Recent advances and current challenges in allogeneic stem cell transplantation in patients with acquired severe aplastic anemia

Allogeneic stem cell transplantation (SCT) from a human leukocyte antigen (HLA)-matched sibling donor (MSD-SCT) is the preferred first-line treatment option for young patients with severe aplastic anemia (SAA). However, only 25% of patients may find an HLA-MSD. SAA patients, who lack a suitable MSD and fail first-line immunosuppressive therapy, may consider SCT from an unrelated donor (URD-SCT) as a treatment option. The results of haplo-identical stem cell transplantation from a related mismatched donor (Haplo-SCT) have improved due to recent advances in controlling graft failure and graft-versus-host disease (GVHD). The use of Haplo-SCT has recently been extended to SAA patients. However, it is important for physicians to select the appropriate conditioning regimen and GVHD prophylaxis to ensure engraftment with reduced toxicity, such as infectious complications and GVHD. This review summarizes recent advances in allogeneic SCT for patients with acquired SAA. Current challenges, including the age of the patients and the effects of donor age, stem cell source, and iron overload on transplantation outcomes are also discussed.