A Novel Antidiabetic Drug, Fasiglifam/TAK-875, Acts as an Ago-Allosteric Modulator of FFAR1

Abstract

Selective free fatty acid receptor 1 (FFAR1)/GPR40 agonist fasiglifam (TAK-875), an antidiabetic drug under phase 3 development, potentiates insulin secretion in a glucose-dependent manner by activating FFAR1 expressed in pancreatic β cells. Although fasiglifam significantly improved glycemic control in type 2 diabetes patients with a minimum risk of hypoglycemia in a phase 2 study, the precise mechanisms of its potent pharmacological effects are not fully understood. Here we demonstrate that fasiglifam acts as an ago-allosteric modulator with a partial agonistic activity for FFAR1. In both Ca2+ influx and insulin secretion assays using cell lines and mouse islets, fasiglifam showed positive cooperativity with the FFAR1 ligand γ-linolenic acid (γ-LA). Augmentation of glucose-induced insulin secretion by fasiglifam, γ-LA, or their combination was completely abolished in pancreatic islets of FFAR1-knockout mice. In diabetic rats, the insulinotropic effect of fasiglifam was suppressed by pharmacological reduction of plasma free fatty acid (FFA) levels using a lipolysis inhibitor, suggesting that fasiglifam potentiates insulin release in conjunction with plasma FFAs in vivo. Point mutations of FFAR1 differentially affected Ca2+ influx activities of fasiglifam and γ-LA, further indicating that these agonists may bind to distinct binding sites. Our results strongly suggest that fasiglifam is an ago-allosteric modulator of FFAR1 that exerts its effects by acting cooperatively with endogenous plasma FFAs in human patients as well as diabetic animals. These findings contribute to our understanding of fasiglifam as an attractive antidiabetic drug with a novel mechanism of action.

Investigation of the Binding Interaction of Fatty Acids with Human G Protein-Coupled Receptor 40 Using a Site-Specific Fluorescence Probe by Flow Cytometry

“…Our results showed that the binding potency of TAK-875 to hGPR40 was 8.1 times higher than that of GW9508, which is inconsistent with the results of agonist activities of them obtained by GPR40-mediated cellular Ca 2+ mobilization, that the agonist activity of TAK-875 was 1.6 times greater than that of GW9508. 13 Furthermore, we determined the binding potencies of 18 FFAs with hGPR40 to obtain some structural information about FFA binding. With the site-specific probe F-TAK-875A, we demonstrated that FFAs bound to hGPR40 specifically at the TAK-875 binding site.…”

Involvement of the Long-Chain Fatty Acid Receptor GPR40 in Depression-Related Behavior

“…The GPR40 agonists, TAK-875 and GW9508, are partial agonists and allosteric modulators that improve the potency of a GPR40 endogenous agonist such as a long-chain fatty acid (16). Therefore, we speculate that the single administration of GW9508 did not reduce the duration of immobility behavior because the endogenous agonist for GPR40 in the hippocampus was reduced immediately after the forced swim test.…”

Development and Characterization of a Potent Free Fatty Acid Receptor 1 (FFA1) Fluorescent Tracer

“…finding is consistent with previous reports that the fatty acids bind to a different site than many synthetic FFA1 agonists. [5][6] Global curve fitting to an allosteric ternary complex model of the lauric acid data allowed for an estimation of its pK B (4.46 ± 0.15) and allosteric cooperativity factor (logα = -0.29 ± 0.09) values.…”

“…It is therefore possible that at least some aspects of the discrepancy between potency and affinity observed for certain chemical series of FFA1 agonists could be related to binding kinetics. A third factor that may contribute to the discrepancy is the apparent presence of the multiple binding sites in FFA1, [5][6] implying the possibility of partial or lack of overlap with 4. In line with these observations, lauric acid was found to behave as an allosteric compound incompetent to fully displace 4, in contrast to the synthetic agonists that all behaved as fully competitive with 4, indicating at least partially overlapping binding sites.…”