title: Metabolism and disposition of the DOT1L inhibitor, pinometostat (EPZ-5676), in rat, dog and human.
abstract: OBJECTIVE
  The metabolism and disposition of the first-in-class DOT1L inhibitor, EPZ-5676 (pinometostat), was investigated in rat and dog. Metabolite profiles were compared with those from adult patients in the first-in-man phase 1 study as well as the cross-species metabolism observed in vitro.
  
  
  METHODS
  EPZ-5676 was administered to rat and dog as a 24-h IV infusion of [(14)C]-EPZ-5676 for determination of pharmacokinetics, mass balance, metabolite profiling and biodistribution by quantitative whole-body autoradiography (QWBA). Metabolite profiling and identification was performed by radiometric and LC-MS/MS analysis.
  
  
  RESULTS
  Fecal excretion was the major route of elimination, representing 79 and 81% of the total dose in and rat and dog, respectively. QWBA in rats showed that the radioactivity was well distributed in the body, except for the central nervous system, and the majority of radioactivity was eliminated from most tissues by 168 h. Fecal recovery of dose-related material in bile duct-cannulated animals as well as higher radioactivity concentrations in the wall of the large intestine relative to liver implicated intestinal secretion as well as biliary elimination. EPZ-5676 underwent extensive oxidative metabolism with the major metabolic pathways being hydroxylation of the t-butyl group (EPZ007769) and N-dealkylation of the central nitrogen. Loss of adenine from parent EPZ-5676 (M7) was observed only in rat and dog feces, suggesting the involvement of gut microbiota. In rat and dog, steady-state plasma levels of total radioactivity and parent EPZ-5676 were attained rapidly and maintained through the infusion period before declining rapidly on cessation of dosing. Unchanged EPZ-5676 was the predominant circulating species in rat, dog and man.
  
  
  CONCLUSIONS
  The excretory and metabolic pathways for EPZ-5676 were very similar across species. Renal excretion of both parent EPZ-5676 and EPZ-5676-related material was low, and in preclinical species fecal excretion of parent EPZ-5676 and EPZ007769 accounted for the majority of drug-related elimination.
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA. nwaters95@gmail.com.
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Waters
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA.
authors.forename: Sherri A
authors.initials: SA
authors.lastname: Smith
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Olhava
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Duncan
authors.affiliation: Quintiles, Indianapolis, IN, 46241, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Burton
authors.affiliation: Charles River Laboratories, Edinburgh, UK.
authors.forename: James
authors.initials: J
authors.lastname: O'Neill
authors.affiliation: Charles River Laboratories, Montreal, Canada.
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Rodrigue
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Pollock
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA.
authors.forename: Mikel P
authors.initials: MP
authors.lastname: Moyer
authors.affiliation: Epizyme, Inc., 400 Technology Square, Cambridge, MA, 02139, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Chesworth
mesh_terms: D000328:Adult; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001345:Autoradiography / Q000379:methods; D001562:Benzimidazoles / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002853:Chromatography, Liquid / Q000379:methods; D004285:Dogs; D005243:Feces / Q000737:chemistry*; D005260:Female; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008780:Methyltransferases / Q000037:antagonists & inhibitors*; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods; D014018:Tissue Distribution
chemical_list: D000970:Antineoplastic Agents; D001562:Benzimidazoles; C583893:EPZ-5676; C473477:DOT1L protein, human; D008780:Methyltransferases; D011495:Histone-Lysine N-Methyltransferase
keywords: DOT1L; Drug disposition; Drug metabolism; Epigenetics; Histone methyltransferase inhibitor; MLL-r leukemia