Fludarabine Melphalan, Reduced-dose Busulfan Versus Fludarabine, Melphalan, Full-dose Busulfan in Patients Receiving Cord Blood Transplantation.

BACKGROUND: Various reduced-intensity conditioning/reduced-toxicity conditioning regimens have been developed for patients receiving allogeneic hematopoietic cell transplantation. The balance between disease relapse and toxicity can be partly dependent on reduced-intensity conditioning/reduced-toxicity conditioning regimens. This retrospective study aimed to compare the nonrelapse mortality, relapse incidence, progression-free survival, and overall survival rates between the fludarabine/melphalan/reduced-dose busulfan (Flu/Mel/Bu2; busulfan at a dose of 6.4 mg/kg intravenously) and fludarabine/melphalan/full-dose busulfan (Flu/Mel/Bu4; busulfan at a dose of 12.8 mg/kg intravenously) regimens in patients receiving umbilical cord blood transplantation.

METHOD: Eighty-seven adult patients who received the Flu/Mel/Bu2 (n = 45) or Flu/Mel/Bu4 (n = 42) regimen as a conditioning regimen before umbilical cord blood transplantation at our institution between January 2013 and December 2022 were included in this study.

RESULTS: There were no significant differences in terms of clinical outcomes including nonrelapse mortality, relapse incidence, progression-free survival, and overall survival rates between the two regimens. Further, even in higher-risk patients classified according to the Refined Disease Risk Index, the Flu/Mel/Bu2 regimen was comparable to the Flu/Mel/Bu4 regimen.

CONCLUSION: The novel Flu/Mel/Bu2 regimen could be applied in clinical settings as it can be tolerated and effective in older patients.