Splenic irradiation before hematopoietic stem cell transplantation for chronic myeloid leukemia: long-term follow-up of a prospective randomized study.

In the context of discussions on the reproducibility of clinical studies, we reanalyzed a prospective randomized study on the role of splenic irradiation as adjunct to the conditioning for hematopoietic stem cell transplantation (HSCT) for chronic myeloid leukemia (CML). Between 1986 and 1989, a total of 229 patients with CML were randomized; of these, 225 (98 %; 112 with, 113 without splenic irradiation) could be identified in the database and their survival updated. Results confirmed the early findings with no significant differences in all measured endpoints (overall survival at 25 years: 42.7 %, 32.0-52.4 % vs 52.9 %, 43.2-62.6 %; p = 0.355, log rank test). Additional splenic irradiation failed to reduce relapse incidence. It did not increase non-relapse mortality nor the risk of late secondary malignancies. Comforting are the long-term results from this predefined consecutive cohort of patients: more than 60 % were alive at plus 25 years when they were transplanted with a low European Society for Blood and Marrow Transplantation (EBMT) risk sore. This needs to be considered today when treatment options are discussed for patients who failed initial tyrosine kinase inhibitor therapy and have an available low risk HLA-identical donor.

Efficacy and outcome of allogeneic transplantation in IgD and nonsecretory myeloma. A report on behalf of the Myeloma Subcommittee of the Chronic Malignancies Working Party of the European Group for Blood and Marrow Transplantation.

We have recently reported on the outcome of autologous transplantation in the rare myelomas (IgD, IgE, IgM, and nonsecretory [NS]) but there is no real information on the outcome of these conditions after allogeneic transplantation. We used the European Group for Blood and Marrow Transplantation myeloma database to compare the outcomes after allogeneic transplantation of 1354 common myelomas (IgG, IgA, and light chain myeloma) with the outcome in 26 IgD myelomas and 52 NS myelomas. There was little difference between common and the IgD and NS myeloma patients with respect to prognostic factors although the IgD group had a higher beta 2 microglobulin at diagnosis, shorter time to transplantation, and more T cell depletion. IgD and NS patients had a significantly greater achievement of complete remission at conditioning but this did not translate into equivalent progression-free survival and overall survival for the IgD patients although the NS outcome was very similar to that of common myeloma. The PFS and OS of IgD, common, and NS myelomas appear similar after allogeneic transplantation, despite a tendency for higher early relapse rate in IgD myeloma. Allogeneic transplantation may, therefore, be an option to investigate in prospective observational studies.

Autologous hematopoietic stem cell transplantation vs intravenous pulse cyclophosphamide in diffuse cutaneous systemic sclerosis: a randomized clinical trial.

IMPORTANCE: High-dose immunosuppressive therapy and autologous hematopoietic stem cell transplantation (HSCT) have shown efficacy in systemic sclerosis in phase 1 and small phase 2 trials. OBJECTIVE: To compare efficacy and safety of HSCT vs 12 successive monthly intravenous pulses of cyclophosphamide. DESIGN, SETTING, AND PARTICIPANTS: The Autologous Stem Cell Transplantation International Scleroderma (ASTIS) trial, a phase 3, multicenter, randomized (1:1), open-label, parallel-group, clinical trial conducted in 10 countries at 29 centers with access to a European Group for Blood and Marrow Transplantation-registered transplant facility. From March 2001 to October 2009, 156 patients with early diffuse cutaneous systemic sclerosis were recruited and followed up until October 31, 2013. INTERVENTIONS: HSCT vs intravenous pulse cyclophosphamide. MAIN OUTCOMES AND MEASURES: The primary end point was event-free survival, defined as time from randomization until the occurrence of death or persistent major organ failure. RESULTS: A total of 156 patients were randomly assigned to receive HSCT (n = 79) or cyclophosphamide (n = 77). During a median follow-up of 5.8 years, 53 events occurred: 22 in the HSCT group (19 deaths and 3 irreversible organ failures) and 31 in the control group (23 deaths and 8 irreversible organ failures). During the first year, there were more events in the HSCT group (13 events [16.5%], including 8 treatment-related deaths) than in the control group (8 events [10.4%], with no treatment-related deaths). At 2 years, 14 events (17.7%) had occurred cumulatively in the HSCT group vs 14 events (18.2%) in the control group; at 4 years, 15 events (19%) had occurred cumulatively in the HSCT group vs 20 events (26%) in the control group. Time-varying hazard ratios (modeled with treatment × time interaction) for event-free survival were 0.35 (95% CI, 0.16-0.74) at 2 years and 0.34 (95% CI, 0.16-0.74) at 4 years. CONCLUSIONS AND RELEVANCE: Among patients with early diffuse cutaneous systemic sclerosis, HSCT was associated with increased treatment-related mortality in the first year after treatment. However, HCST conferred a significant long-term event-free survival benefit. TRIAL REGISTRATION: isrctn.org Identifier: ISRCTN54371254.

High-dose imatinib versus high-dose imatinib in combination with intermediate-dose cytarabine in patients with first chronic phase myeloid leukemia: a randomized phase III trial of the Dutch-Belgian HOVON study group.

Despite the revolutionary change in the prognosis of chronic myeloid leukemia (CML) patients with the introduction of imatinib, patients with resistant disease still pose a considerable problem. In this multicenter, randomized phase III trial, we investigate whether the combination of high-dose imatinib and intermediate-dose cytarabine compared to high-dose imatinib alone, improves the rate of major molecular response (MMR) in newly diagnosed CML patients. This study was closed prematurely because of declining inclusion due to the introduction of second generation tyrosine kinase inhibitors and only one third of the initially required patients were accrued. One hundred nine patients aged 18-65 years were randomly assigned to either imatinib 800 mg (n = 55) or to imatinib 800 mg in combination with two successive cycles of cytarabine 200 mg/m(2) for 7 days (n = 54). After a median follow-up of 41 months, 67 % of patients were still on protocol treatment. The MMR rate at 12 months was 56 % in the imatinib arm and 48 % in the combination arm (p = 0.39). Progression-free survival was 96 % after 1 year and 89 % after 4 years. Four-year overall survival was 97 %. Adverse events grades 3 and 4 were more common in the combination arm. The addition of intermediate-dose of cytarabine to imatinib did not improve the MMR rate at 12 months. However, the underpowering of the study precludes any definitive conclusions. This trial is registered at www.trialregister.nl (NTR674).

Myeloid leukemic progenitor cells can be specifically targeted by minor histocompatibility antigen LRH-1-reactive cytotoxic T cells.

CD8(+) T cells recognizing minor histocompatibility antigens (MiHAs) on leukemic stem and progenitor cells play a pivotal role in effective graft-versus-leukemia reactivity after allogeneic stem cell transplantation (SCT). Previously, we identified a hematopoiesis-restricted MiHA, designated LRH-1, which is presented by HLA-B7 and encoded by the P2X5 purinergic receptor gene. We found that P2X5 is significantly expressed in CD34(+) leukemic subpopulations from chronic myeloid leukemia (CML) and acute myeloid leukemia (AML) patients. Here, we demonstrate that LRH-1-specific CD8(+) T-cell responses are frequently induced in myeloid leukemia patients following donor lymphocyte infusions. Patients with high percentages of circulating LRH-1-specific CD8(+) T cells had no or only mild graft-versus-host disease. Functional analysis showed that LRH-1-specific cytotoxic T lymphocytes (CTLs) isolated from 2 different patients efficiently target LRH-1-positive leukemic CD34(+) progenitor cells from both CML and AML patients, whereas mature CML cells are only marginally lysed due to down-regulation of P2X5. Furthermore, we observed that relative resistance to LRH-1 CTL-mediated cell death due to elevated levels of antiapoptotic XIAP could be overcome by IFN-gamma prestimulation and increased CTL-target ratios. These findings provide a rationale for use of LRH-1 as immunotherapeutic target antigen to treat residual or persisting myeloid malignancies after allogeneic SCT.

Allogeneic hematopoietic stem cell transplantation for adult patients with t(4;11)(q21;q23) KMT2A/AFF1 B-cell precursor acute lymphoblastic leukemia in first complete remission: impact of pretransplant measurable residual disease (MRD) status. An analysis from the Acute Leukemia Working Party of the EBMT.

Adult B-cell precursor acute lymphoblastic leukemia (BCP-ALL) with t(4;11)(q21;q23);KMT2A/AFF1 is a poor-prognosis entity. This registry-based study was aimed to analyze outcome of patients with t(4;11) BCP-ALL treated with allogeneic hematopoietic stem cell transplantation (alloHSCT) in first complete remission (CR1) between 2000 and 2017, focusing on the impact of measurable residual disease (MRD) at the time of transplant. Among 151 patients (median age, 38) allotransplanted from either HLA-matched siblings or unrelated donors, leukemia-free survival (LFS) and overall survival (OS) at 2 years were 51% and 60%, whereas relapse incidence (RI) and non-relapse mortality (NRM) were 30% and 20%, respectively. These results were comparable to a cohort of contemporary patients with diploid normal karyotype (NK) BCP-ALL with equivalent inclusion criteria (n = 567). Among patients with evaluable MRD pre-alloHSCT, a negative status was the strongest beneficial factor influencing LFS (hazard ratio [HR] = 0.2, p < 0.001), OS (HR = 0.14, p < 0.001), RI (HR = 0.23, p = 0.001), and NRM (HR = 0.16, p = 0.002), with a similar outcome to MRD-negative NK BCP-ALL patients. In contrast, among patients with detectable pretransplant MRD, outcome in t(4;11) BCP-ALL was inferior to NK BCP-ALL (LFS: 27% vs. 50%, p = 0.02). These results support indication of alloHSCT in CR1 for t(4;11) BCP-ALL patients, provided a negative MRD status is achieved. Conversely, pre-alloHSCT additional therapy is warranted in MRD-positive patients.

Efficacy of escalated imatinib combined with cytarabine in newly diagnosed patients with chronic myeloid leukemia.

BACKGROUND: In order to improve the molecular response rate and prevent resistance to treatment, combination therapy with different dosages of imatinib and cytarabine was studied in newly diagnosed patients with chronic myeloid leukemia in the HOVON-51 study. DESIGN AND METHODS: Having reported feasibility previously, we hereby report the efficacy of escalated imatinib (200 mg, 400 mg, 600 mg or 800 mg) in combination with two cycles of intravenous cytarabine (200 mg/m(2) or 1000 mg/m(2) days 1 to 7) in 162 patients with chronic myeloid leukemia. RESULTS: With a median follow-up of 55 months, the 5-year cumulative incidences of complete cytogenetic response, major molecular response, and complete molecular response were 89%, 71%, and 53%, respectively. A higher Sokal risk score was inversely associated with complete cytogenetic response (hazard ratio of 0.63; 95% confidence interval, 0.50-0.79, P<0.001). A higher dose of imatinib and a higher dose of cytarabine were associated with increased complete molecular response with hazard ratios of 1.60 (95% confidence interval, 0.96-2.68, P=0.07) and 1.66 (95% confidence interval, 1.02-2.72, P=0.04), respectively. Progression-free survival and overall survival rates at 5 years were 92% and 96%, respectively. Achieving a major molecular response at 1 year was associated with complete absence of progression and a probability of achieving a complete molecular response of 89%. CONCLUSIONS: The addition of intravenous cytarabine to imatinib as upfront therapy for patients with chronic myeloid leukemia is associated with a high rate of complete molecular responses (Clinicaltrials.Gov Identifier: NCT00028847).

Matched unrelated donor stem cell transplant in 131 patients with follicular lymphoma: an analysis from the Lymphoma Working Party of the European Group for Blood and Marrow Transplantation.

Matched unrelated donor stem cell transplantation (MUD-SCT) provides the only curative option for patients with follicular lymphoma (FL) who fail conventional therapies and do not have a sibling donor. The purpose of this study was to analyse the outcome of patients with FL treated with MUD-SCT included in the European Group for Blood and Marrow Transplantation registry. 131 patients treated with reduced-intensity conditioning (RIC, n = 87) or conventional myeloablative (CONV, n = 44) MUD-SCT between 2000 and 2005 were included. Median time from diagnosis to MUD-SCT was 47 months and the median number of previous therapeutic regimens was 4 (previous autograft: 47%). RIC recipients were significantly older, with a longer interval from diagnosis to MUD-SCT and had failed a previous autograft more frequently than CONV recipients. Non-relapse mortality (NRM) was 24% and 30% at 100-d and 1-year, respectively. After a median follow-up of 36 months, 17% of the patients developed disease progression, the 3-year progression-free survival (PFS) being 47%. Three-year overall survival (OS) for the whole series was 51%. On multivariate analysis, RIC regimens were associated with at lower NRM and a significantly longer PFS and OS. This retrospective study demonstrated that MUD-SCT results, even in heavily pre-treated populations, in a meaningful PFS and OS.

KIR2DS5 is associated with leukemia free survival after HLA identical stem cell transplantation in chronic myeloid leukemia patients.

BACKGROUND: Alloreactive NK cells play a role in tumor eradication after allogeneic HLA mismatched stem cell transplantation (SCT). The effect of NK alloreactivity in HLA identical SCT is still under debate and in particular in transplantation for chronic myeloid leukemia (CML) the data are very limited and with conflicting outcome. The aim of our study was to evaluate the effect of KIR genes and KIR ligands on leukemia free survival (LFS) and relapse rate in a well-defined, homogeneous group of CML patients phase upon HLA identical sibling SCT. METHODOLOGY: We retrospectively analyzed the effect of KIRs and KIR ligands (C1 and C2) on LFS and relapse in 70 CML patients in 1st chronic phase, who had received an HLA identical sibling graft. For KIR typing we used a single PCR based KIR typing protocol that also included primers allowing for the identification of the KIR binding site on HLA-Cw (AA 77 and 80). PRINCIPAL FINDINGS: The data show clear differences in transplant outcome between patients having both ligands (C1 and C2) as compared to patients having only one ligand (C1 or C2). In the latter group, the stimulatory KIR2DS5 gene was associated with improved leukemia free survival (p=0.007; hazard ratio 4.3; 95% confidence interval 1.3-6.7) and lower relapse rates (p=0.028; HR 4.3, 95% CI 1.1-9.1). In contrast, in patients carrying both ligands, KIR2DS5 was associated with reduced LFS (p=0.0056; HR 0.3; 95% CI 0.1-0.7) and higher relapse rate (p=0.02; HR 0.35, 95% CI 0.1-0.8). CONCLUSIONS: Our data indicate a role for an NK mediated anti-CML response after HLA identical sibling SCT that is influenced by KIR ligands and, more importantly, by stimulatory KIRs present in the donor.

European experience and risk factor analysis of donor cell-derived leukaemias/MDS following haematopoietic cell transplantation.

Donor cell leukaemia (DCL) is a rare complication of allogeneic haematopoietic cell transplantation (HCT). We have investigated the prevalence and outcome of donor cell haematology malignancies within centres registered with the European Society of Blood and Marrow transplantation (EBMT). We have sought to identify risk factors to shed light on the pathogenesis of DCL as a model for leukaemogenesis. DCL cases were identified by questionnaire and a follow-up questionnaire requested detailed data. Control subjects from the EBMT registry who had not developed DCL were used for a matched pair analysis to identify risk factors. We identified 38 patients with DCL; the estimated prevalence was 80.5/100,000 transplants. Patients were predominantly treated for haematological malignancy. A clone was retrospectively identified in 7/25 (28%) donors for whom data was available. Overall survival was poor with 29/38 patients dead a median of 11 (range 0-91) months after DCL diagnosis. Matched case-pair analysis identified three factors on multivariate analysis as significantly associated with an increased risk for DCL: use of growth factors within the first 100 days after transplantation, in vivo T-cell depletion and multiple allografts. The risk factors identified, support reduced immune surveillance and replicative stress as pathogenic in the development of DCL.

A frameshift polymorphism in P2X5 elicits an allogeneic cytotoxic T lymphocyte response associated with remission of chronic myeloid leukemia.

Minor histocompatibility antigens (mHAgs) constitute the targets of the graft-versus-leukemia response after HLA-identical allogeneic stem cell transplantation. Here, we have used genetic linkage analysis to identify a novel mHAg, designated lymphoid-restricted histocompatibility antigen-1 (LRH-1), which is encoded by the P2X5 gene and elicited an allogeneic CTL response in a patient with chronic myeloid leukemia after donor lymphocyte infusion. We demonstrate that immunogenicity for LRH-1 is due to differential protein expression in recipient and donor cells as a consequence of a homozygous frameshift polymorphism in the donor. Tetramer analysis showed that emergence of LRH-1-specific CD8+ cytotoxic T cells in peripheral blood and bone marrow correlated with complete remission of chronic myeloid leukemia. Furthermore, the restricted expression of LRH-1 in hematopoietic cells including leukemic CD34+ progenitor cells provides evidence of a role for LRH-1-specific CD8+ cytotoxic T cells in selective graft-versus-leukemia reactivity in the absence of severe graft-versus-host disease. These findings illustrate that the P2X5-encoded mHAg LRH-1 could be an attractive target for specific immunotherapy to treat hematological malignancies recurring after allogeneic stem cell transplantation.

Results of hematopoietic stem cell transplantation after treatment with different high-dose total-body irradiation regimens in five Dutch centers.

PURPOSE: To evaluate results of high-dose total-body irradiation (TBI) regimens for hematopoietic stem cell transplantation. METHODS AND MATERIALS: A total of 1,032 patients underwent TBI in one or two fractions before autologous or allogeneic hematologic stem cell transplantation for acute leukemia and non-Hodgkin's lymphoma. The TBI regimens were normalized by using the biological effective dose (BED) concept. The BED values were divided into three dose groups. Study end points were relapse incidence (RI), non-relapse mortality (NRM), relapse-free survival (RFS), and overall survival (OS). Multivariate analysis was performed, stratified by disease. RESULTS: In the highest TBI dose group, RI was significantly lower and NRM was higher vs. the lower dose groups. However, a significant influence on RFS and OS was not found. Relapses in the eye region were found only after shielding to very low doses. Age was of significant influence on OS, RFS, and NRM in favor of younger patients. The NRM of patients older than 40 years significantly increased, and OS decreased. There was no influence of age on RI. Men had better OS and RFS and lower NRM. Type of transplantation significantly influenced RI and NRM for patients with acute leukemia and non-Hodgkin's lymphoma. There was no influence on RFS and OS. CONCLUSIONS: Both RI and NRM were significantly influenced by the size of the BED of single-dose or two-fraction TBI regimens; OS and RFS were not. Age was of highly significant influence on NRM, but there was no influence of age on RI. Hyperfractionated TBI with a high BED might be useful, assuming NRM can be reduced.

Peripheral blood or bone marrow cells in reduced-intensity or myeloablative conditioning allogeneic HLA identical sibling donor transplantation for multiple myeloma.

BACKGROUND AND OBJECTIVES: Peripheral blood stem cells (PBSC) following reduced intensity conditioning (RIC) are being increasingly used for allogeneic transplantation in multiple myeloma. The purpose of this study was to compare outcome of patients transplanted with either PBSC or bone marrow (BM) following RIC or myeloablative conditioning (MAC). DESIGN AND METHODS: Data from 1,667 patients who had received an allogeneic identical sibling donor transplant for multiple myeloma from 1994 to 2003 were analyzed. Comparisons were made between results of PBSC and BM transplants after conditioning with RIC or MAC. RESULTS: The engraftment rate was faster with PBSC than with BM (median: 14 and 18 days for neutrophils and 15 and 25 days for platelets respectively) irrespectively of whether RIC or MAC was used. The incidence of acute graft-versus-host disease (GVHD) did not differ significantly between the groups while chronic GVHD was more prevalent in PBSC recipients irrespectively of whether they had RIC or MAC. Non-relapse mortality did not differ between PBSC and BM recipients, but was significantly higher in those treated with MAC than in those given RIC irrespectively of the cell source. The relapse/progression rate did not differ between PBSC and BM recipients, but was significantly higher in those given RIC, irrespectively of the cell source. There was no significant difference in overall or progression-free survival between patients given PBSC or BM transplants. INTERPRETATION AND CONCLUSIONS: Although transplantation of PBSC is associated with faster engraftment and more frequent chronic GVHD, overall survival, non-relapse mortality, relapse/progression and progression-free survival are similar to those following BM transplants. However both PBSC and BM transplants are associated with lower non-relapse mortality, lower response rate and higher relapse/progression if RIC is used instead of MAC.

Differences between the different conditioning regimens for allogeneic stem cell transplantation.

PURPOSE OF REVIEW: The aim of this article is to compare the differences in efficacy and toxicity between the various conditioning regimens for allogeneic stem cell transplantation. RECENT FINDINGS: Several studies, all retrospective, that compare the impact of various different conditioning regimens amongst each other are presented. Reduced intensity conditioning apparently lowered transplant-related mortality in patients with minimal residual disease who were at high risk for treatment-related mortality. In contrast, patients with active disease could only be salvaged when a myeloablative conditioning regimen was used. By consequence, it was concluded that patients without contraindications for a myeloablative conditioning regimen should not receive reduced regimens outside a prospective randomized trial. SUMMARY: Despite high expectations, non-myeloablative conditioning regimens and regimens that have been reduced in intensity did not prove to be superior in survival when the outcomes were compared with those obtained with conventional myeloablative conditioning. Randomized prospective studies are needed to explore the appropriate niche for the various different regimens.

The origin of epithelial neoplasms after allogeneic stem cell transplantation.

We analyzed five women, who have developed epithelial neoplasms after sex-mismatched stem cell transplants. Using in situ hybridization for sex chromosome-specific DNA probes and immunohistochemistry we identified the origin of the tumor cells. We conclude that none of the non-hematologic malignancies was of donor origin.

Allogeneic stem cell transplantation for patients with acute myeloid leukemia or myelodysplastic syndrome who have chromosome 5 and/or 7 abnormalities.

BACKGROUND AND OBJECTIVES: Chromosome 5 and/or 7 abnormalities are cytogenetic findings indicative of a poor prognosis in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). The only potential cure for such patients is allogeneic stem cell transplantation (SCT). As data on allogeneic SCT in this context are limited we did a retrospective study of allogeneic SCT in patients with AML or MDS who had chromosome 5 and/or 7 abnormalities. DESIGN AND METHODS: This was a retrospective study of 65 patients (16 children, 49 adults) with AML (n=33) or MDS (n=32) who had chromosome 5 and/or 7 abnormalities and who underwent allogeneic SCT in six Dutch Centers between 1983 and 2001. Data on all these patients are recorded in the Netherlands Stem Cell Transplant Registry (Typhon). RESULTS: The 3-year overall survival rate among all patients was 25%. Patients below the age of 40 years had significantly fewer relapses (40%) and better survival (38%) than those above the age of 40 (86% and 8%, respectively). Relapses were less frequent in recipients of unrelated grafts than in those whose grafts were from HLA-identical siblings (30% versus 69%). The development of acute graft-versus-host disease (GVHD) grades II-IV was independently associated with significantly higher transplant-related mortality (TRM). Patients with either chromosome 5 or chromosome 7 abnormalities had a significantly better survival than patients with both chromosome 5 and 7 abnormalities. These patients with poor-risk chromosome 5 and/or 7 abnormalities were compared with a group of patients with a secondary AML/MDS and normal cytogenetics and were found to have significantly more relapses and significantly worse survival but a similar TRM. INTERPRETATION AND CONCLUSIONS: We conclude that patients with AML or MDS with chromosome 5 and/or 7 abnormalities do rather poorly after allogeneic SCT, mainly because of the very high relapse rate. Nevertheless, this is the only approach that can cure some of these patients.

Stem cell transplantation for leukemias following myelodysplastic syndromes or secondary to cytotoxic therapy.

Two main forms of therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML) have been recognized. The most frequent type, occurring after treatment with alkylating agents, is characterized by abnormalities of chromosomes 5 and/or 7 and t-MDS/AML following treatment with topoisomerase II inhibitors and is associated with molecular aberrations of MLL (11q23) and AML-1 (21q22). Individuals with certain polymorphisms associated with impaired detoxification of cytotoxic agents have an increased risk of developing MDS or AML after treatment of unrelated cancers. Multidrug chemotherapy is less effective for patients with MDS, or AML following MDS, or t-MDS/AML when compared with primary AML, and results in lower complete remission (CR) rates and lower long-term survival. Patients with good risk cytogenetic features, such as t(15; 17), t(8; 21) and inversion 16 are an exception as their treatment outcome is comparable with primary AML patients. Patients who attain a polyclonal and/or a cytogenetic CR may be candidates for autologous stem cell transplantation. For the remaining patients, the only curative option is allogeneic stem cell transplantation with stem cells from a histocompatible sibling or an alternative donor. Reduced intensity conditioning regimens may be considered for patients older than 50 years or patients with comorbidities. The advice is to treat patients early after diagnosis and preferably before progression as these patients have the highest chance of a favorable outcome.

Allogeneic stem-cell transplantation in patients with Waldenström macroglobulinemia: report from the Lymphoma Working Party of the European Group for Blood and Marrow Transplantation.

PURPOSE: Allogeneic stem-cell transplantation (alloSCT) is a curative therapeutic option for patients with low-grade lymphoid malignancies. Information regarding alloSCT in Waldenström macroglobulinemia (WM) is limited. This study presents the long-term outcome of a large series of patients with WM treated with alloSCT. PATIENTS AND METHODS: A total of 86 patients received allograft by using either myeloablative (MAC; n = 37) or reduced-intensity conditioning (RIC; n = 49) regimens and were retrospectively studied. The median age was 49 years (range, 23 to 64 years); 47 patients had received three or more previous lines of therapy, and eight patients had experienced failure on a prior autologous stem-cell transplantation. A total of 59 patients (68.6%) had chemotherapy-sensitive disease at the time of alloSCT. Median follow-up of the surviving patients was 50 months (7 to 142 months). RESULTS: Nonrelapse mortality (NRM) at 3 years was 33% for MAC and 23% for RIC. The overall response rate was 75.6%. The relapse rates (RRs) at 3 years were 11% for MAC and 25% for RIC. Fourteen patients received donor lymphocyte infusions (DLIs) for disease relapse. PFS and OS at 5 years were 56% and 62% for MAC and 49% and 64% for RIC, respectively. The occurrence of chronic graft-versus-host disease (cGVHD) was associated with a higher NRM and a lower RR, leading to an improvement in PFS. CONCLUSION: alloSCT can induce durable remissions in a selected population of young and heavily pretreated patients with WM. The low RR, the achievement of additional disease responses after DLIs, and the lower RR in patients developing cGVHD suggest the existence of a clinically relevant graft-versus-WM effect.