Comparison of HLA-matched sibling and unrelated donor transplantation in adult patients with acquired severe aplastic anemia

The recent improvements in the outcomes of severe aplastic anemia (SAA) patients who received allogeneic stem cell transplantation (SCT) from unrelated donors (URD) suggest the possibility of its alternative first-line treatment. To address this issue, results of adult SAA patients receiving allogeneic SCT were compared between the following three donor-type groups: 8/8-matched sibling (MSD; n = 153), 8/8 well-matched unrelated (WM-URD; n = 72), and 6-7/8 partially matched unrelated (PM-URD; n = 33). Proportion of patients who experienced immunosuppressive treatment failures was significantly higher in the URD groups than in the MSD group (P < 0.01). The incidences of graft failure and transplant-related mortality, and graft-vs.-host disease-free, failure-free survival rates of the MSD, WM-URD, and PM-URD groups were 14.6, 0, and 0% (P < 0.01); 6.1, 10.3, and 21.7% (P = 0.03); and 76.7, 55.5, and 51.5% (P < 0.01), respectively. The overall survival (OS) rate of the MSD group (93.9%) was higher than that of the PM-URD (78.3%; P < 0.01) group, but not to that of the WM-URD (86.2%; P = 0.18) group. Our study showed comparable OS between the MSD group and WM-URD group, which suggest that the URD-SCT can be used as a first-line treatment for adult SAA patients with WM-URD.