Comparison of Intravenous with Oral Busulfan in Allogeneic Hematopoietic Stem Cell Transplantation with Myeloablative Conditioning Regimens for Pediatric Acute Leukemia

Recent reports revealed that intravenous (iv) busulfan (BU) may not only reduce early nonrelapse mortality (NRM) but also improve overall survival (OS) probability in adults. Therefore, we retrospectively compared outcomes for 460 children with acute leukemia who underwent hematopoietic stem cell transplantation with either iv-BU (n=198) or oral busulfan (oral-BU) (n=262) myeloablative conditioning. OS at 3years was 53.4%±3.7% with iv-BU and 55.1%±3.1% with oral-BU; the difference was not statistically significant (P= 77). OS at 3years in 241 acute lymphoblastic leukemia and 219 acute myeloid leukemia patients was 56.4%±5.5% with iv-BU and 54.6%±4.1 with oral-BU (P= 51) and 51.0%±5.0% with iv-BU and 55.8%±4.8% with oral-BU (P= 83), respectively. Cumulative incidence of relapse at 3years with iv-BU was similar to that with oral-BU (39.0%±3.6% and 36.4%±3.1%, respectively; P= 67). Cumulative incidence of NRM at 3years was 16.6%±2.7% with iv-BU and 18.3%±2.5% with oral-BU (P= 51). Furthermore, multivariate analysis showed no significant survival advantage with iv-BU. In conclusion, iv-BU failed to show a significant survival advantage in children with acute leukemia.