Long-Term Follow-Up after Reduced-Intensity Conditioning and Stem Cell Transplantation for Childhood Nonmalignant Disorders

Reduced-intensity conditioning (RIC) before hematopoietic stem cell transplantation (HCT) in children could result in fewer complications during follow-up compared with myeloablative regimens. Hence, many RIC regimens are under investigation, but long-term follow-up is essential. We describe late follow-up beyond 2 years post-HCT in 43 children with nonmalignant disorders who underwent related or unrelated donor (56%) HCT on a multicenter study using a RIC regimen (alemtuzumab, fludarabine, and melphalan) followed by bone marrow (n = 30), peripheral blood (n = 3), or umbilical cord blood (n = 10) HCT for immune dysfunction, bone marrow failure, metabolic disorders, or hemoglobinopathy. Recipients (median age, 7.5 years; range, 3 to 26) underwent HCT 2 to 8 years (median, 3.1 years) before this report. Full donor (67%) or stable mixed chimerism (33%) was noted without late graft rejection. Five patients (12%) required systemic immunosuppression therapy (IST) beyond 2 years post-HCT for graft-versus-host disease (GVHD); 2 patients died 38 and 79 months later, whereas the others improved, enabling an IST wean. Overall, 17 complications were documented in 10 patients (23%). Complications not related to GVHD included hypothyroidism (n = 2), low grade neoplasms (n = 2), and delayed puberty (n = 1). One patient with GVHD had ovarian failure; all other postpubertal females resumed normal ovarian function. Twenty-seven of 28 school-age recipients were functioning at grade level. RIC HCT recipients thus had few regimen-related toxicities during long-term follow-up. However, objective long-term follow-up is still necessary to identify complications so timely intervention may be planned.