Objective: To compare the transplant-related toxicity and the efficacy of busulfan/fludarabine (Bu/Flu) and busulfan/cyclophosphamide (Bu/Cy) as conditioning regimen in allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia(AML) in the first complete remission (CR1).
Methods: Totally 32 AML-CR1 patients underwent allo-HSCT were divided into Bu/Cy (Bu 3.2 mg×kg(-1)×d(-1), 7 - 4 days before transplantation; Cy 60 mg×kg(-1)×d(-1), 3 - 2 days before transplantation) and Bu/Flu (Bu 3.2 mg×kg(-1)×d(-1), 5 - 2 days before transplantation; Flu 30 mg×m(-2)×d(-1), 6 - 2 days before transplantation) groups. The regimen-related toxicity (RRT), incidence and severity of graft-versus-host disease (GVHD), 3-year cumulative relapse rate, non-relapse mortality (NRM), 3-year event-free survival (EFS) rate and overall survival (OS) rate were compared between the two groups.
Results: The median follow-up duration was 617.5 (6 - 1261) days. All patients achieved successful engraftment on 30 day after transplantation. There were no significant differences in the median time to neutrophil engraftment (P = 0.121) and platelet engraftment (P = 0.171) between the two groups. The median duration of neutrophil count under 0.1×10(9)/L and platelet count under 20×10(9)/L in the Bu/Cy group were significantly longer than those in the Bu/Flu group (P = 0.000 and P = 0.047). The incidence of grades II-IV RRT were 68.8% and 25.0% (P = 0.032) in the Bu/Cy and the Bu/Flu groups, respectively. There were no significant differences in the incidence of acute GVHD (P = 0.149), chronic GVHD (P = 0.149), incidence of NRM (P = 0.333), 3-year cumulative relapse rates (P = 0.834), 3-year EFS rate (P = 0.362) and OS rate (P = 0.111) between the two groups.
Conclusion: Compared with Bu/Cy, Bu/Flu is a myeloablative condition regimen with milder bone marrow suppression and lower RRT incidence rate in allogeneic HSCT for AML-CR1 patients without compromising the efficacy.