Haploidentical stem cell donor choice for patients with acute myeloid leukemia: A study from the ALWP of the EBMT

• Older donors age and female donor to male recipient had a negative impact on GVHD, NRM and survival in PTCy haploidentical HSCT for AML.

• The use of PB was associated with higher risk of severe acute GVHD and decreased GRFS.

There is a paucity of information to guide selection of the most suitable stem cell donor in haploidentical (Haplo) hematopoietic stem cell transplantation (HSCT). For this reason, we conducted a retrospective analysis in order to evaluate the impact of Haplo family donors characteristics on HSCT outcomes in patients with acute myeloid leukemia (AML) who received graft-versus-host disease prophylaxis with post-transplant cyclophosphamide (PTCy). The primary endpoint was GvHD-free and relapse-free survival (GRFS). Overall, 2200 patients were included. The median age of donors was 37 years (range, 8-71), 820 (37%) were females, including 458 (21%) who were used for male recipients. Additionally, 1631 (74%) donated peripheral blood (PB). Multivariable analysis identified certain donor-related risk factors with a detrimental impact on transplant outcomes. The use of PB, older donor´s age and female donors to male recipients negatively affected GRFS. Donor´s age and female donor to male recipient combination also affected non-relapse mortality, leukemia-free survival and overall survival. In conclusion, donor-related variables significantly influence AML patient outcomes following Haplo-HSCT with PTCy. When possible, younger donors and male donors for male recipients should be prioritized. The use of BM can additionally prevent GVHD.