Graft versus host disease prophylaxis with low-dose cyclosporine-A reduces the risk of relapse in children with acute leukemia given HLA-identical sibling bone marrow transplantation: results of a randomized trial.

Leukemia relapse is a major cause of treatment failure for patients with acute leukemia given allogeneic bone marrow transplantation (BMT). This study evaluated whether a reduction of the dosage of cyclosporine-A (Cs-A) used for graft versus host disease (GVHD) prophylaxis could reduce relapse rate (RR) in children with acute leukemia given BMT. Fifty-nine children who had transplantation from HLA-identical siblings were randomized to receive Cs-A intravenously at a dosage of 1 mg/kg/d (Cs-A1) or of 3 mg/kg/d (Cs-A3) until patients were able to tolerate oral intake. Subsequently, both groups received Cs-A orally at a dosage of 6 mg/kg/d, with discontinuation 5 months after BMT. The probability of developing grade II-IV acute GVHD was 57% for the Cs-A1 group versus 38% for the Cs-A3 group (P =.06); the probability of developing chronic GVHD was 30% for the Cs-A1 group and 26% for the Cs-A3 group (P = NS). Three patients died of grade IV acute GVHD: 2 were in the Cs-A1 and the third in the Cs-A3 group. The RR was 15% for the Cs-A1 group and 41% for the Cs-A3 group (P =.034); 1-year transplant-related mortality estimates were 17% and 7%, respectively (P = NS). With a median observation time of 44 months from BMT, the 5-year event-free survival for children belonging to Cs-A1 and Cs-A3 groups was 70% and 51%, respectively (P =.15). Our data demonstrate that the use of low Cs-A doses is associated with a statistically significant reduction of leukemia relapse, probably due to an increased graft versus leukemia effect. (Blood. 2000;95:1572-1579)