Haploidentical peripheral blood stem cell transplantation improves the survival of older patients with myeloid malignancies under low-dose antithymocyte globin (ATG)/post-cyclophosphamide (PTCy)-based regimen for graft-versus-host disease prophylaxis

Abstract Our study delved into the clinical outcomes of haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) for older patients, utilizing a novel low-dose antithymocyte globin (ATG)/post-cyclophosphamide (PTCy)-based regimen to prevent graft-versus-host disease (GVHD). We juxtaposed these outcomes with transplants from matched unrelated/sibling donors (MUD/MSD) for elderly patients with myeloid malignancies from 2016 to 2023. The study encompassed 127 patients, with 40 undergoing MUD/MSD-PBSCT and 87 receiving haplo-PBSCT. The incidences of grades Ⅱ-Ⅳ and Ⅲ-Ⅳ acute GVHD were similar between the two groups, the haplo-PBSCT cohort displayed a promising trend toward reduced incidence of moderate to severe chronic GVHD compared to MUD/MSD-PBSCT (8.19% vs 23.40%, P = 0.067). The 2-year disease-free survival (74.11% vs 59.67%, P = 0.231) and overall survival (76.30% vs 64.00%, P = 0.482) rates were comparable, while haplo-PBSCT exhibited higher graft-versus-host disease-free, relapse-free survival (GRFS) (68.85% vs 46.61%, P = 0.041) and lower cumulative incidences of relapse (CIR) (11.16% vs 31.98%, P = 0.010) compared to MUD/MSD-PBSCT. Our findings underscore the potential of haploidentical transplants with the low-dose ATG/PTCy-based regimen to yield improved GRFS and lower CIR for older patients with hematologic malignancies. Thus, haploidentical donors, especially when coupled with this specified GVHD prevention strategy, emerge as a viable and appealing graft source for elderly patients requiring allo-SCT.