Clinical pharmacokinetics (PK) of AMN107, a novel inhibitor of Bcr-Abl, in healthy subjects and patients with imatinib resistant or intolerant chronic myelogenous leukemia (CML) or relapsed/refractory Ph+ acute lymphocytic leukemia (Ph+ALL)

Abstract

3095 Background: AMN107, a selective and potent inhibitor of Bcr-Abl tyrosine kinase, has demonstrated activity against imatinib resistant forms of Bcr-Abl in patients with CML or Ph+ALL in a phase I study. This study characterizes clinical PK of AMN107 for the safe and effective use of the drug. Methods: Serum samples were collected in 119 patients with CML or Ph+ALL treated with once (QD) or twice daily (BID) oral AMN107 (doses of 50 to 1200 mg/day). PK parameters were derived from serum concentration-time data by non-compartmental methods. In separate multi-period crossover studies 92 healthy subjects were treated with single doses of AMN107 to assess the food effect on PK, and to assess the potential for drug-drug interactions with medications which inhibit (ketoconazole) or are metabolized by CYP3A4 (midazolam). Results: Steady-state AMN107 PK in patients were stable over time, and showed a dose-dependency with less than dose-proportional increases in systemic exposure at dose levels higher than 400 mg QD. Daily exposure at 400 mg BID, which maintains serum AMN107 levels at least 30 times higher than the IC50 of cellular phosphorylation of Bcr-Abl, was greater than at 800 mg QD. The effective half-life was 15 hours. Bioavailability of AMN107 administered with a high-fat meal was increased by 82% compared to fasting. CYP3A4 inhibition by concomitantly administered ketoconazole produced 3-fold increases in systemic exposure to AMN107, whereas AMN107 appeared a weak inhibitor of CYP3A4 with 30% increase in systemic exposure of midazolam given concomitantly. Conclusions: Systemic AMN107 levels at an oral AMN107 dose of 400 mg BID in patients with CML or Ph+ALL were well above the IC50 of Bcr-Abl. The food/drug interaction results provide further guidance for the safe use of AMN107 in the clinical setting. [Table: see text]