Small Molecule Glucagon-like Peptide-1 Receptor Research Articles

Newer pharmacological interventions directed at gut hormones for obesity.

The objective is to review the newer pharmacological interventions for obesity, specifically single, dual and triple incretin receptor agonists that are either available or in the pipeline for treatment of obesity. The three incretin receptor targets are glucagon like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP) and glucagon. There are several approved single or dual incretin agonists which can be administered subcutaneously daily (e.g., liraglutide) or weekly (e.g., semaglutide, dulaglutide, and exenatide QW), and other experimental dual or triple incretin agonists. Analogues of amylin, peptide YY and oxyntomodulin, as well as the combination of a GLP1R agonist and GIPR antagonist also are in development. Oral semaglutide (administered daily) is approved for type 2 diabetes mellitus and is on track for regulatory review for obesity. The review includes specifically perspectives on the effects of these mechanisms and pharmacological agents on gastric emptying, which contribute to satiation and weight loss, in addition to the established evidence on effects on central mechanisms controlling appetite. In the future, it is anticipated that small molecule GLP-1 receptor agonists (e.g., oral danuglipron) will be developed for treating obesity. These pharmacological agents are having significant impact on glycaemic control and obesity and on their co-morbidities.

Mollugin activates GLP-1R to improve cognitive dysfunction in type 2 diabetic mice

AimsThe incidence of diabetic cognitive dysfunction is increasing year by year, and it has gradually become a research hot spot. Studies have shown that glucagon-like peptide-1 receptor (GLP-1R) agonists can improve cognitive dysfunction in diabetic patients. This study focuses on whether small molecule GLP-1R agonists from traditional Chinese medicine (TCM) can improve the diabetic cognitive dysfunction. Materials and methodsThe small molecules from TCM were screened by cell membrane chromatography (CMC) with GLP-1R-HEK293 cell membrane column. MTT assay, flow cytometry, immunofluorescence cytochemistry and other methods were used to determine the effects of mollugin on the apoptosis rate and reactive oxygen species (ROS) level of high glucose (HG)/hydrogen peroxide (H2O2) induced PC12 cells. Real-Time PCR was used to detect mRNA expression in mouse cerebral cortex. Water maze test was further used to confirm the effect of mollugin on cognitive dysfunction in T2DM mice. Key findingsMollugin bound to GLP-1R, promoted Ca2+ influx, increased insulin secretion and cAMP content in β-TC-6 cells. Mollugin enhanced the cell viability, ameliorated apoptosis, reduced intracellular ROS levels in HG/H2O2-injured PC12 cells. Mollugin reduced the T2DM mice's escape latency, improved neuronal cell damage, decreased the expression of Pik3ca, Akt1 and Mapk1 mRNA in the cerebral cortex tissue. SignificanceThe results suggest that mollugin could improve cognitive dysfunction in T2DM mice through activating GLP-1R/cAMP/PKA signal pathway.

6-Azaspiro[2.5]octanes as small molecule agonists of the human glucagon-like peptide-1 receptor

Activation of the glucagon-like peptide-1 (GLP-1) receptor stimulates insulin release, lowers plasma glucose levels, delays gastric emptying, increases satiety, suppresses food intake, and affords weight loss in humans. These beneficial attributes have made peptide-based agonists valuable tools for the treatment of type 2 diabetes mellitus and obesity. However, efficient, and consistent delivery of peptide agents generally requires subcutaneous injection, which can reduce patient utilization. Traditional orally absorbed small molecules for this target may offer improved patient compliance as well as the opportunity for co-formulation with other oral therapeutics. Herein, we describe an SAR investigation leading to small-molecule GLP-1 receptor agonists that represent a series that parallels the recently reported clinical candidate danuglipron. In the event, identification of a benzyloxypyrimidine lead, using a sensitized high-throughput GLP-1 agonist assay, was followed by optimization of the SAR using substituent modifications analogous to those discovered in the danuglipron series. A new series of 6-azaspiro[2.5]octane molecules was optimized into potent GLP-1 agonists. Information gleaned from cryogenic electron microscope structures was used to rationalize the SAR of the optimized compounds.

95-LB: Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of a Novel Oral Small Molecule GLP-1 Receptor Agonist (HRS-7535) in Healthy Subjects —A Phase 1, Randomized, Double-Blind, Placebo-Controlled, Single- and Multiple-Ascending Dose Study

Background: HRS-7535, a novel, oral small molecule glucagon-like peptide-1 receptor (GLP-1R) agonist, has demonstrated no strict food restriction, and has been found to obviously improve glucose tolerance, promote insulin secretion, and reduce food consumption in preclinical studies. This study aimed to assess the safety, tolerability, pharmacokinetics (PKs), and pharmacodynamics (PDs) of single and multiple ascending doses (SAD and MAD) of HRS-7535 in healthy subjects. Methods: This was a randomized, double-blind, multi-part, phase 1 trial (NCT05347758). Overtly healthy adults 18-55 yrs were eligible, with the body mass index of 19.0-28.0 kg/m2 and the HbA1c of <6.2%. In the SAD, healthy subjects were randomized (6:2) to receive HRS-7535 (15, 60, and 120 mg) or placebo. In the MAD, healthy subjects were randomized (18:6) to receive daily HRS-7535 (120 mg [30/60/90/120 mg titration scheme]) or matching placebo for 4 wks. Results: 24 subjects participated in SAD and 24 participated in MAD, respectively. Most common treatment-emergent adverse events in both SAD and MAD were nausea and vomiting; all TEAEs were mild in severity. PKs were approximately proportional; In SAD, the median Tmax was 5.98-5.99 h and geometric mean t1/2 was 5.28-9.08 h across the HRS-7535 dosing range. In MAD, the median Tmax was 5.98-10.98 h and geometric mean t1/2 was 6.48-8.42 h on Day 28 across the HRS-7535 dosing range. In MAD, the mean reduction in body weight from baseline on Day 29 was 4.38 kg in subjects with HRS-7535. Conclusion: Both SAD and MAD of HRS-7535 showed acceptable safety profile and favorable PKs/PDs. The obvious reductions in body weight could be observed in healthy subjects. These finding support further clinical exploration of HRS-7535 in patients with metabolic syndromes. Disclosure J. Wu: None. S. Feng: Employee; Jiangsu Hengrui Pharmaceuticals Co., Ltd. C. Shu: Employee; Jiangsu Hengrui Pharmaceuticals Co., Ltd. Y. Shen: Employee; Jiangsu Hengrui Pharmaceuticals Co., Ltd. Y. Fan: Employee; Jiangsu Hengrui Pharmaceuticals Co., Ltd. W. Hu: None. Y. Du: None. Q. Zhang: None. R. Zhou: None. Q. Zhang: None. H. Qin: None. Z. Ye: Employee; Jiangsu Hengrui Pharmaceuticals Co., Ltd. Y. Xu: Employee; Jiangsu Hengrui Pharmaceuticals Co., Ltd. Funding Jiangsu Hengrui Pharmaceuticals Co., Ltd.

Efficacy and Safety of Oral Small Molecule Glucagon-Like Peptide 1 Receptor Agonist Danuglipron for Glycemic Control Among Patients With Type 2 Diabetes

Currently available glucagon-like peptide 1 receptor (GLP-1R) agonists for treating type 2 diabetes (T2D) are peptide agonists that require subcutaneous administration or strict fasting requirements before and after oral administration. To investigate the efficacy, safety, and tolerability of multiple dose levels of the novel, oral, small molecule GLP-1R agonist danuglipron over 16 weeks. A phase 2b, double-blind, placebo-controlled, parallel-group, 6-group randomized clinical trial with 16-week double-blind treatment period and 4-week follow-up was conducted from July 7, 2020, to July 7, 2021. Adults with T2D inadequately controlled by diet and exercise, with or without metformin treatment, were enrolled from 97 clinical research sites in 8 countries or regions. Participants received placebo or danuglipron, 2.5, 10, 40, 80, or 120 mg, all orally administered twice daily with food for 16 weeks. Weekly dose escalation steps were incorporated to achieve danuglipron doses of 40 mg or more twice daily. Change from baseline in glycated hemoglobin (HbA1c, primary end point), fasting plasma glucose (FPG), and body weight were assessed at week 16. Safety was monitored throughout the study period, including a 4-week follow-up period. Of 411 participants randomized and treated (mean [SD] age, 58.6 [9.3] years; 209 [51%] male), 316 (77%) completed treatment. For all danuglipron doses, HbA1c and FPG were statistically significantly reduced at week 16 vs placebo, with HbA1c reductions up to a least squares mean difference vs placebo of -1.16% (90% CI, -1.47% to -0.86%) for the 120-mg twice daily group and FPG reductions up to a least squares mean difference vs placebo of -33.24 mg/dL (90% CI, -45.63 to -20.84 mg/dL). Body weight was statistically significantly reduced at week 16 compared with placebo in the 80-mg twice daily and 120-mg twice daily groups only, with a least squares mean difference vs placebo of -2.04 kg (90% CI, -3.01 to -1.07 kg) for the 80-mg twice daily group and -4.17 kg (90% CI, -5.15 to -3.18 kg) for the 120-mg twice daily group. The most commonly reported adverse events were nausea, diarrhea, and vomiting. In adults with T2D, danuglipron reduced HbA1c, FPG, and body weight at week 16 compared with placebo, with a tolerability profile consistent with the mechanism of action. ClinicalTrials.gov Identifier: NCT03985293.

Cinchonine, a Potential Oral Small-Molecule Glucagon-Like Peptide-1 Receptor Agonist, Lowers Blood Glucose and Ameliorates Non-Alcoholic Steatohepatitis.

The glucagon-like peptide-1 receptor (GLP-1R) is an effective therapeutic target for type 2 diabetes mellitus (T2DM) and non-alcoholic steatohepatitis (NASH). Research has focused on small-molecule GLP-1R agonists because of their ease of use in oral formulations and improved patient compliance. However, no small-molecule GLP-1R agonists are currently available in the market. We aimed to screen for a potential oral small-molecule GLP-1R agonist and evaluated its effect on blood glucose and NASH. The Connectivity map database was used to screen for candidate small-molecule compounds. Molecular docking was performed using SYBYL software. Rat pancreatic islets were incubated in different concentrations glucose solutions, with cinchonine or Exendin (9-39) added to determine insulin secretion levels. C57BL/6 mice, GLP-1R-/- mice and hGLP-1R mice were used to conduct oral glucose tolerance test. In addition, we fed ob/ob mice with the GAN diet to induce the NASH model. Cinchonine (50 mg/kg or 100 mg/kg) was administered orally twice daily to the mice. Serum liver enzymes were measured using biochemical analysis. Liver tissues were examined using Hematoxylin-eosin staining, Oil Red O staining and Sirius Red staining. Based on the small intestinal transcriptome of geniposide, a recognized small-molecule GLP-1R agonist, we identified that cinchonine exerted GLP-1R agonist-like effects. Cinchonine had a good binding affinity for GLP-1R. Cinchonine promoted glucose-dependent insulin secretion, which could be attenuated significantly by Exendin (9-39), a specific GLP-1R antagonist. Moreover, cinchonine could reduce blood glucose in C57BL/6 and hGLP-1R mice, an effect that could be inhibited with GLP-1R knockout. In addition, cinchonine reduced body weight gain and food intake in ob/ob-GAN NASH mice dose-dependently. 100 mg/kg cinchonine significantly improved liver function by reducing the ALT, ALP and LDH levels. Importantly, 100 mg/kg cinchonine ameliorated hepatic steatosis and fibrosis in NASH mice. Cinchonine, a potential oral small-molecule GLP-1R agonist, could reduce blood glucose and ameliorate NASH, providing a strategy for developing small-molecule GLP-1R agonists.

339-OR: Oral Small-Molecule GLP-1R Agonist Danuglipron Robustly Reduces Plasma Glucose and Body Weight after Eight Weeks in Japanese Adults with Type 2 Diabetes Mellitus

Danuglipron is an oral small molecule glucagon-like peptide-1 receptor (GLP-1R) agonist shown to reduce plasma glucose and body weight after 28 days of treatment in adults with type 2 diabetes mellitus (T2DM) . This randomized, double-blind (sponsor-open) , placebo-controlled, Phase 1 study investigated the safety, tolerability, pharmacokinetics, and pharmacodynamics of danuglipron in Japanese patients with T2DM. A total of 37 patients with T2DM inadequately controlled on diet and exercise alone were randomized to twice-daily (BID) oral doses of placebo or multiple, ascending doses of danuglipron titrated to 40 mg, 80 mg, and 120 mg for 8 weeks. Multiple, oral doses of danuglipron were generally safe in Japanese participants with T2DM and resulted in approximate dose-proportional increases in exposure and significant reductions in fasting plasma glucose (FPG) , 24-hour mean daily glucose (MDG) , glycated hemoglobin (HbA1c) , and body weight (Table) . Most adverse events (AEs) were mild or moderate, with AEs of nausea, vomiting, abdominal discomfort, diarrhea, and headache reported most frequently. There were no deaths and no serious AEs related to dosing of danuglipron. No clinically significant adverse trends in labs, electrocardiogram, or vital sign abnormalities were apparent. Disclosure R.Ono: Employee; Pfizer Japan Inc. K.Furihata: Other Relationship; Eli Lilly and Company, Pfizer Japan Inc. Y.Ichikawa: Employee; Pfizer Inc., Stock/Shareholder; Pfizer Japan Inc. Y.Nakazuru: Employee; Pfizer Japan Inc., Stock/Shareholder; Pfizer Inc. A.Bergman: Employee; Pfizer Inc., Stock/Shareholder; Pfizer Inc. D.N.Gorman: Employee; Pfizer Inc. A.R.Saxena: Employee; Pfizer Inc. Funding Sponsored by Pfizer Inc.

753-P: RGT-075, an Orally Efficacious Small Molecule GLP-1R Full Agonist in Cynomolgus Monkey Models

Activation of Glucagon-like peptide-1 receptor (GLP-1R) by peptides has been proven clinically to be a very effective treatment approach for type 2 diabetes (T2D) and obesity. Here we describe a small molecule GLP-1R full agonist RGT-075 identified through Computer Accelerated Rational Design (CARD) (Ma et al., Cell Research 2020) with nM potency in G-protein coupled cAMP signaling. RGT-075 displayed much reduced activity in receptor-mediated β-arrestin recruitment and subsequent internalization. It was shown to be selective against other class B G protein-coupled receptors (GPCRs) and was only active for human and monkey GLP-1R. It demonstrated favorable oral bioavailability and pharmacodynamic profile for once-daily oral dosing in monkeys. In food-induced glucose intolerant and prediabetic cynomolgus monkeys, oral administration of RGT-075 improved glucose tolerance to a level comparable to injectable liraglutide. In food-induced type 2 diabetic monkeys, once-daily oral administration of RGT-075 reduced food intake and fasting plasma glucose levels. Together, these data support the development and advancement of RGT-075 into the clinic as a potential therapeutic for T2D and obesity. Disclosure F.Liu: Employee; Regor Pharmaceuticals Inc. X.Sun: Employee; AutoDrug Biotech Co. Ltd., Qilu Regor Therapeutics Inc. W.Huang: None. W.Guo: None. J.Lin: None. W.Zhong: None.

Structural basis of peptidomimetic agonism revealed by small-molecule GLP-1R agonists Boc5 and WB4-24

Glucagon-like peptide-1 receptor (GLP-1R) agonists are effective in treating type 2 diabetes and obesity with proven cardiovascular benefits. However, most of these agonists are peptides and require subcutaneous injection except for orally available semaglutide. Boc5 was identified as the first orthosteric nonpeptidic agonist of GLP-1R that mimics a broad spectrum of bioactivities of GLP-1 in vitro and in vivo. Here, we report the cryoelectron microscopy structures of Boc5 and its analog WB4-24 in complex with the human GLP-1R and Gs protein. Bound to the extracellular domain, extracellular loop 2, and transmembrane (TM) helices 1, 2, 3, and 7, one arm of both compounds was inserted deeply into the bottom of the orthosteric binding pocket that is usually accessible by peptidic agonists, thereby partially overlapping with the residues A8 to D15 in GLP-1. The other three arms, meanwhile, extended to the TM1-TM7, TM1-TM2, and TM2-TM3 clefts, showing an interaction feature substantially similar to the previously known small-molecule agonist LY3502970. Such a unique binding mode creates a distinct conformation that confers both peptidomimetic agonism and biased signaling induced by nonpeptidic modulators at GLP-1R. Further, the conformational difference between Boc5 and WB4-24, two closed related compounds, provides a structural framework for fine-tuning of pharmacological efficacy in the development of future small-molecule therapeutics targeting GLP-1R.

Design, synthesis, and biological evaluation of a small molecule oral agonist of the glucagon-like-peptide-1 receptor

An absolute or relative deficiency of pancreatic β-cells mass and functionality is a crucial pathological feature common to type 1 diabetes mellitus and type 2 diabetes mellitus. Glucagon-like-peptide-1 receptor (GLP1R) agonists have been the focus of considerable research attention for their ability to protect β-cell mass and augment insulin secretion with no risk of hypoglycemia. Presently commercially available GLP1R agonists are peptides that limit their use due to cost, stability, and mode of administration. To address this drawback, strategically designed distinct sets of small molecules were docked on GLP1R ectodomain and compared with previously known small molecule GLP1R agonists. One of the small molecule PK2 (6-((1-(4-nitrobenzyl)-1H-1,2,3-triazol-4-yl)methyl)-6H-indolo[2,3-b]quinoxaline) displays stable binding with GLP1R ectodomain and induces GLP1R internalization and increasing cAMP levels. PK2 also increases insulin secretion in the INS-1 cells. The oral administration of PK2 protects against diabetes induced by multiple low-dose streptozotocin administration by lowering high blood glucose levels. Similar to GLP1R peptidic agonists, treatment of PK2 induces β-cell replication and attenuate β-cell apoptosis in STZ-treated mice. Mechanistically, this protection was associated with decreased thioredoxin-interacting protein expression, a potent inducer of diabetic β-cell apoptosis and dysfunction. Together, this report describes a small molecule, PK2, as an orally active nonpeptidic GLP1R agonist that has efficacy to preserve or restore functional β-cell mass.

Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist S6 Stimulates Insulin Secretion From Rat Islets.

Glucagon-like peptide-1 receptor (GLP-1R) agonist-based therapeutics for type 2 diabetes mellitus have attracted worldwide attention. However, there are challenges in the development of small molecule GLP-1R agonists owing to the complexity of ligand recognition and signal induction mechanisms. Here, we attained S6 using virtual screening and fluorescent imaging plate reader (FLIPR)-based calcium assays. The purpose of this study was to identify and characterize S6, a novel small molecule GLP-1R agonist. Data from cellular thermal shift assay (CETSA) and Bio-Layer Interferometry (BLI) indicated that S6 could bind potently with GLP-1R. Radioimmunoassay data showed that S6 potentiated insulin secretion in a glucose-dependent manner and the insulinotropic effect was mediated by GLP-1R. Calcium imaging techniques suggested that S6 elevated the intracellular calcium concentration [(Ca2+)i] by activating GLP-1R. In patch-clamp experiments, we demonstrated that S6 inhibited voltage-dependent K+ (Kv) channels in a GLP-1R-dependent fashion. Besides, S6 significantly prolonged action potential duration but had no effect on voltage-dependent Ca2+ channels. In summary, these findings indicate that S6 stimulates glucose-dependent insulin secretion mainly by acting on GLP-1R, inhibiting Kv channels, increasing (Ca2+)i. This study will provide direction for the screening and development of novel small-molecule agents targeting GLP-1R in the future.

In silico prediction of GLP-1R agonists using machine learning approach

Glucagon-like peptide 1 receptor (GLP-1R) is a well-known drug target for the treatment of type 2 diabetes mellitus (T2DM). However, the currently marketed peptidyl GLP-1R agonist drugs are restricted by the requirement of injection. Hence, there is a continued need to develop orally bioavailable small molecule GLP-1R agonist drugs that could be beneficial for the treatment of T2DM. In this study, we report a new strategy to predict small molecule GLP-1R agonists with machine learning approach. Several regression and classification models were built based on support vector machine algorithm and diverse compounds with molecular properties and structural fingerprints as descriptors. For regression models, the ten-fold cross-validation squared correlation coefficient (q2, for training sets) and determination coefficient (r2, for test sets) of the optimized models were greater than 0.6, respectively. For classification models, the overall predictive accuracies were around or over 90% (for test sets). The results demonstrated that these reliable models could be used to identify highly active agonists for the purpose of virtual screening. The important properties and structural fragments for GLP-1R agonists derived from these models can be used for the novel GLP-1R agonist scaffold design.

The putative binding site and SAR rationalization of small molecules against glucagon-like peptide-1 receptor using homology model and crystal structures: a comparative study

Glucagon-like peptide-1 (GLP-1) is involved in glucose-stimulated insulin secretion and weight regulating actions through the activation of the GLP-1 receptor (GLP-1R). Clinical effectiveness of GLP-1 mimetics is effective in improving glucose control in patients. Thus, identifying and developing orally active small-molecule agonists are highly desirable. This study summarizes the structure-function relationship of hGLP-1R through computational approaches and search of small molecule GLP-1R agonists. We carried out mutation guided data-driven study, for developing the GLP-1R model to explore and validate the putative site for quinoxaline analogues. The developed GLP-1R homology model was subjected to 500 ns MD simulation for validation. Various snapshots were considered to identify the best structure of GLP-1R based on correlation between experimental pEC50 and various theoretical parameters (docking score, MM-GBSA ΔG bind, WM/MM ΔG bind). The putative binding site (Sitemap and WaterMap has been predicted and it matched well with the available data. Excellent correlation (R2 =0.94), between pEC50 and WM/MM ΔG bind for the snapshot at 350 ns was observed after including induced-fit docking results of the most potent molecule. Enrichment calculation indicates better AUC (=0.75) for predicted complex structure. A comparison of the developed GLP-1R model with the available crystal structure shows excellent similarities and it was used for virtual screening to find small molecule agonists. The good correlation of our model with crystal structures of GLP-1R may help to understand the structure-function relationship of other secretin families.

353-OR: Oral Small Molecule GLP-1R Agonist PF-06882961 Robustly Reduces Plasma Glucose and Body Weight after 28 Days in Adults with T2DM

Background: PF-06882961 is an oral small molecule glucagon-like peptide-1 receptor (GLP-1R) agonist with efficacy in nonclinical models comparable to injectable peptidic GLP-1R agonists. This randomized, double-blind, placebo-controlled, multiple ascending dose, Phase 1 study investigated the safety, tolerability, pharmacokinetics and pharmacodynamics (PD) of PF–06882961 administered for 28 days in patients with type 2 diabetes mellitus (T2DM). Methods: A total of 98 patients with T2DM taking metformin were randomized, in 8 cohorts (5 planned, 3 optional), to PF–06882961 (up to 120 mg twice daily [BID]) or placebo in a 3:1 ratio for 28 days, and 92 completed the inpatient study. Fasting plasma glucose (FPG), 24-hour mean daily glucose (MDG) and body weight were assessed at baseline and at Day 28. Results: Multiple, oral doses of PF-06882961 were safe and well tolerated in adult participants with T2DM, and resulted in robust reductions in FPG, MDG and body weight at Day 28. The majority of adverse events (AEs) were mild, with AEs of nausea, dyspepsia, diarrhea, headache, constipation, and vomiting most commonly reported. There were no deaths and no serious AEs related to dosing of PF–06882961. No clinically significant adverse trends in labs, electrocardiogram or vital sign abnormalities were apparent. Disclosure A. Saxena: Employee; Self; Pfizer Inc. Stock/Shareholder; Self; Pfizer Inc. D. Gorman: Employee; Self; Pfizer Inc. K. Chidsey: None. C. Buckeridge: Employee; Self; Pfizer Inc. A.M. Kim: Employee; Self; Pfizer Inc. A. Bergman: Employee; Self; Pfizer Inc.

939-P: HD-7671, a Nonpeptide Small Molecule for Orally Available GLP-1 Receptor Agonist, Improves Glucose Tolerance by Increasing Insulin Secretion

Glucagon-like peptide-1 (GLP-1) mediates antidiabetogenic effects through the GLP-1 receptor (GLP-1R), which is targeted for the treatment of type 2 diabetes. Currently, GLP-1R agonists comprise a growing class of agents that deliver unprecedented efficacy in diabetes. We discovered a new small molecule GLP-1R agonist, HD-7671, and examined its efficacy in cynomolgus monkeys. The in vitro potency of HD-7671 was evaluated by measuring cAMP accumulation in cells with stable expression of human GLP-1R. HD-7671 stimulated cAMP accumulation and its EC50 value was 2.0 nM. In the cells transfected with human or cynomolgus monkey GLP-1R, HD-7671 promoted cAMP accumulation and its EC50 values for human and cynomolgus monkey GLP-1Rs were 4.5 nM and 7.1 nM, respectively. In contrast, HD-7671 showed no stimulatory activity on other animal species GLP-1Rs. In pharmacokinetic properties, the elimination half-life following oral administration(T1/2) was 0.99 hr in rats and 5.62 hr in cyno monkeys and Cmax was 10,183 ng/ml in rats and 1,423 ng/ml at 10mg/kg, respectively. To evaluate the in vivo insulinotropic effects of HD-7671, glucose stimulated insulin secretion was measured in compound treated in cyno monkeys undergoing an IVGTT. HD-7671 (dosed at 10mg/kg) decreased the blood glucose level and increased insulin secretion. These results demonstrate that HD-7671 has full agonistic activity on human and cynomolgus GLP-1R and improves glucose tolerance by stimulating insulin secretion.

Design, Synthesis, and Pharmacological Evaluation of Potent Positive Allosteric Modulators of the Glucagon-like Peptide-1 Receptor (GLP-1R).

The therapeutic success of peptidic GLP-1 receptor agonists for treatment of type 2 diabetes mellitus (T2DM) motivated our search for orally bioavailable small molecules that can activate the GLP-1 receptor (GLP-1R) as a well-validated target for T2DM. Here, the discovery and characterization of a potent and selective positive allosteric modulator (PAM) for GLP-1R based on a 3,4,5,6-tetrahydro-1H-1,5-epiminoazocino[4,5-b]indole scaffold is reported. Optimization of this series from HTS was supported by a GLP-1R ligand binding model. Biological in vitro testing revealed favorable ADME and pharmacological profiles for the best compound 19. Characterization by in vivo pharmacokinetic and pharmacological studies demonstrated that 19 activates GLP-1R as positive allosteric modulator (PAM) in the presence of the much less active endogenous degradation product GLP1(9-36)NH2 of the potent endogenous ligand GLP-1(7-36)NH2. While these data suggest the potential of small molecule GLP-1R PAMs for T2DM treatment, further optimization is still required towards a clinical candidate.

Synthesis and in vitro biological evaluation of new pyrimidines as glucagon-like peptide-1 receptor agonists

The therapeutic success of peptide glucagon-like peptide-1 (GLP-1) receptor agonists for the treatment of type 2 diabetes mellitus has inspired discovery efforts aimed at developing orally available small-molecule GLP-1 receptor agonists. In this study, two series of new pyrimidine derivatives were designed and synthesized using an efficient route, and were evaluated in terms of GLP-1 receptor agonist activity. In the first series, novel pyrimidines substituted at positions 2 and 4 with groups varying in size and electronic properties were synthesized in a good yield (78–90%). In the second series, the designed pyrimidine templates included both urea and Schiff base linkers, and these compounds were successfully produced with yields of 77–84%. In vitro experiments with cultured cells showed that compounds 3a and 10a (10−15–10−9M) significantly increased insulin secretion compared to that of the control cells in both the absence and presence of 2.8mM glucose; compound 8b only demonstrated significance in the absence of glucose. These findings represent a valuable starting point for the design and discovery of small-molecule GLP-1 receptor agonists that can be administered orally.

Myricetin: a potent approach for the treatment of type 2 diabetes as a natural class B GPCR agonist.

The physiologic properties of glucagon-like peptide 1 (GLP-1) make it a potent candidate drug target in the treatment of type 2 diabetes mellitus (T2DM). GLP-1 is capable of regulating the blood glucose level by insulin secretion after administration of oral glucose. The advantages of GLP-1 for the avoidance of hypoglycemia and the control of body weight are attractive despite its poor stability. The clinical efficacies of long-acting GLP-1 derivatives strongly support discovery pursuits aimed at identifying and developing orally active, small-molecule GLP-1 receptor (GLP-1R) agonists. The purpose of this study was to identify and characterize a novel oral agonist of GLP-1R (i.e., myricetin). The insulinotropic characterization of myricetin was performed in isolated islets and in Wistar rats. Long-term oral administration of myricetin demonstrated glucoregulatory activity. The data in this study suggest that myricetin might be a potential drug candidate for the treatment of T2DM as a GLP-1R agonist. Further structural modifications on myricetin might improve its pharmacology and pharmacokinetics.—Li, Y., Zheng, X., Yi, X., Liu, C., Kong, D., Zhang, J., Gong, M. Myricetin: a potent approach for the treatment of type 2 diabetes as a natural class B GPCR agonist.

Positive Allosteric Modulation of the Glucagon-like Peptide-1 Receptor by Diverse Electrophiles

Therapeutic intervention to activate the glucagon-like peptide-1 receptor (GLP-1R) enhances glucose-dependent insulin secretion and improves energy balance in patients with type 2 diabetes mellitus. Studies investigating mechanisms whereby peptide ligands activate GLP-1R have utilized mutagenesis, receptor chimeras, photo-affinity labeling, hydrogen-deuterium exchange, and crystallography of the ligand-binding ectodomain to establish receptor homology models. However, this has not enabled the design or discovery of drug-like non-peptide GLP-1R activators. Recently, studies investigating 4-(3-benzyloxyphenyl)-2-ethylsulfinyl-6-(trifluoromethyl)pyrimidine (BETP), a GLP-1R-positive allosteric modulator, determined that Cys-347 in the GLP-1R is required for positive allosteric modulator activity via covalent modification. To advance small molecule activation of the GLP-1R, we characterized the insulinotropic mechanism of BETP. In guanosine 5′-3-O-(thio)triphosphate binding and INS1 832-3 insulinoma cell cAMP assays, BETP enhanced GLP-1(9–36)-NH2-stimulated cAMP signaling. Using isolated pancreatic islets, BETP potentiated insulin secretion in a glucose-dependent manner that requires both the peptide ligand and GLP-1R. In studies of the covalent mechanism, PAGE fluorography showed labeling of GLP-1R in immunoprecipitation experiments from GLP-1R-expressing cells incubated with [3H]BETP. Furthermore, we investigated whether other reported GLP-1R activators and compounds identified from screening campaigns modulate GLP-1R by covalent modification. Similar to BETP, several molecules were found to enhance GLP-1R signaling in a Cys-347-dependent manner. These chemotypes are electrophiles that react with GSH, and LC/MS determined the cysteine adducts formed upon conjugation. Together, our results suggest covalent modification may be used to stabilize the GLP-1R in an active conformation. Moreover, the findings provide pharmacological guidance for the discovery and characterization of small molecule GLP-1R ligands as possible therapeutics.

Small Molecule Allosteric Modulation of the Glucagon-Like Peptide-1 Receptor Enhances the Insulinotropic Effect of Oxyntomodulin

Identifying novel mechanisms to enhance glucagon-like peptide-1 (GLP-1) receptor signaling may enable nascent medicinal chemistry strategies with the aim of developing new orally available therapeutic agents for the treatment of type 2 diabetes mellitus. Therefore, we tested the hypothesis that selectively modulating the low-affinity GLP-1 receptor agonist, oxyntomodulin, would improve the insulin secretory properties of this naturally occurring hormone to provide a rationale for pursuing an unexplored therapeutic approach. Signal transduction and competition binding studies were used to investigate oxyntomodulin activity on the GLP-1 receptor in the presence of the small molecule GLP-1 receptor modulator, 4-(3-benzyloxyphenyl)-2-ethylsulfinyl-6-(trifluoromethyl)pyrimidine (BETP). In vivo, the intravenous glucose tolerance test characterized oxyntomodulin-induced insulin secretion in animals administered the small molecule. BETP increased oxyntomodulin binding affinity for the GLP-1 receptor and enhanced oxyntomodulin-mediated GLP-1 receptor signaling as measured by activation of the α subunit of heterotrimeric G protein and cAMP accumulation. In addition, oxyntomodulin-induced insulin secretion was enhanced in the presence of the compound. BETP was pharmacologically characterized to induce biased signaling by oxyntomodulin. These studies demonstrate that small molecules targeting the GLP-1 receptor can increase binding and receptor activation of the endogenous peptide oxyntomodulin. The biased signaling engendered by BETP suggests that GLP-1 receptor mobilization of cAMP is the critical insulinotropic signaling event. Because of the unique metabolic properties of oxyntomodulin, identifying molecules that enhance its activity should be pursued to assess the efficacy and safety of this novel mechanism.