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• Lower GVHD after haploidentical transplant with posttransplant cyclophosphamide compared with HLA-matched unrelated donor transplant.• Comparable overall survival after haploidentical compared with matched unrelated donor transplant for AML.We studied adults with acute myeloid leukemia (AML) after haploidentical (n 5 192) and 8/8 HLA-matched unrelated donor (n 5 1982) transplantation. Haploidentical recipients received calcineurin inhibitor (CNI), mycophenolate, and posttransplant cyclophosphamide for graft-versus-host disease (GVHD) prophylaxis; 104 patients received myeloablative and 88 received reduced intensity conditioning regimens. Matched unrelated donor transplant recipients received CNI with mycophenolate or methotrexate for GVHD prophylaxis; 1245 patients received myeloablative and 737 received reduced intensity conditioning regimens. In the myeloablative setting, day 30 neutrophil recovery was lower after haploidentical compared with matched unrelated donor transplants (90% vs 97%, P 5 .02). Corresponding rates after reduced intensity conditioning transplants were 93% and 96% (P 5 .25). In the myeloablative setting, 3-month acute grade 2-4 (16% vs 33%, P < .0001) and 3-year chronic GVHD (30% vs 53%, P < .0001) were lower after haploidentical compared with matched unrelated donor transplants. Similar differences were observed after reduced intensity conditioning transplants, 19% vs 28% (P 5 .05) and 34% vs 52% (P 5 .002). Among patients receiving myeloablative regimens, 3-year probabilities of overall survival were 45% (95% CI, 36-54) and 50% (95% CI, 47-53) after haploidentical and matched unrelated donor transplants (P 5 .38). Corresponding rates after reduced intensity conditioning transplants were 46% (95% CI, 35-56) and 44% (95% CI, 0.40-47) (P 5 .71). Although statistical power is limited, these data suggests that survival for patients with AML after haploidentical transplantation with posttransplant cyclophosphamide is comparable with matched unrelated donor transplantation. (Blood. 2015;126(8):1033-1040

The outcomes of 293 patients with leukemia undergoing HLA-identical sibling (n ‫؍‬ 158) or related HLA-mismatched (n ‫؍‬ 135) hematopoietic cell transplantation (HCT) performed during the same time period were compared. Patients received BUCY2 in HLA-identical sibling HCT or BUCY2 ؉ ATG in mismatched HCT as conditioning regimens, followed by unmanipulated marrow and/or peripheral blood (PB) transplantation. All patients achieved full engraftment. The cumulative incidences of grades II to IV acute graft-versus-host disease (aGVHD) in the matched and mismatched cohorts were 32% (CI, 25%-39%) versus 40% (CI, 32%-48%, P ‫؍‬ .13), respectively, with the relative risk (RR) ‫؍‬ 0.64 (95% CI, 0.43-0.94), P ‫؍‬ .02. The incidence of chronic GVHD did not differ significantly between the cohorts (P ‫؍‬ .97). Two-year incidences of treatment-related mortality and relapse for matched versus mismatched were 14% (range, 9%-20%) versus 22% (range, 15%-29%) with P ‫؍‬ .10 and 13% (range, 8%-19%) versus 18% (range, 10%-27%) with P ‫؍‬ .40, respectively. Two-year adjusted leukemia-free survival (LFS) and overall survival were 71% (range, 63%-78%) versus 64% (range, 54%-73%) with P ‫؍‬ .27 and 72% (range, 64%-79%) versus 71% (range, 62%-77%) with P ‫؍‬ .72, respectively. Multivariate analyses showed that only advanced disease stage and a diagnosis of acute leukemia had increased risk of relapse, treatment failure, and overall mortality. In summary, HCT performed with related HLA-mismatched donors is a feasible approach with acceptable outcomes. (Blood. 2006;107:3065-3073)