Combining the G-protein-coupled receptor 40 agonist fasiglifam with sitagliptin improves glycaemic control in patients with type 2 diabetes with or without metformin: A randomized, 12-week trial

First-in-human study of CPL207280, a novel G-protein-coupled receptor 40/free fatty acid receptor 1 agonist, in healthy volunteers after single and multiple administration

AIM

To assess the safety, tolerability and pharmacokinetic (PK) profile of single and multiple doses of CPL207280, a new G-protein-coupled receptor 40 agonist developed to treat type 2 diabetes (T2D).

METHODS

The phase 1 study in healthy volunteers (White, age 18-55 years, body mass index 18.5-29.9 kg/m2 ) was performed after single (24 subjects, 5-480 mg) and multiple (32 subjects, 60-480 mg) once-daily administration of CPL207280.  The effect of food intake and interaction with metformin were evaluated in additional cohort (12 subjects, 120 mg). The primary objective was the safety and tolerability of CPL207280. Secondary objectives included PK and pharmacodynamic (PD) characteristics (glucose, insulin, C-peptide, proinsulin, glucagon levels) observed during the 14-day treatment period.

RESULTS

No deaths or serious adverse events (AEs) were reported. All reported AEs were classified as unrelated to the study product. No clinically significant differences in safety parameters were observed between cohorts and no food or metformin effect on safety parameters was identified. The ascending dose of CPL207280 caused an increase in the PK parameters maximum observed plasma concentration (Cmax ) or area under the plasma concentration-time curve up to 24 h. However, dose-normalized Cmax decreased with ascending dose. There was no relationship between the CPL207280 dose or prandial state and terminal elimination half-life and terminal elimination rate constant. No clear relationship between CPL207280 dose and PD area under the effect curve values was observed.

CONCLUSIONS

CPL207280 was found to be safe and well tolerated by healthy volunteers (with a low risk of hepatotoxicity) for up to 14 days of administration. The PK profile of CPL207280 supports single-daily administration and justifies further development of this therapy for patients with T2D.

Hypothalamic free fatty acid receptor-1 regulates whole-body energy balance

OBJECTIVE

Free fatty acid receptor-1 (FFAR1) is a medium- and long-chain fatty acid sensing G protein-coupled receptor that is highly expressed in the hypothalamus. Here, we investigated the central role of FFAR1 on energy balance.

METHODS

Central FFAR1 agonism and virogenic knockdown were performed in mice. Energy balance studies, infrared thermographic analysis of brown adipose tissue (BAT) and molecular analysis of the hypothalamus, BAT, white adipose tissue (WAT) and liver were carried out.

RESULTS

Pharmacological stimulation of FFAR1, using central administration of its agonist TUG-905 in diet-induced obese mice, decreases body weight and is associated with increased energy expenditure, BAT thermogenesis and browning of subcutaneous WAT (sWAT), as well as reduced AMP-activated protein kinase (AMPK) levels, reduced inflammation, and decreased endoplasmic reticulum (ER) stress in the hypothalamus. As FFAR1 is expressed in distinct hypothalamic neuronal subpopulations, we used an AAV vector expressing a shRNA to specifically knockdown Ffar1 in proopiomelanocortin (POMC) neurons of the arcuate nucleus of the hypothalamus (ARC) of obese mice. Our data showed that knockdown of Ffar1 in POMC neurons promoted hyperphagia and body weight gain. In parallel, these mice developed hepatic insulin resistance and steatosis.

CONCLUSIONS

FFAR1 emerges as a new hypothalamic nutrient sensor regulating whole body energy balance. Moreover, pharmacological activation of FFAR1 could provide a therapeutic advance in the management of obesity and its associated metabolic disorders.

GPCR-mediated effects of fatty acids and bile acids on glucose homeostasis

Fatty acids and glucose are key biomolecules that share several commonalities including serving as energy substrates and as signaling molecules. Fatty acids can be synthesized endogenously from intermediates of glucose catabolism via de-novo lipogenesis. Bile acids are synthesized endogenously in the liver from the biologically important lipid molecule, cholesterol. Evidence abounds that fatty acids and bile acids play direct and indirect roles in systemic glucose homeostasis. The tight control of plasma glucose levels during postprandial and fasted states is principally mediated by two pancreatic hormones, insulin and glucagon. Here, we summarize experimental studies on the endocrine effects of fatty acids and bile acids, with emphasis on their ability to regulate the release of key hormones that regulate glucose metabolism. We categorize the heterogenous family of fatty acids into short chain fatty acids (SCFAs), unsaturated, and saturated fatty acids, and highlight that along with bile acids, these biomolecules regulate glucose homeostasis by serving as endogenous ligands for specific G-protein coupled receptors (GPCRs). Activation of these GPCRs affects the release of incretin hormones by enteroendocrine cells and/or the secretion of insulin, glucagon, and somatostatin by pancreatic islets, all of which regulate systemic glucose homeostasis. We deduce that signaling induced by fatty acids and bile acids is necessary to maintain euglycemia to prevent metabolic diseases such as type-2 diabetes and related metabolic disorders.

Free fatty acid receptor 1: a ray of hope in the therapy of type 2 diabetes mellitus

Free fatty acid receptor 1 (FFAR1) is a G-protein coupled receptor with prominent expression on pancreatic beta cells, bones, intestinal cells as well as the nerve cells. This receptor mediates a multitude of functions in the body including release of incretins, secretion of insulin as well as sensation of pain. Since FFAR1 causes secretion of insulin and regulates glucose metabolism, efforts were made to unfold its structure followed by discovering agonists for the receptor and the utilization of these agonists in the therapy of type 2 diabetes mellitus. Development of such functional FFAR1 agonists is a necessity because the currently available therapy for type 2 diabetes mellitus has numerous drawbacks, of which, the major one is hypoglycemia. Since the most prominent effect of the FFAR1 agonists is on glucose concentration in the body, so the major research is focused on treating type 2 diabetes mellitus, though the agonists could benefit other metabolic disorders and neurological disorders as well. The agonists developed so far had one major limitation, i.e., hepatotoxicity. Although, the only agonist that could reach phase 3 clinical trials was TAK-875 developed by Takeda Pharmaceuticals but it was also withdrawn due to toxic effects on the liver. Thus, there are numerous agonists for the varied binding sites of the receptor but no drug available yet. There does seem to be a ray of hope in the drugs that target FFAR1 but a lot more efforts towards drug discovery would result in the successful management of type 2 diabetes mellitus.

Recent Updates on Free Fatty Acid Receptor 1 (GPR-40) Agonists for the Treatment of Type 2 Diabetes Mellitus

BACKGROUND

The global incidence of type 2 diabetes mellitus (T2DM) has enthused the development of new antidiabetic targets with low toxicity and long-term stability. In this respect, free fatty acid receptor 1 (FFAR1), which is also recognized as a G protein-coupled receptor 40 (GPR40), is a novel target for the treatment of T2DM. FFAR1/GPR40 has a high level of expression in β-cells of the pancreas, and the requirement of glucose for stimulating insulin release results in immense stimulation to utilise this target in the medication of T2DM.

METHODS

The data used for this review is based on the search of several scienctific databases as well as various patent databases. The main search terms used were free fatty acid receptor 1, FFAR1, FFAR1 agonists, diabetes mellitus, G protein-coupled receptor 40 (GPR40), GPR40 agonists, GPR40 ligands, type 2 diabetes mellitus and T2DM.

RESULTS

The present review article gives a brief overview of FFAR1, its role in T2DM, recent developments in small molecule FFAR1 (GPR40) agonists reported till now, compounds of natural/plant origin, recent patents published in the last few years, mechanism of FFAR1 activation by the agonists, and clinical status of the FFAR1/GPR40 agonists.

CONCLUSION

The agonists of FFAR1/GRP40 showed considerable potential for the therapeutic control of T2DM. Most of the small molecule FFAR1/GPR40 agonists developed were aryl alkanoic acid derivatives (such as phenylpropionic acids, phenylacetic acids, phenoxyacetic acids, and benzofuran acetic acid derivatives) and thiazolidinediones. Some natural/plant-derived compounds, including fatty acids, sesquiterpenes, phenolic compounds, anthocyanins, isoquinoline, and indole alkaloids, were also reported as potent FFAR1 agonists. The clinical investigations of the FFAR1 agonists demonstrated their probable role in the improvement of glucose control. Though, there are some problems still to be resolved in this field as some FFAR1 agonists terminated in the late phase of clinical studies due to "hepatotoxicity." Currently, PBI-4050 is under clinical investigation by Prometic. Further investigation of pharmacophore scaffolds for FFAR1 full agonists as well as multitargeted modulators and corresponding clinical investigations will be anticipated, which can open up new directions in this area.

Pharmacology of Free Fatty Acid Receptors and Their Allosteric Modulators

The physiological function of free fatty acids (FFAs) has long been regarded as indirect in terms of their activities as educts and products in metabolic pathways. The observation that FFAs can also act as signaling molecules at FFA receptors (FFARs), a family of G protein-coupled receptors (GPCRs), has changed the understanding of the interplay of metabolites and host responses. Free fatty acids of different chain lengths and saturation statuses activate FFARs as endogenous agonists via binding at the orthosteric receptor site. After FFAR deorphanization, researchers from the pharmaceutical industry as well as academia have identified several ligands targeting allosteric sites of FFARs with the aim of developing drugs to treat various diseases such as metabolic, (auto)inflammatory, infectious, endocrinological, cardiovascular, and renal disorders. GPCRs are the largest group of transmembrane proteins and constitute the most successful drug targets in medical history. To leverage the rich biology of this target class, the drug industry seeks alternative approaches to address GPCR signaling. Allosteric GPCR ligands are recognized as attractive modalities because of their auspicious pharmacological profiles compared to orthosteric ligands. While the majority of marketed GPCR drugs interact exclusively with the orthosteric binding site, allosteric mechanisms in GPCR biology stay medically underexploited, with only several allosteric ligands currently approved. This review summarizes the current knowledge on the biology of FFAR1 (GPR40), FFAR2 (GPR43), FFAR3 (GPR41), FFAR4 (GPR120), and GPR84, including structural aspects of FFAR1, and discusses the molecular pharmacology of FFAR allosteric ligands as well as the opportunities and challenges in research from the perspective of drug discovery.

Pharmacological potential of novel agonists for FFAR4 on islet and enteroendocrine cell function and glucose homeostasis

BACKGROUND

To investigate the metabolic effects of FFAR4-selective agonists on islet and enteroendocrine cell hormone release and the combined therapeutic effectiveness with DPP-IV inhibitors.

METHODS

Insulinotropic activity and specificity of FFAR4 agonists were determined in clonal pancreatic BRIN-BD11 cells. Expression of FFAR4 was assessed by qPCR and western blotting following agonist treatment in BRIN-BD11 cells and by immunohistochemistry in mouse islets. Acute in-vivo effects of agonists was investigated after intraperitoneal (i.p.) or oral administration in lean and HFF-obese diabetic mice.

RESULTS

GSK137647 (10^-11-10^-4 M) and Compound-A (10^-10-10^-4 M) stimulated insulin secretion at 5.6 mM (p < 0.05-p < 0.001) and 16.7 mM (p < 0.05-p < 0.001) glucose in BRIN-BD11 cells, with no cytotoxicity effects as assessed by MTT. FFAR4 antagonist (AH-7614) abolished the insulintropic effect of GSK137647 (p < 0.05-p < 0.001), whilst FFAR1 antagonist (GW1100) had no effect. Incubation of BRIN-BD11 cells with GSK137647 and Compound-A increased FFAR4 (p < 0.01) gene expression at 16.7 mM glucose, with a corresponding increase in FFAR4 (p < 0.01) protein concentrations. FFAR4 upregulation was attenuated under normoglycaemic conditions. Immunohistochemistry demonstrated co-localisation of FFAR4 and insulin in mouse islets. Orally administered GSK137647 or Compound-A (0.1 µmol/kgBW) improved glucose tolerance (p < 0.001), increased plasma insulin (p < 0.001), GLP-1 (p < 0.05), GIP (p < 0.05) and induced satiety (p < 0.001) in HFF mice, with glucose-lowering effects enhanced in combination with DPP-IV inhibitor (Sitagliptin) (p < 0.05).

CONCLUSIONS

Specific FFAR4 agonism improves glucose tolerance through insulin and incretin secretion, with enhanced DPP-IV inhibition in combination with Sitagliptin.

GENERAL SIGNIFICANCE

These findings have for the first time demonstrated that selective FFAR4 activation regulates both islet and enteroendocrine hormone function with agonist combinational therapy, presenting a promising strategy for the treatment of type-2-diabetes.

Metformin Reduces Lipotoxicity-Induced Meta-Inflammation in β-Cells through the Activation of GPR40-PLC-IP3 Pathway

BACKGROUND AND PURPOSE

Metformin, a widely used antidiabetic drug, has been shown to have anti-inflammatory properties; nevertheless, its influence on β-cell meta-inflammation remains unclear. The following study investigated the effects of metformin on meta-inflammatory in β-cells and whether the underlying mechanisms were associated with the G protein-coupled receptor 40-phospholipase C-inositol 1, 4, 5-trisphosphate (GPR40-PLC-IP3) pathway.

MATERIALS AND METHODS

Lipotoxicity-induced β-cells and the high-fat diet-induced obese rat model were used in the study.

RESULTS

Metformin-reduced lipotoxicity-induced β-cell meta-inflammatory injury was associated with the expression of GPR40. GPR40 was involved in metformin reversing metabolic inflammation key marker TLR4 activation-mediated β-cell injury. Furthermore, downstream signaling protein PLC-IP3 of GPR40 was involved in the protective effect of metformin on meta-inflammation, and the above process of metformin was partially regulated by AMPK activity. In addition, the anti-inflammatory effects of metformin were observed in obese rats.

CONCLUSION

Metformin can reduce lipotoxicity-induced meta-inflammation in β-cells through the regulation of the GPR40-PLC-IP3 pathway and partially via the regulation of AMPK activity.

Muscarinic Agonist Ameliorates Insulin Secretion in Wfs1-Deficient Mice

OBJECTIVES

Similar to patients with Wolfram syndrome and to heterozygous Wolframin1 (Wfs1) mutation carriers, Wfs1-deficient mice exhibit impaired glucose tolerance and lower plasma insulin levels. Muscarinic receptor 3 agonists have previously been shown to potentiate glucose-stimulated insulin secretion. Therefore, the aim of this study was to investigate insulin-secretion dynamics in Wfs1-deficient mice and evaluate carbachol, muscarinic agonist and the ability to ameliorate the insulin secretion deficits caused by the Wfs1 mutation.

METHODS

Wild-type Wfs1 heterozygous and Wfs1 mutant mice were used. Blood glucose was measured after glucose and carbachol administration. Insulin secretion was measured from serum using ELISA.

RESULTS

Glucose administration causes hyperglycemia in Wfs1-deficient mice due to decreased insulin secretion. This deficit is abolished by administration of the muscarinic agonist carbachol.

CONCLUSIONS

Activation of the muscarinic pathway to potentiate insulin secretion may present a target to manage diabetes resulting from Wfs1 deficiency.

Free fatty acid receptor 1 agonist, MR1704, lowers blood glucose levels in rats unresponsive to the sulfonylurea, glibenclamide

Preclinical Research & Development MR1704 is a selective G protein-coupled receptor 40/free fatty acid receptor 1 agonist, which exhibited favorable pharmacokinetic profiles and glucose-lowering effects in animal models. We studied the effects of MR1704 in a sulfonylurea-desensitized Sprague-Dawley rat model and evaluated the risk of pancreatic β-cell exhaustion compared to that of glibenclamide in Zucker fatty rats. Rats fed ad libitum a diet containing 0.03% glibenclamide exhibited lower non-fasting blood glucose levels compared to those in rats fed a control diet during the first 6 days. However, the response to glibenclamide disappeared on day 9. In a rat oral glucose tolerance test (OGTT), MR1704 reduced the plasma glucose excursion, whereas glibenclamide did not show this effect. In Zucker fatty rats, oral administration of MR1704 reduced glucose excursion during the OGTT, and the effects of MR1704 were maintained after 2-week treatment. In contrast, the glucose-lowering effects of glibenclamide were diminished, and glucose tolerance was aggravated after 2-week treatment. These results indicated that MR1704 provided more sustainable effects compared to those of the sulfonylurea, glibenclamide suggesting that MR1704 may be an attractive therapeutic option for diabetic patients who are unresponsive to sulfonylurea treatment.