Safety and Tolerability Study of Voreloxin and Cytarabine Combination in Acute Myeloid Leukemia in Humans

An open-label, Phase 1b/2 study using a dose-escalation design with expansion at the maximum tolerated dose (MTD) using 2 dosing schedules: During the Schedule A dose-escalation phase, patients with relapsed or refractory acute myeloid leukemia (AML) enrolled in cohorts of at least 3 patients to identify the MTD. Begin with a starting dosing regimen of vosaroxin of 10 mg/m2 on Days 1 and 4 of each cycle in combination with a 24-hour continuous intravenous (CIV) infusion of cytarabine 400 mg/m2/day × 5 days. If none of the 3 patients or 1 of 6 patients experience a dose-limiting toxicity (DLT) at the vosaroxin starting dose, dose-escalate vosaroxin. If 2 of 6 patients experienced a DLT at the vosaroxin starting dose, reduce the dose of cytarabine to reduced to 200 mg/m2 (only case in which the cytarabine could have been reduced). The vosaroxin dose escalated following a modified Fibonacci schema. For Schedule B dose-escalation phase, patients with relapsed or refractory AML enrolled in cohorts of at least 3 patients to identify the MTD. Begin with a starting dose regimen of vosaroxin of 70 mg/m2 on Days 1 and 4 in combination with cytarabine as a 2-hour infusion of 1 g/m2/day × 5 days. No reductions of cytarabine allowed in Schedule B. If none of the 3 patients or 1 of 6 patients experienced a DLT in the first cohort of Schedule B, escalate the dose of vosaroxin. If DLTs occurred in 2 of 6 patients during the starting dose, reduce the vosaroxin dose to 50 mg/m2. For both Schedules, the highest dose at which fewer than 2 of 6 patients experienced a DLT during induction became the MTD and the recommended future dose. Once the MTD of vosaroxin was determined for Schedule A, first relapse patients were enrolled in the expansion phase at that dose level to obtain additional safety and efficacy information. When the MTD of vosaroxin was determined for Schedule B, first relapse patients and patients with primary refractory disease were enrolled in the expansion phase at that dose level to characterize the safety and efficacy profile in this population.