Health · Medical Research · 1 hr ago
Experimental drug retatrutide reduced weight and knee pain in trials
Two phase 3 trials found retatrutide reduced weight and knee pain in people with obesity and painful knee osteoarthritis.
The studies, led by Northwestern University, included more than 1,000 participants and tested the experimental weekly injection.
Those taking the highest dose lost about one-quarter of their body weight on average.
About two-thirds had at least a 50% reduction in knee pain, compared with 38% of people who received a placebo.
Losing weight can reduce pressure on the knees, making movement easier, but the trials do not show whether the drug slows arthritis or prevents knee replacement.
Diet, exercise and lifestyle changes remain the first steps, and retatrutide is not yet approved for this use.
Researchers say approval and further answers are still needed before it could become a treatment option.
Two phase 3 trials involving more than 1,000 people found that retatrutide reduced knee pain and disability in people with obesity or overweight and knee osteoarthritis.
In a pooled analysis, about two-thirds of participants taking retatrutide had at least a 50% reduction in knee pain, compared with 38% taking placebo.
Participants taking the highest dose lost about one-quarter of their body weight on average.
Retatrutide is an experimental injectable drug developed by Eli Lilly and is not stated to be approved for this use.
Researchers said diet, exercise and lifestyle changes remain the foundation of care, and noted that questions remain about whether the drug slows osteoarthritis progression.
- Who
- More than 1,000 participants with knee osteoarthritis who were overweight or had obesity took part in the trials.
- What
- Two phase 3 trials found retatrutide reduced knee pain and disability and led to weight loss.
- When
- Findings were presented and scheduled for publication on Nov. 8, 2026.
- Where
- The trials were led by Northwestern University. One trial’s findings were presented at an American College of Rheumatology meeting in Orlando, Florida.
- Why
- Researchers studied whether retatrutide could help people with knee osteoarthritis and excess weight. Losing weight can reduce the load on the knees.
This story does not have two clearly opposing sides.
Findings from the two trials were scheduled for publication in the New England Journal of Medicine.
Results from TRIUMPH-4 and TRIUMPH-1-OA were scheduled for presentation at the American College of Rheumatology annual meeting and in a separate poster session.
- Trials
- Two phase 3 studies led by Northwestern University
- Participants
- More than 1,000 combined
- Pain response
- About two-thirds on retatrutide had at least a 50% reduction in knee pain, versus 38% on placebo
- Weight loss
- About one-quarter of body weight on average among participants taking the highest dose
- Drug status
- Experimental injectable developed by Eli Lilly
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What people are saying
The findings are really saying for people who are overweight and have OA, if you lose a significant amount of weight with this treatment, there is a good chance that you're going to get a meaningful reduction in your knee pain.
Participants had remarkable responses,