Long-term outcome of cord blood transplantation from unrelated donors as an initial transplantation procedure for children with AML in Japan.

To assess the outcome of unrelated umbilical cord blood transplantation (UCBT), 141 children with AML who underwent UCBT (39 in first CR (CR1), 33 in CR2, 4 in CR3 and 65 at more advanced stages (not in CR)) were analyzed in a retrospective multicenter study in Japan. Short-term MTX was used for prophylaxis of acute GVHD in 80 cases (57%). The cumulative incidences of neutrophil recovery, platelet recovery and acute GVHD (grades 2-4) were 78.7, 62.4 and 40.1%, respectively, and the 100-day transplantation-related mortality (TRM) was 10.8%. Multivariate analysis showed that an infused CD34(+) cell dose of 1.35 x 10(5) cells per kg or more was associated with favorable neutrophil and platelet recovery, and that short-term MTX was associated with a lower 100-day TRM. The 6-year relapse rate was 38.8% and was associated with disease status. Six-year overall survival was 45.8% (70.4+/-8.3% in CR1, 59.3+/-11.3% in CR2, 75.5+/-21% in CR3 and 20.6+/-6.2% for children with non-CR). We conclude that the results of UCBT are particularly promising for children with a karyotype suggesting a poor prognosis, and for those who receive transplants in CR2 and CR3 after an early relapse.