TRIUMPH-4 Completes: Retatrutide Studied in Obesity-Related Knee Osteoarthritis
The Phase 3 trial testing retatrutide in patients with obesity and knee osteoarthritis has completed, with 10 Canadian sites participating. Results could expand the drug's potential indications beyond weight loss alone.
The TRIUMPH-4 trial — part of Eli Lilly's Phase 3 TRIUMPH program — reached its primary completion date in November 2025. This trial tested retatrutide in adults with obesity or overweight and knee osteoarthritis, a common and disabling comorbidity of excess weight.
## Why knee OA?
Obesity is the strongest modifiable risk factor for knee osteoarthritis. Mechanical stress from excess weight damages joint cartilage over time, and obesity-related systemic inflammation may accelerate the process. Weight loss is a first-line recommendation in OA management guidelines, but achieving and maintaining clinically meaningful weight loss is difficult.
TRIUMPH-4 tested whether retatrutide — already shown to produce substantial weight loss — could improve both weight and OA-specific outcomes:
- **Primary endpoints:** Change in knee pain (WOMAC pain subscale) and physical function (WOMAC physical function subscale), plus percent change in body weight
- **Population:** Adults with BMI ≥30 (or ≥27 with a weight-related comorbidity) and symptomatic knee OA
- **Design:** Randomized, double-blind, placebo-controlled
## Canadian participation
[TRIUMPH-4 included 10 Canadian trial sites](https://clinicaltrials.gov/study/NCT05931367), reflecting strong Canadian investigator interest in obesity-related OA research. Canada has a high prevalence of both obesity and osteoarthritis, with OA affecting approximately 1 in 7 Canadian adults.
## What to expect
Results from TRIUMPH-4 have not yet been published or presented. If positive, they could:
- Support a separate indication for obesity-related knee OA, potentially broadening the patient population eligible for treatment
- Provide evidence for OA-specific outcomes (pain, function) beyond weight loss alone
- Influence clinical guidelines that currently recommend weight loss for OA but lack effective pharmacologic tools to achieve it
The detailed results timeline is unknown, but data from completed Phase 3 trials in the TRIUMPH program are typically presented at major medical conferences within 6–12 months of study completion. We will update this page when results are available.
## Sources
- [ClinicalTrials.gov — TRIUMPH-4 (NCT05931367)](https://clinicaltrials.gov/study/NCT05931367)
- [TRIUMPH trial design paper](https://doi.org/10.1111/dom.70209) — Diabetes, Obesity and Metabolism | DOI: 10.1111/dom.70209
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*This article reports on clinical trial milestones using publicly available registry data. It does not speculate on unconfirmed trial results.*