Next generation GLP-1/GIP/glucagon triple agonists normalize body weight in obese mice

Abstract

Objective: Pharmacological strategies that engage multiple mechanisms-of-action have demonstrated synergistic benefits for metabolic disease in preclinical models. One approach, concurrent activation of the glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and glucagon (Gcg) receptors (i.e. triagonism), combines the anorectic and insulinotropic activities of GLP-1 and GIP with the energy expenditure effect of glucagon. While the efficacy of triagonism in preclinical models is known, the relative contribution of GcgR activation remains unassessed. This work aims to addresses that central question.

Methods: Herein, we detail the design of unimolecular peptide triagonists with an empirically optimized receptor potency ratio. These optimized peptide triagonists employ a protraction strategy permitting once-weekly human dosing. Additionally, we assess the effects of these peptides on weight-reduction, food intake, glucose control, and energy expenditure in an established DIO mouse model compared to clinically relevant GLP-1R agonists (e.g. semaglutide) and dual GLP-1R/GIPR agonists (e.g. tirzepatide).

Results: Optimized triagonists normalize body weight in DIO mice and enhance energy expenditure in a manner superior to that of GLP-1R mono-agonists and GLP-1R/GIPR co-agonists.

Conclusions: These pre-clinical data suggest unimolecular poly-pharmacology as an effective means to target multiple mechanisms contributing to obesity and further implicate GcgR activation as the differentiating factor between incretin receptor mono- or dual-agonists and triagonists.

Keywords: GIP; GLP-1; Glucagon; Obesity; Pharmacology; Triagonist.

Figure 1

Pharmacological effects of GLP-1R, GIPR, and GcgR agonism alone or in combination in DIO mice. Body weight (A–C) and IPGTT blood glucose (D–F) for DIO mice. Animals were given subcutaneous injections once per day with semaglutide (1; 1 nmol/kg), acyl-GLP-1R/GIPR co-agonist (2; 1 nmol/kg), acyl-GcgR agonist (3; 3 nmol/kg), or combinations thereof. Body weight was measured daily over 8 days. The IPGTT was performed on day 8 (24 h after compound administration). In vitro potency at mouse-derived receptors is provided in panel G. Average starting body weight for mice in these studies was 62.6 g and did not differ significantly between any group. ∗ indicate a p-value < 0.05 compared to vehicle control; ˆ indicate a p-value < 0.05 relative to a treatment group as indicated.

Figure 2

GcgR agonism provides additional body weight lowering efficacy over GLP-1R agonism and GLP-1R/GIPR co-agonism in DIO mice. Body weight (A) and food intake (B) for DIO mice given subcutaneous injections once per day with semaglutide 1, acyl-GLP-1R/GIPR co-agonist 17, acyl-GLP-1R/GcgR co-agonist 18, imbalanced GLP-1R/GIPR/GcgR triple agonist 19, and balanced GLP-1R/GIPR/GcgR triple agonist 16. Dosing concentrations and dose-escalation schedule is provided in panel C. The in vitro potency at mouse-derived receptors is provided in panel D. Average starting body weight for mice in these studies was 59.0 g and did not differ significantly between any group. ∗ indicate a p-value < 0.05 compared to vehicle control; ˆ indicate a p-value < 0.05 relative to a treatment group as indicated.

Figure 3

Triple receptor agonism of GLP-1R, GIPR, and GcgR produces superior body weight lowering efficacy compared to GLP-1/GIPR co-agonist tirzpatide in DIO mice. Body weight (A) and food intake (B) for DIO mice given subcutaneous injections once per day with tirzepatide or GLP-1R/GIPR/GcgR triple agonist 16. Dosing concentrations and dose-escalation schedule is provided in panel C. Average starting body weight for mice in these studies was 61.2 g and did not differ significantly between any group. ∗ indicate a p-value < 0.05 compared to vehicle control; ˆ indicate a p-value < 0.05 relative to the equimolar dose of tirzepatide as indicated.

Figure 4

Triple receptor agonism of GLP-1R, GIPR, and GcgR but not the dual receptor agonism of GLP-1 and GIPR induces energy expenditure in DIO mice. Energy expenditure (A), respiratory exchange ratio (B) and locomoter activity (C) for DIO mice given subcutaneous injections once per day with tirzepatide (3 nmol/kg) or GLP-1R/GIPR/GcgR triple agonist 16 (3 nmol/kg). ∗ indicate a p-value < 0.05 compared to vehicle control; ˆ indicate a p-value < 0.05 relative to tirzepatide as indicated.

Figure 5

Comparison of in vivo efficacy of next-generation triagonists to published triagonists. Weight-loss (A,B), food intake (C,D) fat mass (E,F), and lean mass (G,H) for DIO mice treated with either vehicle (black), SAR441255 (green), first generation triagonist (red), 19 (blue), or 16 (purple) at either 1 nmol/kg (A,C,E,G; solid symbols) or 2 nmol/kg (B,D,F,H; open symbols). Glucose excursion during an IPGTT in DIO mice treated with indicated compounds either 1 h after injection on day 0 of the studies (I,J) or 24 h after compound injection on day 18 (K,L) and glucose area under the curve (AUC; M). Average starting body weight for mice in these studies was 60.2 g and did not differ significantly between any group. ∗ indicate p-value > 0.05 compared to vehicle or as indicated; ˆ indicate p-value > 0.05 between groups as indicated; ╧ indicate p-value > 0.05 compared to SAR441255.