Donor Characteristics Affecting Graft Failure, Graft-versus-Host Disease, and Survival after Unrelated Donor Transplantation with Reduced-Intensity Conditioning for Hematologic Malignancies

We examined the effect of donor characteristics on graft failure (<5% donor chimerism within 3 months after transplantation), acute and chronic graft-versus-host disease (aGVHD, cGVHD), and survival after unrelated donor reduced-intensity conditioning (RIC) transplantation in 709 patients with hematologic malignancies. Donor–recipient pairs were HLA typed at HLA-A, -B, -C, and -DRB1 (allele-level). A total of 501 patients were >95% donor chimerism, 145 patients were 5% to 95%, and 63 patients were <5%. The only donor characteristic associated with transplantation outcome was donor–recipient HLA matching. One- or 2-loci mismatched transplants led to higher grade 2-4 (relative risk [RR] = 1.27, P = .035) and grade 3-4 (RR = 1.85, P < .001) aGVHD and 2-loci mismatched transplants higher mortality (RR = 2.22, P < .001). Graft failure was higher after transplantation of bone marrow (RR = 2.33, P = .002). Donor age, parity, and donor sex match were not associated with transplantation outcome. Donor–recipient HLA matching is the only donor characteristic predictive for survival after RIC regimens for hematologic malignancies.