Alternative donor transplants for severe aplastic anemia: current experience

Patients with acquired severe aplastic anemia (SAA), who lack a human leukocyte antigen (HLA) identical sibling donor (SIB), have two therapeutic options: immunosuppressive therapy with anti-thymocyte globulin (ATG) and cyclosporine (CsA), or a transplant from an alternative donor. In these patients, the current guidelines of the European Group for Blood and Marrow Transplantation (EBMT) call for a course of ATG + CsA first and transplantation in case of no response. The alternative donor source can be an unrelated donor (UD), a cord blood (CB) unit, or a family mismatched member, in most instances genetically HLA haplo-mismatched (HAPLO). In the present review, we will discuss recent results of transplants from matched UD and SIB donors, with significantly improved outcome, especially with UD in the past decade. We will also be looking at CB transplants, and the problems of limited stem cell dose. Finally HAPLO grafts have been explored in patients lacking or having rejected an unrelated or CB graft: early results seem encouraging, though the procedure should still be considered experimental.