Background:
Cyclosporine (CSA) plus 4 doses of methotrexate (MTX) is the commonly used regimen for GVHD prophylaxis. It has been previously found that the omission of the day +11 dose of MTX was associated with an increased risk of acute GVHD in the allogeneic BMT setting. However, little is known about its impact in the PBSCT setting.
Methods:
Of the 68 patients, 30 patients (44%) received 4 doses of MTX (the MTX4 group), while 38 patients (56%) received less than 4 doses (the MTX3 group) because of their severe mucositis, hepatic dysfunction or renal failure.
Results:
The cumulative incidence of acute GVHD was 60% in the MTX4 and 86% in the MTX3 group (P=0.038), while that of grade III and IV acute GVHD was 7% in the MTX4 group and 39% in the MTX3 group (P=0.017). Of the 61 patients evaluated for chronic GVHD, the cumulative incidence of chronic GVHD was 54% in the MTX4 group and 97% in the MTX3 group (P=0.001), while that of extensive chronic GVHD was 26% in the MTX4 group and 63% in the MTX3 group (P=0.004). There were no differences in the overall survival and the incidence of relapse between the two groups. On multivariate analyses, MTX3 was a poor prognostic factor in terms of acute GVHD and extensive chronic GVHD.
Conclusion:
This study suggested that omitting day +11 MTX and the clinical situation of the MTX3 group seemed to be associated with an increased incidence of acute and chronic GVHD. Accordingly, administration of day +11 MTX accompanied by active treatment of mucositis may prevent GVHD in the allogeneic PBSCT setting, but we need to conduct a large scale prospective study.

Keywords: Methotrexate, Graft-versus-host disease, Allogeneic peripheral blood stem cell transplantation