Triple Agonism Based Therapies for Obesity.

Purpose of the review: Glucagon-like peptide 1 (GLP-1) receptor agonists (RA) have transformed obesity and type 2 diabetes (T2D) management. Tirzepatide, the first dual GLP-1/glucose-dependent insulinotropic polypeptide (GIP) RA approved for both conditions, has paved the way for next-generation incretin-based therapies. Among these, triple agonists targeting GLP-1, GIP, and glucagon receptors represent a promising next step. This review outlines the rationale for their development and summarizes clinical trial data, focusing on retatrutide, the most advanced candidate.

Recent findings: Retatrutide is the first triple agonist (acting on GLP-1/GIP/glucagon receptors) with published phase 2 data in people with obesity as well as in people with T2D. Retatrutide achieved up to 24.2% mean weight loss after 48 weeks in individuals with obesity and 16.9% in those with T2D after 36 weeks. In the T2D study, HbA1c improved by 2.2%, with 82% of participants reaching HbA1c ≤ 6.5%. Retatrutide also improved multiple cardiometabolic parameters, including blood pressure, lipids, waist circumference, and liver fat (82% reduction in hepatic steatosis). Gastrointestinal symptoms were the most common side effects; no major safety concerns were observed. A comprehensive phase 3 program is ongoing to evaluate efficacy, safety, and cardiovascular/renal outcomes in people with obesity and/or T2D. Other unimolecular triple agonists and combination regimens involving tirzepatide with additional mono agonists are also in development.

Summary: Retatrutide, a triple agonist now in phase 3 trials, has the potential to become the most effective pharmacological treatment for obesity while also offering substantial benefits in T2D management and other cardiometabolic risk factors.