CD25-based graft-versus-host disease prophylaxis after haploidentical hematopoietic stem cell transplantation: comparison of two prophylactic strategies

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is widely used for hematologic malignancies, yet balancing graft-versus-host disease (GVHD) prophylaxis and immune reconstitution remains challenging. In this prospective, nonrandomized study, we compared a higher-dose anti-CD25 strategy that omitted methotrexate with a conventional lower-dose anti-CD25 regimen that included methotrexate. Lower cumulative anti-thymocyte globulin exposure was observed in the higher-dose group. From May 2022 to January 2025, 276 patients were enrolled (lower-dose group, n=149; higher-dose group, n=127). After a median follow-up of 28.4 months, the higher-dose strategy was associated with a lower 100-day cumulative incidence of grade III-IV acute GVHD (7.9% vs. 17.5%; adjusted subdistribution hazard ratio, 0.39; 95% confidence interval, 0.18-0.88; p=0.022) and improved graft-versus-host diseasefree, relapse-free survival (GRFS) (adjusted hazard ratio, 0.59; 95% confidence interval, 0.43-0.83; p=0.002). Chronic GVHD, overall survival, disease-free survival, relapse, and non-relapse mortality did not differ significantly between groups. Exploratory immune monitoring showed transiently lower CD4+ T-cell counts at day +30 in the higherdose group, whereas longitudinal immune reconstitution trajectories and infectious complications were broadly comparable. These findings suggest that a higher-dose anti-CD25, methotrexate-free prophylactic approach may reduce acute GVHD and improve GRFS after haplo-HSCT, while its effects on long-term disease control and survival require confirmation in multicenter randomized trials. Trial registration: Chinese Clinical Trial Registry, ChiCTR2200060184.