Nonmyeloablative transplantation in children. Current status and future prospects

Over the last few years a variety of conditioning regimens have been developed that allow allogeneic hematopoietic stem cell engraftment with significantly decreased transplant related-toxicity. While these reduced-intensity regimens have offered hope for patients with malignancies formerly not eligible for myeloablative transplantation due to excessive morbidity (older patients and patients with significant organ toxicity), the role of nonmyeloablative hematopoietic cell transplantation (NM-HCT) in children is unclear. A review of the available literature for pediatric and adult studies shows several malignancies in which approaches designed to limit long-term complications in children may be appropriate. In addition, NM-HCT may offer a safer approach for children with inherited disorders curable by marrow transplantation, such as immunodeficiencies, hemoglobinopathies, or storage diseases. Finally, use of this approach to establish partial donor chimerism may provide an immunologic platform that will allow specific cellular therapies, targeted gene therapy, or immunologic tolerance in solid organ transplantation.