Hematopoietic Stem Cell Transplant for Pediatric Acute Promyelocytic Leukemia

The optimal form of treatment for children with relapsed or refractory acute promyelocytic leukemia (APL) is unclear. We retrospectively analyzed the results of 32 (11 autologous, 21 allogeneic) hematopoietic stem cell transplants (HSCT) performed for children originally treated on either the Eastern Cooperative Group E2491 Trial or the Cancer and Leukemia Group B C9710 Trial and subsequently diagnosed with relapsed or refractory APL. For autologous HSCT, the incidence of treatment-related mortality (TRM) and relapse was 0% (95% confidence interval [CI], 0%-30%) and 27% (95% CI, 9%-57%), respectively. The 5-year event-free survival (EFS) and overall survival (OS) following autologous HSCT was 73% (95% CI, 43%-91%) and 82% (95% CI, 51%-96%), respectively. For allogeneic HSCT, the incidence of TRM and relapse was 19% (95% CI, 7%-41%) and 10% (95% CI, 2%-30%), respectively. The 5-year EFS and OS following allogeneic HSCT was 71% (95% CI, 50%-86%) and 76% (95% CI, 55%-90%), respectively. There was no significant difference in EFS or OS between autologous and allogeneic HSCT. This data demonstrates that autologous and allogeneic HSCT are both effective therapies for treatment of children with relapsed or refractory APL. Autologous HSCT is associated with a low incidence of TRM, whereas allogeneic HSCT is associated with a low incidence of relapse, suggesting a strong GVL effect against residual APL.