TRIUMPH-4 Results: The First Retatrutide Phase 3 Win (December 11, 2025)
TRIUMPH-4 results, Dec 11, 2025: retatrutide's first Phase 3 win, with 28.7% weight loss on 12 mg and knee pain down about three-quarters in 68 weeks.
Event date Last verified Primary source Eli Lilly and Company (PR Newswire)
The TRIUMPH-4 results, released by Lilly on December 11, 2025, were retatrutide's first Phase 3 win: in adults with knee osteoarthritis, 12 mg took off 28.7% of body weight on average over 68 weeks, against 2.1% on placebo, and knee pain fell by about three-quarters. Those are Lilly's efficacy estimand figures. The primary source is Lilly's December 11 release.
Key takeaways
- TRIUMPH-4, reported on December 11, 2025, was the first retatrutide Phase 3 trial to read out, in adults with knee osteoarthritis and obesity or overweight.
- Weight fell 26.4% on 9 mg and 28.7% on 12 mg against 2.1% on placebo after 68 weeks (efficacy estimand).
- Knee pain fell by about three-quarters on both doses, against about 40% on placebo; the percentages are post hoc.
- Dropouts for side effects were high on 12 mg (18.2%), and Lilly said they tracked with how heavy people were at the start.
This page is the dated record of the first readout. The trial in full is on the TRIUMPH-4 page.
What Lilly announced on December 11, 2025
TRIUMPH-4 randomized 445 adults with a BMI of 27 or more, knee osteoarthritis and no diabetes, 1:1:1 to 9 mg, 12 mg or placebo, double-blind, for 68 weeks. Most were heavy at the start: 84.0% had a BMI of 35 or more, and the average was 40.4. Everyone started at 2 mg and stepped up every 4 weeks. The trial had two co-primary goals, knee pain on the WOMAC scale and percent weight change.
One trap: the release cites NCT05869903, but ClinicalTrials.gov lists that number as ATTAIN-1, an orforglipron trial. TRIUMPH-4's own record is NCT05931367.
The TRIUMPH-4 results by dose
| Measure (68 weeks, efficacy estimand) | 9 mg | 12 mg | Placebo |
|---|---|---|---|
| Weight change (from 112.7 kg, 248.5 lb) | -26.4% (-64.2 lb) | -28.7% (-71.2 lb) | -2.1% (-4.6 lb) |
| Lost 25% or more of body weight | 47.7% | 58.6% | 1.3% |
| WOMAC knee pain (from 6.0, scale 0 to 10) | -4.5 points (-75.8%) | -4.4 (-74.3%) | -2.4 (-40.3%) |
| WOMAC physical function (from 5.8) | -4.1 (-71.8%) | -4.2 (-73.7%) | -2.1 (-35.6%) |
| Completely free of knee pain (post hoc) | 14.1% | 12.0% | 4.2% |
The pain percentages are post hoc. Counting everyone randomized (the treatment-regimen estimand), weight fell 20.0% and 23.7% against 4.6%, and knee pain 4.0 and 3.7 points against 2.1. Systolic blood pressure fell 14.0 mmHg at the highest dose.
Side effects and dropouts
Nausea hit 38.1% and 43.2% of people on 9 and 12 mg against 10.7% on placebo, and vomiting 20.4% and 20.9% against none. Burning or oversensitive skin (dysesthesia) was reported by 8.8% and 20.9% against 0.7%, generally mild. Stopping because of side effects ran 12.2% and 18.2% against 4.0%. Lilly said those dropouts tracked with starting BMI and included people who stopped because they felt they were losing too much weight; among people starting at a BMI of 35 or more, the rates were 8.8% and 12.1% against 4.8%.
Our read: on knee pain, 9 mg did as well as 12 mg with fewer dropouts. It's one trial, and it's a reason not to assume the top dose is the better one for joint pain.
What TRIUMPH-4 can't tell you yet
Everything above comes from one press release. We found no journal paper for TRIUMPH-4 as of October 31, 2026, so there are no serious adverse event rates and no results by sex. The only comparison was with placebo, so the trial can't say how retatrutide does against tirzepatide or semaglutide for knee pain. And systolic blood pressure is the only heart risk factor with a number: Lilly said non-HDL cholesterol, triglycerides and hsCRP fell too, without figures.
What came after TRIUMPH-4
Lilly said in December 2025 that 7 more Phase 3 trials in obesity and type 2 diabetes were expected to finish in 2026. By October 31, 2026 there were six positive Phase 3 readouts in all, starting with this one; the next was TRANSCEND-T2D-1 in March, and the biggest was TRIUMPH-1 in May. The Phase 3 trials page lines them all up, and the results page turns them into what to expect.
No approved version exists yet, and anything listed as retatrutide for sale online isn't the drug this trial tested.
Frequently asked questions
What were the TRIUMPH-4 results?
After 68 weeks, weight fell 26.4% on 9 mg and 28.7% on 12 mg against 2.1% on placebo, and WOMAC knee pain fell 4.5 and 4.4 points against 2.4, from a starting score of 6.0. All are Lilly's efficacy estimand figures.
Did retatrutide get rid of knee pain?
For some people. In a post hoc analysis, 14.1% on 9 mg and 12.0% on 12 mg were completely free of knee pain at 68 weeks, against 4.2% on placebo.
Why did so many people stop 12 mg in TRIUMPH-4?
Lilly said stopping for side effects tracked with starting BMI and included people who stopped because they felt they'd lost too much weight. In people starting at a BMI of 35 or more, 12.1% stopped 12 mg against 4.8% on placebo.
Is TRIUMPH-4 published?
We found no journal paper for TRIUMPH-4 as of October 31, 2026. Everything on this page comes from Lilly's December 11, 2025 release.
Sources
- Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial (TRIUMPH-4 topline). Eli Lilly and Company (PR Newswire), 2025. prnewswire.com
- TRIUMPH-4 registry record, NCT05931367. ClinicalTrials.gov, U.S. National Library of Medicine, 2026. clinicaltrials.gov
- ATTAIN-1 registry record, NCT05869903 (the ID cited in the TRIUMPH-4 release). ClinicalTrials.gov, U.S. National Library of Medicine, 2026. clinicaltrials.gov
- Europe PMC search: journal articles with retatrutide or LY3437943 in the title, June to December 2026. Europe PMC, 2026. ebi.ac.uk
Dr. Juan Pablo Frías, MD
Physician-Scientist & Clinical Trialist • Endocrinology, Diabetes & Metabolism
Dr. Frías earned his M.D. from Vanderbilt University School of Medicine and completed his endocrinology fellowship at UC San Diego. A principal investigator on landmark incretin trials (including retatrutide, tirzepatide and semaglutide), he reviews all guides on Retatrutide360 for clinical accuracy, dosing safety and evidence fidelity.
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