Mitigating a Bioactivation Liability with an Azetidine-Based Inhibitor of Diacylglycerol Acyltransferase 2 (DGAT2) En Route to the Discovery of the Clinical Candidate Ervogastat.

Abstract

We recently disclosed SAR studies on systemically acting, amide-based inhibitors of diacylglycerol acyltransferase 2 (DGAT2) that addressed metabolic liabilities with the liver-targeted DGAT2 inhibitor PF-06427878. Despite strategic placement of a nitrogen atom in the dialkoxyaromatic ring in PF-06427878 to evade oxidative O-dearylation, metabolic intrinsic clearance remained high due to extensive piperidine ring oxidation as exemplified with compound 1. Piperidine ring modifications through alternate N-linked heterocyclic ring/spacer combination led to azetidine 2 that demonstrated lower intrinsic clearance. However, 2 underwent a facile cytochrome P450 (CYP)-mediated α-carbon oxidation followed by azetidine ring scission, resulting in the formation of ketone (M2) and aldehyde (M6) as stable metabolites in NADPH-supplemented human liver microsomes. Inclusion of GSH or semicarbazide in microsomal incubations led to the formation of Cys-Gly-thiazolidine (M3), Cys-thiazolidine (M5), and semicarbazone (M7) conjugates, which were derived from reaction of the nucleophilic trapping agents with aldehyde M6. Metabolites M2 and M5 were biosynthesized from NADPH- and l-cysteine-fortified human liver microsomal incubations with 2, and proposed metabolite structures were verified using one- and two-dimensional NMR spectroscopy. Replacement of the azetidine substituent with a pyridine ring furnished 8, which mitigated the formation of the electrophilic aldehyde metabolite, and was a more potent DGAT2 inhibitor than 2. Further structural refinements in 8, specifically introducing amide bond substituents with greater metabolic stability, led to the discovery of PF-06865571 (ervogastat) that is currently in phase 2 clinical trials for the treatment of nonalcoholic steatohepatitis.

• Authors: Raman Sharma, Matthew S Dowling, Kentaro Futatsugi, Amit S Kalgutkar
• Journal: Chemical research in toxicology (Chem Res Toxicol) Vol. 36 Issue 6 Pg. 934-946 (06 19 2023) ISSN: 1520-5010 [Electronic] United States
• PMID: 37148271 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Diacylglycerol O-Acyltransferase
• Thiazolidines
• NADP
• ervogastat
• Glutathione
• Piperidines
• Azetidines
• Amides
• DGAT2 protein, human

Topics

• Humans
• Diacylglycerol O-Acyltransferase (metabolism)
• Thiazolidines (metabolism)
• NADP (metabolism)
• Glutathione (metabolism)
• Microsomes, Liver (metabolism)
• Piperidines (metabolism)
• Azetidines (pharmacology, metabolism)
• Amides (metabolism)