Methotrexate Reduces the Incidence of Severe Acute Graft-versus-Host Disease without Increasing the Risk of Relapse after Reduced-Intensity Allogeneic Stem Cell Transplantation from Unrelated Donors.

Optimized prophylaxis against graft-versus-host disease (GVHD) after unrelated reduced-intensity allogeneic transplantation when preceded by a conditioning regimen utilizing antithymocyte globulin (ATG) is poorly defined. To investigate the effects of methotrexate (MTX) in this treatment setting, we conducted a retrospective analysis. Sixty-three patients were selected based on the administration of a total dose of 5 mg/kg of ATG in the conditioning regimen and then separated into either group M+ (n = 39), which received MTX or group M- (n = 24), which did not. All patients received cyclosporine. In the M- and M+ groups, cumulative incidences (CI) of grade III-IV acute GVHD (aGVHD) were 43% and 10%, respectively (P = .002). Multivariate analysis indicated that grade III-IV aGVHD was favored by both the absence of MTX and the provision of a female donor for a male recipient. At 2 years, the M+ and M- groups exhibited, respectively: overall survival of 69% and 40% (P = .06), disease-free survival of 57% and 43% (P = .2), nonrelapse mortality of 20% and 44% (P = .1), and incidence of relapse of 27% and 35% (P = .6). These data suggest that MTX reduces the incidence of severe aGVHD without increasing the risk of relapse but with an accompanying trend toward improved survival after unrelated reduced-intensity transplantation with ATG in the conditioning regimen.