Eli Lilly’s next-generation obesity drug candidate retatrutide showed effectiveness in weight loss and easing knee osteoarthritis pain in a large clinical trial. The findings have drawn attention as they suggest it could reduce joint burden while cutting weight.

Medical News Today reported on Nov. 11 that retatrutide showed greater weight loss and pain improvement than placebo in two recently released phase 3 trials. The results were published in The New England Journal of Medicine (NEJM).

Researchers assessed the effect of a once-weekly retatrutide injection in 1,019 adults who did not have type 2 diabetes and who were overweight or obese with knee osteoarthritis.

In the TRIUMPH-4 trial involving 445 people, WOMAC scores measuring knee pain fell by 3.96 points in the 9 mg group and by 3.74 points in the 12 mg group after 68 weeks. The placebo group fell by 2.12 points. Weight loss was 20.0 percent and 23.7 percent, respectively, well above 4.6 percent for placebo.

In the TRIUMPH-1-OA trial involving 574 people, pain scores fell by 3.22 points, 3.48 points and 3.64 points after 80 weeks in the 4 mg, 9 mg and 12 mg groups, respectively. The placebo group fell by 1.87 points.

Retatrutide is a triple-agonist that acts on three receptors at the same time: GLP-1, GIP and glucagon, which are involved in appetite and energy metabolism.

Experts analysed that reduced load on the knee from weight loss was likely the main reason for pain relief. However, effects such as regenerating cartilage or reversing osteoarthritis progression have not been proven.

Safety also needs to be verified. In both trials, serious adverse events were more frequent in the retatrutide groups than in the placebo group, and common side effects were gastrointestinal symptoms such as nausea and diarrhoea.

Retatrutide is an investigational drug that has not yet been approved by the U.S. Food and Drug Administration (FDA). Eli Lilly plans to pursue an FDA approval application in the first quarter of the following year.