Older matched sibling donor versus young haplo-identical donor for elderly patients with acute myeloid leukemia.

Selection of a suitable donor for allogeneic hematopoietic stem cell transplantation (allo-HCT) has mainly relied on human leukocyte antigen matching, and to date, a matched sibling donor (MSD) remains the first choice. However, patients with acute myeloid leukemia (AML) are older and therefore, have older siblings. Haplo-identical donors (HID) are easily available, and offspring are younger than siblings. As donor age has been associated with worse outcomes, a younger HID might be a better choice than an older MSD for older AML transplanted in first complete remission (CR1). We selected from the EBMT registry database, patients with AML, aged ≥60 years and transplanted in CR1, either from MSD aged ≥50 years or HID £ 40 years. All HID received post-transplant cyclophosphamide as graft-versus-host disease (GvHD) prophylaxis and MSD receiving in vivo T-cell depletion were included. A total of 1247 patients were identified, including 721 MSD and 526 HID. In univariate analysis, HID was associated with lower relapse incidence (p=0.01), higher non-relapse mortality (NRM) (p=0.01) and higher incidence of grade II-IV acute GvHD (p=0.01). The 2-year probability of overall survival (OS), leukemia-free survival (LFS) and GvHD-free and relapse-free survival (GRFS) were 62.5%, 56% and 47%, respectively, without any significant difference between groups. In multivariate analysis, we confirmed that HID was associated with less relapse but more NRM, which translated into similar OS, LFS and GRFS. Based on this retrospective study, young HID led to less relapse but higher NRM than older MSD after allo-HCT in an older AML population in CR1.