A Sequential Dual GLP-1R/GIPR Agonist-To-Antagonist Molecule Achieves Superior Weight Loss in Obese Mice

Background The GLP-1 receptor (GLP-1R) and GIP receptor (GIPR) are key targets for diabetes and obesity therapies. Pharmacological agents including GLP-1R agonists (e.g., Semaglutide), dual GLP-1R/GIPR agonists (e.g., Tirzepatide) and a GLP-1R agonist/GIPR antagonist (AMG133) have demonstrated considerable promise in anti-diabetic and weight management applications. However, a systematic comparison of the specific contributions of GIPR activation versus GIPR inhibition to weight loss within the context of GLP-1/GIP dual-targeting therapies remains unexplored. Research Design and Methods To address this, we designed three IgG4 Fc-fusion proteins: a GLP-1R agonist/GIPR agonist, (i) GLP-1(A8G)/GIP(A2G)-Fc; a GLP-1R agonist/GIPR inhibitor, (ii) GLP-1(A8G)/GIP(3–30)-Fc; and a sequential molecule that hypothesised to transition from dual GLP-1R/GIPR agonism to GLP-1R agonism/GIPR inhibition, (iii) GLP-1(A8G)/GIP(1–30)-Fc. Mono-agonist GLP-1(A8G)-Fc and dual-agonist GLP-1(A8G)/GIP(A2G)-Fc were used as controls to investigate the weight loss effects of GIPR activation and inhibition in DIO mice. Results Our findings revealed that the sequential molecule GLP-1(A8G)/GIP(1–30)-Fc produced the greatest body weight reduction (21.59%), significantly outperforming GLP-1(A8G)/GIP(3–30)-Fc (14.5%; p < 0.001). Furthermore, both GIPR activation and inhibition, when combined with GLP-1R agonism, markedly improved serum and hepatic lipid metabolism, as evidenced by reduced triglycerides and total cholesterol. Conclusion Together, these findings validate a peptide-based inhibitory strategy for synergistic weight loss and provide insights into the differential metabolic roles of GIPR activation versus inhibition, guiding the development of novel anti-obesity therapeutics.