Non-T depleted haploidentical stem cell transplantation in AML patients achieving first complete remission after one versus two induction courses: a study from the ALWP/EBMT

There are no data indicating whether the number of induction courses needed to achieve first complete remission (CR1) is of prognostic significance in Haploidentical transplantation (HaploSCT). We compared transplantation outcomes of adults with AML that underwent HaploSCT in CR1, achieved following one or two induction courses. A total of 635 patients were included: 469 (74%) with 1 and 166 (26%) with two induction chemotherapy courses. A total of 429 (91.5%) and 151 (91%) patients had de novo AML and 40 (8.5%) and 15 (9%) had secondary AML (p = 0.84). Engraftment rates were 97.2 and 97.6%. Day 180 incidence of acute GVHD II-IV and III-IV was similar in both induction groups (31.1 and 34.8%, and 10 and 10.6 %), as was 2-4 year total and extensive chronic GVHD (33.7 and 36.5 %, and 12.2 and 12.1%), respectively. Two-year relapse incidence (RI) was higher while leukemia-free survival (LFS), overall survival (OS) and GVHD-free, relapse-free survival (GRFS) were inferior for patients achieving CR1 with 2 vs 1 course and were 29.1% vs 15.1%, 88 (p = 0.001), 56.2% vs 66.9% (p = 0.03), 58.8% vs 72.2% (p = 0.044) and 44% vs 55.6% (p = 0.013), respectively. Non-relapse mortality (NRM) did not differ, 18% vs 14.6% 90 (p = 0.25). These results were confirmed by multivariate analysis.