Lilly's retatrutide delivered powerful weight loss in Phase III obesity trial

21 May 2026

US pharma major Eli Lilly (NYSE: LLY), the maker of Zepbound (tirzepatide) and Foundayo (orforglipron), today announced positive top-line results from TRIUMPH-1, a Phase II clinical trial.

The study is evaluating the efficacy and safety of retatrutide, an investigational, first-in-class GIP, GLP-1, and glucagon triple hormone receptor agonist, in adults with obesity or overweight and at least one weight-related comorbidity and without diabetes. At 80 weeks, all doses of retatrutide (4mg, 9mg, and 12mg) met the primary and key secondary endpoints for obesity, delivering clinically meaningful weight loss, coming in at just over 28%.

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