Eli Lilly said Thursday it plans to seek regulatory approval in the first quarter of 2027 for its experimental obesity drug retatrutide after the treatment cleared two additional late-stage clinical trials.
The company detailed that one of the new studies evaluated adults with severe obesity and established cardiovascular disease who did not have diabetes. After 80 weeks of treatment, participants receiving retatrutide lost an average of 22.6% of their body weight while also showing improvements in several cardiometabolic risk factors.
A second Phase 3 trial focused on adults with obesity or overweight who also had Type 2 diabetes. Patients receiving the highest dose achieved average weight loss of 20.8% over the same 80-week period while reducing A1C, a key measure of long-term blood sugar control, by approximately 1.6 percentage points.
"Across five positive Phase 3 studies, retatrutide has shown powerful efficacy, and we believe it could be an important future tool in the management of cardiometabolic health," said Kenneth Custer, Ph.D., executive vice president and president, Lilly Cardiometabolic Health.
The latest Phase 3 results add to a growing body of evidence supporting retatrutide, an investigational therapy that has generated significant attention because it targets three different metabolic hormones rather than the single or dual hormone mechanisms used by current blockbuster obesity drugs.
The drug belongs to a new class of so-called triple agonists, simultaneously activating GLP-1, GIP and glucagon receptors. Current market leaders such as Lilly's Zepbound and Novo Nordisk's Wegovy primarily rely on one or two of those hormone pathways. Researchers believe adding glucagon activity may help increase energy expenditure in addition to suppressing appetite, potentially leading to greater weight loss.
Lilly said the two studies represent the latest successes in its broader TRIUMPH Phase 3 clinical program. Earlier trials demonstrated that retatrutide produced weight reductions approaching 30% in some patients, results that many experts have compared with those typically achieved through bariatric surgery.
"Participants taking retatrutide 4 mg, 9 mg, and 12 mg lost an average of 29.8 lbs (12.7%), 45.4 lbs (19.1%), and 49.6 lbs (20.8%), respectively, alongside A1C reductions of up to an average of 1.6%," Lilly said in a press release.
The company now expects to submit its application to the U.S. Food and Drug Administration during the first quarter of 2027, potentially paving the way for another major product in Lilly's rapidly expanding obesity portfolio. The company already markets injectable obesity drug Zepbound and earlier this year received FDA approval for its oral GLP-1 obesity treatment, Foundayo, known generically as orforglipron.
While the new data were largely positive, Lilly acknowledged that one cardiovascular outcomes study showed a numerically higher rate of major adverse cardiovascular events among patients receiving retatrutide compared with placebo. However, the company said the total number of events was too small to draw definitive conclusions, and the findings require further evaluation.
As with other drugs in the GLP-1 family, the most commonly reported side effects were gastrointestinal, including nausea, vomiting, diarrhea and constipation. These adverse events were generally consistent with previous studies involving incretin-based obesity therapies.
Lilly executives have previously described retatrutide as a potential next-generation therapy capable of establishing a new benchmark for obesity treatment. Beyond helping patients lose substantial amounts of weight, the company is studying whether the medicine can improve a range of obesity-related complications, potentially broadening its commercial opportunity if approved.
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