Unité de Greffes de moelle, Services des Maladies du Sang, CHRU, Lille, France

Correspondence to: Dr F Morschhauser, Services des Maladies du Sang, CHRU de Lille, 59037 Lille, France

The role of allogeneic BMT for follicular lymphoma remains to be established. From 1995 to 2000, 16 patients with follicular lymphoma underwent allogeneic BMT at our center. At the time of transplantation, two patients were in complete remission, 11 in partial remission and three had refractory disease. Fourteen patients were transplanted using a standard myeloablative conditioning regimen and two a nonmyeloablative conditioning regimen. With a median follow-up of 1184 days (range 403-1999 days) after BMT, 11 patients were alive, whereas five died of transplant-related mortality. Eight patients remained in CR 284+ to 1022+ days (median 560+ days) after BMT. Two patients relapsed 63 and 1073 days after BMT. They achieved a further complete remission after salvage treatment and remained alive 403 and 1224 days after BMT, respectively. One patient with autologous reconstitution had never been in CR after BMT. He was retreated with salvage chemotherapy but only achieved CR with subsequent rituximab treatment and was still alive, 1999 days after transplantation. The estimated 2-year overall survival and event-free survival rates were 68% and 55%, respectively. Age greater than 37 years at diagnosis, positive recipient CMV serology and ECOG performance status 1 at diagnosis were associated with shorter overall survival (P = 0.05, P = 0.009 and P = 0.03, respectively). Ann Arbor III-IV stage at diagnosis was associated with shorter event-free survival (P < 0.04). Allogeneic BMT seems to be effective for patients with follicular lymphoma. However, the relatively high rate of early transplant-related mortality emphasizes the need to define indications and use prospective protocols involving a less toxic transplant procedure.

Bone Marrow Transplantation (2002) 30, 229-234. doi:10.1038/sj.bmt.1703625

follicular lymphoma; bone marrow transplantation, graft-versus-leukemia

Follicular non-Hodgkin's lymphomas (FL), as defined by the REAL classification, are usually characterized by a slowly progressive clinical course, with a transient response on standard chemotherapy and a pattern of repeated relapses until the disease is ultimately progressive and fatal,¹ the median survival being 7 to 9 years.^2,3

Standard first-line treatment for advanced FL consists of an alkylating agent alone or in association with an anthracycline, with or without interferon alpha.⁴ Other approaches have been developed, mostly as secondary therapy, including purine analogs alone⁵ or in combination with alkylators⁶ or mitoxantrone.⁷ Although variable success can be obtained with high-dose cytotoxic therapy associated with autologous stem cell transplantation,^8,9 and more recently with anti-CD20 monoclonal antibody treatment,^10,11,12,13 the disease is still incurable and the most appropriate treatment remains to be clearly established.

As for other malignant hematological disorders, allogeneic bone marrow transplantation (BMT) seems to be a potentially curative treatment in FL with a probable graft-versus-lymphoma effect.¹⁴ This approach has generally been restricted to young patients with advanced low-grade lymphoma. Some groups have reported encouraging results with extended disease-free survivals.^{15,16,17,18,19,20} We report our single center experience of allogeneic BMT in patients with FL.

Patients and methods

Patients

Between October 1995 and October 2000, 16 patients from our center, CHRU (University Hospital) of Lille, France, underwent allogeneic BMT for the treatment of FL. Patient characteristics at diagnosis and at BMT are presented in Table 1. According to World Health Organization (WHO) classification,²¹ 13 patients had grade 1 FL, one had grade 2 FL and the remaining two patients had transformed FL. The classical t(14;18) chromosome translocation was observed in six of seven lymph node biopsies and 10 of 13 marrow smears where karyotyping was performed. Bcl2 protein expression was observed in seven of nine lymph node biopsies and bcl2-JH gene rearrangement was found in seven of nine and six of 10 marrow smears evaluated. According to Ann Arbor staging²² at diagnosis, 14 patients had stage III-IV and two had stage II. Thirteen patients had bone marrow infiltration at diagnosis, six with concomitant blood infiltration. One patient with transformed FL had liver infiltration without blood or marrow infiltration. Eight patients had bulky tumor defined as the presence of at least one of the following criteria: (tumor diameter 7 cm, pleural effusion or presence of more than one extra nodal localization). Four patients had serum LDH levels above the normal value and two had serum 2-microglobulin levels >3 mg/l. Initial therapy was based on chemotherapy alone (n = 11), initial chemotherapy followed by rituximab as salvage treatment (n = 4) or chemotherapy plus autologous transplant (n = 1) (Table 2). Median time from diagnosis to BMT was 293 days (range 160-1287 days).

Transplantation modalities

Patients (n = 14) who underwent a standard BMT procedure received marrow stem cell grafts. Donors were identical siblings (n = 13) and one locus HLA-mismatched related (n = 1). The conditioning regimens were fractionated total body irradiation (TBI, 12 Gy) plus cyclophosphamide (CPM) (60 mg/kg/day, 2 days) (n = 11) and other drug combinations without TBI (n = 3). The remaining two patients underwent nonmyeloablative BMT procedures and received identical sibling peripheral blood stem cell grafts with a donor lymphocyte infusion (DLI) (10 ´ 10⁷ CD3/kg) on day 100 post BMT. Their conditioning regimens were based on TBI at 6 Gy, low-dose CPM (30 mg/kg/day, 2 days) and antithymocyte globulin.

Graft-versus-host disease (GVHD) prophylaxis was based on cyclosporin A plus short methotrexate courses for all patients. Clinical criteria were used for diagnosis of veno-occlusive disease of the liver.^23,24 Acute and chronic GVHD were scored according to standard criteria.²⁵

Statistical analysis

The analysis was performed on the reference date of 15 July 2001. Overall survival (OS) was defined as the time elapsed from BMT to death, whatever the cause of death. Relapse of lymphoma was defined as the reappearance of lymphoma cell infiltration after sustained CR with or without evidence of autologous reconstitution. Transplant related-mortality (TRM) was defined as death resulting from the graft procedure without evidence of disease progression. Event-free survival (EFS) was defined as survival with no evidence of relapse. All censored criteria were calculated from the time of transplantation. Distributions over time were estimated by the Kaplan-Meier product limit method.²⁶ Estimated 2-year event rates were reported because the number of events beyond 2 years was insufficient for accurate estimates. The log-rank statistic²⁷ was used to test the prognostic value of patient characteristics at diagnosis and at BMT for the occurrence of the event. Multivariable analysis was not done because of the small number of patients. SPSS software (9.0, Chicago, IL, USA) was used.

Results

Engraftment and transplantation toxicity

One patient died 18 days after BMT without neutrophil engraftment. All other patients experienced a sustained neutrophil count 0.5 ´ 10⁹ cells/l between 18 and 43 days after transplant (median 22 days). Fourteen patients reached spontaneous platelet counts of 50 ´ 10⁹ platelets/l within a median of 21 days after BMT (range 15-158). No secondary graft rejection was observed. Chimerism was assessed by means of ABO blood grouping (n = 4), by bone marrow karyotype (n = 3) or by DNA polymorphism (n = 4). Eight of those patients had total donor chimerism, two had partial chimerism and one had autologous reconstitution. Ten patients (62%) developed acute (grade II) GVHD, including two with grade III-IV disease. Four of the 13 assessable patients developed chronic GVHD, including one with extensive disease. One patient developed VOD and two developed interstitial pneumonia.

Patient outcome

One patient was lost to follow-up 284 days after transplantation, at which time he was alive and in CR. At the reference date of 15 July 2001, median follow-up from BMT was 1184 days (range 403-1999 days), and 11 patients were alive and in CR. Median survival time was not reached. Two patients relapsed 63 and 1073 days after transplantation. They achieved subsequent CR after localized radiotherapy plus DLI (1 ´ 10⁷ CD3/kg), and rituximab alone, respectively, and remained alive 403 and 1224 days after BMT. The patient with autologous reconstitution had never been in CR after BMT. He was retreated from day 523 post BMT with salvage chemotherapy but only achieved CR with subsequent rituximab and was still alive, 1999 days after transplantation. Two patients with refractory disease before BMT underwent nonmyeloablative transplantation. They were still alive and in CR 614 and 711 days after BMT, respectively. Five patients died between day 18 and day 255 after transplantation, of interstitial pneumonia (n = 2), viral infection (n = 1), multi-organ failure (n = 1) and extensive chronic GVHD (n = 1).

The estimated 2-year OS and EFS were 68 ± 11% and 55 ± 12%, respectively (Figure 1). None of the following variables at diagnosis seemed to influence the outcome of BMT: sex, blood and/or marrow infiltration, constitutional symptoms, serum 2-microglobulin (2 mg/l vs >2 mg/l), serum LDH and/or at BMT ( normal value vs > normal value), time from diagnosis to BMT (293 days vs >293 days), prior anti-CD 20 antibody treatment, disease status at BMT, donor CMV serology and the use of TBI in the conditioning regimen. OS was adversely influenced by age greater than 37 years at diagnosis, positive recipient CMV serology and ECOG performance status 1 at diagnosis (P = 0.05, P = 0.009 and P = 0.03, respectively). Only initial Ann Arbor III-IV stage was found to adversely influence EFS (P < 0.04).

Discussion

We observed a 2-year OS rate of 68% with a plateau after 2 years and a 2-year EFS rate of 55%. Our results seemed to be slightly better than those reported by others. Van Besien et al¹⁸ reported 3-year OS and EFS rates of 49% and 49%, in 113 patients who underwent allogeneic BMT from HLA-identical sibling donors for advanced low-grade lymphoma, including 83 FL. Stein et al²⁰ reported a 3-year OS of 30% in 15 patients with follicular small cleaved cell lymphoma. Other groups have also reported a large proportion of long-term remissions.^15,17 The large number of patients who had chemo-sensitive disease at BMT (only 3/16 patients had refractory disease), the short time interval from lymphoma diagnosis to BMT (median 293 days) and the relative short follow-up time, probably contributed to the better OS and EFS rates in our study.

As reported by others,^18,28 older age and positive recipient CMV serology were significantly associated with a shorter survival. In contrast, disease status before BMT was not found to influence outcome of BMT. The engraftment and post-transplantation complications in our study were similar to those reported in the literature.^15,18,29,30 However, the five recorded deaths occurred earlier after BMT (between day 18 and day 255) and were directly due to the transplantation procedure. Two out of 10 evaluable long-term survivors relapsed 63 and 1073 days after transplantation and the remaining patient, with autologous reconstitution, had never been in CR after BMT. These data, despite the small number of patients, confirm what has been reported by others. Verdonck et al,¹⁷ in a study comparing 10 patients with allogeneic BMT to 18 patients with autologous BMT, observed that the probability of disease progression after allogeneic transplant was 0% vs 83% for autologous recipients (P = 0.002) and that the 2-year progression-free survival was 68% and 22%, respectively (P = 0.049). Van Besien et al¹⁸ reported a relapse probability of 16% and a TRM probability of 28% in patients with allogeneic BMT for advanced low-grade lymphoma. Attal et al,¹⁹ in a retrospective case-control analysis of 216 patients (72 allogeneic BMT and 144 autologous BMT), observed that allogeneic transplants had a significantly lower relapse rate of 12% at 60 months with a plateau, compared with 55% after autologous transplantation, without an apparent plateau (P < 0.001).

FL is an indolent disease with a median survival of 7 to 9 years.^2,3 Patients responding to initial therapy have a median remission duration of 3 to 5 years. However, after relapse, the median progression-free survival is less than 18 months with salvage therapy.³¹ The high early TRM reduces the potential efficacy of standard allogeneic BMT procedures (with a myeloablative conditioning regimen), especially in those patients with a relatively long survival with conventional treatment. Thus, standard allogeneic BMT does not seem to be indicated as first-line therapy in patients with FL but should be proposed later in the disease course, after the failure of other therapeutic options.

Myeloablative conditioning regimens considerably increase post-transplant morbidity and mortality. In order to reduce post-transplant complications, a new strategy has recently been explored, consisting of nonmyeloablative conditioning where the goal is not to eradicate the malignant cells, but to provide sufficient immunosuppression to achieve allogeneic engraftment and induce a graft-versus-lymphoma effect.^32,33,34 Two of our patients with refractory disease before BMT underwent non-myeloablative transplantation with DLI on day 100. They achieved CR and were still alive 614 and 711 days after BMT. Another patient who relapsed after BMT also received DLI and achieved a further CR. These observations, together with what has been reported by others,^32,35,36 suggest that a beneficial immune-mediated graft-versus-leukemia (GVL) effect of allogeneic BMT probably exists for FL. The major obstacle to successful allogeneic bone marrow transplantation with non-myeloablative preparative regimens remains the risk of severe GVHD. The separation of GVL effect from GVHD is being explored and several strategies have been proposed, including in vivo T depletion with anti-CD52 monoclonal antibodies,³⁷ infusion of escalating doses of T lymphocytes,³⁸ CD8⁺-depleted donor lymphocyte infusion³⁹ or HSV-TK-transduced donor lymphocytes which can be medically ablated in patients developing GVHD.⁴⁰

In conclusion, this study shows that allogeneic BMT provides the opportunity of long-term survival in patients with FL. Nevertheless, as patients with FL have prolonged survival with conventional treatments, the early TRM rate we and others observed suggests that BMT should only be indicated in patients with progressive disease after other therapeutic options. Further improvement in tolerance of allogeneic nonmyeloablative stem cell transplantation seems a key issue in the treatment of FL.

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Figure 1 (a) Overall survival and (b) event-free survival of the 16 patients.

Table 1 Initial characteristics at diagnosis and at BMT in the 16 patients

Table 2 Prior treatment, type and year of BMT, disease status at BMT and outcome of the 16 patients