Second allogeneic transplants in children: twelve years of experience

Introduction: A second hematopoietic stem cell transplant is required when the first transplant fails, usually due to relapse or graft failure, and is associated with increased morbidity and mortality. Survival rates range from 74 to 82% in non-neoplastic diseases and from 39 to 58% in neoplastic conditions. Evidence on second hematopoietic stem cell transplant in children is limited, particularly in low- and middle-income countries. Objective: To describe the clinical characteristics, complications, and outcomes of children who underwent a second transplant at a high-complexity center between 2012 and 2024. Materials and methods: Case series study with descriptive and survival analysis using the Kaplan-Meier method in Stata 14™. Results: A total of 346 allogeneic transplants were performed, of which 20 patients underwent a second transplant. Of these, 17 received a haploidentical donor for their second transplant, and the primary indication was a neoplastic disease in 13 cases. The second transplant was performed due to graft failure in 11 of the 20 patients, and due to relapse in the remaining 9. The mean age was 10.7 ± 5 years, with a male predominance (14 out of 20). Haploidentical transplants accounted for 16 of the 20 cases, and 11 used the same donor. The most common complications were acute graft-versus-host disease in 7 cases, 2 of grade III, cytomegalovirus infection in 10 cases, and graft failure after the second transplant in 4 cases: 3 primary, 1 secondary. Transplant-related mortality was 31%. The 2-year overall survival was 54%, with a median follow-up of 11 months. Conclusions: Second hematopoietic stem cell transplant is a viable therapeutic option when no other alternatives are available, particularly in resource-limited settings.