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BACKGROUND Genetic mutations drive the pathogenesis of the myelodysplastic syndrome (MDS) and are closely associated with clinical phenotype. Therefore, genetic mutations may predict clinical outcomes after allogeneic hematopoietic stem-cell transplantation. METHODS We performed targeted mutational analysis on samples obtained before transplantation from 1514 patients with MDS who were enrolled in the Center for International Blood and Marrow Transplant Research Repository between 2005 and 2014. We evaluated the association of mutations with transplantation outcomes, including overall survival, relapse, and death without relapse. RESULTS TP53 mutations were present in 19% of the patients and were associated with shorter survival and a shorter time to relapse than was the absence of TP53 mutations, after adjustment for significant clinical variables (P<0.001 for both comparisons). Among patients 40 years of age or older who did not have TP53 mutations, the presence of RAS pathway mutations was associated with shorter survival than was the absence of RAS pathway mutations (P= 0.004), owing to a high risk of relapse, and the presence of JAK2 mutations was associated with shorter survival than was the absence of JAK2 mutations (P = 0.001), owing to a high risk of death without relapse. The adverse prognostic effect of TP53 mutations was similar in patients who received reduced-intensity conditioning regimens and those who received myeloablative conditioning regimens. By contrast, the adverse effect of RAS pathway mutations on the risk of relapse, as compared with the absence of RAS pathway mutations, was evident only with reduced-intensity conditioning (P<0.001). In young adults, 4% of the patients had compound heterozygous mutations in the Shwachman–Diamond syndrome–associated SBDS gene with concurrent TP53 mutations and a poor prognosis. Mutations in the p53 regulator PPM1D were more common among patients with therapy-related MDS than those with primary MDS (15% vs. 3%, P<0.001). CONCLUSIONS Genetic profiling revealed that molecular subgroups of patients undergoing allogeneic hematopoietic stem-cell transplantation for MDS may inform prognostic stratification and the selection of conditioning regimen. (Funded by the Edward P. Evans Foundation and others.)

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Background Of the cancers treated with allogeneic hematopoietic stem-cell transplantation (HSCT), acute myeloid leukemia (AML) is most sensitive to natural killer (NK)–cell reactivity. The activating killer-cell immunoglobulin-like receptor (KIR) 2DS1 has ligand specificity for HLA-C2 antigens and activates NK cells in an HLA-dependent manner. Donor-derived NK reactivity controlled by KIR2DS1 and HLA could have beneficial effects in patients with AML who undergo allogeneic HSCT. Methods We assessed clinical data, HLA genotyping results, and donor cell lines or genomic DNA for 1277 patients with AML who had received hematopoietic stem-cell transplants from unrelated donors matched for HLA-A, B, C, DR, and DQ or with a single mismatch. We performed donor KIR genotyping and evaluated the clinical effect of donor KIR genotype and donor and recipient HLA genotypes. Results Patients with AML who received allografts from donors who were positive for KIR2DS1 had a lower rate of relapse than those with allografts from donors who were negative for KIR2DS1 (26.5% vs. 32.5%; hazard ratio, 0.76; 95% confidence interval [CI], 0.61 to 0.96; P = 0.02). Of allografts from donors with KIR2DS1, those from donors who were homozygous or heterozygous for HLA-C1 antigens could mediate this antileukemic effect, whereas those from donors who were homozygous for HLA-C2 did not provide any advantage (24.9% with homozygosity or heterozygosity for HLA-C1 vs. 37.3% with homozygosity for HLA-C2; hazard ratio, 0.46; 95% CI, 0.28 to 0.75; P = 0.002). Recipients of KIR2DS1-positive allografts mismatched for a single HLA-C locus had a lower relapse rate than recipients of KIR2DS1-negative allografts with a mismatch at the same locus (17.1% vs. 35.6%; hazard ratio, 0.40; 95% CI, 0.20 to 0.78; P = 0.007). KIR3DS1, in positive genetic linkage disequilibrium with KIR2DS1, had no effect on leukemia relapse but was associated with decreased mortality (60.1%, vs. 66.9% without KIR3DS1; hazard ratio, 0.83; 95% CI, 0.71 to 0.96; P = 0.01). Conclusions Activating KIR genes from donors were associated with distinct outcomes of allogeneic HSCT for AML. Donor KIR2DS1 appeared to provide protection against relapse in an HLA-C–dependent manner, and donor KIR3DS1 was associated with reduced mortality. (Funded by the National Institutes of Health and others.)

Background Transplantation of hematopoietic cells from unrelated donors can cure blood disorders but carries a significant risk of acute graft-versus-host disease (GVHD). The risk is higher when the recipient and donor are HLA-DPB1–mismatched, but the mechanisms leading to GVHD are unknown. The HLA-DPB1 regulatory region variant rs9277534 is associated with HLA-DPB1 expression. We tested the hypothesis that the GVHD risk correlates with the rs9277534 allele linked to the mismatched HLA-DPB1 in the recipient. Methods We genotyped rs9277534 in 3505 persons to define rs9277534-DPB1 haplotypes. Among 1441 recipients of transplants from HLA-A,B,C,DRB1,DQB1–matched unrelated donors with only one HLA-DPB1 mismatch, linkage of the rs9277534 A and G alleles to the mismatched HLA-DPB1 was determined. HLA-DPB1 expression was assessed by means of a quantitative polymerase-chain-reaction assay. The risk of acute GVHD among recipients whose mismatched HLA-DPB1 allele was linked to rs9277534G (high expression) was compared with the risk among recipients whose mismatched HLA-DPB1 allele was linked to rs9277534A (low expression). Results The mean HLA-DPB1 expression was lower with rs9277534A than with rs9277534G. Among recipients of transplants from donors with rs9277534A-linked HLA-DPB1, the risk of acute GVHD was higher for recipients with rs9277534G-linked HLA-DPB1 mismatches than for recipients with rs9277534A-linked HLA-DPB1 mismatches (hazard ratio, 1.54; 95% confidence interval [CI], 1.25 to 1.89; P<0.001), as was the risk of death due to causes other than disease recurrence (hazard ratio, 1.25; 95% CI, 1.00 to 1.57; P = 0.05). Conclusions The risk of GVHD associated with HLA-DPB1 mismatching was influenced by the HLA-DPB1 rs9277534 expression marker. Among recipients of HLA-DPB1–mismatched transplants from donors with the low-expression allele, recipients with the high-expression allele had a high risk of GVHD. (Funded by the National Institutes of Health and others.)

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Purpose-The association between human leukocyte antigen (HLA) matching and outcome in unrelated donor, peripheral blood stem cell (PBSC) transplantation has not been established. Patients and Methods