Intravenous compared with oral busulfan as preparation for allogeneic hematopoietic progenitor cell transplantation for AML and MDS.

BU and CY is a common conditioning regimen for allogeneic hematopoietic progenitor cell transplantation (HPCT). I.v. BU is increasingly used in place of the oral formulation for conditioning. We compared the outcomes of 135 consecutively treated AML and myelodysplastic syndrome patients who underwent allogeneic HPCT at our institution with BUCY2 using oral (n=93) or i.v. (n=42) BU, without dose adjustment. The i.v. BU patients had a lower incidence of any severity of oral mucositis (3 versus 55%, P=0.002) and severe mucositis (3 versus 24%, P=0.005). Other post transplant outcomes were comparable between the groups. In all 26 i.v. BU and 33 oral BU patients are alive; however, the median follow-up was significantly longer for the oral BU group. One- and two-year non-relapse mortality for the i.v. BU patients was 21% for both, and for the oral BU group was 23% and 29%, respectively. One- and two-year relapse mortality for the i.v. BU patients was 21% for both, and for the oral BU group was 24% and 29%, respectively. Substituting i.v. for oral BU reduces variability in drug exposure and potentially improves toxicity as suggested by our finding of significantly less oral mucositis and decreased severity with i.v. BU.