Reduced-Intensity Conditioning Regimens for Allogeneic Transplantation in Children with Acute Lymphoblastic Leukemia

Reduced-intensity conditioning regimens have been used extensively in adults with hematologic malignancies. To address whether this is a feasible approach for children with acute lymphoblastic leukemia, we evaluated transplant outcomes in 38 recipients transplanted from 1995-2005 for whom this was their first transplant. The median age at transplant was 12 years, and 47% had performance scores <90%. Disease status was first complete remission (CR) in 13%, ≥CR2 in 60% of patients, and 22% had active disease at transplantation. Matched related donors were available for a third of patients, about half of whom received bone marrow (BM) and the others, peripheral blood progenitor cells. Sixty percent of unrelated donor transplant recipients received peripheral blood progenitor cells. The day-100 probability of grade II-IV acute graft-versus-host disease was 37% and the 3-year probability of chronic graft-versus-host disease, 26%. At 3 years, the probability of treatment-related mortality was 40%, relapse 37%, and disease-free survival 30%. These data indicate long-term DFS can be achieved using reduced-intensity conditioning regimens in children with acute lymphoblastic leukemia. Given the relatively small cohort, these findings must be validated in a larger population.