Post-transplant cyclophosphamide/tacrolimus/mycophenolate mofetil outperformed tacrolimus/methotrexate as a prophylaxis for graft-versus-host disease (GVHD) in patients with an indication for reduced-intensity conditioning allogeneic stem cell transplantation (RIC ASCT).

The results of the phase 3 BMT CTN 1703 trial were presented by Dr. Shernan Holtan (University of Minnesota)1 at the 2022 annual meeting of the American Society of Hematology. The study included adult patients receiving RIC ASCT (N=431), who were randomized 1:1 to post-transplant cyclophosphamide/tacrolimus/mycophenolate mofetil (PTCy/Tac/MMF) or tacrolimus/methotrexate (Tac/MTX). The primary endpoint was 1-year GVHD-free relapse-free survival (GRFS), a composite endpoint of grade III–IV acute GVHD, chronic GVHD requiring systemic immunosuppression, relapse/progression, or death.

The primary endpoint was met, with a 1-year GRFS of 52.7% in the PTCy/Tac/MMF arm and a 1-year GRFS of 34.9% in the Tac/MTX arm (HR, 0.64; P<0.001). The effect was driven by a reduction in grade III–IV acute GVHD (6.3% vs 14.7%, respectively; P=0.001) and a decrease in chronic GVHD requiring systemic immunosuppression (12.5% vs 25%, respectively; P=0.001). Dr. Holtan added that relapse/progression rates were similar, with 20.8% in the PTCy/Tac/MMF arm and 20.2% in the Tac/MTX arm (P=0.906).

There were more grade 2–3 infections in the experimental arm (40.0% vs 30.4; P=0.018), mostly explained by an increased rate of grade 2 infections. Also, fewer patients in the experimental arm achieved an absolute lymphocyte count higher than 1,000 (53.8% vs 63.2%; P<0.001). After 1 year of follow-up, it appeared that patients in the Tac/MTX arm were more likely to die from acute GVHD (14.3% vs 4.2%), whereas patients in the PTCy/Tac/MMF arm were more likely to die from organ failure (22.9% vs 10.7%).

Dr. Holtan and colleagues concluded that PTCy/Tac/MMF should become the standard-of-care GVHD prophylaxis in adults receiving RIC ASCT.


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