Introduction

Myelodysplastic syndromes (MDSs) are a heterogeneous group of neoplastic BM disorders characterized by ineffective hematopoiesis, peripheral blood cytopenias and the potential for evolution to AML.¹ The only potential curative approach for patients with MDS is allogeneic hematopoietic cell transplantation (HCT). Disease progression remains the leading cause of mortality after transplantation, occurring in 5–40% of HCT recipients, depending upon disease stage at HCT.² The optimal management for recurrent MDS after HCT has not been defined. Available strategies include withdrawal of immunosuppressive treatment in an attempt to optimize a graft-versus-leukemia effect, chemotherapy, hematopoietic growth factors, immunomodulators,^{3, 4} second HCT^{5, 6} or donor lymphocyte infusion (DLI).^{7, 8}

While DLI represents the treatment of choice for patients with recurrent chronic myelogenous leukemia after HCT, with more than 75% complete responses among patients in chronic phase with cytogenetic or molecular relapse,^{8, 9, 10, 11} sustained CRs are attained in only a minority of patients with other diagnoses.^{8, 9, 12, 13, 14} Only a few patients treated with DLI for relapsed MDS after HCT have been reported to date.⁷ We reviewed results in 16 patients treated with DLI for MDS in hematologic relapse after HCT at our center, and summarized previous reports of DLI for recurrent MDS after HCT.

Patients and methods

From March 1993 to February 2004, 16 patients with recurrent MDS after allogeneic HCT were treated with DLI at our center. Characteristics of patients at the time of transplantation are summarized in Table 1. Patient characteristics, international prognostic scoring system (IPSS) classification at diagnosis, FAB classification at the time of DLI, DLI cell dose and donor types are detailed in Table 2.

Table 1 - Patient characteristics.

Full table

Table 2 - DLI characteristics.

Full table

Donors were HLA-identical siblings in 12 cases and HLA-matched unrelated individuals in four cases. The hematopoietic stem cell source consisted of BM in 12 patients and peripheral blood progenitors cells (PBPC) in four patients. Fifteen patients received myeloablative-conditioning regimens and one patient received a nonmyeloablative-conditioning regimen before HCT. Transplant regimens and GVHD prophylaxis are shown in Table 1. Among DLI donors, six were treated with G-CSF (10 g kg^-1 per day s.c.) for 4 days before leukapheresis, while in 10 cases donor lymphocytes were collected without cytokine manipulation.

Relapse of MDS was defined as BM myeloblast count >5% by morphologic or flow cytometric analysis, recurrence of cytopenias with dysplastic features, with or without recurrent cytogenetic abnormalities. Complete response after DLI was defined as normalization of complete blood cell counts, disappearance of previous cytogenetic abnormalities, disappearance of residual recipient cells in the marrow, and normal BM by pathologic and flow cytometric criteria. The cause of death was considered AML or MDS if malignant cells were present at the time of death. Acute and chronic GVHD were classified as described previously.^{15, 16}

Given the small number of patients, most results are descriptive in nature. The only statistical analyses included the impact of GVHD on response, where GVHD was modeled as a time-dependent covariate for the time-to-event end point of response, and the assessment of the impact of response on overall survival, where response was modeled as a time-dependent covariate on the time-to-event end point of mortality. Each of these analyses was conducted using Cox regression.

Results

Patients and disease characteristics at the time of DLI

Table 2 summarizes patient and DLI characteristics. Fourteen patients had hematologic evidence of recurrent MDS at the time of DLI. Two patients were in CR after chemotherapy and before DLI and could not be evaluated for response. The median time from HCT to relapse was 7 (range, 2.4–24) months. Disease stage at DLI was refractory anemia (RA) (n=1), RA with ring sideroblasts (RARS) (n=2), RA with excess of blasts (RAEB) (n=7), RAEB in transformation (n=1), AML (n=3) and AML in CR after chemotherapy (n=2). Cytogenetic analysis at the time of relapse revealed normal karyotype (n=4), complex karyotype (n=5), monosomy 7 (n=3), other clonal abnormalities (n=4). Four patients received therapy with -interferon before DLI. Three patients received induction chemotherapy, which was followed by remission in two. The total dose of DLI ranged from 0.1 10⁸ to 1.5 10⁸ CD3+ cells kg^-1, with a median dose of 1 10⁸ CD3+ cells kg^-1. One patient received 2.45 10⁶ mononuclear cells, and the CD3+ cell dose was not available. Twelve patients received a single DLI, and four received two infusions given at 0.5–1.4 months after the first infusion, respectively. DLI-induced cytopenia could not be evaluated, since most patients had cytopenia at the time of DLI. Cytopenia was not observed in the two patients in CR at the time of DLI.

Response to DLI and survival

Outcomes of patients after DLI are summarized in Table 3. CR was attained in 3 of the 14 (21%) patients who could be evaluated. In these cases, CR was documented at days 39, 41 and 58 after DLI. One of these patients had recurrent MDS at 5.4 months after DLI and died with AML 5.6 months following DLI. The other two survived with CR for 65 and 68 months after DLI, respectively, and both died with pneumonia. Three non-responders received a second HCT, and died 8, 18 and 20 months after DLI, respectively, with persistent MDS. The remaining 10 non-responders died with persistent MDS between 0.1 and 15 months after DLI (Table 3).

Table 3 - Outcome after DLI.

Full table

Survival is shown in Figure 1. When treated as a time-dependent covariate, response to DLI was associated with a decreased hazard of mortality compared to lack of response, but the difference was not statistically significant (hazard ratio (HR)=0.17; 95% confidence interval (CI) 0.02–1.37; P=0.09). Figure 1 shows overall survival after DLI for the entire group. Two of three responders developed grades III–IV acute GVHD following HCT (but before DLI) compared to 0 of 11 non-responders (P=0.03, Fisher's exact test). Three of five patients with high-risk IPSS at diagnosis responded compared to 0 of 9 patients with intermediate-risk IPSS (P=0.03, Fisher's exact test). All three responders and 8 out of 11 non-responders had excess of blasts (>5%) at the time of DLI.

Figure 1.

Kaplan–Meier estimate of survival after DLI for relapsed MDS. DLI=donor lymphocyte infusion; MDS=myelodysplastic syndrome.

Full figure and legend (8K)

GVHD after DLI

Patients received no GVHD prophylaxis after DLI. Treatment decisions for GVHD after DLI were based on the attending physician's assessment of the severity of acute GVHD, and the usual initial treatment was prednisone at 1–2 mg kg^-1 per day for 7–14 days followed by tapering of steroid doses. Treatment for extensive chronic GVHD was generally with prednisone alone at 1 mg kg per day followed by a taper to alternate day corticosteroids. Calcineurin inhibitor was generally added if no response of either acute or chronic GVHD was observed within 72 h after initiation of treatment with prednisone, or sooner if GVHD progressed. Several interventions were used if acute or chronic GVHD did not improve after initial treatment, including administration of psoralen and ultraviolet A radiation (UVA) (for refractory skin involvement), mycophenolate mofetil and extracorporeal photopheresis. Treatment of chronic GVHD was continued for at least 9 months, unless changes in therapy were clinically indicated. Supportive care for patients with chronic GVHD was consistent with recent report recommendations.¹⁷

Six patients (37.5%) developed acute GVHD after DLI (1 grade I, 1 grade II, 3 grade III and 1 grade IV). The median time to development of acute GVHD was 28 days after DLI. Acute GVHD occurred in all 3 responders (2 grade III and 1 grade IV) before clinical response, and in 3 of 11 non-responders (1 grade I, 1 grade II and 1 grade III) (Table 3). Attainment of CR was more likely among patients who developed grades II–IV acute GVHD after DLI (modeled as a time-dependent covariate) when compared to patients with grades 0–I acute GVHD (P=0.01 with an infinite HR). Five patients (31%) developed extensive chronic GVHD, three among responders (at days 151, 160 and 202) and two among non-responders (at days 30 and 106) (Table 3).

One long-term responder developed serious chronic GVHD,¹⁸ characterized by severe skin and joint contractures. The responder also had liver, mouth and eye involvement, requiring 19 months of immunosuppressive treatments including prednisone, mycophenolate mofetil, CYA, PUVA and extracorporeal photopheresis. The second long-term responder had extensive chronic GVHD of skin, mouth and eyes, recurrent CMV, herpes simplex esophagitis and disseminated herpes zoster virus reactivations, recurrent lung infections and pulmonary aspergillosis that culminated in pulmonary failure, leading to death. This patient received 20 months of immunosuppressive treatment including prednisone, mycophenolate mofetil, CYA and PUVA. Both patients continued treatment with prednisone until death.

Discussion

Therapeutic options for patients with MDS relapsing after HCT are limited. While potentially curative approaches in this setting include second transplant and DLI, it remains unclear who might benefit from these interventions.

Previous investigators reported response rates of 14–40% to DLI in smaller cohorts of patients with recurrent MDS.^{7, 10, 11, 14, 19} Depil et al.⁷ reported outcomes in a series of 14 patients and observed a response rate of 14%, with the two responders remaining disease free for more than 5 years after DLI. Shiobara et al.¹⁴ observed 27% complete responses among 11 patients treated with DLI, including pediatric patients, with one patient (9%) surviving without MDS for more than 3 years. Response rates of 25 and 40%, respectively, were reported by Kolb et al.¹¹ and Collins et al.¹⁰ A preliminary report from a European survey of DLI for AML and MDS found a 41% response rate, which included patients with de novo AML and patients receiving chemotherapy before DLI.²⁰

In the present study, complete responses to DLI were observed in 3 of 14 patients (21%) who could be evaluated, and 2 (14%) were disease free for greater than 5 years. Table 4 summarizes prior reported studies and the current series. While the small number of responders limits the strength of conclusions, patients who developed grades II–IV acute GVHD after DLI were more likely to respond than patients who had grades 0–I acute GVHD. In addition, 2 of 3 responders had a prior history of grades III–IV acute GVHD after HCT compared to 0 of 11 non-responders. The relationship between pre-DLI GVHD and response to DLI is not well defined, and controversial results have been reported.^{10, 11} The present correlation of grades II–IV acute GVHD after DLI and response to DLI is consistent with the findings of previous studies.^{12, 21}

Table 4 - Summary of previous reports and current series of treatment with DLI for recurrent MDS.

Full table

The use of G-CSF-mobilized DLI did not appear to influence outcomes in our series, in agreement with previous reports in which G-CSF mobilization did not seem to significantly influence the rates of cytopenia, response or GVHD after DLI.^{22, 23} Nonetheless, in the absence of results of randomized trials, it remains to be determined whether the outcomes after G-CSF-mobilized DLI are different from standard DLI.

Three of five patients with high-risk IPSS responded to DLI compared to none of the nine patients with intermediate-risk IPSS in our series, and all three responders had excess blasts (>5%) at the time of DLI. This finding may seem counterintuitive, since low tumor burden is a predictor of response to DLI.²¹ Nevertheless, besides tumor burden, the underlying disease also plays a major role in the response to DLI, and since MDS is a heterogeneous group of hematologic disorders, it is plausible that subsets of patients have an increased sensitivity to graft-versus-leukemia effects. For example, treatment response might be impacted by cytogenetics;^{21, 24} however, the number of patients in our study was too small to determine such an effect after DLI. Additionally, several tumor-associated antigens, such as BMI1,²⁵ PRAME,²⁶ and WT1,^{27, 28} whose expression increases in parallel with disease progression have been identified in MDS. The aberrant expression of WT1 in BM of MDS patients is frequently associated with cellular^{29, 30} and humoral^{31, 32} WT1-specific immune responses. Humoral and cellular autoimmune responses have also been detected against BMI1 in patients with hepatocellular carcinoma,³³ and against PRAME in AML patients.³⁴ One could speculate that the superior response to DLI observed in the high-risk IPSS patients might be related to the higher expression of tumor-associated antigens in this group, which could render the neoplastic clone more susceptible to immunologic attack after DLI. The use of PBSC, when compared with BM, as the source of stem cells for HCT, has been associated with lower treatment failure rates and improved outcome for all MDS subgroups except RA patients.³⁵ This observation suggests that increased GVL reactivity attained with the use of PBSC might not influence the outcome for patients with early MDS.

Our findings of durable responses to DLI limited to patients with advanced MDS, if confirmed by other studies, suggest that patients with recurrent low-risk MDS after HCT may not benefit from DLI and should be offered participation in clinical trials.

Therapy with hypomethylating agents, such as 5-aza-2'-deoxycytidine, with or without subsequent DLI, deserves further investigation, considering that its activity appears to involve the expression of tumor-associated antigens in patients with MDS or AML³⁶ or other malignancies.^{37, 38} Moreover, upregulation of HLA class I and co-stimulatory molecules have been documented in melanoma cell lines after exposure to 5-aza-2'-deoxycytidine, suggesting that this class of drugs may have a role as adjuvants in immunotherapy.³⁷

Although definitive conclusions cannot be extracted from the current study or from other small retrospective studies, some preliminary points should be highlighted (Table 4). Combining the results of the current series and the prior reported series, 62 patients have received DLI for recurrent MDS after HCT. Among 58 patients who could be evaluated, CR was attained in 15 (26%), and 5 of the 15 survived for at least 3 years after DLI without MDS. The incidence rates of acute and chronic GVHD varied from 34 to 60% and 14 to 33%, respectively.

In summary, DLI appears to induce long-term remission in a small subset of MDS patients. However, severe GVHD and its associated immunodeficiency accounts for high morbidity and mortality. Further efforts should be directed toward exploring new therapies in a multicenter setting. Enrollment in clinical trials should be encouraged, especially for patients with recurrent low-risk MDS after HCT. Finally, if the cancer stem cell theory^{39, 40} holds true for MDS, future efforts should focus on infusion of donor lymphocytes enriched for T cells targeting polymorphic minor histocompatibility antigens or neoplastic antigens⁴¹ expressed in myelodysplastic stem cells, which have yet to be identified.

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Acknowledgements

We thank the staff of the Long-Term Follow-Up for invaluable assistance with data collection, and Helen Crawford and Bonnie Larson for typing the article. We are also very grateful to our patients for their participation in clinical trials and our attending and medical staff for their excellent care provided to patients and families. Supported in part by grants CA78902, CA18029, CA15704, CA106512, HL82941 and HL36444, from the NIH, DHHS, Bethesda, MD, USA.