Post-transplant cyclophosphamide at 80mg/kg with low dose post-engraftment anti-thymocyte globulin in haploidentical transplantation with myeloablative conditioning

Abstract

Abstract While post-transplant cyclophosphamide (PTCy) is commonly used as graft-versus-host disease (GvHD) prophylaxis in haploidentical stem cell transplantation (haplo-HSCT), the dose remains a matter of debate due to side effect concerns. Standard dose PTCy associated with tacrolimus and post-engraftment anti-thymocyte globulin (ATG) was used as the reference GvHD prophylaxis in our center and had demonstrated encouraging results. Though PTCy 80 mg/kg was shown to be feasible in patients in reduced intensity conditioning, whether it exerts equivalent GvHD prophylactic efficacy in myeloablative conditioning (MAC) setting has not been confirmed. Here, we retrospectively analyzed the efficacy and safety of PTCy 80mg/kg combined with tacrolimus and post-engraftment ATG as GvHD prophylaxis in patients aged more than 55 years or with cardiac antecedents or HCT-CI score > 2 undergoing haplo-HSCT with MAC. The cumulative incidence of grade III-IV aGvHD at day 100 and moderate-to-severe cGvHD at 1 year was 4.8%±3.4% and 19.9%±7.0%, respectively. When compared with patients receiving the reference regimen, patients from the PTCy 80mg/kg group had similar incidence of GvHDs and survival as their younger counterparts. Thus, PTCy 80 mg/kg seems to be feasible for patients treated with MAC conditioning regimens in haplo-HSCT, inviting further investigation notably in frail patients.