RT Journal Article
SR Electronic
T1 Roles of UGT, P450, and Gut Microbiota in the Metabolism of Epacadostat in Humans
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1668
OP 1674
DO 10.1124/dmd.116.070680
VO 44
IS 10
A1 Jason Boer
A1 Ruth Young-Sciame
A1 Fiona Lee
A1 Kevin J. Bowman
A1 Xiaoqing Yang
A1 Jack G. Shi
A1 Frank M. Nedza
A1 William Frietze
A1 Laurine Galya
A1 Andrew P. Combs
A1 Swamy Yeleswaram
A1 Sharon Diamond
YR 2016
UL http://dmd.aspetjournals.org/content/44/10/1668.abstract
AB Epacadostat (EPA, INCB024360) is a first-in-class, orally active, investigational drug targeting the enzyme indoleamine 2,3-dioxygenase 1 (IDO1). In Phase I studies, EPA has demonstrated promising clinical activity when used in combination with checkpoint modulators. When the metabolism of EPA was investigated in humans, three major, IDO1-inactive, circulating plasma metabolites were detected and characterized: M9, a direct O-glucuronide of EPA; M11, an amidine; and M12, N-dealkylated M11. Glucuronidation of EPA to form M9 is the dominant metabolic pathway, and in vitro, this metabolite is formed by UGT1A9. However, negligible quantities of M11 and M12 were detected when EPA was incubated with a panel of human microsomes from multiple tissues, hepatocytes, recombinant human cytochrome P450s (P450s), and non-P450 enzymatic systems. Given the reductive nature of M11 formation and the inability to define its source, the role of gut microbiota was investigated. Analysis of plasma from mice dosed with EPA following pretreatment with either antibiotic (ciprofloxacin) to inhibit gut bacteria or 1-aminobenzotriazole (ABT) to systemically inhibit P450s demonstrated that gut microbiota is responsible for the formation of M11. Incubations of EPA in human feces confirmed the role of gut bacteria in the formation of M11. Further, incubations of M11 with recombinant P450s showed that M12 is formed via N-dealkylation of M11 by CYP3A4, CYP2C19, and CYP1A2. Thus, in humans three major plasma metabolites of EPA were characterized: two primary metabolites, M9 and M11, formed directly from EPA via UGT1A9 and gut microbiota, respectively, and M12 formed as a secondary metabolite via P450s from M11.