New myeloablative conditioning regimen with fludarabine and busulfan for allogeneic stem cell transplantation: comparison with BuCy2

A regimen of busulfan and cyclophosphamide (BuCy2) is regarded as the standard myeloablative regimen for SCT. This study evaluated the hypothesis that fludarabine can replace cyclophosphamide for myeloablative allogeneic SCT. Ninety-five patients underwent allogeneic SCT from HLA-identical donors, following BuCy2 (n 55) or busulfan + fludarabine (BF, n 40). The efficacy of fludarabine compared to cyclophosphamide was retrospectively evaluated. The BF group exhibited a shorter duration until engraftment (P=0.001), lower incidence of acute and chronic GVHD (P<0.001 and P = 0.003, respectively), and non-relapse mortality ( NRM) ( P = 0.039). Furthermore, the event-free survival and overall survival were significantly higher for the BF group compared to the BuCy2 group (P = 0.004 and 0.002, respectively). After adjusting for age, the risk status of disease, GVHD prophylaxis and donor type, the BF regimen was found to be an independent favorable risk factor for event-free survival ( hazard ratio (HR), 0.181; 95% confidence interval, 0.045-0.720; P = 0.016) and overall survival ( HR, 0.168; 0.035-0.807; P = 0.026). The replacement of cyclophosphamide with fludarabine for myeloablative conditioning seems to be more effective in terms of short-term NRM, and GVHD compared to BuCy2 regimen in allogeneic transplantation.