Retatrutide reduced knee pain in two phase 3 trials

Two phase 3 trials found that the investigational drug retatrutide reduced knee pain and improved physical function more than a placebo in adults with obesity and knee osteoarthritis. Participants also lost substantially more weight, though the trials did not determine whether the drug slows damage to the joints or prevents knee replacement.

The results, published in the New England Journal of Medicine on November 8, 2026, came from the TRIUMPH4 and TRIUMPH1OA trials. Together, they enrolled more than 1,000 adults with painful knee osteoarthritis and excess weight. Participants received once-weekly retatrutide or placebo, with outcomes measured over 68 weeks in TRIUMPH4 and 80 weeks in TRIUMPH1OA.

In TRIUMPH4, knee-pain scores on the WOMAC scale, which ranges from zero to 10, fell by about 3.7 to 4 points in the retatrutide groups after 68 weeks, compared with just over 2 points with placebo. The separate TRIUMPH1OA trial also found significantly greater pain reductions with retatrutide than placebo at week 80. Physical-function scores improved more with the drug in TRIUMPH4 as well.

Weight loss was substantial in TRIUMPH4: participants taking 9 milligrams lost an average of...