Allogeneic Stem Cell Transplantation for FLT3-Mutated Acute Myeloid Leukemia: In vivo T-Cell Depletion and Posttransplant Sorafenib Maintenance Improve Survival. A Retrospective Acute Leukemia Working Party-European Society for Blood and Marrow Transplant Study

Acute myeloid leukemia (AML) with FLT3-mutation carries a poor prognosis, and allogeneic stem cell transplantation (allo-SCT) is recommended at first complete remission (CR1). We assessed 462 adults (median age 50 years) with FLT3-mutated AML allografted between 2010 and 2015 from a matched related (40%), unrelated (49%), or haploidentical donor (11%). The median follow-up of alive patients was 39 months. Day-100 acute graft versus host disease (GVHD) grades II–IV and III–IV were encountered in 26% and 9%, whereas the 2-year incidence of chronic and extensive chronic GVHD were 34% and 16%, respectively. The 2-year incidences of relapse and nonrelapse mortality were 34% and 15%, respectively. The 2-year leukemia-free survival, overall survival (OS), and GVHD relapse-free survival (GRFS) were 51%, 59%, and 38%, respectively. In multivariate analysis, NPM1-mutation, transplantation in CR1, in vivo T-cell depletion, and posttransplant sorafenib improved OS, whereas more than one induction (late CR1) negatively affected OS. Similarly, NPM1-mutation, a haploidentical donor, T-cell depletion, and sorafenib maintenance improved GRFS, whereas late CR1 or persistent disease negatively affected it. In conclusion, FLT3-mutated AML remains a challenge even following allo-SCT. In vivo T-cell depletion and posttransplant sorafenib significantly improve OS and GRFS, and may be considered as standard of care.