Effectiveness of Fludarabine- and Busulfan-Based Conditioning Regimens in Patients With Acute Myeloblastic Leukemia: 8-Year Experience in a Single Center

Abstract Objective Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for acute myeloblastic leukemia (AML). Because the conditioning regimen of busulfan plus cyclophosphamide carries significant risks of toxicity, we evaluated the factors affecting survival after fludarabine replacement instead of cyclophosphamide. Methods The study included 55 patients who underwent allo-HSCT for AML and received busulfan, fludarabine, and antithymocyte globulin (ATG). Results Forty-eight patients received a myeloablative regimen; 7 patients received a reduced-intensity conditioning regimen. The neutrophil and platelet engraftment times were 12 days (range 9 to 20) and 12 days (range 7 to 19), respectively. Graft-vs-host disease (GvHD) developed in 10% and 50% of the patients, respectively. Seven patients received donor lymphocyte infusion. Of them, 5 patients developed grade I or II GvHD, one grade IV GvHD. The median follow-up period was 20.6 months. The predicted progression-free survival (PFS) at 1 and 3 years after transplantation was 78% and 74%, respectively. The overall survival (OS) at 1, 3, and 5 years was 76%, 74%, and 62%, respectively. Treatment-related mortality (infection in 1 patient, GvHD in 2 patients) occurred in 3 patients (5.5%). Multivariate analysis revealed that OS and PFS were not influenced by age, dose of busulfan or ATG, or presence of cytomegalovirus antigenemia. Acute GvHD and pretransplantation minimal residual disease positivity negatively affected the transplant outcome. The presence of active disease at the time of transplantation was found as an independent risk factor for AML. Conclusions Busulfan- and fludarabine-based conditioning regimens are effective for AML, and have acceptable toxicity, morbidity, and mortality.