1521-009X/44/8/1148–1157$25.00 http://dx.doi.org/10.1124/dmd.115.067496 DRUG METABOLISM AND DISPOSITION Drug Metab Dispos 44:1148–1157, August 2016 Copyright ª 2016 by The American Society for Pharmacology and Experimental Therapeutics Metabolism and Disposition of Pan-Genotypic Inhibitor of Hepatitis C Virus NS5A Ombitasvir in Humans s Jianwei Shen, Michael Serby, Bruce Surber, Anthony J. Lee, Junli Ma, Prajakta Badri, Rajeev Menon, Olga Kavetskaia, 1 Sonia M. de Morais, Jens Sydor, and Volker Fischer Drug Metabolism and Pharmacokinetics, Research and Development (Ji.S., M.S., A.J.L., J.M., S.M.M., V.F.), Process Chemistry (B.S.), Drug Analysis (O.K., Je.S.), and Clinical Pharmacology and Pharmacometrics–Clinical Pharmacokinetics/Pharmacodynamics (P.B., R.M.), AbbVie, North Chicago, Illinois Received October 1, 2015; accepted May 11, 2016 ABSTRACT Ombitasvir (also known as ABT-267) is a potent inhibitor of hepatitis C virus (HCV) nonstructural protein 5A (NS5A), which has been de- veloped in combination with paritaprevir/ritonavir and dasabuvir in a three direct-acting antiviral oral regimens for the treatment of patients infected with HCV genotype 1. This article describes the mass balance, metabolism, and disposition of ombitasvir in humans without coadministration of paritaprevir/ritonavir and dasabuvir. Following the administration of a single 25-mg oral dose of [ 14 C]ombitasvir to four healthy male volunteers, the mean total percentage of the administered radioactive dose recovered was 92.1% over the 192- hour sample collection in the study. The recovery from the individual subjects ranged from 91.4 to 93.1%. Ombitasvir and corresponding metabolites were primarily eliminated in feces (90.2% of dose), mainly as unchanged parent drug (87.8% of dose), but minimally through renal excretion (1.9% of dose). Biotransformation of ombitasvir in human involves enzymatic amide hydrolysis to form M23 (dianiline), which is further metabolized through cytochrome P450–mediated oxidative metabolism (primarily by CYP2C8) at the tert-butyl group to generate oxidative and/or C-desmethyl metabolites. [ 14 C]Ombitasvir, M23, M29, M36, and M37 are the main components in plasma, representing about 93% of total plasma radioactivity. The steady- state concentration measurement of ombitasvir metabolites by liquid chromatography–mass spectrometry analysis in human plasma following multiple doses of ombitasvir, in combination with paritaprevir/ritonavir and dasabuvir, confirmed that ombitasvir is the main component (51.9% of all measured drug-related components), whereas M29 (19.9%) and M36 (13.1%) are the major circulating metabolites. In summary, the study characterized ombitasvir me- tabolites in circulation, the metabolic pathways, and the elimination routes of the drug. Introduction Hepatitis C virus (HCV) infection affects approximately 170 million individuals worldwide (World Health Organization, 2011). Untreated chronic HCV infection can result in cirrhosis or hepatocellular carcinoma, both of which are leading causes of liver transplantation (Pawlotsky, 2004; Lavanchy, 2011; Mohd Hanafiah et al., 2013). Recently, several interferon-free combinations of direct-acting antivirals (DAAs) have been developed to cure chronic HCV infection with high success rates (Shah et al., 2013; Zeuzem, 2014). Ombitasvir has been developed for the HCV genotype-1 infection in combination with an NS3 protease inhibitor, paritaprevir with ritonavir, and/or a nonstructural protein 5B (NS5B) non-nucleoside polymerase inhibitor (dasabuvir) with or without ribavirin (Feld et al., 2014; Ferenci et al., 2014; Kowdley et al., 2014; Poordad et al., 2014). Ombitasvir is an inhibitor of HCV NS5A (DeGoey et al., 2014; Krishnan et al., 2015). Ombitasvir exhibited picomolar activities against HCV genotype 1a and 1b subgenomic replicons in vitro, with EC 50 values of 14 and 5 pM, respectively. Ombitasvir also demonstrated robust in vivo responses with mean maximum decreases in HCV RNA up to 3.10 log10 IU/ml following 3-day monotherapy in treatment-naïve HCV genotype-1– infected subjects (Lawitz et al., 2012). Clinically, ombitasvir has favorable safety, tolerability, and pharma- cokinetic profiles when given as a monotherapy or combination therapy at doses administered to date (Dumas et al., 2011; Menon et al., 2013). Ombitasvir shows linear pharmacokinetics with dose-proportional increases in exposure over the range of 5–100 mg after once-daily multiple-dose administration. Ombitasvir has a half-life (t 1/2 ) of approximately 24 hours when administered once daily. The mean C max and area under the curve (0–24-hour) (AUC 0-24h ) values of ombitasvir were 27 and 62% higher, respectively, on day 10 compared with day 1 following 5- to 200-mg once-daily (QD) multiple doses, suggesting minimal accumulation (Dumas et al., 2011). This report describes the metabolism and disposition of a single 25-mg oral dose of [ 14 C]ombitasvir in four healthy human subjects. The purpose of this study was to assess the mass balance, elucidate the routes 1 Current affiliation: Global Clinical Pharmacology, Pfizer, Groton, Connecticut. Disclosure Statement: The design, study conduct, and financial support for this study were provided by AbbVie. AbbVie participated in the interpretation of data, writing, review, and approval of the publication. All authors are current employees of AbbVie, except Olga Kavetskaia, who was an AbbVie employee at the time the manuscript was developed. dx.doi.org/10.1124/dmd.115.067496. s This article has supplemental material available at dmd.aspetjournals.org. ABBREVIATIONS: ABT-267, ombitasvir; AUC, area under the curve; C max , maximum plasma concentration; DAA, direct-acting antiviral agent; HCV, hepatitis C virus; HPLC, high-performance liquid chromatography; LC, liquid chromatography; LSC, liquid scintillation counting; MS, mass spectrometry; MS/MS, tandem mass spectrometry; Mu, unknown metabolites in urine; NS, nonstructural protein; QD, once daily; SPE, solid-phase extraction; t 1/2 , half-life. 1148 http://dmd.aspetjournals.org/content/suppl/2016/05/13/dmd.115.067496.DC1 Supplemental material to this article can be found at: at ASPET Journals on May 21, 2020 dmd.aspetjournals.org Downloaded from