Scientists designed a new peptide that hits three hormone receptors (GLP‑1, glucagon, and GIP) but hits the GIP receptor less strongly. It caused weight loss as good as the drug tirzepatide and worked about as well as retatrutide, even though its GIP activity was weaker. This shows you don’t need super‑strong activation of all three receptors to get big metabolic benefits.

Triple activation of the glucagon-like peptide 1 receptor (GLP-1R), the GIP receptor (GIPR), and the glucagon receptor (GCGR) is an innovative strategy for treating obesity and diabetes. We report the rational design of triple GLP-1R/GCGR/GIPR agonists, featuring potent GLP-1R and GCGR activity with weaker GIPR activation. Using sequence analysis, molecular dynamics simulations, docking, and amino acid optimization, we developed xGLP-1-based triagonists, with xGLP/GCG/GIP-32 exhibiting a unique activation profile. It shows superior weight loss effects compared to tirzepatide and similar metabolic efficacy to retatrutide, despite significantly less potent GIPR activity. Preliminary mechanistic studies revealed that xGLP/GCG/GIP-32 exhibits biased agonism toward the GIPR and GCGR. These activity data suggest it may not be imperative to focus solely on potent activation of all three receptors. Especially for triple agonists with receptor-biased agonism, there may be room to explore optimal receptor activation ratios.