Reduced-dose anti-thymocyte globulin combined with post-transplant cyclophosphamide versus standard ATG for graft-versus-host disease prophylaxis in haploidentical hematopoietic stem cell transplantation: a focus on chronic GVHD reduction.

This retrospective study aimed to compare reduced-dose anti-thymocyte globulin (ATG) plus post-transplant cyclophosphamide (PTCy) versus standard ATG for GVHD prophylaxis in haplo-HSCT. A total of 61 patients (median age, 35 years; range, 4-62) who received a myeloablative conditioning regimen between 2019 and 2024 were included. Patients received either reduced-dose ATG with PTCy (n = 30) or standard ATG (n = 31). The primary outcome was chronic GVHD (cGVHD) incidence. With a 38.5-month median follow-up, the 2-year cGVHD rate was significantly lower in the ATG-PTCy group (10.0% vs. 38.7%, p = 0.012). Rates of grade II-IV acute GVHD, engraftment times, infections (CMV/EBV), non-relapse mortality, and relapse were statistically comparable between groups. Consequently, 2-year overall survival (83.3% vs. 77.4%) and disease-free survival (80.0% vs. 71.0%) showed no significant difference. A favorable trend toward less hemorrhagic cystitis was observed with ATG-PTCy. In conclusion, the combination of reduced-dose ATG with PTCy is associated with a significantly reduced risk of chronic GVHD after haplo-HSCT.