Non-T-Depleted Haploidentical Transplantation with Post-Transplant Cyclophosphamide in Patients with Relapsed/Refractory Secondary Versus De Novo AML: A Study from the ALWP/EBMT

Background: Secondary acute myeloid leukemia (sAML) is a distinct type of AML. Transplantation, a potentially curative therapy, outcomes are inferior compared to de novo AML. We recently demonstrated (J Hematol Oncol 2023) that results of non-T-cell depleted haploidentical stem cell transplantation (HaploSCT) with post-transplant cyclophosphamide (PTCy) in sAML in complete remission are not significantly different from those in de novo AML. However, the challenge in relapse (Rel)/primary refractory (PR) AML is much higher. Methods:The study aim was to compare the outcomes of HaploSCT with PTCy, performed between 2010 and 2022, in first Rel(Rel1)/PR sAML versus those in Rel1/PR de novo AML. Statistical tests included a multivariate analysis (MVA) adjusting for potential confounding factors using a Cox proportional-hazards regression model for main outcomes. Results: A total of 719 patients (pts) met the inclusion criteria, 129 with sAML and 590 with de novo AML. Median follow-up was 45.6 (IQR] 39.1-57.9) and 43.5 (IQR, 37.5-48.0) months for pts with sAML and de novo AML, respectively (p=0.20). Pts with de novo AML were younger, with a median age of 55.4 (range 18-77.8) versus 61.3 (21-78.8) years, (p3 in 40.3% vs 21.9%, respectively (p