Lower relapse incidence with haploidentical versus matched sibling or unrelated donor hematopoietic cell transplantation for core‐binding factor AML patients in CR2: A study from the Global Committee and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Abstract Allogeneic hematopoietic cell transplantation (allo‐HCT) is recommended for core‐binding factor mutated (CBF) AML patients achieving second complete remission (CR2). However, approximately 20% of patients may relapse after transplant and donor preference remains unclear. We compared in this EBMT global multicenter registry‐based analysis the allo‐HCT outcomes using either haploidentical (Haplo), matched siblings donors (MSD), or 10/10 matched unrelated donors (MUD). Data from 865 de novo adult CBF AML patients in CR2 receiving allo‐HCT in 227 EBMT centers from 2010 to 2022 were analyzed, in which 329 MSD, 374 MUD, and 162 Haplo‐HCTs were included. For the entire cohort, 503 (58%) patients were inv(16)/CBFB‐MYH11 and 362 patients (42%) were t (8;21)/RUNX1‐RUNX1T1 AML. On multivariate analysis, Haplo‐HCT was associated with a lower Relapse Incidence (RI) compared to either MSD (hazard ratio HR = 0.56, 95% CI 0.32–0.97; p < .05) or MUD (HR = 0.57, 95% CI: 0.33–0.99, p < .05). No significant difference was observed among the 3 types of donors on LFS, OS and GRFS. CBF‐AML with t (8;21) was associated with both higher RI (HR = 1.79, 95% CI 1.3–2.47; p < .01) and higher NRM (HR = 1.58, 95% CI 1.1–2.27; p < .01) than CBF‐AML with inv(16), which led to worse LFS, OS and GRFS. To conclude, for CBF‐AML patients in CR2, Haplo‐HCTs were associated with a lower RI compared to MSD and MUD allo‐HCTs. There was no difference on LFS, OS or GRFS. CBF AML patients with inv(16) had a better progonosis than those with t (8;21) after allo‐HCT in CR2.