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Recent studies have found that glucose-dependent insulinotropic polypeptide receptor (GIPR) agonism can enhance the metabolic efficacy of glucagon-like peptide–1 receptor agonist treatment by promoting both weight-dependent and -independent improvements on systemic insulin sensitivity. These findings have prompted new investigations aimed at better understanding the broad metabolic benefit of GIPR activation. Herein, we determined whether GIPR agonism favorably influenced the pharmacologic efficacy of the insulin-sensitizing thiazolidinedione (TZD) rosiglitazone in obese insulin-resistant (IR) mice. Genetic and pharmacological approaches were used to examine the role of GIPR signaling on rosiglitazone-induced weight gain, hyperphagia, and glycemic control. RNA sequencing was conducted to uncover potential mechanisms by which GIPR activation influences energy balance and insulin sensitivity. In line with previous findings, treatment with rosiglitazone induced the mRNA expression of the GIPR in white and brown fat. However, obese GIPR-null mice dosed with rosiglitazone had equivalent weight gain to that of wild-type (WT) animals. Strikingly, chronic treatment of obese IR WT animals with a long-acting GIPR agonist prevented rosiglitazone-induced weight-gain and hyperphagia, and it enhanced the insulin-sensitivity effect of this TZD. The systemic insulin sensitization was accompanied by increased glucose disposal in brown adipose tissue, which was underlined by the recruitment of metabolic and thermogenic genes. These findings suggest that GIPR agonism can counter the negative consequences of rosiglitazone treatment on body weight and adiposity, while improving its insulin-sensitizing efficacy at the same time. Article Highlights: Body weight gain resulting from treatment with the insulin-sensitizing thiazolidinedione rosiglitazone does not require the glucose-dependent insulinotropic polypeptide receptor (GIPR). Treatment with a GIPR agonist prevents the hyperphagic and obesogenic activity of rosiglitazone. Activation of the GIPR improves the insulin-sensitizing actions of rosiglitazone. [ABSTRACT FROM AUTHOR]

Tirzepatide (LY3298176), a dual GIP and GLP-1 receptor (GLP-1R) agonist, delivered superior glycemic control and weight loss compared with GLP-1R agonism in patients with type 2 diabetes. However, the mechanism by which tirzepatide improves efficacy and how GIP receptor (GIPR) agonism contributes is not fully understood. Here, we show that tirzepatide is an effective insulin sensitizer, improving insulin sensitivity in obese mice to a greater extent than GLP-1R agonism. To determine whether GIPR agonism contributes, we compared the effect of tirzepatide in obese WT and Glp-1r-null mice. In the absence of GLP-1R-induced weight loss, tirzepatide improved insulin sensitivity by enhancing glucose disposal in white adipose tissue (WAT). In support of this, a long-acting GIPR agonist (LAGIPRA) was found to enhance insulin sensitivity by augmenting glucose disposal in WAT. Interestingly, the effect of tirzepatide and LAGIPRA on insulin sensitivity was associated with reduced branched-chain amino acids (BCAAs) and ketoacids in the circulation. Insulin sensitization was associated with upregulation of genes associated with the catabolism of glucose, lipid, and BCAAs in brown adipose tissue. Together, our studies show that tirzepatide improved insulin sensitivity in a weight-dependent and -independent manner. These results highlight how GIPR agonism contributes to the therapeutic profile of dual- receptor agonism, offering mechanistic insights into the clinical efficacy of tirzepatide., Introduction Type 2 diabetes mellitus (T2DM) is a global pandemic, placing significant strain on healthcare systems world wide (1). Driven primarily by excess body weight, systemic insulin resistance (IR) is [...]

Aim: To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of single and multiple doses of orforglipron (LY3502970), an oral, non‐peptide glucagon‐like peptide‐1 receptor agonist (GLP‐1RA) in healthy participants. Materials and Methods: This was a double‐blind, placebo‐controlled, Phase 1 study. Overtly healthy adults aged 18 to 65 years with body mass index of 20 to 40 kg/m2 and glycated haemoglobin concentration of 47.5 mmol/mol (<6.5%) were eligible. In Part A, participants received single‐dose orforglipron, with four cohorts receiving escalating doses (0.3‐6 mg). In Part B, participants received 4 weeks of daily repeated oral orforglipron with doses escalating weekly to four different final target doses (2‐24 mg). Results: Ninety‐two participants enrolled and received at least one study drug dose (32 in Part A [mean age 43.4 years] and 60 in Part B [mean age 42.5 years]). The most common adverse events were gastrointestinal tract‐related. Pharmacokinetics were approximately dose proportional, and the mean t1/2 was 24.6 to 35.3 hours after a single dose (0.3‐6 mg). On Day 28, the mean t1/2 was 48.1 to 67.5 hours across the dose range (2‐24 mg). Substantial reductions in body weight of up to 5.4 kg were observed after 4 weeks in orforglipron‐treated participants, compared to a reduction of 2.4 kg with placebo (P < 0.05). Orforglipron decreased fasting glucose levels across Days 1 to 28, and gastric emptying was delayed on Day 28. Conclusions: Orforglipron's long half‐life (25‐68 hours) allows once‐daily oral dosing, without water and food restrictions. Orforglipron had a pharmacodynamic and safety profile similar to that of injectable GLP‐1RAs, which supports continued clinical development. [ABSTRACT FROM AUTHOR]

Aim: To report the results of a Phase 1b trial evaluating the safety, pharmacokinetics and pharmacodynamics of orforglipron (LY3502970), an oral, non‐peptide glucagon‐like peptide‐1 receptor agonist (GLP‐1RA), in patients with type 2 diabetes (T2D). Materials and Methods: This was a double‐blind, placebo‐controlled Phase 1 study evaluating five different dosing regimens. The first group established that weekly dose escalation of the daily doses of orforglipron was generally well tolerated. This enabled a parallel‐arm design for the four groups following. Participants were randomized 3:1 to daily doses of orforglipron or placebo for 12 weeks. Eligible participants with T2D were aged 18 to 70 years and had glycated haemoglobin (HbA1c) levels ≥53.0 mmol/mol (7.0%) and ≤91.3 mmol/mol (10.5%). Results: A total of 51 participants received orforglipron and 17 received placebo. In the placebo and orforglipron groups, respectively, baseline HbA1c was 8.1% and 8.0%, and baseline body weight was 90.3 and 88.4 kg. The most common adverse events were gastrointestinal‐related, and occurred early in treatment, similar to findings with other GLP‐1RAs. At Week 12, mean t1/2 ranged from 29 to 49 hours. Mean HbA1c change ranged from −1.5% to −1.8% across orforglipron doses, versus −0.4% with placebo, and body weight change was −0.24 to −5.8 kg across orforglipron doses, versus 0.5 kg with placebo. Conclusions: Orforglipron treatment resulted in meaningful reductions in HbA1c and body weight, with an adverse event profile consistent with that of other GLP‐1RAs. Orforglipron may provide a safe and effective once‐daily oral treatment alternative to injectable GLP‐1RAs or peptide oral formulations without water and food restrictions. [ABSTRACT FROM AUTHOR]

We evaluated the potential for a monoclonal antibody antagonist of the glucagon receptor (Ab-4) to maintain glucose homeostasis in type 1 diabetic rodents. We noted durable and sustained improvements in glycemia which persist long after treatment withdrawal. Ab-4 promoted β-cell survival and enhanced the recovery of insulin+ islet mass with concomitant increases in circulating insulin and C peptide. In PANIC-ATTAC mice, an inducible model of β-cell apoptosis which allows for robust assessment of β-cell regeneration following caspase-8-induced diabetes, Ab-4 drove a 6.7-fold increase in β-cell mass. Lineage tracing suggests that this restoration of functional insulin-producing cells was at least partially driven by α-cell-to-β-cell conversion. Following hyperglycemic onset in nonobese diabetic (NOD) mice, Ab-4 treatment promoted improvements in C-peptide levels and insulin+ islet mass was dramatically increased. Lastly, diabetic mice receiving human islet xenografts showed stable improvements in glycemic control and increased human insulin secretion. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide-1 receptor (GLP-1R) agonists are efficacious antidiabetic medications that work by enhancing glucose-dependent insulin secretion and improving energy balance. Currently approved GLP-1R agonists are peptide based, and it has proven difficult to obtain small-molecule activators possessing optimal pharmaceutical properties. We report the discovery and mechanism of action of LY3502970 (OWL833), a nonpeptide GLP-1R agonist. LY3502970 is a partial agonist, biased toward G protein activation over ß-arrestin recruitment at the GLP-1R. The molecule is highly potent and selective against other class B G protein-coupled receptors (GPCRs) with a pharmacokinetic profile favorable for oral administration. A highresolution structure of LY3502970 in complex with active-state GLP- 1R revealed a unique binding pocket in the upper helical bundle where the compound is bound by the extracellular domain (ECD), extracellular loop 2, and transmembrane helices 1, 2, 3, and 7. This mechanism creates a distinct receptor conformation that may explain the partial agonism and biased signaling of the compound. Further, interaction between LY3502970 and the primate-specific Trp33 of the ECD informs species selective activity for the molecule. In efficacy studies, oral administration of LY3502970 resulted in glucose lowering in humanized GLP-1R transgenic mice and insulinotropic and hypophagic effects in nonhuman primates, demonstrating an effect size in both models comparable to injectable exenatide. Together, this work determined the molecular basis for the activity of an oral agent being developed for the treatment of type 2 diabetesmellitus, offering insights into the activation of class B GPCRs by nonpeptide ligands. [ABSTRACT FROM AUTHOR]