Allogeneic bone marrow transplantation for juvenile myelomonocytic leukaemia: a single centre experience and review of the literature

Juvenile myelomonocytic leukaemia (JMML) is a rare paediatric disease and a llogeneic stem cell transplantation is the only curative approach. The role s of pretransplant treatment, conditioning regimen and graft-versus-host di sease (GVHD) are still unclear. Eleven children with JMML underwent allogen eic BMT in our institution. Donors were matched unrelated (n = 6) matched s iblings (n = 4) and one mismatch family donor. Transplant-related mortality (TRM) was 36%. Three patients relapsed after transplantation. Two of three patients with relapse are in continuous remission after donor lymphocyte i nfusion or second BMT, respectively. To evaluate the role of pretransplant treatment, conditioning regimen and GVHD, we have summarised our series wit h other published single centre reports and give an overview on a total of 65 patients with JMML who underwent allogeneic BMT, No significant correlat ion between pretransplant treatment, conditioning regimen and TRM could be observed. Overall relapse rate is high (47%). TBI is associated with a sign ificantly higher relapse rate (P = 0.012). Other conditioning modalities, i ntensive chemotherapy and splenectomy prior to stem cell transplantation do not seem to have a significant impact on relapse rate. Patients with or wi thout GVHD showed no significant difference in relapse rate (58% vs 45%). I n the event of relapse after transplantation withdrawal of immunosuppressio n, donor lymphocyte infusion or second transplant was successful in 6/11 pa tients. Graft-versus-leukaemia effect seems to play an essential role in bo ne marrow transplantation for JMML.