Purpose: Barasertib (AZD1152) is a pro-drug that rapidly undergoes phosphatase-mediated cleavage in serum to release barasertib-hQPA, a selective Aurora B kinase inhibitor that has shown preliminary activity in clinical studies of patients with acute myeloid leukemia (AML). The pharmacokinetic (PK), metabolic and excretion profiles of barasertib and barasertib-hQPA were characterized in this open-label Phase I study.
Methods: Five patients with poor prognosis AML (newly diagnosed, relapsed or refractory) received barasertib 1,200 mg as a 7-day continuous infusion every 28 days. On Day 2 of Cycle 1 only, patients also received a 2-hour infusion of [(14)C]-barasertib. Blood, urine and feces samples were collected at various time points during Cycle 1. Safety and preliminary efficacy were also assessed.
Results: Barasertib-hQPA was extensively distributed to tissues, with a slow rate of total clearance (CL = 31.4 L/h). Overall, 72-82 % of radioactivity was recovered, with approximately double the amount recovered in feces (mean = 51 %) compared with urine (mean = 27 %). The main metabolism pathways for barasertib were (1) cleavage of the phosphate group to form barasertib-hQPA, followed by oxidation and (2) loss of the fluoroaniline moiety to form barasertib-hQPA desfluoroaniline, followed by oxidation. One of the four patients evaluable for response entered complete remission. No new or unexpected safety findings were observed; the most common adverse events were nausea and stomatitis.
Conclusions: The PK profile of barasertib is similar to previous studies using the same dosing regimen in patients with AML. The majority of barasertib-hQPA clearance occurred via hepatic metabolic routes.