Allogeneic Stem Cell Transplantation with Post-Transplantation Cyclophosphamide in Patients with Acute Myeloid Leukemia Achieving First Complete Remission after One Versus Two Inductions: a Study from the ALWP/EBMT

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a potentially curative treatment for high-risk acute myeloid leukemia (AML), and outcomes are strongly influenced by disease status at transplantation. In transplants using conventional graft-versus-host disease (GVHD) prophylaxis, outcomes also depend on the number of induction courses required to achieve first complete remission (CR1); however, this has not been evaluated in patients receiving post-transplant cyclophosphamide (PTCy). We retrospectively analyzed 677 adult AML patients transplanted in CR1 between 2012 and 2022 using PTCy-based GVHD prophylaxis. Outcomes were compared between patients achieving CR1 after one induction course (n = 518) and those requiring two courses (n = 159). Baseline characteristics, donor type, conditioning intensity, graft source, engraftment, and rates of acute and chronic GVHD were comparable between groups. Patients requiring two inductions had a higher 2-year cumulative incidence of relapse (27% vs. 19.3%; HR 1.75, p = 0.003). However, no significant differences were observed in 2-year overall survival (62.8% vs. 69%), leukemia-free survival (61.1% vs. 65%), GVHD-free/relapse-free survival (46.3% vs. 50.4%), or non-relapse mortality (11.9% vs. 15.7%). In AML patients receiving alloHSCT with PTCy, outcomes were largely similar regardless of whether CR1 was achieved after one or two-induction courses, with relapse incidence being higher in patients requiring 2 inductions.