Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity

BACKGROUND: Retatrutide is a triple-receptor agonist of glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1, and glucagon receptors. METHODS: In this phase 3, randomized, double-blind trial, we assigned adults with obesity without diabetes to receive a once-weekly subcutaneous injection of retatrutide (at a dose of 4 mg, 9 mg, or 12 mg) or placebo for 80 weeks. Primary outcomes (evaluated in the 9-mg and 12-mg groups each vs. placebo) were the percent change in body weight and the change in the WOMAC pain score (ranging from 1 to 10, with higher scores indicating worse pain) in the subgroup of 574 participants with knee osteoarthritis and the change in the apnea-hypopnea index in the 243 participants with obstructive sleep apnea. For weight-related end points, intercurrent events were handled by a treatment-regimen estimand (intention-to-treat [ITT]). For end points in participants with knee osteoarthritis or obstructive sleep apnea, a hybrid-treatment estimand was applied, with a hypothetical strategy for intercurrent events suggesting treatment failure; ITT results are also reported. RESULTS: A total of 2339 participants underwent randomization. The mean percent change in body weight in the retatrutide groups was -17.6% (4-mg dose), -23.7% (9-mg dose), and -25.0% (12-mg dose) versus -3.9% in the placebo group (differences, -19.8 and -21.0 percentage points, respectively; P<0.001 for both comparisons). Among the participants with knee osteoarthritis, the corresponding changes in the pain score in the retatrutide groups for the hybrid estimand were -3.2, -3.5, and -3.6 versus -1.9 with placebo (differences, -1.6 and -1.8 points; both P<0.001); the corresponding changes for the ITT estimand were -3.4, -3.9, and -4.1 versus -2.5 with placebo (differences, -1.4 and -1.6 points; both P<0.001). Among the participants with obstructive sleep apnea, the corresponding changes in events per hour in the retatrutide groups for the hybrid-treatment estimand were -22.9, -34.3, and 31.7 versus -9.9 (differences, -24.4 and -21.9; both P<0.001); the corresponding changes for the ITT estimand were -22.8, -34.3, and -32.1 versus -9.6 (differences, -24.7 and -22.5; both P<0.001). The most common adverse events were gastrointestinal. CONCLUSIONS: In adults with obesity, retatrutide resulted in significant weight reduction, reduced pain in participants with knee osteoarthritis, and reduced apnea-hypopnea events in participants with obstructive sleep apnea. (Funded by Eli Lilly; TRIUMPH-1 ClinicalTrials.gov number, NCT05929066.).