Eli Lilly retatrutide shows 28% weight loss

Eli Lilly said on May 21 that its experimental obesity drug retatrutide delivered up to 28.3% average weight loss in a late-stage trial, extending the company’s push beyond its already marketed obesity medicine Zepbound. The results came from TRIUMPH-1, a Phase 3 study in adults with obesity or overweight and at least one weight-related condition, but without diabetes. Lilly said the trial tested once-weekly doses of 4 mg, 9 mg and 12 mg against placebo over 80 weeks. The company described retatrutide as an investigational triple hormone receptor agonist targeting GIP, GLP-1 and glucagon. ### How much weight did patients lose in TRIUMPH-1? Lilly said patients on the 12-mg dose lost an average 70.3 pounds, or 28.3% of body weight, at 80 weeks. Patients on 9 mg lost 25.9% on average, and those on 4 mg lost 19.0%, according to the company’s topline results. The placebo group lost 2.2%. (investor.lilly.com) The company also said 45.3% of participants on 12 mg achieved at least 30% weight loss by 80 weeks. In a study extension, participants with a baseline body mass index of at least 35 reached average weight loss of 30.3%, or 85 pounds, at 104 weeks, Lilly said. (investor.lilly.com) ### Who was studied in this trial? TRIUMPH-1 enrolled 2,339 adults with obesity, or overweight plus at least one weight-related comorbidity, and excluded patients with diabetes, according to Lilly. The study was randomized, double-blind and placebo-controlled, the company said. (investor.lilly.com) Reuters reported on May 21 that the trial was one of the key studies investors and obesity specialists were watching as Lilly develops a next generation of weight-loss medicines. CNBC reported the data move Lilly closer to filing for approval of retatrutide. That is an inference from the company’s late-stage readout; Lilly’s announcement itself did not give a filing date in the material reviewed. (investor.lilly.com) ### How is retatrutide different from Lilly’s current obesity drug? Lilly said retatrutide activates three hormone pathways — GIP, GLP-1 and glucagon — while its marketed drug tirzepatide targets GIP and GLP-1. The added glucagon component is one of the main distinctions Lilly has highlighted in describing retatrutide’s mechanism. (cnbc.com) Scientific American reported that retatrutide belongs to a newer group of obesity medicines designed to target three hormone receptors rather than one or two. That comparison reflects the broader competitive framing around obesity drugs now on the market or in development. (investor.lilly.com) ### What did Lilly say about side effects? Lilly said the most common adverse events were gastrointestinal and were generally mild to moderate in severity. The company said the safety profile was consistent with incretin-based therapies, and that adverse events were most frequent during dose escalation. (scientificamerican.com) At the 4-mg dose, Lilly said discontinuation due to adverse events was lower than at higher doses. Other outlets reporting on the topline data said analysts were also watching whether side effects could affect how competitive the drug looks against existing obesity treatments. (investor.lilly.com) ### What happens next? Lilly said it will present detailed TRIUMPH-1 results at a future medical meeting and submit the data to a peer-reviewed journal. The company is also running additional studies in the TRIUMPH program as it develops retatrutide in obesity and related conditions. (morningstar.com) May 21 was the first topline disclosure from TRIUMPH-1, and the next milestones are the fuller dataset, outside review in a medical journal, and any regulatory filing timelines Lilly later provides. (investor.lilly.com)