An international expert panel, active within the European Society for Blood and Marrow Transplantation, European LeukemiaNet, Blood and Marrow Transplant Clinical Trial Group, and the International Myelodysplastic Syndromes Foundation developed recommendations for allogeneic hematopoietic stem cell transplantation (HSCT) in myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML). Disease risks scored according to the revised International Prognostic Scoring System (IPSS-R) and presence of comorbidity graded according to the HCT Comorbidity Index (HCT-CI) were recognized as relevant clinical variables for HSCT eligibility. Fit patients with higher-risk IPSS-R and those with lower-risk IPSS-R with poor-risk genetic features, profound cytopenias, and high transfusion burden are candidates for HSCT. Patients with a very high MDS transplantation risk score, based on combination of advanced age, high HCT-CI, very poor-risk cytogenetic and molecular features, and high IPSS-R score have a low chance of cure with standard HSCT and consideration should be given to treating these patients in investigational studies. Cytoreductive therapy prior to HSCT is advised for patients with ≥10% bone marrow myeloblasts. Evidence from prospective randomized clinical trials does not provide support for specific recommendations on the optimal high intensity conditioning regimen. For patients with contraindications to high-intensity preparative regimens, reduced intensity conditioning should be considered. Optimal timing of HSCT requires careful evaluation of the available effective nontransplant strategies. Prophylactic donor lymphocyte infusion (DLI) strategies are recommended in patients at high risk of relapse after HSCT. Immune modulation by DLI strategies or second HSCT is advised if relapse occurs beyond 6 months after HSCT.

To develop a novel acute graft-versus-host disease (GVHD) risk score, we examined the GVHD clinical stage and grade of 1723 patients at the onset of treatment with systemic steroids. Using clinical grouping, descriptive statistics and recursive partitioning, we identified poorly responsive, high-risk (HR) acute GVHD by the number of involved organs and severity of GVHD at onset. The overall response (complete response/partial response) rate 28 days after initiation of steroid therapy for acute GVHD was lower in the 269 patients with HR-GVHD than in the 1454 patients with standard risk (SR)-GVHD (44% [95% confidence interval (CI) 38% to 50%] versus 68% [95% CI, 66% to 70%], P < .001). Patients with HR-GVHD were less likely to respond at day 28 (odds ratio [OR], .3; 95% CI, .2 to .4; P < .001) and had higher risks of mortality (relative risk, 2.1; 95% CI, 1.7 to 2.6; P < .001) and transplant-related mortality (relative risk, 2.5; 95% CI, 2.0% to 3.2%, P < .001) than patients with SR-GVHD. This refined definition of acute GVHD risk is a better predictor of response, survival, and transplant-related mortality than other published acute GVHD risk scores. Patients with HR-GVHD are candidates for studies investigating new treatment approaches. Likewise, patients with SR-GVHD are candidates for studies investigating less toxic therapy.

Purpose: To compare a reduced-intensity conditioning regimen (RIC) with a myeloablative conditioning regimen (MAC) before allogeneic transplantation in patients with myelodysplastic syndrome (MDS) within a randomized trial. Patients and Methods: Within the European Society of Blood and Marrow Transplantation, we conducted a prospective, multicenter, open-label, randomized phase III trial that compared a busulfan-based RIC with MAC in patients with MDS or secondary acute myeloid leukemia. A total of 129 patients were enrolled from 18 centers. Patients were randomly assigned in a 1:1 ratio and were stratified according to donor, age, and blast count. Results: Engraftment was comparable between both groups. The CI of acute graft-versus-host disease II to IV was 32.3% after RIC and 37.5% after MAC ( P = .35). The CI of chronic graft-versus-host disease was 61.6% after RIC and 64.7% after MAC ( P = .76). The CI of nonrelapse mortality after 1 year was 17% (95% CI, 8% to 26%) after RIC and 25% (95% CI, 15% to 36%) after MAC ( P = .29). The CI of relapse at 2 years was 17% (95% CI, 8% to 26%) after RIC and 15% (95% CI, 6% to 24%) after MAC ( P = .6), which resulted in a 2-year relapse-free survival and overall survival of 62% (95% CI, 50% to 74%) and 76% (95% CI, 66% to 87%), respectively, after RIC, and 58% (95% CI, 46% to 71%) and 63% (95% CI, 51% to 75%), respectively, after MAC ( P = .58 and P = .08, respectively). Conclusion: This prospective, randomized trial of the European Society of Blood and Marrow Transplantation provides evidence that RIC resulted in at least a 2-year relapse-free survival and overall survival similar to MAC in patients with MDS or secondary acute myeloid leukemia.

Purpose: To investigate the impact of prior-to-transplantation azacitidine (AZA) on patient outcome after allogeneic stem-cell transplantation (alloSCT) for myelodysplastic syndrome (MDS). Patients and Methods: Of the 265 consecutive patients who underwent alloSCT for MDS between October 2005 and December 2009, 163 had received cytoreductive treatment prior to transplantation, including induction chemotherapy (ICT) alone (ICT group; n = 98), AZA alone (AZA group; n = 48), or AZA preceded or followed by ICT (AZA-ICT group; n = 17). At diagnosis, 126 patients (77%) had an excess of marrow blasts, and 95 patients (58%) had intermediate-2 or high-risk MDS according to the International Prognostic Scoring System (IPSS). Progression to more advanced disease before alloSCT was recorded in 67 patients. Donors were sibling (n = 75) or HLA-matched unrelated (10/10; n = 88). They received blood (n = 142) or marrow (n = 21) grafts following either myeloablative (n = 33) or reduced intensity (n = 130) conditioning. Results: With a median follow-up of 38.7 months, 3-year outcomes in the AZA, ICT, and AZA-ICT groups were 55%, 48%, and 32% (P = .07) for overall survival (OS); 42%, 44%, and 29% (P = .14) for event-free survival (EFS); 40%, 37%, and 36% (P = .86) for relapse; and 19%, 20%, and 35% (P = .24) for nonrelapse mortality (NRM), respectively. Multivariate analysis confirmed the absence of statistical differences between the AZA and the ICT groups in terms of OS, EFS, relapse, and NRM. Conclusion: With the goal of downstaging underlying disease before alloSCT, AZA alone led to outcomes similar to those for standard ICT.

Interleukin 10 (IL-10)–producing B cells (regulatory B cells [Bregs]) regulate autoimmunity in mice and humans, and a regulatory role of IL-10–producing plasma cells has been described in mice. Dysfunction of B cells that maintain homeostasis may play a role in the pathogenesis of chronic graft-versus-host disease (cGVHD) after allogeneic stem cell transplantation. Here, we found a relation between decreased Breg frequencies and cGVHD severity. An impaired ability of B cells to produce IL-10, possibly linked to poor signal transducer and activator of transcription 3 and extracellular signal-regulated kinase phosphorylation, was found in patients with active cGVHD. IL-10 production was not confined to a single B-cell subset, but enriched in both the CD24^hiCD27⁺ and CD27^hiCD38^hi plasmablast B-cell compartments. In vitro plasmablast differentiation increased the frequency of IL-10–producing B cells. We confirmed that allogeneic transplant recipients had an impaired reconstitution of the memory B-cell pool. cGVHD patients had less CD24^hiCD27⁺ B cells and IL-10–producing CD24^hiCD27⁺ B cells. Patients with cGVHD had increased plasmablast frequencies but decreased IL-10–producing plasmablasts. These results suggest a role of CD24^hiCD27⁺ B-cell and plasmablast-derived IL-10 in the regulation of human cGVHD. Key Points Chronic graft-versus-host disease is associated with a global Breg defect. This defect is particularly accentuated in the CD24^hiCD27⁺ Breg compartment.