RT Journal Article SR Electronic T1 6-Chloro-5-[4-(1-hydroxycyclobutyl)phenyl]-1H-indole-3-carboxylic Acid (PF-06409577) is a Highly Selective Substrate for Glucuronidation by Uridine Diphosphoglucuronosyl Transferase (UGT) 1A1, Relative to b-Estradiol JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP dmd.118.083709 DO 10.1124/dmd.118.083709 A1 Kimberly Lapham A1 Jian Lin A1 Jonathan Novak A1 Christine Orozco A1 Mark Niosi A1 Li Di A1 Theunis C Goosen A1 Sangwoo Ryu A1 Keith Riccardi A1 Heather Eng A1 Kimberly O. Cameron A1 Amit S. Kalgutkar YR 2018 UL http://dmd.aspetjournals.org/content/early/2018/09/07/dmd.118.083709.abstract AB 6-Chloro-5-[4-(1-hydroxycyclobutyl)phenyl]-1H-indole-3-carboxylic acid (PF-06409577) is a direct activator of the human β1-containing adenosine monophosphate-activated protein kinase (AMPK)isoforms. The clearance mechanism of PF-06409577 in animals and humans involves uridine diphosphoglucuronosyl transferase (UGT)-mediated glucuronidation to an acyl glucuronide metabolite M1, which retains selective activation of human 1-containing AMPK isoforms. This manuscript describes a detailed characterization of the human UGT isoform(s) responsible for glucuronidation of PF-06409577 to M1. Studies using a panel of 13 human recombinant UGT (hrUGT) enzymes indicated that PF-06409577 was converted to M1 in a highly selective fashion by UGT1A1, which was further verified in human liver microsomes (HLM) treated with specific chemical inhibitors, and in different UGT1A1 expressers. Conversion of PF-06409577 to M1 by UGT1A1 occurred in a relatively selective fashion, compared to β-estradiol (ES), a conventional probe substrate of UGT1A1. KM and Vmax values describing the formation of M1 from PF-06409577 in hrUGT1A1 and microsomal preparations from human intestine, liver and kidney ranged from 131-212 μM (KM) and 107-3834 pmol/min/mg (Vmax) in the presence of 2% bovine serum albumin (BSA). Relative activity factors (RAF) were determined for UGT1A1 using PF-06409577 and ES to enable estimation of intrinsic clearance from various tissues. RAF values from PF-06409577 and ES were generally comparable with the exception of intestinal microsomes where ES over-estimated the RAF of UGT1A1 due to glucuronidation by intestinal UGT1A8 and UGT1A10. Our results suggest a potential utility of PF-06409477 as a selective probe UGT1A1 substrate for UGT reaction phenotyping and inhibition studies in preclinical discovery/development.