Treatment of leukemia relapse with recombinant granulocyte‐macrophage colony stimulating factor (rhGM‐CSF) following unrelated umbilical cord blood transplant: Induction of graft‐vs.‐leukemia

: An infant with congenital leukemia in complete remission (CR1) received an unrelated donor umbilical cord blood cell transplant from a one‐HLA disparate donor. The conditioning regimen consisted of thiotepa, busulfan and cyclophosphamide. GVHD prophylaxis consisted of tacrolimus and mini‐methotrexate. Engraftment occurred and a bone marrow aspirate obtained on day 28 showed 100% donor cells. The post‐transplant course was complicated by skin and liver GVHD, grade III, that responded to therapy with methylprednisolone, anti‐thymocyte globulin and daclizumab (Zenapax), in addition to tacrolimus. A bone marrow aspirate obtained on day 187 showed relapse, with 17% blasts. The patient was then treated for 30 days with recombinant human granulocyte‐macrophage colony‐stimulating factor treatment (rhGM‐CSF). A bone marrow aspirate obtained 17 days after the initiation of rhGM‐CSF treatment showed 2% blasts. Ascites was the predominant side‐effect of the rhGM‐CSF treatment. The patient remains in complete remission 24 months after relapse and 30 months after transplantation. This case documents that rhGM‐CSF and withdrawal of immunosuppression can induce a durable complete remission after relapse following an unrelated donor cord blood transplant.