Alternative donor bone marrow transplantation for children with juvenile myelomonocytic leukemia.

The purpose of this study was to evaluate the outcome of children with juvenile myelomonocytic leukemia (JMML) treated with alternative donor bone marrow transplantation (BMT). Twelve consecutive patients with JMML confirmed by in vitro clonogenic assays underwent alternative donor BMT. Ten patients received pretransplant chemotherapy for one to seven cycles (cytosine arabinoside regimens). Eight underwent splenectomy before the transplant. Donors were unrelated for nine patients and partially matched related for three. Conditioning included total body irradiation for all but one patient. Graft-versus-host disease (GVHD) prophylaxis included in vitro partial T-lymphocyte depletion for five patients with cyclosporine arabinoside, and cyclosporine arabinoside and methotrexate for seven. Acute GVHD developed in all patients, and chronic GVHD developed in 7 of 11 evaluable patients. Relapses occurred in two patients, and two died of transplant-related causes. Eight patients remain in remission with a median follow-up of 31 months after the BMT. The event-free survival rate for this series is 64% (95% confidence interval, 27%-85%). The roles of pretransplant chemotherapy and splenectomy for leukemic reduction to prevent relapse, and the use of conditioning regimens with total body irradiation require study in a larger series of patients. GVHD may be beneficial in preventing relapses, which has been the major cause of treatment failure for these patients.