Topline
Eli Lilly, the GLP-1 maker behind Mounjaro and Zepbound, said it would file for Food and Drug Administration approval of its powerful retatrutide weight-loss drug after studies found participants lost an average of nearly 56 pounds after 80 weeks on the medication.
Eli Lilly says it plans to file for regulatory approval for retatrutide. (Photo by Smith Collection/Gado/Getty Images)
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Key Facts
Lilly announced the results of two phase 3 trials on Thursday, saying it will file for FDA approval of the drug—potentially adding another GLP-1 to its lineup—in the first quarter of 2027.
One study of adults with severe obesity showed an average weight loss of 22.6%, or 55.8 pounds, after 80 weeks, while another study of adults with obesity and diabetes showed participants lost an average of 20.8% of their weight, or about 49.6 pounds.
The study also found “major adverse cardiovascular events”—like heart attack or failure—occurred “less frequently than anticipated.”
Retatrutide is considered likely the most powerful weight loss drug yet, as it targets multiple hormones—GLP-1, GIP and glucagon—that impact appetite and metabolism, whereas other drugs currently on the market target one or two of those hormones.
Approval of the drug would be a win for Lilly as it tries to maintain dominance over the GLP-1 market, where it has already overtaken rival company Novo Nordisk, manufacturer of Ozempic and Wegovy.
How Big Could Retatrutide Be?
Analysts have suggested retatrutide could become a blockbuster weight loss drug if approved. In January, TD Cowen analysts estimated retatrutide could generate $3.8 billion in sales in 2030, while GlobalData forecasts sales of $15.6 billion by 2031. Demand for the drug is already so intense some people have turned to an online black market, facilitated through WhatsApp or other websites, to buy what sellers say is retatrutide from Chinese labs, the New York Times reported.
tangent
Novo Nordisk sued Eli Lilly on Tuesday, accusing the company of using outdated studies in its advertisements that exaggerate the efficacy of Lilly’s products. The suit accused Lilly of demonstrating a “nationwide pattern of deceptive advertising,” saying one of its ad campaigns uses an outdated dose of Novo’s Wegovy to compare it unfavorably to Lilly’s Zepbound. Novo’s suit seeks a permanent injunction from the court that would require Lilly to pull “misleading comparative advertising” campaigns and conduct a “corrective advertising campaign.”
key background
Lilly and Novo are chief rivals in the GLP-1 market, but Lilly now captures a greater share of prescriptions, CNN reported in February. BMO analysts said last year they expected Lilly’s drugs to “continue to take incremental U.S. share from Novo’s” GLP-1 medications. “While Novo had the headstart with approval of semaglutide, we believe that this first mover advantage has waned, with Lilly’s tirezepatide taking share rapidly,” the analysts wrote, adding Lilly’s dominance could accelerate with retatrutide. CNBC reported in February Novo Nordisk was bracing for a 5% to 13% decline in sales and profit for 2026, while Lilly expected about a 25% boost in sales. Earlier this year, Novo Nordisk said it would slash prices on its flagship medications in 2027 as it tries to win over customers.
further reading
Novo Nordisk Sues GLP-1 Rival Eli Lilly For Misleading Advertising (Forbes)