Current status of allogeneic bone marrow transplantation in acquired aplastic anemia.

Bone marrow transplantation is an effective therapy for aplastic anemia. Infusion of allogeneic hematopoietic stem cells after high-dose immune suppression restores normal hematopoiesis in most patients and long-term follow-up has confirmed the durability of donor hematopoiesis. However, success of this approach is limited by transplant-related complications, such as graft failure, graft-versus-host disease, and various organ toxicities. Long-term survival rates range from less than 40% to more than 90% in reported series. These rates have improved over the past 20 years due to significant reductions in graft-versus-host disease, interstitial pneumonitis, and early transplant-related mortality. Most long-term survivors have excellent performance status. Late effects such as cataracts, thyroid disorders, joint problems, and therapy-related cancers are observed, especially in patients who received radiation for pretransplant conditioning. Results are best in young patients transplanted with bone marrow from a human leukocyte antigen (HLA)-identical sibling; early transplantation is appropriate in this group. For older patients or those without an HLA-identical related donor, transplants are better reserved for those who fail to respond to immunosuppressive therapy.