Lilly reports TRIUMPH-4 retatrutide results

Eli Lilly reported positive Phase 3 results for retatrutide in adults with obesity or overweight and knee osteoarthritis, but the key point is what TRIUMPH-4 actually tested. Lilly said on December 11, 2025, that the once-weekly experimental drug met co-primary endpoints on both body weight and pain at 68 weeks. The study enrolled people without diabetes and paired the drug with diet and physical activity, according to Lilly and the ClinicalTrials.gov listing. (investor.lilly.com) The trial is one of Lilly’s late-stage obesity studies for retatrutide, a triple agonist targeting GIP, GLP-1 and glucagon receptors. ### What did TRIUMPH-4 measure? TRIUMPH-4 was a Phase 3 randomized, double-blind, placebo-controlled trial in adults with obesity or overweight and osteoarthritis of the knee, according to ClinicalTrials.gov. (investor.lilly.com) The study’s main purpose was to evaluate the safety and efficacy of once-weekly retatrutide in that population, and the record lists actual enrollment at 445 participants. ClinicalTrials.gov says the study started in August 2023 and reached primary completion on November 14, 2025. Lilly said the co-primary endpoints were percent change in body weight and change in WOMAC pain subscale score at 68 weeks. WOMAC is a standard osteoarthritis measure covering pain and physical function, and Lilly said the trial also assessed physical-function outcomes as key secondary endpoints. (investor.lilly.com) ### How large were the weight-loss and pain results? Lilly said participants taking retatrutide 12 mg lost an average 28.7% of body weight, or 71.2 pounds, using the efficacy estimand. The 9 mg dose showed average weight loss of 26.4%, while placebo patients lost 2.1%, Lilly said. Baseline average body weight was 112.7 kilograms, or 248.5 pounds. (clinicaltrials.gov) The same Lilly release said WOMAC pain scores fell by as much as an average of 4.5 points, or 75.8%. Lilly also said physical-function measures improved significantly and that more than 1 in 8 retatrutide-treated patients were completely free from knee pain at the end of the trial. (investor.lilly.com) ### Did the study include diabetes patients? Lilly said TRIUMPH-4 enrolled adults with obesity or overweight and knee osteoarthritis “without diabetes.” That matters because some online summaries have mixed TRIUMPH-4’s weight-loss and pain data with separate retatrutide diabetes results. (investor.lilly.com) A March 19, 2026 Lilly release for a different Phase 3 trial, TRANSCEND-T2D-1, reported A1C reductions of 1.7% to 2.0% at 40 weeks in adults with type 2 diabetes. Those A1C figures came from that diabetes study, not from TRIUMPH-4, based on Lilly’s releases. ### Who did Lilly say could use the drug if approved? (investor.lilly.com) Kenneth Custer, Lilly’s executive vice president and president of cardiometabolic health, said in the December 11 release that people with obesity and knee osteoarthritis often live with pain, restricted mobility and may eventually require total joint replacement. He said the TRIUMPH-4 results highlighted effects on body weight, pain and physical function. Lilly has not yet posted full peer-reviewed TRIUMPH-4 results in the sources reviewed here. The ClinicalTrials.gov record says no results were posted as of the January 21, 2026 update, even though the study is listed as completed. ### What comes next in the retatrutide program? (investor.lilly.com) Lilly said in the December 11, 2025 release that seven additional Phase 3 retatrutide readouts were expected in 2026. The company separately reported positive Phase 3 diabetes data from TRANSCEND-T2D-1 on March 19, 2026, marking another late-stage readout for the same drug candidate. ClinicalTrials.gov lists TRIUMPH-4 as completed, and Lilly’s investor release remains the primary public source for the topline osteoarthritis findings reviewed here. (investor.lilly.com) Any next step on filing, publication or presentation would likely come through future Lilly disclosures or updates to the trial record. (clinicaltrials.gov)