Successful treatment of primary refractory acute myeloid leukemia with megadose stem cell transplantation, bone marrow boost and reduced intensity conditioning avoiding chronic graft vs. host disease and severe late toxicity

We report on a 9-yr-old boy suffering from primary refractory AML. Remission was not achieved after two courses of induction therapy, leading to prolonged aplasia for more than 3 months and severe infection. Therefore, the boy was treated with a reduced intensity conditioning regimen consisting of fludarabine, cyclophosphamide and OKT3. Megadose transplantation of highly enriched CD34⁺ peripheral stem cells from his HLA-identical brother, followed on day + 11 by a boost of unmanipulated bone marrow, was performed. Regeneration of donor hematopoiesis was rapid and led to resolution of infection. No additional donor lymphocyte infusions were necessary. More than 4 1/2 yr after the transplant the boy remains in complete continuous remission with no evidence for chronic GvHD or other late effects. Therefore, we conclude that reduced intensity conditioning in combination with allogeneic megadose stem cell transplantation and bone marrow boost may have helped to achieve cure from primary refractory AML as well as a good quality of life for this boy.