Successful engraftment of sibling cord-blood stem cell transplantation in a child with acute promyelocytic leukemia.

Cord blood stem cell transplantation (CBSCT) was performed on a patient with acute promyelocytic leukemia. The patient was a boy 3 years and 8 months old, who had shown complete remission following treatment with intensive chemotherapy. However, after the final course of consolidation chemotherapy, chromosome analysis of his bone marrow aspirates revealed 46XY, t(15,17)(q22;q21), and a PML-RAR alpha fusion gene was detected by the reverse transcriptase-polymerase chain reaction test. All-trans retinoic acid diminished the chromosomal abnormality, but the PML-RAR alpha fusion gene remained. The patient was then treated with CBSCT from an HLA-matched sibling donor. The number of nucleated cells in the cord blood was 2.2 x 10(7)/kg of body weight, and that of granulocyte-macrophage colony-forming units 0.6 x 10(4)/kg. Methotrexate was given, on days 3 and 6, as prophylaxis against graft-versus-host disease (GVHD). The neutrophil count rose to above 500/microliters on day 22. The platelet count exceeded 50,000/microliters on day 48. Platelet transfusions were given 12 times after CBSCT, the last one on day 36. Grade I acute GVHD was treated with steroids. The patient was well and discharged on day 103, without symptoms or laboratory data suggestive of relapse. Following this experience we instituted a project of the Kanagawa Cord Blood Bank, which is scheduled for expansion nationwide.