Alternative-donor hematopoietic stem-cell transplantation for severe aplastic anemia.

Bone marrow transplantation (BMT) from a human leukocyte antigen (HLA)-matched sibling is the treatment of choice in children and young adults with severe aplastic anemia (SAA). However, because only 30% of patients have a suitable donor, more aggressive nontransplant immunosuppressive regimens have been used, with reasonable results. The use of mismatched family member and unrelated donors, initially fraught with problems of nonengraftment and severe graft-versus-host disease (GVHD), has improved markedly over the past 10 years. The establishment of donor registries, more precise HLA typing methods, and better supportive care are significant factors in the improved outcomes. The challenge for the future is to assemble the optimal combination of donor selection, conditioning regimen, and GVHD prophylaxis to enhance disease-free survival. These better outcomes should encourage the treating physician to consider stem-cell transplant at an earlier stage of disease.