Long-term survival after alternative donor transplantation in children with acute leukemia.

Abstract

10006 Background: Most reports describing long-term survival after allogeneic transplantation are in adults after transplantation of bone marrow (BM) from HLA-matched siblings. This report compares long-term survival after transplantation of unrelated donor BM to that after umbilical cord blood (UCB) in children with acute leukemia. Methods: Included were patients aged less than 18 years with acute myeloid or lymphoblastic leukemia, alive and leukemia-free for at least 1 year after transplantation. Transplants occurred 2000-2009. Patients received BM grafts that were HLA-matched (N = 205) or mismatched at 1-HLA locus (N = 112) and UCB grafts that were matched (N = 55) or mismatched at 1 (N = 160) or 2 HLA-loci (N = 134). Multivariate Cox regression models were constructed to explore differences in survival between groups. UCB transplants were treated as a single group as there were no significant differences between HLA-matched and mismatched UCB grafts. Multivariate models held 3 treatment groups: HLA-matched BM, HLA-mismatched BM and UCB grafts. Results: The disease characteristics of the three groups were similar. There were differences in patient and transplant characteristics. Recipients of UCB transplants were younger, more likely non-Caucasian, and more likely to have received a non-irradiation-containing conditioning regimen, in-vivo T-cell depletion and GVHD prophylaxis with cyclosporine and either prednisone or mycophenolate. In multivariate analysis, the risks of long-term mortality were not significantly different after UCB and HLA-matched BM transplants (HR 0.83, p=0.41). Mortality risks were significantly higher after HLA-mismatched BM transplants compared to UCB (HR 1.66, p=0.03) and HLA-matched BM transplants (HR 2.00, p=0.008). In this cohort, surviving disease-free at least 1-year after transplantation, the 8-year probabilities of overall survival after UCB, HLA-matched and HLA-mismatched BM transplants were 78%, 81% and 68%. Conclusions: This is the first report to document long-term durability of UCB grafts. The data continue to support the use of UCB grafts either in the absence of an HLA-matched donor or when transplantation is needed urgently for children with acute leukemia.