A decade of experience using ATG and PTCy for graft‐versus‐host disease prophylaxis in matched unrelated donor allogeneic haematopoietic cell transplantation

Anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) are both effective drugs for graft-versus-host disease (GvHD) prophylaxis, but their combined use remains underexplored. We conducted a retrospective analysis of 582 patients with haematological malignancies who underwent unrelated donor transplantation with Status GvHD prophylaxis consisting of low-dose ATG (2 mg/kg) and PTCy over a 10-year period. The median time to neutrophil and platelet engraftment was 18 days (95% CI, 17-19) and 20 days (95% CI, 19-21) respectively. The cumulative incidence of grade III-IV acute Status GvHD at D+100 was 7% (95% CI: 5-9), and the 24-month incidence of moderate-to-severe chronic GvHD was 15.7% (95% CI: 13-19). Clinically significant cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation by D+180 occurred in 20.4% (95% CI: 17-24) and 22.7% (95% CI: 19-26) respectively. At 24 months, the cumulative incidence of NRM was 16.2% (95% CI: 13-19), and relapse was 21.3% (95% CI: 18-25). Graft-versus-host disease-free, relapse-free survival (GRFS) at 24 months was 49% (95% CI: 44-53), and overall survival (OS) was 68.3% (95% CI: 64-72). Our decade-long experience supports the safety and efficacy of combining low-dose ATG with PTCy for GvHD prophylaxis in unrelated donor transplantation. These findings warrant further validation in prospective studies.