Successful reduced-intensity stem cell transplant from one-locus HLA-mismatched unrelated cord blood after rejection of unrelated bone marrow in an infant with myelogenous leukemia.

An 8-month-old girl had acute myelogenous leukemia (EAB M2) that relapsed 5 months after diagnosis during intensive consolidation chemotherapy. She underwent bone marrow transplantation (BMT) from an HLA-A, -B, -C and -DR phenotypically matched, but one locus DRB1 genotypically mismatched unrelated donor, but rejection occurred.Subsequently, she received reduced-intensity transplant (fludarabine/cytosine arabinoside/cyclophosphamide) from one locus HLA-A-mismatched, but DRB1 genotypically matched unrelated cord blood stem cells and remission was induced by acute GVHD (grade II) that progressed to chronic GVHD with involvement of the skin, liver, and gastrointestinal tract. In this case, it seems that remission was induced by an adequate graft-versus-leukemia effect and mild chronic graft-versus-disease due to the HLA-A difference more than DRB1 matched between the patient and the cord blood stem cells.