Gut hormone pharmacology of a novel GPR119 agonist (GSK1292263), metformin, and sitagliptin in type 2 diabetes mellitus: results from two randomized studies

Glucagon-like peptide-1 and interleukin-6 interaction in response to physical exercise: An in-silico model in the framework of immunometabolism

BACKGROUND AND OBJECTIVE

Glucagon-like peptide 1 (GLP-1) is classically identified as an incretin hormone, secreted in response to nutrient ingestion and able to enhance glucose-stimulated insulin secretion. However, other stimuli, such as physical exercise, may enhance GLP-1 plasma levels, and this exercise-induced GLP-1 secretion is mediated by interleukin-6 (IL-6), a cytokine secreted by contracting skeletal muscle. The aim of the study is to propose a mathematical model of IL-6-induced GLP-1 secretion and kinetics in response to physical exercise of moderate intensity.

METHODS

The model includes the GLP-1 subsystem (with two pools: gut and plasma) and the IL-6 subsystem (again with two pools: skeletal muscle and plasma); it provides a parameter of possible clinical relevance representing the sensitivity of GLP-1 to IL-6 (k0). The model was validated on mean IL-6 and GLP-1 data derived from the scientific literature and on a total of 100 virtual subjects.

RESULTS

Model validation provided mean residuals between 0.0051 and 0.5493 pg⋅mL-1 for IL-6 (in view of concentration values ranging from 0.8405 to 3.9718 pg⋅mL-1) and between 0.0133 and 4.1540 pmol⋅L-1 for GLP-1 (in view of concentration values ranging from 0.9387 to 17.9714 pmol⋅L-1); a positive significant linear correlation (r = 0.85, p<0.001) was found between k0 and the ratio between areas under GLP-1 and IL-6 curve, over the virtual subjects.

CONCLUSIONS

The model accurately captures IL-6-induced GLP-1 kinetics in response to physical exercise.

GPR119 agonists for type 2 diabetes: past failures and future hopes for preclinical and early phase candidates

INTRODUCTION

Type 2 diabetes (T2D) is metabolic disorder associated with a decrease in insulin activity and/or secretion from the β-cells of the pancreas, leading to elevated circulating glucose. Current management practices for T2D are complex with varying long-term effectiveness. Agonism of the G protein-coupled receptor GPR119 has received a lot of recent interest as a potential T2D therapeutic.

AREAS COVERED

This article reviews studies focused on GPR119 agonism in animal models of T2D and in patients with T2D.

EXPERT OPINION

GPR119 agonists in vitro and in vivo can potentially regulate incretin hormone release from the gut, then pancreatic insulin release which regulates blood glucose concentrations. However, the success in controlling glucose homeostasis in rodent models of T2D and obesity, failed to translate to early-stage clinical trials in patients with T2D. However, in more recent studies, acute and chronic dosing with the GPR119 agonist DS-8500a had increased efficacy, although this compound was discontinued for further development. New trials on GPR119 agonists are needed, however it may be that the future of GPR119 agonists lie in the development of combination therapy with other T2D therapeutics.

GPCRs involved in metabolic diseases: pharmacotherapeutic development updates

G protein-coupled receptors (GPCRs) are expressed in a variety of cell types and tissues, and activation of GPCRs is involved in enormous metabolic pathways, including nutrient synthesis, transportation, storage or insulin sensitivity, etc. This review intends to summarize the regulation of metabolic homeostasis and mechanisms by a series of GPCRs, such as GPR91, GPR55, GPR119, GPR109a, GPR142, GPR40, GPR41, GPR43 and GPR120. With deep understanding of GPCR's structure and signaling pathways, it is attempting to uncover the role of GPCRs in major metabolic diseases, including metabolic syndrome, diabetes, dyslipidemia and nonalcoholic steatohepatitis, for which the global prevalence has risen during last two decades. An extensive list of agonists and antagonists with their chemical structures in a nature of small molecular compounds for above-mentioned GPCRs is provided as pharmacologic candidates, and their preliminary data of preclinical studies are discussed. Moreover, their beneficial effects in correcting abnormalities of metabolic syndrome, diabetes and dyslipidemia are summarized when clinical trials have been undertaken. Thus, accumulating data suggest that these agonists or antagonists might become as new pharmacotherapeutic candidates for the treatment of metabolic diseases.

New Horizons: Emerging Antidiabetic Medications

Over the past century, since the discovery of insulin, the therapeutic offer for diabetes has grown exponentially, in particular for type 2 diabetes (T2D). However, the drugs in the diabetes pipeline are even more promising because of their impressive antihyperglycemic effects coupled with remarkable weight loss. An ideal medication for T2D should target not only hyperglycemia but also insulin resistance and obesity. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and the new class of GLP1 and gastric inhibitory polypeptide dual RAs counteract 2 of these metabolic defects of T2D, hyperglycemia and obesity, with stunning results that are similar to the effects of metabolic surgery. An important role of antidiabetic medications is to reduce the risk and improve the outcome of cardiovascular diseases, including coronary artery disease and heart failure with reduced or preserved ejection fraction, as well as diabetic nephropathy, as shown by SGLT2 inhibitors. This review summarizes the main drugs currently under development for the treatment of type 1 diabetes and T2D, highlighting their strengths and side effects.

Targeting the Enteroendocrine System for Treatment of Obesity

Mimetics of the anorexigenic gut hormone glucagon-like peptide 1 (GLP-1) were originally developed as insulinotropic anti-diabetic drugs but also evoke significant weight loss, leading to their recent approval as obesity therapeutics. Co-activation of receptors for GLP-1 and other gut hormones which reduce food intake - peptide YY (PYY_3-36), cholecystokinin (CCK) and glucose-dependent insulinotropic peptide (GIP) - is now being explored clinically to enhance efficacy. An alternative approach involves pharmacologically stimulating endogenous secretion of these hormones from enteroendocrine cells (EECs) to recapitulate the metabolic consequences of bariatric surgery, where highly elevated postprandial levels of GLP-1 and PYY_3-36 are thought to contribute to improved glycaemia and weight loss.

A novel GPR119 agonist DA-1241 preserves pancreatic function via the suppression of ER stress and increased PDX1 expression

DA-1241 is a novel small molecule G protein-coupled receptor 119 (GPR119) agonist in early clinical development for type 2 diabetic patients. This study aimed to elucidate the pharmacological characteristics of DA-1241 for its hypoglycemic action. DA-1241 potently and selectively activated GPR119 with enhanced maximum efficacy. DA-1241 increased intracellular cAMP in HIT-T15 insulinoma cells (EC50, 14.7 nM) and increased insulin secretion (EC50, 22.3 nM) in association with enhanced human insulin promoter activity. Accordingly, postprandial plasma insulin levels were increased in mice after single oral administration of DA-1241. Postprandial glucose excursion was significantly reduced by single oral administration of DA-1241 in wild-type mice but not in GPR119 knockout mice. GLP-1 secretion was increased by DA-1241 treatment in mice. Thus, upon combined sitagliptin and DA-1241 treatment in high-fat diet/streptozotocin (HFD/STZ)-induced diabetic mice, plasma active GLP-1 levels were synergistically increased. Accordingly, blood glucose and triglyceride levels were significantly lowered both by DA-1241 and sitagliptin alone and in combination. Immunohistochemical analysis revealed that β-cell mass with reduced PDX1 levels in the islets from HFD/STZ diabetic mice was significantly preserved by DA-1241, whereas increased glucagon and BiP levels were significantly suppressed. In HIT-T15 insulinoma cells subjected to ER stress, decreased cell viability was significantly rescued by treatment with DA-1241. Additionally, increased apoptosis was largely attenuated by DA-1241 by inhibiting BiP and CHOP expression through suppression of p38 MAPK. In conclusion, these studies provide evidence that DA-1241 can be a promising antidiabetic drug by potentially preserving pancreatic functions through suppressing ER stress and increasing PDX1 expression.

Treatment of type 2 diabetes: challenges, hopes, and anticipated successes

Despite the successful development of new therapies for the treatment of type 2 diabetes, such as glucagon-like peptide-1 (GLP-1) receptor agonists and sodium-glucose cotransporter-2 inhibitors, the search for novel treatment options that can provide better glycaemic control and at reduce complications is a continuous effort. The present Review aims to present an overview of novel targets and mechanisms and focuses on glucose-lowering effects guiding this search and developments. We discuss not only novel developments of insulin therapy (eg, so-called smart insulin preparation with a glucose-dependent mode of action), but also a group of drug classes for which extensive research efforts have not been rewarded with obvious clinical impact. We discuss the potential clinical use of the salutary adipokine adiponectin and the hepatokine fibroblast growth factor (FGF) 21, among others. A GLP-1 peptide receptor agonist (semaglutide) is now available for oral absorption, and small molecules activating GLP-1 receptors appear on the horizon. Bariatric surgery and its accompanying changes in the gut hormonal milieu offer a background for unimolecular peptides interacting with two or more receptors (for GLP-1, glucose-dependent insulinotropic polypeptide, glucagon, and peptide YY) and provide more substantial glycaemic control and bodyweight reduction compared with selective GLP-1 receptor agonists. These and additional approaches will help expand the toolbox of effective medications needed for optimising the treatment of well delineated subgroups of type 2 diabetes or help develop personalised approaches for glucose-lowering drugs based on individual characteristics of our patients.

Chemosensing in enteroendocrine cells: mechanisms and therapeutic opportunities

PURPOSE OF REVIEW

Enteroendocrine cells (EECs) are scattered chemosensory cells in the intestinal epithelium that release hormones with a wide range of actions on intestinal function, food intake and glucose homeostasis. The mechanisms by which gut hormones are secreted postprandially, or altered by antidiabetic agents and surgical interventions are of considerable interest for future therapeutic development.

RECENT FINDINGS

EECs are electrically excitable and express a repertoire of G-protein coupled receptors that sense nutrient and nonnutrient stimuli, coupled to intracellular Ca2+ and cyclic adenosine monophosphate. Our knowledge of EEC function, previously developed using mouse models, has recently been extended to human cells. Gut hormone release in humans is enhanced by bariatric surgery, as well as by some antidiabetic agents including sodium-coupled glucose transporter inhibitors and metformin.

SUMMARY

EECs are important potential therapeutic targets. A better understanding of their chemosensory mechanisms will enhance the development of new therapeutic strategies to treat metabolic and gastrointestinal diseases.

Targeting lipid GPCRs to treat type 2 diabetes mellitus - progress and challenges

Therapeutic approaches to the treatment of type 2 diabetes mellitus that are designed to increase insulin secretion either directly target β-cells or indirectly target gastrointestinal enteroendocrine cells (EECs), which release hormones that modulate insulin secretion (for example, incretins). Given that β-cells and EECs both express a large array of G protein-coupled receptors (GPCRs) that modulate insulin secretion, considerable research and development efforts have been undertaken to design therapeutic drugs targeting these GPCRs. Among them are GPCRs specific for free fatty acid ligands (lipid GPCRs), including free fatty acid receptor 1 (FFA1, otherwise known as GPR40), FFA2 (GPR43), FFA3 (GPR41) and FFA4 (GPR120), as well as the lipid metabolite binding glucose-dependent insulinotropic receptor (GPR119). These lipid GPCRs have demonstrated important roles in the control of islet and gut hormone secretion. Advances in lipid GPCR pharmacology have led to the identification of a number of synthetic agonists that exert beneficial effects on glucose homeostasis in preclinical studies. Yet, translation of these promising results to the clinic has so far been disappointing. In this Review, we present the physiological roles, pharmacology and clinical studies of these lipid receptors and discuss the challenges associated with their clinical development for the treatment of type 2 diabetes mellitus.

GPR119 and GPR55 as Receptors for Fatty Acid Ethanolamides, Oleoylethanolamide and Palmitoylethanolamide

Oleoylethanolamide and palmitoylethanolamide are members of the fatty acid ethanolamide family, also known as acylethanolamides. Their physiological effects, including glucose homeostasis, anti-inflammation, anti-anaphylactic, analgesia, and hypophagia, have been reported. They have affinity for different receptor proteins, including nuclear receptors such as PPARα, channels such as TRPV1, and membrane receptors such as GPR119 and GPR55. In the present review, the pathophysiological functions of fatty acid ethanolamides have been discussed from the perspective of receptor pharmacology and drug discovery.

Leveraging the Gut to Treat Metabolic Disease

25 years ago, the future of treating obesity and diabetes focused on end organs known to be involved in energy balance and glucose regulation, including the brain, muscle, adipose tissue, and pancreas. Today, the most effective therapies are focused around the gut. This includes surgical options, such as vertical sleeve gastrectomy and Roux-en-Y gastric bypass, that can produce sustained weight loss and diabetes remission but also extends to pharmacological treatments that simulate or amplify various signals that come from the gut. The purpose of this Review is to discuss the wealth of approaches currently under development that seek to further leverage the gut as a source of novel therapeutic opportunities with the hope that we can achieve the effects of surgical interventions with less invasive and more scalable solutions.

Noninvasive Evaluation of GPR119 Agonist Effects on β-Cell Mass in Diabetic Male Mice Using 111In-Exendin-4 SPECT/CT

Longitudinal observation of pancreatic β-cell mass (BCM) remains challenging because noninvasive techniques for determining BCM in vivo have not been established. Such observations would be useful for the monitoring of type 2 diabetes mellitus, a progressive disease involving loss of pancreatic BCM and function. An indium 111 (111In)-labeled exendin-4 derivative ([Lys12(111In-BnDTPA-Ahx)]exendin-4) targeting the glucagon-like peptide-1 receptor has been developed recently as a promising probe for quantifying the BCM noninvasively. In the present study, we used the 111In-exendin-4 single-photon emission CT/CT (SPECT/CT) technique to investigate the efficacy of DS-8500a, a novel G protein-coupled receptor-119 agonist currently under investigation for type 2 diabetes mellitus treatment in prediabetic db/db mice under dietary restriction. During the 8-week study, the treatment of mice with DS-8500a delayed and attenuated the progression of glucose intolerance compared with mice under dietary restriction alone. 111In-exendin-4 SPECT/CT of db/db mice revealed continuously decreasing radioactive isotope (RI) intensity in the pancreas during the 8-week intervention. DS-8500a attenuated this decrease and preserved pancreatic RI accumulation compared with dietary restriction alone at the end of the observation period. This result was corroborated not only by ex vivo pancreatic analysis using the [Lys12(111In-BnDTPA-Ahx)]exendin-4 probe but also by conventional histological BCM analysis. These results indicate that DS-8500a attenuates the progression of BCM loss beyond that of dietary restriction alone in prediabetic db/db mice. These results have shown that 111In-exendin-4 SPECT/CT will be useful for noninvasive longitudinal investigation of BCM in vivo.

Identification of Novel, Structurally Diverse, Small Molecule Modulators of GPR119

GPR119 drug discovery efforts in the pharmaceutical industry for the treatment of type 2 diabetes mellitus (T2DM) and obesity, were initiated based on its restricted distribution in pancreas and GI tract, and its possible role in glucose homeostasis. While a number of lead series have emerged, the pharmacological endpoints they provide have not been clear. In particular, many lead series have demonstrated loss of efficacy and significant toxic side effects. Thus, we sought to identify novel, potent, positive modulators of GPR119. In this study, we have successfully developed and optimized a high-throughput screening strategy to identify GPR119 modulators using a live cell assay format that utilizes a cyclic nucleotide-gated channel as a biosensor for cAMP production. Our high-throughput screening (HTS) approach is unique to that of previous HTS approaches targeting this receptor, as changes in cAMP were measured both in the presence and absence of an EC₁₀ of the endogenous ligand, oleoylethanolamide, enabling detection of both agonists and potential allosteric modulators in a single assay. From these efforts, we have identified positive modulators of GPR119 with similar as well as unique scaffolds compared to existing compounds and similar as well as unique signaling properties. Our compounds will not only serve as novel molecular probes to better understand GPR119 pleiotropic signaling and the underlying physiological consequences of receptor activation, but are also well-suited for translation as potential therapeutic agents.

GLP-1: Molecular mechanisms and outcomes of a complex signaling system

Meal ingestion provokes the release of hormones and transmitters, which in turn regulate energy homeostasis and feeding behavior. One such hormone, glucagon-like peptide-1 (GLP-1), has received significant attention in the treatment of obesity and diabetes due to its potent incretin effect. In addition to the peripheral actions of GLP-1, this hormone is able to alter behavior through the modulation of multiple neural circuits. Recent work that focused on elucidating the mechanisms and outcomes of GLP-1 neuromodulation led to the discovery of an impressive array of GLP-1 actions. Here, we summarize the many levels at which the GLP-1 signal adapts to different systems, with the goal being to provide a background against which to guide future research.

Targeting GPCRs Activated by Fatty Acid-Derived Lipids in Type 2 Diabetes

G protein-coupled receptors (GPCRs) are the most intensively studied drug targets, because of their diversity, cell-specific expression, and druggable sites accessible at the cell surface. Preclinical and clinical studies suggest that targeting GPCRs activated by fatty acid-derived lipids may have potential to improve glucose homeostasis and reduce complications in patients with type 2 diabetes (T2D). Despite the discontinued development of fasiglifam (TAK-875), the first FFA1 agonist to reach late-stage clinical trials, lipid-sensing receptors remain a viable target, albeit with a need for further characterization of their binding mode, intracellular signaling, and toxicity. Herein, we analyze general discovery trends, various signaling pathways, as well as possible challenges following activation of GPCRs that have been validated clinically to control blood glucose levels.

G protein-coupled receptor 119 agonist DS-8500a effects on pancreatic β-cells in Japanese type 2 diabetes mellitus patients

AIMS/INTRODUCTION

Pancreatic β-cell dysfunction contributes to type 2 diabetes mellitus progression. Drugs that improve insulin secretion might be a valuable treatment approach. The present study aimed to evaluate the effect of the G protein-coupled receptor 119 agonist DS-8500a on insulin secretory capacity in Japanese type 2 diabetes mellitus patients.

MATERIALS AND METHODS

This single-center, 4-week, randomized, double-blind, cross-over study enrolled 21 Japanese drug-naïve type 2 diabetes mellitus patients aged ≥20 years with glycated hemoglobin ≥7.0 and <9.0% (NCT02669732, JapicCTI 163126). Patients received 75 mg of DS-8500a or a placebo orally daily for 4 weeks in a random order. A combined euglycemic-hyperinsulinemic and hyperglycemic clamp test was carried out to assess insulin secretion and insulin sensitivity before and after each 4-week treatment period. Primary end-points were first-phase insulin secretion (insulin area under the curve [AUC]180-190 min and C-peptide AUC180-190 min during the clamp test) and second-phase insulin secretion (insulin AUC190-300 min and C-peptide AUC190-300 min ). Insulin sensitivity (M and M/I values), disposition index and changes in lipid profile were also assessed.

RESULTS

DS-8500a significantly increased first- and second-phase insulin AUC (P = 0.0011, P = 0.0112) and C-peptide AUC (P = 0.0012, P < 0.0001) compared with the placebo. At day 28, M and M/I values were comparable with those of the placebo, whereas the disposition index for insulin and C-peptide was significantly increased (P = 0.0108, P = 0.0002). Total cholesterol, low-density lipoprotein cholesterol and triglyceride concentrations were significantly reduced, and high-density lipoprotein cholesterol concentrations were significantly increased compared with the placebo. No significant treatment-emergent adverse events occurred.

CONCLUSION

DS-8500a enhanced insulin secretory capacity, but not insulin sensitivity.

DS-8500a, an Orally Available G Protein-Coupled Receptor 119 Agonist, Upregulates Glucagon-Like Peptide-1 and Enhances Glucose-Dependent Insulin Secretion and Improves Glucose Homeostasis in Type 2 Diabetic Rats

G protein-coupled receptor 119 (GPR119) has been shown to be highly expressed in small intestinal L-cells and pancreatic β-cells and mediates intracellular cAMP concentration, glucagon-like peptide (GLP-1) secretion, and glucose-stimulated insulin secretion (GSIS). This study examined the pharmacological effects of 4-(5-{(1R)-1-[4-(cyclopropylcarbonyl) phenoxy]propyl}-1,2,4-oxadiazol-3-yl)-2-fluoro-N-[(2R)-1-hydroxypropan-2-yl]benzamide (DS-8500a), a novel, orally available, selective GPR119 agonist. In in vitro studies, DS-8500a increased intracellular cAMP in a concentration-dependent manner in human, rat, and mouse GPR119-expressing Chinese hamster ovary (CHO)-K1 cells, with EC₅₀ values of 51.5, 98.4, and 108.1 nmol/l, respectively. DS-8500a had no effect on intracellular cAMP in pcDNA3.1/CHO-K1 cells. In in vivo studies, DS-8500a augmented plasma GLP-1 concentration in Zucker fatty (ZF) rats, and enhanced GSIS and did not change plasma glucose concentration in fasted Sprague-Dawley (SD) rats. A single dose of DS-8500a showed dose-dependent glucose-lowering effects at oral glucose tolerance test (OGTT) in ZF rats. In a repeat-dosing study, DS-8500a had statistically significant glucose-lowering effects at OGTT performed at the 1st day and after 2 weeks of treatment in neonatal streptozotocin-treated (nSTZ) rats, and the efficacy levels of DS-8500a in each test were greater than those of GSK1292263 or MBX-2982, which had been clinically tested previously as GPR119 agonists. Through pharmacokinetics and pharmacodynamics assessment, the high intrinsic activity of DS-8500a was suggested to be one of the reasons for the greater glucose lowering effect in the nSTZ rats. DS-8500a is a useful compound among GPR119 agonists that can maximize the potential benefit of GPR119 in type 2 diabetes.

Beyond Glucagon-like Peptide-1: Is G-Protein Coupled Receptor Polypharmacology the Path Forward to Treating Metabolic Diseases?

The glucagon-like peptide-1 receptor (GLP-1R) is a class B G-protein coupled receptor (GPCR) that has proven to be an effective target for developing medicines that treat type 2 diabetes mellitus (T2DM). GLP-1R agonists improve T2DM by enhancing glucose-stimulated insulin secretion, delaying gastric transit, decreasing glucagon levels, and reducing body weight due to anorexigenic actions. The therapeutic successes of these agents helped inspire the design of new multifunctional molecules that are GLP-1R agonists but also activate receptors linked to pathways that enhance insulin sensitization and/or energy expenditure. Herein, these agents are discussed in the context of polypharmacological approaches that may enable even further improvement in treatment outcomes. Moreover, we revisit classical polypharmaceutical GPCR approaches and how they may be utilized for treatment of T2DM. To determine optimal combination regimens, changes in drug discovery practices are likely needed because compensatory mechanisms appear to underlie progression of T2DM and limit the ability of current therapies to induce disease regression or remission.

Efficacy and safety of the G protein-coupled receptor 119 agonist DS-8500a in Japanese type 2 diabetes mellitus patients with inadequate glycemic control on sitagliptin: A phase 2 randomized placebo-controlled study

Introduction

We evaluated the efficacy and safety of DS‐8500a as add‐on therapy to sitagliptin in Japanese type 2 diabetes mellitus patients.

Materials and Methods

This multicenter, randomized, double‐blind, placebo‐controlled, phase 2 trial randomized patients aged ≥20 years with hemoglobin A1c ≥7.0% and <9.0%, and inadequate glycemic control with sitagliptin 50‐mg monotherapy to receive 25 or 75 mg DS‐8500a, or a placebo, orally. The primary end‐point was change from baseline to day 28 in 24‐h weighted mean glucose. Secondary end‐points included change from baseline in fasting plasma glucose, 2‐h postprandial plasma glucose and lipid profiles.

Results

Overall, 29, 28 and 27 patients in the placebo, 25‐ and 75‐mg groups, respectively, were analyzed. A significant dose‐dependent reduction was observed in 24‐h weighted mean glucose (linear: P = 0.0006, saturated at 25 mg: P = 0.0003, responded from 75 mg: P = 0.0176) when compared with the placebo (25 mg: −13.19 mg/dL [−0.73 mmol/L], P = 0.0044 vs placebo and 75 mg: −16.12 mg/dL [−0.89 mmol/L], P = 0.0006 vs placebo). A significant reduction in fasting plasma glucose at 75 mg vs placebo was observed (P < 0.001). At 25 and 75 mg, significant reductions of 2‐h postprandial plasma glucose (after breakfast), total cholesterol, low‐cholesterol and triglycerides were observed (all P < 0.05), with a (non‐significant) trend towards increased high‐density lipoprotein cholesterol. Both doses of DS‐8500a were well tolerated. There were no significant treatment‐emergent adverse events leading to discontinuation during the study.

Conclusions

DS‐8500a was well tolerated, and showed significant glycemic benefits and favorable changes in lipid profile in Japanese type 2 diabetes mellitus patients with inadequate glycemic control with sitagliptin therapy.

Discovery of MK-8282 as a Potent G-Protein-Coupled Receptor 119 Agonist for the Treatment of Type 2 Diabetes

The ever-growing prevalence of type 2 diabetes in the world has necessitated an urgent need for multiple orally effective agents that can regulate glucose homeostasis with a concurrent reduction in body weight. G-Protein coupled receptor 119 (GPR119) is a GPCR target at which agonists have demonstrated glucose-dependent insulin secretion and shows beneficial effects on glycemic control. Herein, we describe our efforts leading to the identification of a potent, oral GPR-119 agonist, MK-8282, which shows improved glucose tolerance in multiple animal models and has excellent off-target profile. The key design elements in the compounds involved a combination of a fluoro-pyrimidine and a conformationally constrained bridged piperidine to impart good potency and efficacy.

The current state of GPCR-based drug discovery to treat metabolic disease

One approach of modern drug discovery is to identify agents that enhance or diminish signal transduction cascades in various cell types and tissues by modulating the activity of GPCRs. This strategy has resulted in the development of new medicines to treat many conditions, including cardiovascular disease, psychiatric disorders, HIV/AIDS, certain forms of cancer and Type 2 diabetes mellitus (T2DM). These successes justify further pursuit of GPCRs as disease targets and provide key learning that should help guide identifying future therapeutic agents. This report reviews the current landscape of GPCR drug discovery with emphasis on efforts aimed at developing new molecules for treating T2DM and obesity. We analyse historical efforts to generate GPCR-based drugs to treat metabolic disease in terms of causal factors leading to success and failure in this endeavour.

LINKED ARTICLES

This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.

Efficacy and Safety of GPR119 Agonist DS-8500a in Japanese Patients with Type 2 Diabetes: a Randomized, Double-Blind, Placebo-Controlled, 12-Week Study

Introduction

G protein-coupled receptor 119 (GPR119) is a promising target for the treatment of type 2 diabetes mellitus (T2DM), as both insulin and glucagon-like peptide-1 secretion can be promoted with a single drug. We compared the efficacy and safety of the GPR119 agonist DS-8500a with placebo and sitagliptin 50 mg in Japanese patients with T2DM.

Methods

This randomized, double-blind, parallel-group comparison study was conducted in Japan (trial registration NCT02628392, JapicCTI-153068). Eligible patients aged ≥ 20 years with T2DM and hemoglobin A1c (HbA1c) ≥ 7.0% and < 10.0% were randomized to receive placebo, DS-8500a (25, 50, or 75 mg), or sitagliptin 50 mg once daily for 12 weeks. The primary efficacy endpoint was change in HbA1c from baseline to week 12. Secondary endpoints included change in fasting plasma glucose (FPG), glucose AUC_0–3h during a meal tolerance test, 2-hour postprandial glucose (2hr-PPG), and changes in lipid parameters (total, low-density lipoprotein (LDL-) and high-density lipoprotein (HDL-) cholesterol, and triglycerides) at week 12. Safety endpoints included adverse events, hypoglycemia, and clinical/laboratory variables.

Results

DS-8500a demonstrated dose-dependent HbA1c lowering compared with placebo at week 12: change from baseline − 0.23% (p = 0.0173), − 0.37% (p = 0.0001), and − 0.44% (p < 0.0001) in the 25-mg, 50-mg, and 75-mg groups, respectively. At 50- and 75-mg doses, DS-8500a significantly lowered FPG, glucose AUC_0–3h, and 2hr-PPG compared with placebo. The glucose-lowering effect was maintained up to 12 weeks. DS-8500a did not lower any of the above parameters to a greater extent than sitagliptin. Compared with placebo and sitagliptin, DS-8500a 50 and 75 mg significantly reduced total cholesterol, LDL-cholesterol, and triglycerides, and significantly increased HDL-cholesterol. All DS-8500a doses were well tolerated. Two cases of clinically relevant drug-related hypoglycemia occurred in the DS-8500a 50-mg group.

Conclusion

DS-8500a was well tolerated and demonstrated significant glucose-lowering effects and favorable changes in lipid profiles up to 12 weeks in Japanese patients with T2DM.

Funding

Daiichi Sankyo Co. Ltd.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0668-2) contains supplementary material, which is available to authorized users.

YH18968, a Novel 1,2,4-Triazolone G-Protein Coupled Receptor 119 Agonist for the Treatment of Type 2 Diabetes Mellitus

G protein-coupled receptor 119 (GPR119) is expressed in the pancreas and gastrointestinal tract, and its activation promotes insulin secretion in the beta cells of the pancreatic islets as well as the secretion of glucagon-like peptide-1 (GLP-1) in intestinal L cells, consequently improving glucose-stimulated insulin secretion. Due to this dual mechanism of action, the development of small-molecule GPR119 agonists has received significant interest for the treatment of type 2 diabetes. We newly synthesized 1,2,4-triazolone derivatives of GPR119 agonists, which demonstrated excellent outcomes in a cyclic adenosine monophosphate (cAMP) assay. Among the synthesized derivatives, YH18968 showed cAMP=2.8 nM; in GLUTag cell, GLP-1secretion=2.3 fold; in the HIT-T15 cell, and insulin secretion=1.9 fold. Single oral administration of YH18968 improved glucose tolerance and combined treatment with a dipeptidyl peptidase 4 (DPP-4) inhibitor augmented the glucose lowering effect as well as the plasma level of active GLP-1 in normal mice. Single oral administration of YH18968 improved glucose tolerance in a diet induced obese mice model. This effect was maintained after repeated dosing for 4 weeks. The results indicate that YH18968 combined with a DPP-4 inhibitor may be an effective therapeutic candidate for the treatment of type 2 diabetes.

Therapeutic application of GPR119 ligands in metabolic disorders

GPR119 belongs to the G protein-coupled receptor family and exhibits dual modes of action upon ligand-dependent activation: pancreatic secretion of insulin in a glucose-dependent manner and intestinal secretion of incretins. Hence, GPR119 has emerged as a promising target for treating type 2 diabetes mellitus without causing hypoglycaemia. However, despite continuous efforts by many major pharmaceutical companies, no synthetic GPR119 ligand has been approved as a new class of anti-diabetic agents thus far, nor has any passed beyond phase II clinical studies. Herein, we summarize recent advances in research concerning the physiological/pharmacological effects of GPR119 and its synthetic ligands on the regulation of energy metabolism, and we speculate on future applications of GPR119 ligands for the treatment of metabolic diseases, focusing on non-alcoholic fatty liver disease.

Chemistry and Hypoglycemic Activity of GPR119 Agonist ZB-16

This article is to highlight the chemical properties and primary pharmacology of novel GPR119 agonist ZB-16 and its analogs, which were rejected during the screening. Experiments were performed in vitro (specific activity, metabolism and cell toxicity) and in vivo (hypoglycemic activity and pharmacokinetics). ZB-16 exhibits nanomolar activity (EC50 = 7.3-9.7 nM) on target receptor GPR119 in vitro associated with hypoglycemic activity in vivo. In animals with streptozotocin-nicotinamide induced type 2 diabetes mellitus (STZ-NA T2D) daily oral dose of ZB-16 (1 mg/kg) or sitagliptin (10 mg/kg) for 28 days resulted in the reduction of blood glucose levels. The effects of ZB-16 were comparable to the hypoglycemic action of sitagliptin. ZB-16 demonstrated relatively low plasma exposition, high distribution volume, mild clearance and a prolonged half-life (more than 12 h). The present study demonstrates that the targeted search for selective GPR119 receptor agonists is a well-founded approach for developing novel drugs for the therapy of T2D. Based on the combination of high in vitro activity (compared to competitor standards), a useful ADME profile, distinct hypoglycemic activity which is comparable to the efficacy of sitagliptin in rats with experimental T2D, and the acceptable pharmacokinetic profile, we recommend the ZB-16 compound for further research.

Gut Microbiota Dysbiosis Drives and Implies Novel Therapeutic Strategies for Diabetes Mellitus and Related Metabolic Diseases

Accumulating evidence over the past decade has linked the development of metabolic syndrome related to diabetes to variations in gut microbiota, an emerging, critical homeostatic regulator of host energy metabolism and immune responses. Mechanistic studies in rodent models have revealed an ever-increasing multitude of molecular mechanisms whereby the gut microbiota interacts with various host sensing and signaling pathways, leading to modulation of endocrine system, immune responses, nervous system activity, and hence, the predisposition to metabolic diseases. Remarkably, the microbiota-driven immune responses in metabolic tissues and the host nutrient-sensing mechanisms of gut microbial metabolites, in particular short-chain fatty acids, have been significantly associated with the proneness to diabetes and related disorders. This review will synthesize the recent efforts on unraveling the mediating role of gut microbiota in the pathogenesis of metabolic diseases, aiming to reveal new therapeutic opportunities.

Commensal bacteria make GPCR ligands that mimic human signalling molecules

Commensal bacteria are believed to have important roles in human health. The mechanisms by which they affect mammalian physiology remain poorly understood, but bacterial metabolites are likely to be key components of host interactions. Here we use bioinformatics and synthetic biology to mine the human microbiota for N-acyl amides that interact with G-protein-coupled receptors (GPCRs). We found that N-acyl amide synthase genes are enriched in gastrointestinal bacteria and the lipids that they encode interact with GPCRs that regulate gastrointestinal tract physiology. Mouse and cell-based models demonstrate that commensal GPR119 agonists regulate metabolic hormones and glucose homeostasis as efficiently as human ligands, although future studies are needed to define their potential physiological role in humans. Our results suggest that chemical mimicry of eukaryotic signalling molecules may be common among commensal bacteria and that manipulation of microbiota genes encoding metabolites that elicit host cellular responses represents a possible small-molecule therapeutic modality (microbiome-biosynthetic gene therapy).

Design, synthesis, and biological evaluation of aryl N-methoxyamide derivatives as GPR119 agonists

A series of N-methoxyamide derivatives was identified and evaluated as GPR119 agonists. Several N-methoxyamides with thienopyrimidine and pyridine scaffolds showed potent GPR119 agonistic activities. Among them, compound 9c displayed good in vitro activity and potency. Moreover, compound 9c lowered glucose excursion in mice in an oral glucose tolerance test and increased GLP-1 secretion in intestinal cells.

Cannabinoid Receptor-Related Orphan G Protein-Coupled Receptors

Of the druggable group of G protein-coupled receptors in the human genome, a number remain which have yet to be paired with an endogenous ligand-orphan GPCRs. Among these 100 or so entities, 3 have been linked to the cannabinoid system. GPR18, GPR55, and GPR119 exhibit limited sequence homology with the established CB₁ and CB₂ cannabinoid receptors. However, the pharmacology of these orphan receptors displays overlap with CB₁ and CB₂ receptors, particularly for GPR18 and GPR55. The linking of GPR119 to the cannabinoid receptors is less convincing and emanates from structural similarities of endogenous ligands active at these GPCRs, but which do not cross-react. This review describes the evidence for describing these orphan GPCRs as cannabinoid receptor-like receptors.

YH18421, a novel GPR119 agonist exerts sustained glucose lowering and weight loss in diabetic mouse model

G-protein-coupled receptor 119 (GPR119) represents a promising target for the treatment of type 2 diabetes as it can increase both GLP-1 secretion from intestinal L cells and glucose-stimulated insulin secretion (GSIS) from pancreatic β cells. Due to this dual mechanism of action, the development of small molecule GPR119 agonists has received much interest for the treatment of type 2 diabetes. Here, we identified a novel small-molecule GPR119 agonist, YH18421 and evaluated its therapeutic potential. YH18421 specifically activated human GPR119 with high potency and potentiated GLP-1 secretion and GSIS in vitro cell based systems. In normal mice, single oral administration of YH18421 improved glucose tolerance. Combined treatment of YH18421 and the DPP-4 inhibitor augmented both plasma active GLP-1 levels and glycemic control. In diet induced obese (DIO) mice model, glucose lowering effect of YH18421 was maintained after 4 weeks of repeat dosing and YH18421 acted additively with DPP-IV inhibitor. We also observed that YH18421 inhibited weight gain during 4 weeks of administration in DIO mice. These data demonstrate that YH18421 is capable of delivering sustained glucose control and preventing weight gain and combination with the DPP-IV inhibitor maybe an effective strategy for the treatment of type 2 diabetes.

β-Cell Inactivation of Gpr119 Unmasks Incretin Dependence of GPR119-Mediated Glucoregulation

GPR119 was originally identified as an orphan β-cell receptor; however, subsequent studies demonstrated that GPR119 also regulates β-cell function indirectly through incretin hormone secretion. We assessed the importance of GPR119 for β-cell function in Gpr119^-/- mice and in newly generated Gpr119^βcell-/- mice. Gpr119^-/- mice displayed normal body weight and glucose tolerance on a regular chow (RC) diet. After high-fat feeding, Gpr119^-/- mice exhibited reduced fat mass, decreased levels of circulating adipokines, improved insulin sensitivity, and better glucose tolerance. Unexpectedly, oral and intraperitoneal glucose tolerance and the insulin response to glycemic challenge were not perturbed in Gpr119^βcell-/- mice on RC and high-fat diets. Moreover, islets from Gpr119^-/- and Gpr119^βcell-/- mice exhibited normal insulin responses to glucose and β-cell secretagogues. Furthermore, the selective GPR119 agonist AR231453 failed to directly enhance insulin secretion from perifused islets. In contrast, AR231453 increased plasma glucagon-like peptide 1 (GLP-1) and insulin levels and improved glucose tolerance in wild-type and Gpr119^βcell-/- mice. These findings demonstrate that β-cell GPR119 expression is dispensable for the physiological control of insulin secretion and the pharmacological response to GPR119 agonism, findings that may inform the lack of robust efficacy in clinical programs assessing GPR119 agonists for the therapy of type 2 diabetes.

Mechanisms of the amplifying pathway of insulin secretion in the β cell

Pancreatic islet β cells secrete insulin in response to nutrient secretagogues, like glucose, dependent on calcium influx and nutrient metabolism. One of the most intriguing qualities of β cells is their ability to use metabolism to amplify the amount of secreted insulin independent of further alterations in intracellular calcium. Many years studying this amplifying process have shaped our current understanding of β cell stimulus-secretion coupling; yet, the exact mechanisms of amplification have been elusive. Recent studies utilizing metabolomics, computational modeling, and animal models have progressed our understanding of the metabolic amplifying pathway of insulin secretion from the β cell. New approaches will be discussed which offer in-roads to a more complete model of β cell function. The development of β cell therapeutics may be aided by such a model, facilitating the targeting of aspects of the metabolic amplifying pathway which are unique to the β cell.

Glucose-lowering effects and safety of DS-8500a, a G protein-coupled receptor 119 agonist, in Japanese patients with type 2 diabetes: results of a randomized, double-blind, placebo-controlled, parallel-group, multicenter, phase II study

OBJECTIVE

DS-8500a is a novel G protein-coupled receptor 119 agonist being developed for the treatment of type 2 diabetes. The study objective was to assess the efficacy and safety of DS-8500a in Japanese patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this double-blind, parallel-group, phase II study, 99 Japanese patients with type 2 diabetes were randomized to receive placebo, or DS-8500a 10 mg or 75 mg once daily for 28 days. The primary efficacy endpoint was change in the 24-hour weighted mean glucose (WMG) from baseline (day -1) to day 28. Other endpoints included changes in fasting plasma glucose, postprandial glucose, lipids, and safety.

RESULTS

The 24-hour WMG decreased significantly after 28 days of treatment in the 10 mg and 75 mg groups with placebo-subtracted least squares mean differences (95% CI) of -0.74 (-1.29 to -0.19) mmol/L and -1.05 (-1.59 to -0.50) mmol/L, respectively. Reductions in 24-hour WMG in both DS-8500a groups were observed on day 14 and were greater on day 28 than on day 14. The reductions in fasting plasma glucose and 2-hour postprandial glucose were significantly greater in the 75 mg DS-8500a group versus placebo. Total cholesterol, low-density lipoprotein cholesterol, and triglycerides decreased significantly; high-density lipoprotein cholesterol increased significantly in the 75 mg group versus placebo. Both doses of DS-8500a were well tolerated without significant treatment-related adverse events, hypoglycemia, or discontinuations due to adverse events.

CONCLUSIONS

DS-8500a significantly improved glycemic control and lipids and was well tolerated over 28 days of administration in Japanese patients with type 2 diabetes.

TRIAL REGISTRATION NUMBER

NCT02222350; Post-results.

Future glucose-lowering drugs for type 2 diabetes

The multivariable and progressive natural history of type 2 diabetes limits the effectiveness of available glucose-lowering drugs. Constraints imposed by comorbidities (notably cardiovascular disease and renal impairment) and the need to avoid hypoglycaemia, weight gain, and drug interactions further complicate the treatment process. These challenges have prompted the development of new formulations and delivery methods for existing drugs alongside research into novel pharmacological entities. Advances in incretin-based therapies include a miniature implantable osmotic pump to give continuous delivery of a glucagon-like peptide-1 receptor agonist for 6-12 months and once-weekly tablets of dipeptidyl peptidase-4 inhibitors. Hybrid molecules that combine the properties of selected incretins and other peptides are at early stages of development, and proof of concept has been shown for small non-peptide molecules to activate glucagon-like peptide-1 receptors. Additional sodium-glucose co-transporter inhibitors are progressing in development as well as possible new insulin-releasing biological agents and small-molecule inhibitors of glucagon action. Adiponectin receptor agonists, selective peroxisome proliferator-activated receptor modulators, cellular glucocorticoid inhibitors, and analogues of fibroblast growth factor 21 are being considered as potential new approaches to glucose lowering. Compounds that can enhance insulin receptor and post-receptor signalling cascades or directly promote selected pathways of glucose metabolism have suggested opportunities for future treatments. However, pharmacological interventions that are able to restore normal β-cell function and β-cell mass, normalise insulin action, and fully correct glucose homoeostasis are a distant vision.

G Protein-Coupled Receptor 119 (GPR119) Agonists for the Treatment of Diabetes: Recent Progress and Prevailing Challenges

In this Perspective, recent advances and challenges in the development of GPR119 agonists as new oral antidiabetic drugs will be discussed. Such agonists are expected to exhibit a low risk to induce hypoglycemia as well as to have a beneficial impact on body weight. Many pharmaceutical companies have been active in the search for GPR119 agonists, making it a highly competitive area in the industrial environment. Several GPR119 agonists have been entered into clinical studies, but many have failed either in phase I or II and none has progressed beyond phase II. Herein we describe the strategies chosen by the different medicinal chemistry teams in academia and the pharmaceutical industry to improve potency, physicochemical properties, pharmacokinetics, and the safety profile of GPR119 agonists in the discovery phase in order to improve the odds for successful development.

GSK2374697, a long duration glucagon-like peptide-1 (GLP-1) receptor agonist, reduces postprandial circulating endogenous total GLP-1 and peptide YY in healthy subjects

We investigated the effects of a long-duration glucagon-like peptide-1 (GLP-1) receptor agonist, GSK2374697, on postprandial endogenous total GLP-1 and peptide YY (PYY). Two cohorts of healthy subjects, one normal/overweight and one obese, were randomized to receive GSK2374697 2 mg (n = 8 each) or placebo (n = 4 and n = 2) subcutaneously on days 1, 4 and 7. Samples for plasma endogenous GLP-1 and PYY were collected after breakfast on days -1 and 12. Weighted mean area under the curve (0-4 h) of total GLP-1 and PYY in treated subjects was reduced compared with placebo. The least squares mean difference for change from baseline was -1.24 pmol/l [95% confidence interval (CI) -2.33, -0.16] and -4.47 pmol/l (95% CI -8.74, -0.20) for total GLP-1 and PYY, respectively, in normal/overweight subjects (p < 0.05 for both), and -1.56 (95% CI -2.95, -0.16) and -3.02 (95% CI -8.58, 2.55), respectively, in obese subjects (p < 0.05 for GLP-1). In healthy subjects, GSK2374697 reduced postprandial total GLP-1 and PYY levels, suggesting feedback suppression of enteroendocrine L-cell secretion of these peptides.

Synergistic Effects of a GPR119 Agonist with Metformin on Weight Loss in Diet-Induced Obese Mice

G protein-coupled receptor 119 (GPR119) is a G protein-coupled receptor expressed predominantly in pancreatic β-cells and gastrointestinal enteroendocrine cells. Metformin is a first-line treatment of type 2 diabetes, with minimal weight loss in humans. In this study, we investigated the effects of GSK2041706 [2-([(1S)-1-(1-[3-(1-methylethyl)-1,2,4-oxadiazol-5-yl]-4-piperidinyl)ethyl]oxy)-5-[4-(methylsulfonyl)phenyl]pyrazine], a GPR119 agonist, and metformin as monotherapy or in combination on body weight in a diet-induced obese (DIO) mouse model. Relative to vehicle controls, 14-day treatment with GSK2041706 (30 mg/kg b.i.d.) or metformin at 30 and 100 mg/kg b.i.d. alone caused a 7.4%, 3.5%, and 4.4% (all P < 0.05) weight loss, respectively. The combination of GSK2041706 with metformin at 30 or 100 mg/kg resulted in a 9.5% and 16.7% weight loss, respectively. The combination of GSK2041706 and metformin at 100 mg/kg caused a significantly greater weight loss than the projected additive weight loss of 11.8%. This body weight effect was predominantly due to a loss of fat. Cumulative food intake was reduced by 17.1% with GSK2041706 alone and 6.6% and 8.7% with metformin at 30 and 100 mg/kg, respectively. The combination of GSK2041706 with metformin caused greater reductions in cumulative food intake (22.2% at 30 mg/kg and 37.5% at 100 mg/kg) and higher fed plasma glucagon-like peptide 1 and peptide tyrosine tyrosine levels and decreased plasma insulin and glucose-dependent insulinotropic polypeptide levels compared with their monotherapy groups. In addition, we characterized the effect of GSK2041706 and metformin as monotherapy or in combination on neuronal activation in the appetite regulating centers in fasted DIO mice. In conclusion, our data demonstrate the beneficial effects of combining a GPR119 agonist with metformin in the regulation of body weight in DIO mice.

Direct activation of the proposed anti-diabetic receptor, GPR119 in cardiomyoblasts decreases markers of muscle metabolic activity

GPR119 agonists are emerging rapidly as a pharmaceutical treatment of diabetes. Diabetes is a known risk factor for cardiovascular disease yet the cardiac-specific consequences of GPR119 activation are unknown. This study demonstrated that GPR119 agonism in cardiac myoblasts reduces metabolic activity in high and low concentrations of fatty acids, with high concentrations of palmitate largely attenuating the effects of the GPR119 agonist, PSN632408. The effects of GPR119 activation on gene and protein markers of metabolism were dependent on fatty acid exposure. Activating GPR119 did not affect cell hypertrophy of lipid accumulation regardless of lipid exposure. These results suggest that the pathways activated in response to GPR119 modulation in cardiac muscle cells differ between healthy and metabolically dysregulated states. However regardless of the pathway activated by GPR119, these effects may cause detrimental reductions to oxidative/metabolic capacity under both conditions. Thus further development of GPR119 agonists for treating metabolic diseases is warranted.

Addressing unmet medical needs in type 2 diabetes: a narrative review of drugs under development

The global burden of type 2 diabetes is increasing worldwide, and successful treatment of this disease needs constant provision of new drugs. Twelve classes of antidiabetic drugs are currently available, and many new drugs are under clinical development. These include compounds with known mechanisms of action but unique properties, such as once-weekly DPP4 inhibitors or oral insulin. They also include drugs with new mechanisms of action, the focus of this review. Most of these compounds are in Phase 1 and 2, with only a small number having made it to Phase 3 at this time. The new drug classes described include PPAR agonists/modulators, glucokinase activators, glucagon receptor antagonists, anti-inflammatory compounds, G-protein coupled receptor agonists, gastrointestinal peptide agonists other than GLP-1, apical sodium-dependent bile acid transporter (ASBT) inhibitors, SGLT1 and dual SGLT1/SGLT2 inhibitors, and 11beta- HSD1 inhibitors.