% CI: 54%-64%; p=0.020). This translated into a longer 1-year OS in the CsA5 group with 81% (95% CI: 74%-87%) vs. 70% (95% CI: 66%-75%; p=0.001) in the CsA3 group, respectively.

Conclusions: With a higher CsA starting dose of 5mg/kg, significantly greater rates of aGVHD preventing drug levels above 193 µg/L on day 10 after allo-HCT could be achieved and resulted in advanced outcome with prolonged PFS and OS. Additionally, the degree of immune suppression during the early post-HCT phase may also influence late complications such as cGVHD.

Disclosure: Nothing to declare.

P211 Success of Immunosuppression in Patients with Chronic GVHD: Analysis on 108 Adult long-term Survivors after Matched and HAPLO HSCT

Maria Teresa Lupo-Stanghellini ¹, Francesca Lorentino¹, Fabio Serpenti², Andrea Assanelli¹, Carlo Messina¹, Sara Mastaglio¹, Stefania Girlanda¹, Fabio Giglio¹, Raffaella Greco¹, Sarah Marktel¹, Francesca Lunghi¹, Elena Guggiari¹, Magda Marcatti¹, Matteo G. Carrabba¹, Massimo Bernardi¹, Consuelo Corti¹, Jacopo Peccatori¹, Fabio Ciceri^1,3

¹IRCCS San Raffaele Scientific Institute, Milano, Italy, ²Università degli Studi di Milano, Milan, Italy, ³University Vita-Salute San Raffaele, Milan, Italy

Background: Allogeneic stem cell transplantation (HSCT) is today a mainstay for the cure of malignant and non-malignant diseases. Over time, the application of HSCT has increased dramatically, but control of graft-versus-host disease (GvHD) is still unsatisfactory.

As recently confirmed by a FHCRC study on 250 patients with chronic (ch)GvHD followed for more than 5y after diagnosis, patients with chGVHD usually receive multiple lines and years of IST (immunosuppressive therapy), with only a third permanently off-IST, alive, and free of malignancy.

Primary endpoint of our study was to assess outcome of chGvHD as for overall survival, exposure and discontinuation of IST therapy. Secondary endpoint was to evaluate the power of our immune reconstitution (IR) prognostic score in predicting the possibility of IST discontinuation since chGvHD declaration.

Methods: The study cohort included 108 adult patients who had previously undergone HSCT at our Institute between Jan-2011 and Dec-2014 and subsequently received IST for chGVHD starting from a median time after HSCT of 189 days (range 31-1304). All patients received as 1^st line therapy prednisone 0.5-1mg/Kg and NIH criteria were applied for diagnosis and response evaluation. Patients were eligible regardless of graft source, donor type, or GVHD prophylaxis.

Results: Patient characteristics are summarized in Table-1.

After a median follow-up of 5,8 years for all survivors, 19 (18%) were still on-IST (median time of IST exposure 1752 days - range 1189-2820), regardless of previous attempts to discontinue IST. Fifty patients (46%) were alive, in complete remission and off-IST (median time of IST exposure 373 days - range 93-1399). Thirty-nine (36%) have relapsed or died (Figure-1).

[Figure 1. Cumulative incidence of events]

In univariate analysis the probability of being alive, disease free and off-IST at 2 and 5 year was 41% and 64% for patient with moderate chGvHD vs 7% and 20% for patient with severe chGvHD (p < 0,001), 31% and 56% for patient with classic GvHD vs 21% and 28% for patient with overlap GvHD respectively (p 0,007); 40% and 72% for patient with IR-score low vs 30% and 44% for patient with IR-score intermediate vs 14% and 18% for patients with IR-score high (p< 0,001). Disease risk index, donor/patient sex, conditioning, stem cell source, donor, GVHD prophylaxis, prior acute GvHD did not differ in univariate analysis.

In multivariable logistic regression analysis, successfully stopping IST was associated with NIH GvHD severity: patients with severe chGvHD have less probability of being alive, disease free and off-IST (HR, 10.3; 95% CI, 3.38 to 31.5; p < 0.0001).

Conclusions: Patients with chGVHD are exposed to long-time IST: less than half of the patients is off-IST, alive, and free of malignancy at 5y after chGVHD diagnosis. Definition of parameters and biomarker able to predict the trajectory of chGvHD and the probability of survivorship disease-free and IST-free are warranted.

Table 17

Disclosure: Nothing to declare.

P212 Incidence and Outcome of Liver Chronic graft-versus-host Disease During Tapering or after Stopping Calcineurin Inhibitors in Allogeneic Hematopoietic Stem Cell Transplant Recipients

Kazuki Yoshimura, Shun-Ichi Kimura, Masakatsu Kawamura, Shunto Kawamura, Junko Takeshita, Nozomu Yoshino, Yukiko Misaki, Shinpei Matsumi, Ayumi Gomyo, Yu Akahoshi, Masaharu Tamaki, Machiko Kusuda, Kazuaki Kameda, Hidenori Wada, Koji Kawamura, Miki Sato, Kiriko Terasako-Saito, Aki Tanihara, Hideki Nakasone, Shinichi Kako, Yoshinobu Kanda

Jichi Medical University Saitama Medical Center, Saitama, Japan

Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients sometimes develop liver chronic graft-versus-host-disease (cGVHD) during tapering or soon after stopping immunosuppressant. However, the clinical characteristics of liver cGVHD during low dose immunosuppressant are still unclear.

Methods: We retrospectively analyzed 242 patients who underwent their first or second allo-HSCT at our center between January 2007 and December 2016, survived more than 100 days after allo-HSCT and experienced dose reduction of calcineurin inhibitors (CI) to lower doses (less than 40mg of cyclosporin A or 0.4mg of tacrolimus by oral administration) for clarifying the risk factors and the clinical characteristics of liver cGVHD during low dose CI. Liver injury was defined as an elevation of any liver enzyme levels (total bilirubin (T.Bil), direct bilirubin (D.Bil), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)) to more than 2× upper limit of normal (ULN) or more than 5×ULN if initial liver enzyme levels during low dose CI were more than 2×ULN. We categorized liver injuries into “proven”, “probable” and “possible” cGVHD according to the definition by the German Working Group on Bone Marrow and Blood Stem Cell Transplantation and we defined proven and probable liver injury as liver cGVHD in this study. We also compared the clinical characteristics of liver GVHD during low dose CI to that in other periods. In addition, we evaluated the treatment efficacy with CI or corticosteroid for cGVHD during low dose CI.

Results: Sixty patients (25%) developed liver cGVHD during low dose CI. Multivariate analysis showed donor age of ≥40 years (HR 2.20, P=0.02), myeloablative conditioning (HR 2.19, P=0.02), female donors to male recipients (HR 2.53, P< 0.01) and recipient seropositivity for herpes simplex virus (HR 2.52, P< 0.01) were identified as significant risk factors of liver cGVHD during low dose CI period. Peak AST and ALT levels were higher in patients with liver cGVHD during low dose CI period than those in other periods, but T.Bil, ALP and ALP/ALT ratio showed no significant differences. Eighteen (30%) cases received no treatment because cGVHD improved spontaneously, whereas 27 (45%) cases were initially treated with restart or increase of CI and 21 patients responded to CI treatment. Eighteen (30%) patients were treated with corticosteroids and 13 patients responded to corticosteroids therapy.

Conclusions: The risk factors of liver cGVHD during low dose CI shown in this study were similar to previously reported risk factors of cGVHD. Some liver cGVHD during low dose CI could improve without treatment or with CI but others needed corticosteroids therapy. Peak T. Bil was identified as a significant factor to predict the response to corticosteroid therapy.

Disclosure: Nothing to declare.

P213 Post-transplant Cyclophosphamide after Matched Sibling and Matched Unrelated Compared to Haploidentical Donor Transplants in Patients with Acute Myeloid Leukemia, a Study on Behalf of Geth

Mi Kwon ¹, Rebeca Bailén¹, Maria Jesus Pascual Cascon², Lucia Lopez Corral³, Arancha Bermudez⁴, Pilar Herrera⁵, Antonia Sampol⁶, Inmaculada Heras⁷, Carmen Martin Calvo⁸, Jaime Sanz⁹, Isabel Sanchez Ortega¹⁰, Melissa Torres¹¹, Jose Rifon Roca¹², Karem Humala¹³, Cristina Muñoz¹, Ignacio Gomez Centurion¹, Gillen Oarbeacoa¹, Nieves Dorado¹, Jose Luis Diez Martin¹

¹Hospital General Universitario Gregorio Marañón, Madrid, Spain, ²Hospital Regional de Málaga, Malaga, Spain, ³Hospital Universitario de Salamanca, Salamanca, Spain, ⁴Hospital Universitario Marques de Valdecilla, Santander, Spain, ⁵Hospital Universitario Ramón y Cajal, Madrid, Spain, ⁶Hospital Universitario Son Espases, Palma de Mallorca, Spain, ⁷Hospital General Universitario Morales Meseguer, Murcia, Spain, ⁸Hospital Universitario Reina Sofia, Cordoba, Spain, ⁹Hospital Universitario y Politécnico La Fe, Valencia, Spain, ¹⁰Hospital Duran i Reynals, Barcelona, Spain, ¹¹Hospital Universitario de Gran Canaria Doctor Negrín, Las Palmas de Gran Canaria, Spain, ¹²Clínica Universidad de Navarra, Pamplona, Spain, ¹³Hospital Universitario La Paz, Madrid, Spain

Background: Post-transplant cyclophosphamide (PTCy) effectively prevents GVHD in unmanipulated haploidentical (Haplo) transplants, and results in lower rates of GVHD in the HLA matched donor setting compared to standard prophylaxis.

Methods: In this retrospective study, we analyzed adult patients with AML who underwent a first allogeneic HSCT with PTCy from MSD and MUD (n=62) performed between 2013 and 2018, and Haplo donors (n=132) performed between 2012 and 2017 and reported in the GETH registry (Grupo Español de Trasplante Hematopoyético y Terapia Celular). Median follow-up was 15 months for the MSD/MUD cohort and 17 months for the Haplo cohort.

Results: Median age of the patients was 51 years for both cohorts (16-75). HCT-CI/age score was 0-2 in 56% of MSD/MUD patients and 54% of Haplo patients. Compared to MSD and MUD, Haplo patients included a higher proportion of high/very high disease risk index AML (65% vs 30%). Disease status at transplantation was CR1 in 66% and 68%, respectively. Peripheral blood (PB) was used as the stem cell source in 81% and 86%, respectively. MAC conditioning was used in 66% of MSD/MUD transplants and in 54% of Haplo transplants. Most used regimens contained busulfan/fludarabine in Haplo transplants (87%) while MSD/MUD received busulfan/fludarabine in 56% and TBF in 42%. All Haplo transplants received PTCy on days +3+4 followed by CNI+MMF from day +5. MSD/MUD transplants were performed with PTCy days +3+5 with CNI from day 0 in 14%, PTCy +3+4 with CNI alone from day +5 in 21%, and PTCy +3+4 with CNI+MMF from day +5 in 65%. No patient received anti-thymocyte globulin. Cumulative incidence of neutrophil recovery at 35 days for MSD/MUD and Haplo was 100% and 98%, in a median of 16 days and 17 days, respectively. The cumulative incidence of acute GVHD grade II-IV and III-IV at 180 days were 14% vs 49% (p=0.002) and 0% vs 7% (0.006), respectively. The 2-year chronic GVHD rate were 36% vs 48% (p=0.7), respectively. Cumulative incidence of relapse and non-relapse mortality at 1 year were 17% and 19% (p=0.59) and 20% and 18% (p=0.67) for MSD/MUD and Haplo cohorts, respectively. Event-free survival and overall survival at 1 year for the whole cohort were 62% (95% CI 54-71) and 68% (95% CI 59-76), respectively, with no significant differences between both cohorts. The most frequent cause of non-relapse related death was infection for both MSD/MUD (n= 5, 38%) and for Haplo (n=12, 48%).

Conclusions: PTCy as GVHD prophylaxis in HSCT from MSD, MUD and Haplo for patients with AML using mostly PB stem cells effectively prevents GVHD and provides comparable rates of relapse, NRM and survival. Acute GVHD II-IV and III-IV rates were markedly low in the MSD/MUD cohort. Prospective studies are needed to confirm these results and to assess the optimal immunosuppression combination for PTCy in the setting of PB stem cell transplants.

Disclosure: The authors have no conflicts of interest to declare.

P214 T-lymphocyte Transcriptional Signature in ECP-treated Paediatric Patients with Acute graft-versus-host Disease

Aisling M Flinn ^1,2, Janet Chou³, Anna Ehrlich¹, Xiao Nong Wang¹, Raif S Geha³, Andrew R Gennery^1,2

¹Newcastle University, Newcastle upon Tyne, United Kingdom, ²Great North Childrens’ Hospital, Newcastle upon Tyne, United Kingdom, ³Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States

Background: Acute graft-versus-host disease (aGVHD) remains a leading cause of morbidity and mortality following allogeneic haematopoietic stem cell transplantation (allo-HSCT). Extracorporeal photopheresis (ECP) treatment for aGVHD is believed to be immunomodulatory specifically targeting activated T-lymphocytes with in vitro evidence suggesting involvement of regulatory T-lymphocytes (Tregs). Our objective was to investigate cellular and transcriptional changes in T-lymphocytes in aGVHD treated with ECP.

Methods: Transcriptional analysis was performed on T-lymphocytes from 3 responding and 2 non-responding paediatric patients pre and post ECP for treatment of aGVHD following allo-HSCT. The Ion AmpliSeq Transcriptome Human Gene Expression Kit was utilized to generate barcoded libraries. Differential gene expression analysis was performed using the ampliSeqRNA plugin. Pathway analysis was done using Ingenuity Pathway Analysis (Qiagen). Immunophenotypic analysis for naïve T-lymphocytes (CD3⁺CD4⁺CD45RA⁺CD31⁺), Tregs (CD3⁺CD4⁺CD25^hiCD127^lo) and activated T-lymphocytes (CD3⁺CD4⁺HLA-DR⁺) was performed using the Fortessa X-20 flow cytometer.

Results: ECP responders demonstrated reduced frequency of activated T-lymphocytes and increased naive T-lymphocytes with treatment progression correlating with clinical improvement. Treg frequency increased in the ECP-responders; however, this occurred at different time points in treatment. In the evaluation of Treg function, allo-reactive T-lymphocyte proliferation initially declined in the ECP responders, increasing at the end of treatment, indicating most effective Treg suppression of T-lymphocyte proliferation mid-ECP treatment, and becoming less effective at the end. Non-responders demonstrated the opposite trend. The transcriptional profile of the ECP-responders identified significant downregulation in genes involved in effector T-lymphocyte (Teff) metabolism compared to that of the non-responders. Whole transcriptome analysis in responders pre- and post-ECP treatment identified significant downregulation of the ERRα (a metabolic regulator of Teffs) and GαS (important for Th1 and Th17 differentiation and function) T-lymphocyte activation pathways. ERRα downregulation in the setting of ECP therapy may reduce aGVHD-causing Teff production and function, and divert T-lymphocyte differentiation towards Treg or naive T-lymphocyte generation. There was reduced gene expression of cytokines associated with the pathogenesis of aGVHD (IL-3, IL-5, IL-26, IL-27). The Type I interferons (IFN) comprised the largest subtype of differentially expressed cytokines. Reduced type I IFNs in T-lymphocytes after a successful response to ECP parallels thymic recovery and increased naïve T-lymphocytes observed in these patients.

Conclusions: These findings indicate that the T-lymphocyte transcriptional signature from ECP responders is characterized by decreased expression of genes important for Teff function and a reduction in proinflammatory genes. These data suggest that ECP reduces T-lymphocyte activation, potentially via ERRα and GαS pathways. This transcriptional signature is previously unreported and may be unique to ECP therapy. Further evaluation in additional responding and non-responding ECP patients is required, as well as analysis to determine if ERRα and GαS downregulation are causative of these observed effects.

Disclosure: Educational grant from Mallinckrodt Pharmaceuticals

P215 Efficacy of low-dose Ruxolitinib as Savage Therapy in Heavily Pretreated Patients with Moderate/severe steroid-refractory Chronic graft-versus-host Disease

Yanmin Zhao, Jimin Shi, Yi Luo, Yamin Tan, Jian Yu, Huarui Fu, Xiaoyu Lai, He Huang

The First Affiliated Hospital, Zhejiang University, Hangzhou, China

Background: Moderate/severe chronic graft-versus-host disease (cGVHD) remains a devastating complication after allogeneic hematopoietic stem cell transplantation (allo-SCT), especially for the heavily pretreated patients. Inhibition of the Janus-associated kinases (JAK) with ruxolitinib (RUX) reduces GVHD in preclinical and clinical models. We aimed to assess the efficacy and safety of low-dose RUX in the treatment of moderate/severe steroid-refractory cGVHD (SR-cGVHD) after allo-SCT.

Methods: This retrospective study included 31 allograft recipients (males n=22; median age: 30 yrs (range: 17-56)) with moderate/severe SR-cGVHD in a single institution, who received RUX as ≥3nd line salvage between December 2017 and June 2019. The stem cell source was peripheral stem cells. The donors were from matched sibling donors (MSD, n = 7) and HLA-haploidentical related donors (HRD, n = 24). The regimens were based on the myeloablative BuCy regimen. ATG Fresenius 10mg/kg was applied to patients with HRD. The patients received cyclosporine A plus short-time MTX ± MMF as GVHD prophylaxis. For the salvage treatment of SR-cGVHD, RUX was administered orally at 5 mg twice daily for patients ≥ 50 kg or 5 mg once daily if < 50 kg.

Results: The median number of previous lines of therapy was 5 (range 3-8). Overall 21 patients achieved response (ORR, 67.7%), including 8 (25.8%) CR and 13 (41.9%) PR. The response (complete/partial) rate per organ was 94.7% for oral, 90.9% for cutaneous, 91.7% for ocular, 90.0% for hepatic, 66.7% for musculoskeletal, 55.5% for gastro-intestinal, 57.1% for scleroderma and 50.0% for pulmonary chronic GVHD (bronchitis obliterans, BO), respectively. Among the 21 responders, responses occurred at median time of 60 days after RUX and were sustained which enabled discontinuation (6/21, 28.6%) or reduction of steroids to physiologic doses (13/21, 61.9%). Among 31 patients in the study cohort, only five of patients (5/31, 16.1%) experienced at least one CMV reactivation, and no one develop CMV disease. Fifteen patients (5/31, 25.8%) experienced EBV reactivation, but no post-transplantation lymphoproliferative disorder was observed. Eight patients (8/31, 25.8%) were complicated with severe pulmonary infection >= 3 grade. The incidence of severe pulmonary infection was significantly higher in BO group than in non-BO group (46.67% vs. 6.25%, p=0.01). HBV Hepatitis B virus (HBV) was re-activated in two patients (6.45%). After a median follow-up of 325 days (range 48-654) after RUX, relapse of the underlying malignancy occurred in 14.3% (3/21) of the patients with SR-cGVHD. The 1-year overall survival estimate and 1-year non-relapse mortality after RUX was 73.6% (49.0%-87.7%, 95%CI) and 15.9% (1.0%-33.1%, 95%CI), respectively.

Conclusions: Low dose ruxolitinib in the real-life setting is an effective treatment option for GVHD, which could successfully spare long-term steroids use, with an ORR of 67.7% for refractory moderate/severe cGVHD, in heavily pretreated patients. However, lung is the worst responsive organ. And pulmonary infection events deserve more attention, especially in patients with bronchitis obliterans.

[Percent patients responding to RUX]

Disclosure: Nothing to declare.

P216 Restrictive use of Intravenous Antibiotics in Allogeneic SCT Pts with Fever due to Cytokine Release Syndrome Allows Microbiota Protection without Increase of Infections and TRM

Ernst Holler, Daniela Weber, Joachim Hahn, Cornelia Mittermaier, Klaus-Georg Kreitmeier, Andreas Hiergeist, Bernd Salzberger, Daniel Wolff, Andre Gessner, Wolfgang Herr, Matthias Edinger

University of Regensburg, Regensburg, Germany

Background: Loss of early microbiota diversity has been reported as a major risk factor of gastrointestinal GvHD and early mortality following allogeneic SCT. Use of intravenous broad spectrum antibiotics (ABX) is a major risk factor of microbiota damage but empiric immediate treatment is needed in pts with fever and the risk of neutropenic infections. As previously shown, most broad spectrum ABX induce severe microbiota damage; thus changes in strategy might be more helpful in microbiota protection than selection of individual ABX.

Methods: Therefore, we introduced a restrictive policy regarding use of ABX in pts with fever and a high likelihood of cytokine release syndrome (e.g. due to antithymocyte globuline) based on repeated careful clinical examination and defined risk criteria since 9/2017. Initiation of broad spectrum ABX was postponed to the next period of fever for 24hrs in these pts. We now compared 146 pts with standard use of ABX from 2014-2015 with a cohort of 130 consecutive pts treated according to the restricted policy.

Results: Advanced stages (41%) and unrelated donors (75%) were equally distributed between the 2 cohorts, all pts received rifaximin as an oral prophylaxis. Overall, the restricted strategy led to a significant reduction of the use of ABX prior to the day of SCT from 49.3% to 28.7% (p 0.003), which translated in a significantly delayed start of systemic ABX (3d before vs 1.8 d after SCT (p 0.000) and an overall reduced length of ABX treatment (21.2 vs 16.6 d, p 0.001) in the restricted use cohort. As a result, urinary indoxylsulfate levels at day 7 were significantly higher in the restricted use group indicating prolonged partial protection of commensal bacteria. Incidence of bacteremia was unchanged in both cohorts, and no increase in neutropenic sepsis (4.3 vs 3.3%) or early treatment related mortality until 30d (3.8% vs 0.8%) was observed. Incidence of GI GvHD grade 2-4 (13% vs 8%) and 1 yr TRM (16% vs 7%) even showed a trend for further reduction in the cohort receiving restricted ABX.

Conclusions: Overall, these data indicate that improved antibiotic stewardship may help to reduce microbiota damage in allogeneic SCT provided careful timely and continuous clinical supervision of pts is warranted.

Clinical Trial Registry: Not applicable

Disclosure: Ernst Holler - advisory board MaatPharma

all other authors nothing to declare.

P217 Extracorporeal Photopheresis (ECP) as first-line Treatment for Acute GVHD (AGVHD) in Pediatric Patients who underwent T-depleted Haploidentical Stem Cell Transplantation (APLO-HSCT)

Maria Speranza Massei ¹, Claudia Del Fante², Santina Recupero², Ilaria Capolsini¹, Cristina Mortellaro², Olivia Minelli¹, Marina Onorato¹, Nicola Albi¹, Elisa Pierini¹, Katia Perruccio¹, Elena Mastrodicasa¹, Grazia Gurdo¹, Carla Cerri¹, Francesco Arcioni¹, Mauro Marchesi¹, Cesare Perotti², Marco Zecca¹, Maurizio Caniglia¹

¹Santa Maria della Misericordia Hospital, Perugia, Italy, ²Fondazione IRCCS Policlinico San Matteo, Pavia, Italy

Background: Intensive immunosuppressive therapy administered for aGVHD is a risk factor for infections, disease relapse, organ failure and adversely affects quality of life. In the pediat