Aims: This study compares the outcomes of patients with high-risk acute myeloid leukemia (AML) who underwent allogeneic stem cell transplantation (SCT) after conditioning combining busulfan (16 mg/kg orally) and cyclophosphamide (120 mg/kg intravenously) (BU-CY) with those allografted after administration of fludarabine (150 mg/m(2) intravenously), busulfan (12 mg/kg orally) and thymoglobulin (6 mg/kg intravenously) (FLU-BU12-TG).
Material and methods: SCT after BU-CY and FLU-BU12-TG was performed in 21 and 10 AML patients. There were no significant differences between groups in number of patients treated in complete disease remission, gender, age, donors, CD34+, mononuclear cell (MNC) count in the graft and follow-up period. However, significantly more SCTs from unrelated (90% vs. 19%; p=0.00018) and HLA-mismatched donors (50% vs. 0%; p=0.0004) were performed in the FLU-BU12-TG group. The Cox proportional hazards model was used to assess the risk of post-transplant AML relapse and non-relapse mortality (NRM). The probability of post-transplant 2-year event-free survival (EFS) and overall survival (OS) were calculated using the Kaplan-Meier method.
Results: No significant differences were found between the FLU-BU12-TG and BU-CY groups in risk of AML relapse (HR=1.036; 95% CI [0.102 - 10.47]; p=0.9), post-transplant NRM (HR=0.25; 95% CI [0.031 - 1.96]; p=0.18), 2-year EFS (89% vs. 43%; p=0.19) or OS (79% vs. 57%; p=0.23).
Conclusion: These pilot results demonstrate the efficacy of the new FLU-BU12-TG conditioning regimen in patients allografted for high-risk AML. This conditioning might become an alternative approach in patients at high risk of severe post-transplant complications after the standard BU-CY myeloablative regimen.