Impact of Post-transplant cyclophosphamide (PTCy)-Based Prophylaxis in Matched Sibling Donor Allogeneic Haematopoietic Cell Transplantation for Patients with Myelodysplastic Syndrome: A Retrospective Study on Behalf of the Chronic Malignancies Working Party of the EBMT

Abstract

Abstract Allo-HCT remains the only curative option for individuals with myelodysplastic syndrome (MDS). Use of PTCy for GVHD prevention is increasingly prevalent. We retrospectively compared outcomes of 404 MDS patients undergoing 1st matched sibling donor allo-HCT receiving either PTCy-based (n=66) or other ‘conventional prophylaxis’ (n=338; mostly calcineurin inhibitor + methotrexate or MMF). Baseline characteristics were balanced, except for higher use of myeloablative regimens in the PTCy group (52.3% vs. 38.2%, p=0.047). Day +28 incidences of neutrophil (68% vs. 97%, p=0.011) and platelet (71% vs. 92%, p<0.001) engraftment were lower for PTCy-based. Day +100 cumulative incidences (CI) of grade II-IV and III-IV aGVHD, and 5-y CI of extensive cGVHD were 32%, 18% and 18% for PTCy-based and 25% (p=0.3), 13% (p=0.4) and 31% (p=0.09) for the conventional cohort. Five-year OS (51% vs. 52%, p=0.6) and GRFS (33% vs. 25%, p=0.6), were similar between groups. Patients receiving PTCy had a trend to lower relapse (20% vs. 33% (p=0.06)) not confirmed on multivariate analysis (p=0.3). Higher NRM rates, however, were evident with PTCy use on multivariable analysis (HR 1.79, p=0.03), without affecting OS (HR 1.23, p=0.4). Based on these data, the indication of PTCy in this setting should be questioned and needs further evaluation.