Structural basis for GPR40 allosteric agonism and incretin stimulation.

Activation of free fatty acid receptor 1 (GPR40) by synthetic partial and full agonists occur via distinct allosteric sites. A crystal structure of GPR40-TAK-875 complex revealed the allosteric site for the partial agonist. Here we report the 2.76-Å crystal structure of human GPR40 in complex with a synthetic full agonist, compound 1, bound to the second allosteric site. Unlike TAK-875, which acts as a Gαq-coupled partial agonist, compound 1 is a dual Gαq and Gαs-coupled full agonist. compound 1 binds in the lipid-rich region of the receptor near intracellular loop 2 (ICL2), in which the stabilization of ICL2 by the ligand is likely the primary mechanism for the enhanced G protein activities. The endogenous free fatty acid (FFA), γ-linolenic acid, can be computationally modeled in this site. Both γ-linolenic acid and compound 1 exhibit positive cooperativity with TAK-875, suggesting that this site could also serve as a FFA binding site.

Discovery of LY3104607: A Potent and Selective G Protein-Coupled Receptor 40 (GPR40) Agonist with Optimized Pharmacokinetic Properties to Support Once Daily Oral Treatment in Patients with Type 2 Diabetes Mellitus.

As a part of our program to identify potent GPR40 agonists capable of being dosed orally once daily in humans, we incorporated fused heterocycles into our recently disclosed spiropiperidine and tetrahydroquinoline acid derivatives 1, 2, and 3 with the intention of lowering clearance and improving the maximum absorbable dose (Dabs). Hypothesis-driven structural modifications focused on moving away from the zwitterion-like structure. and mitigating the N-dealkylation and O-dealkylation issues led to triazolopyridine acid derivatives with unique pharmacology and superior pharmacokinetic properties. Compound 4 (LY3104607) demonstrated functional potency and glucose-dependent insulin secretion (GDIS) in primary islets from rats. Potent, efficacious, and durable dose-dependent reductions in glucose levels were seen during glucose tolerance test (GTT) studies. Low clearance, volume of distribution, and high oral bioavailability were observed in all species. The combination of enhanced pharmacology and pharmacokinetic properties supported further development of this compound as a potential glucose-lowering drug candidate.

The Discovery, Preclinical, and Early Clinical Development of Potent and Selective GPR40 Agonists for the Treatment of Type 2 Diabetes Mellitus (LY2881835, LY2922083, and LY2922470).

The G protein-coupled receptor 40 (GPR40) also known as free fatty acid receptor 1 (FFAR1) is highly expressed in pancreatic, islet ß-cells and responds to endogenous fatty acids, resulting in amplification of insulin secretion only in the presence of elevated glucose levels. Hypothesis driven structural modifications to endogenous FFAs, focused on breaking planarity and reducing lipophilicity, led to the identification of spiropiperidine and tetrahydroquinoline acid derivatives as GPR40 agonists with unique pharmacology, selectivity, and pharmacokinetic properties. Compounds 1 (LY2881835), 2 (LY2922083), and 3 (LY2922470) demonstrated potent, efficacious, and durable dose-dependent reductions in glucose levels along with significant increases in insulin and GLP-1 secretion during preclinical testing. A clinical study with 3 administered to subjects with T2DM provided proof of concept of 3 as a potential glucose-lowering therapy. This manuscript summarizes the scientific rationale, medicinal chemistry, preclinical, and early development data of this new class of GPR40 agonists.