Influence of alternative donor type on early survival after hematopoietic stem cell transplantation for acute myeloid leukemia lacking a sibling donor

Allogeneic hematopoietic stem cell transplantation is the only potentially curative therapy for high-risk acute myeloid leukemia. In the absence of an HLA-matched related or unrelated donor (MRD or MUD), the best alternative donor source remains controversial. Umbilical cord blood and haploidentical donors offer a time advantage when considering the duration from treatment indication to transplantation. This retrospective multicenter study of a French registry compares overall survival for alternative donor transplants in the 18 months following decision to transplant in the absence of a MRD between four groups of transplanted patients: MUD (control); HLA-mismatched MUD (mMUD); umbilical cord blood (UCB); and haploidentical (haplo). Between March 2012 and July 2016, 1302 patients were transplanted with MUD (n=803), mMUD (n=219), UCB (n=153) and haplo (n=127) donors. Multivariate analyses were conducted for overall survival 18 months after registration, overall survival after transplant, and transplant-related mortality, with adjustment for the several variables. After adjustment, the type of donor did not influence any of the three endpoints. Our results confirmed the significant negative impact of a longer time interval between registration and transplant: HR=1.04 [1.02–1.06] (p<0.0001). This indicates a positive correlation between better survival and shorter registration-to-transplantation wait time. In the absence of a matched related donor, the alternative stem cell source does not impact early survival in high-risk acute myeloid leukemia patients. When selecting an alternative donor, shorter registration-to-transplantation time must be privileged over donor type.