Haploidentical/Mismatched Hematopoietic Stem Cell Transplantation for Nonresponders to Immunosuppressive Therapy Compared with First-Line Rabbit Antithymocyte Immunoglobulin Treatment Against Acquired Severe Aplastic Anemia

We treated 86 patients with SAA, 31 patients who failed to respond to previous therapy underwent haploidentical hematopoietic SCT (haplo-HSCT, n=26) or mismatched unrelated donor HSCT (MMUD-HSCT, n=5). The other 55 patients were treated with immunosuppressive therapy (IST). At 6 months post-treatment, the treatment failure rates of HSCT and IST groups were 19.35% and 29.09% (P=0.320). Hematopoietic recovery time was shorter in the HSCT group than IST group (P > 0.05). The estimated OS at 3 years was 79.2% ± 7.7% in HSCT group and 89.7% ± 4.4% in the IST group (P=0.058). The estimated failure-free survival (FFS) at 3 years was 79.2% ± 7.7% in the HSCT group and 62.9% ± 8.0% in the IST group (P=0.391). The estimated FFS at 3 years in SAA that had progressed from non-SAA (NSAA) of HSCT was 71.6% ± 14.0% and 16.7% ± 13.6% of IST (P=0.021). Within the HSCT group, 38.71% of the patients developed grade II-IV acute GVHD, and 18.52% of the patients experienced moderate-severe chronic GVHD. These results suggest that haplo-HSCT/MMUD-HSCT and IST have similar treatment failure rate, OS and FFS. haplo-HSCT/MMUD-HSCT might provide a better chance of FFS than IST for SAA that had progressed from NSAA.