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.