Comparison of Matched Sibling, Unrelated and Haploidentical Donor Transplants Using Post-Transplant Cyclophosphamide in Patients with Acute Myeloid Leukemia, a Study of the ALWP EBMT

Introduction The use of post-transplant cyclophosphamide (PTCy) is highly effective in preventing graft-versus-host disease (GVHD) in the haploidentical (Haplo) transplant setting and is being increasingly used in matched sibling (MSD) and matched unrelated (MUD) transplants. There is no information on the impact of donor types using homogeneous prophylaxis with PTCy. Methods We retrospectively analysed outcomes of adult patients with acute myeloid leukemia (AML) in first complete remission (CR1) that received a first allogeneic stem cell transplantation (SCT) with PTCy as GVHD prophylaxis from MSD (n=215), MUD (n=235) and Haplo (n=789) donors registered in the EBMT database between 2010 and 2017. The median follow up period of the entire cohort was 2 years. Results Median age of patients was 52 years (range, 18-76), 693 (56%) were male and 928 (78%) were CMV seropositive. 47 (6%),543 (66%) and 239 (29%) had standard, intermediate and high risk cytogenetics, respectively. Peripheral blood (PB) was used in 814 (66%) patients and myeloablative conditioning (MAC) in 739 (59%). Compared to MSD and MUD, Haplo patients were older (p Conclusions The use of PTCy in patients with AML in CR1 receiving SCT from MSD, MUD and Haplo is safe and effective and rates of GVHD are low, especially chronic. HLA mismatch in Haplo has a negative impact on acute GVHD and NRM in this setting but also offers increased anti-leukemic efficacy. As seen in other transplant scenarios, PB is associated with more GVHD and less relapse.