At a Glance
- Company: Eli Lilly
- Location: Global
- Deal value or headline figures: 28.7% weight loss, 75.8% pain reduction
- Focus area: Obesity and knee osteoarthritis
- Next steps: Seven more retatrutide trials planned for 2026
What happened?
Eli Lilly announced phase 3 results for retatrutide, a triple hormone agonist targeting obesity and knee osteoarthritis. Patients on the highest dose lost an average of 28.7% of their body weight and reported a 75.8% reduction in pain scores, exceeding previous expectations. However, a significant proportion of patients discontinued treatment due to adverse events, with 18.2% dropping out on the highest dose.
Why does it matter?
Retatrutide’s efficacy surpasses that of current obesity drugs, including Lilly’s own Mounjaro and Zepbound, as well as Novo Nordisk’s semaglutide. The results signal a potential leap in obesity and osteoarthritis treatment, but high discontinuation rates due to side effects raise concerns about real-world tolerability and adoption.
Who’s behind it?
Eli Lilly developed retatrutide and conducted the phase 3 Triumph-4 trial in 445 patients with obesity or overweight and knee osteoarthritis. The company is preparing for additional trials in obesity and type 2 diabetes, with data expected in 2026.
How was it achieved?
The Triumph-4 trial tested two doses of retatrutide (9 mg and 12 mg) against placebo, with patients receiving once-weekly injections for 68 weeks. The primary endpoints were weight loss and reduction in osteoarthritis pain scores. The higher dose yielded 28.7% average weight loss and a 75.8% pain reduction, outperforming analyst predictions and previous trial results. Adverse events, including dysesthesia, led to higher discontinuation rates, especially in those with lower baseline BMI.
What’s next?
Eli Lilly plans to complete seven more retatrutide trials in obesity and type 2 diabetes in 2026, including studies on a 4-mg maintenance dose. Further data will clarify the drug’s safety profile and optimal dosing for different patient populations.
What are people saying?
Analysts noted that while efficacy exceeded even their bull-case scenarios, the higher discontinuation rates could limit uptake. One analyst suggested Lilly’s share price could rise 5% to 10% if tolerability improves, but the current results led to a modest 1% increase in premarket trading.