Multiple models of donor killer immunoglobulin receptor (KIR) alloreactivity or KIR genotype have been reported to be protective against leukemia relapse after allogeneic transplantation. However, few studies have addressed this topic in the pediatric population. Here, we assessed the outcomes of allogeneic transplantation in children with acute lymphoblastic leukemia (ALL; n 5 372) or acute myeloid leukemia (AML; n 5 344) who received unrelated donor (URD) transplantation and were reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) from 2005 to 2016. As expected in this pediatric population, most patients underwent myeloablative conditioning while in remission and with bone marrow as a stem cell source. We tested KIR ligand mismatch, KIR gene content (centromeric [Cen] B), KIR2DS1 mismatching, and Cen B/telomeric A using Cox regression models and found that none were signiﬁcantly associated with either relapse or disease-free survival when considering the entire cohort of patients (ALL and AML), AML, or ALL separately. Moreover, there was no signiﬁcant association with outcomes in the in vivo T-cell-depleted (ie, serotherapy) cohort. This study, which is the largest analysis of donor KIR in the pediatric acute leukemia population, does not support the use of KIR in the selection of URDs for children undergoing T-replete transplantation.
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