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 allogeneic stem cell transplantation is the only curative approach. The roles of pretransplant treatment, conditioning regimen and graft-versus-host disease (GVHD) are still unclear. Eleven children with JMML underwent allogeneic BMT in our institution. Donors were matched unrelated (n = 6) matched siblings (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 infusion or second BMT, respectively. To evaluate the role of pretransplant treatment, conditioning regimen and GVHD, we have summarised our series with other published single centre reports and give an overview on a total of 65 patients with JMML who underwent allogeneic BMT. No significant correlation between pretransplant treatment, conditioning regimen and TRM could be observed. Overall relapse rate is high (47%). TBI is associated with a significantly higher relapse rate (P = 0.012). Other conditioning modalities, intensive chemotherapy and splenectomy prior to stem cell transplantation do not seem to have a significant impact on relapse rate. Patients with or without GVHD showed no significant difference in relapse rate (58% vs 45%). In the event of relapse after transplantation withdrawal of immunosuppression, donor lymphocyte infusion or second transplant was successful in 6/11 patients. Graft-versus-leukaemia effect seems to play an essential role in bone marrow transplantation for JMML.