Transplantation-Related Mortality, Graft Failure, and Survival after Reduced-Toxicity Conditioning and Allogeneic Hematopoietic Stem Cell Transplantation in 100 Consecutive Pediatric Recipients

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) with myeloablative conditioning is associated with a 10%-40% risk of day +100 transplantation-related mortality (TRM). We evaluated the feasibility and safety of reduced-toxicity conditioning and allo-HSCT in 100 consecutive children and adolescent recipients (mean age, 9.2 +/- 6.8 years). The mean duration of follow-up was 1278 +/- 1042 days. Fifty patients had malignant disease: The median time to neutrophil recovery was 18 days, and the median time to platelet recovery was 43 days. Median donor chimerism in engrafted patients was 98% on day +100 and 98% on day +365. The cumulative incidence of acute graft-versus-host disease (GVHD) was 20% (95% confidence interval [CI], 12.1%-27.9%), and that of chronic GVHD was 13.5% (95% Cl, 6.6%-20.4%). TRM was 3% (95% CI, 0%-6.4%) by day +100 and 13.6% (95% CI, 6.7%-20.5%) for the entire study period. The incidence of primary graft failure (PGF) was 16% overall, 31.4% after umbilical cord blood transplantation (UCBT), and 0% after allo-HSCT with matched unrelated or matched sibling donors (P < .0001). The incidence of PGF in UCBT recipients was 46.7% (14 of 30) in chemotherapy-naive recipients, versus 9.5% (2 of 21) in non chemotherapy-naive recipients (P = .019). Five-year event-free survival was 59.5% +/- 5%, and 5-year overall survival was 72.9% +/- 5%. Only PGF and poor-risk disease status were significantly associated with decreased overall survival (P = .03). Reduced-toxicity conditioning allo-HSCT in pediatric recipients is associated with low TRM; however, chemotherapy-naive UCBT recipients have a significantly higher incidence of PGF. (C) 2013 American Society for Blood and Marrow Transplantation.