Risk-adapted GVHD prophylaxis with post-transplantation cyclophosphamide in adults after related, unrelated, and haploidentical transplantations

Introduction: Although a number of studies were published on the efficacy of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis, no large studies prospectively evaluated this strategy in related, unrelated, and haploidentical grafts. Methods: In this study, GVHD prophylaxis for 57 matched bone marrow (MBM) grafts consisted of single-agent PTCy, for 88 matched PBSC grafts (MPBSC) consisted of PTCy, tacrolimus, and mycophenolate mofetil (MMF) 30 mg/kg, and for 55 mismatched grafts (MMGs) consisted of PTCy, tacrolimus and MMF 45 mg/kg. Results: The study met the primary endpoint to demonstrate equivalent rates of acute GVHD grade II-IV (11%, 17%, 19%, P=.46), III-IV (7%, 2%, 6%, P=.41), and moderate and severe chronic GVHD (22%, 11%, 15%, P=.23). There was also no differences in non-relapse mortality (11% vs 15% vs 17%, P=.75), overall survival (63% vs 71% vs 56%, P=.72), event-free-survival (51% vs 66% vs 48%, P=.32) for MBM, MPBSC, and MMG groups, respectively. Toxicity was comparable between groups except higher incidence of nephrotoxicity in combination arms (P=.0005) and higher incidence of graft failures in MMG group (P=.004). Conclusion: The suggested risk-adapted PTCy-based prophylaxis is feasible and is associated with low GVHD incidence and mortality in all types of grafts.