Safety and Efficacy of Once-Daily Intravenous Busulfan in Allogeneic Transplantation: A Matched-Pair Analysis

Compared with 4-times-daily infusion of intravenous busulfan (ivBU4), the safety and efficacy of once-daily infusion of ivBU (ivBU1) has not been fully clarified. We have been routinely using ivBU1 in a conditioning regimen in adult patients with myeloid malignancy who undergo allogeneic hematopoietic stem cell transplantation. In this study, a total of 91 patients who received ivBU1 for 2 days (n = 18) or 4 days (n = 73) in our institutions were compared with 273 control patients who received ivBU4, who were matched for age, sex, performance status, disease risk, conditioning regimen, and donor type, selected from the database of the Japanese Society for Hematopoietic Cell Transplantation using optimal matching algorithms. One-year overall survival (56.8% versus 57.1%, P =.94), disease-free survival (51.6% versus 50.8%, P =.73), relapse rate (28.5% versus 26.2%, P =.94), nonrelapse mortality (19.9% versus 23.0%, P =.71), and the incidence of graft-versus-host disease were not significantly different between the ivBU1 and ivBU4 groups. In patients who received ivBU1, neutrophil recovery was slower (median days: 22 versus 17, P =.001), and the incidence of veno-occlusive disease was lower (2.6% versus 17.4%, P =.04). In conclusion, ivBU1 can be safely administered with clinical outcomes similar to those with ivBU4.