Sirolimus demonstrates activity in the primary therapy of acute graft-versus-host disease without systemic glucocorticoids.

Background: Advances in acute graft-versus-host disease therapy are needed.
Design and Methods: We examined the efficacy of sirolimus as primary therapy for acute graft-versus-host disease in 32 patients.
Results: Acute graft-versus-host disease involved the skin in 53% of cases, gastrointestinal tract in 66%, liver in 16%. The syndrome was overall grade 1 in 12% cases, grade 2 in 75%, and grade 3 in 13%. Sirolimus was targeted to achieve serum trough levels of 5-14 ng/mL. Sixteen (50%) patients achieved sustained, complete resolution of acute graft-versus-host disease with sirolimus alone. In contrast, 19 of 32 (59%) matched historical controls treated with standard 1 mg/kg steroids achieved complete response (P=0.47). With median follow-up time for surviving patients of 16 (range 6-26) months, one year overall survival was 56% (95% CI 38-74%). The cumulative incidence of relapse at one year was 37% (95% CI 23-60%), and mortality in remission was 20% (95% CI 10-42%). The cumulative incidence of chronic graft-versus-host disease was 55% (95% CI 39-79%). Thrombotic microangiopathy occurred in 3 cases (grade 1 n=1; grade 2 n=2), and responded to dose reduction of calcineurin inhibitor.
Conclusions: In this retrospective series, sirolimus demonstrates activity comparable to that of high-dose glucocorticoids in the primary therapy of acute graft-versus-host disease. Confirmation of this activity requires prospective clinical trials.