Dual glucagon‐like peptide‐1 receptor/glucagon receptor agonist SAR425899 improves beta‐cell function in type 2 diabetes

Type 2 diabetes is characterized by reduced insulin secretion from the pancreas and overproduction of glucose by the liver. Glucagon-like peptide-1 (GLP-1) promotes glucose-dependent insulin secretion from the pancreas, while glucagon promotes glucose output from the liver. Taking advantage of the homology between GLP-1 and glucagon, a GLP-1/glucagon hybrid peptide, dual-acting peptide for diabetes (DAPD), was identified with combined GLP-1 receptor agonist and glucagon receptor antagonist activity. To overcome its short plasma half-life DAPD was PEGylated, resulting in dramatically prolonged activity in vivo. PEGylated DAPD (PEG-DAPD) increases insulin and decreases glucose in a glucose tolerance test, evidence of GLP-1 receptor agonism. It also reduces blood glucose following a glucagon challenge and elevates fasting glucagon levels in mice, evidence of glucagon receptor antagonism. The PEG-DAPD effects on glucose tolerance are also observed in the presence of the GLP-1 antagonist peptide, exendin(9–39). An antidiabetic effect of PEG-DAPD is observed in db/db mice. Furthermore, PEGylation of DAPD eliminates the inhibition of gastrointestinal motility observed with GLP-1 and its analogues. Thus, PEG-DAPD has the potential to be developed as a novel dual-acting peptide to treat type 2 diabetes, with prolonged in vivo activity, and without the GI side-effects.

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Dual GIP and GLP-1 Receptor Agonist Tirzepatide Improves Beta-cell Function and Insulin Sensitivity in Type 2 Diabetes

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/clinem/dgaa863 ◽

2020 ◽

Author(s):

Melissa K Thomas ◽

Amir Nikooienejad ◽

Ross Bray ◽

Xuewei Cui ◽

Jonathan Wilson ◽

...

Keyword(s):

Type 2 Diabetes ◽

Regression Analysis ◽

Insulin Sensitivity ◽

Beta Cell ◽

Beta Cell Function ◽

Receptor Agonist ◽

Cell Function ◽

Linear Regression Analysis ◽

Multiple Linear Regression Analysis

Abstract Context Novel dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist (RA) tirzepatide demonstrated substantially greater glucose control and weight loss (WL) compared with selective GLP-1RA dulaglutide. Objective Explore mechanisms of glucose control by tirzepatide. Design Post hoc analyses of fasting biomarkers and multiple linear regression analysis. Setting Forty-seven sites in 4 countries. Patients or other Participants Three hundred and sixteen subjects with type 2 diabetes. Interventions Tirzepatide (1, 5, 10, 15 mg), dulaglutide (1.5 mg), placebo. Main Outcome Measures Analyze biomarkers of beta-cell function and insulin resistance (IR) and evaluate WL contributions to IR improvements at 26 weeks. Results Homeostatic model assessment (HOMA) 2-B significantly increased with dulaglutide and tirzepatide 5, 10, and 15 mg compared with placebo (P ≤ .02). Proinsulin/insulin and proinsulin/C-peptide ratios significantly decreased with tirzepatide 10 and 15 mg compared with placebo and dulaglutide (P ≤ .007). Tirzepatide 10 and 15 mg significantly decreased fasting insulin (P ≤ .033) and tirzepatide 10 mg significantly decreased HOMA2-IR (P = .004) compared with placebo and dulaglutide. Markers of improved insulin sensitivity (IS) adiponectin, IGFBP-1, and IGFBP-2 significantly increased by 1 or more doses of tirzepatide (P < .05). To determine whether improvements in IR were directly attributable to WL, multiple linear regression analysis with potential confounding variables age, sex, metformin, triglycerides, and glycated hemoglobin A1c was conducted. WL significantly (P ≤ .028) explained only 13% and 21% of improvement in HOMA2-IR with tirzepatide 10 and 15 mg, respectively. Conclusions Tirzepatide improved markers of IS and beta-cell function to a greater extent than dulaglutide. IS effects of tirzepatide were only partly attributable to WL, suggesting dual receptor agonism confers distinct mechanisms of glycemic control.

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