Targeted i.v. BU and fludarabine (t-i.v. BU/Flu) provides effective control of AML in adults with reduced toxicity.

Myeloablative doses of BU and fludarabine followed by allogeneic hematopoietic cell transplantation offer effective therapy for AML. We anticipated that pharmacokinetic targeting of i.v. BU to 5300 μM/L min/day × 4 (targeted i.v. BU and fludarabine (t-i.v. BU/Flu)) would limit nonrelapse mortality (NRM) in adults up to 70 years of age. We assessed the safety and efficacy of t-i.v. BU/Flu in a series of 100 adults (median age 48, range 22-69 years) with AML in the first CR (CR1) with high risk of treatment failure (n=49), second CR (CR2, n=25), relapsed disease (REL, n=9), primary induction failure (PIF, n=16) and untreated (n=1). NRM was 3% at 100 days and 15% at 1 year. The cumulative incidence of relapse was 30.6% for CR1, 41.7% for CR2, 55.6% for REL and 58.6% for PIF. OS for primary AML in CR1 was 66% (95% confidence interval (CI): 46-80%) at 1 year, and 62% (95% CI: 42-77%) at 2 years. On multivariable modeling, remission status, moderate/severe chronic GVHD and day-90 BM chimerism ≥90% predicted improved OS. Importantly, there was no effect of age. t-i.v. BU/Flu provides effective disease control with encouraging NRM in patients up to age of 70 years.