Evaluation of risk for graft-versus-host disease in children who receive less than the full doses of mini-dose methotrexate for graft-versus-host disease prophylaxis in allogeneic hematopoietic stem cell transplantation

Purpose: The use of cyclosporine and mini-dose methotrexate (MTX) is a common strategy for graftversus-host disease (GVHD) prophylaxis in allogeneic transplants. We investigated whether patients who receive fewer than the planned MTX doses are at increased risk for GVHD. Methods: The study cohort included 103 patients who received allogeneic transplants at the Department of Pediatrics of The Catholic University of Korea College of Medicine, from January 2010 to December 2011. MTX was administered on days 1, 3, 6, and 11 after transplant at a dose of 5 mg/m2 each. Within the cohort, 76 patients (74%) received all 4 doses of MTX [MTX(4) group], while 27 patients (26%) received 0-3 doses [MTX(0-3) group]. Results: Although there was no difference in neutrophil engraftment between the 2 groups, platelet engraftment was significantly faster in the MTX(4) group (median, 15 days), compared to the MTX(0-3) group (median, 25 days; P =0.034). The incidence of grades II-IV acute GVHD was not different between the MTX(4) and MTX(0-3) groups (P =0.417). In the multivariate study, human leukocyte antigen mismatch was the most significant factor causing grades II-IV acute GVHD (P =0.002), followed by female donor to male recipient transplant (P =0.034). No difference was found between the MTX(4) and MTX (0-3) groups regarding grades III-IV acute GVHD, chronic GVHD, and disease-free survival. Conclusion: Our results indicate that deviations from the full dose schedule of MTX for GVHD prophylaxis do not lead to increased incidence of either acute or chronic GVHD.