Efficacy and safety of FABT versus FCA regimens in allogeneic hematopoietic stem cell transplantation for aplastic anemia patients

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the primary curative treatment for Aplastic anemia (AA), especially for severe aplastic anemia (SAA). The Baltimore regimen and Fludarabine plus Cyclophosphamide/Antithymocyte globulin (FCA) regimen are commonly used non-ex vivo T-cell depletion regimens, but challenges like graft failure and delayed engraftment persist. We modified the traditional Baltimore regimen into FABT to enhance engraftment and reduce graft-versus-host disease (GVHD) incidence. We retrospectively analyzed 62 AA patients who underwent allo-HSCT with either the FABT (n = 28) or FCA (n = 34) regimen between April 2022 and December 2023. This study compared the efficacy and safety of two regimens for treating AA. No significant differences were observed between the FABT and FCA groups in engraftment, cGVHD, and survival. However, the FABT group showed a significantly lower incidence of aGVHD (10.7% vs. 38.2%, p = 0.018) and CMV reactivation (10.7% vs. 35.3%, p = 0.027). The 1-year graft-versus-host disease and relapse-free survival (GRFS) was significantly higher in the FABT group (89.3% vs. 64.7%, p = 0.022). The novel FABT regimen achieves comparable efficacy and survival to the FCA regimen but with a significantly lower aGVHD incidence and CMV reactivation rate, suggesting better treatment outcomes and quality of life for AA patients undergoing allo-HSCT. Larger, prospective, randomized controlled trials are warranted to confirm these findings.