Recent clinical trials led by Northwestern University have shown promising results for retatrutide, an experimental injectable drug aimed at addressing knee osteoarthritis (OA) in overweight individuals. In two phase 3 trials with over 1,000 participants, those receiving the highest dose of retatrutide lost an average of 25% of their body weight, contributing to significant pain relief.
A pooled analysis of the trials revealed that approximately two-thirds of participants who received retatrutide experienced at least a 50% reduction in knee pain, compared to only 38% of those on placebo. This reduction in pain, alongside weight loss, was linked to other health benefits such as lower blood pressure and reduced levels of inflammation and lipids.
The findings from these trials are set to be published on November 8 in the New England Journal of Medicine. Dr. Thomas Schnitzer, a professor at Northwestern University Feinberg School of Medicine, emphasized the results, stating, “For people who are overweight and have OA, losing a significant amount of weight with this treatment leads to a meaningful reduction in knee pain.” He explained that decreased weight lessens the load on the knees, which enhances overall function.
Potential Treatment for a Common Condition
About 5% of the U.S. population, or approximately 15 million people, suffer from painful knee OA. Current treatment options, including corticosteroid injections and oral medications, often provide only short-term relief. While losing 5% to 10% of body weight can alleviate OA symptoms, Dr. Schnitzer noted that significant weight loss through diet and exercise is challenging, especially for individuals already dealing with knee pain.
Retatrutide, developed by Eli Lilly, distinguishes itself from other GLP-1 drugs by activating receptors for three hormones rather than just one or two. This led to a greater average weight loss of 20% to 25% among participants, compared to 10% to 20% with existing GLP-1 options. “Many participants had remarkable responses, with some losing over a hundred pounds,” Dr. Schnitzer stated.
While diet and exercise remain essential components of managing OA, Schnitzer suggested that retatrutide could become a viable alternative for patients who struggle to lose weight through traditional methods, pending FDA approval.
However, the study faced limitations, as participants requiring knee replacements were excluded. Dr. Schnitzer highlighted that a critical follow-up question is whether retatrutide can also slow OA progression to lessen the need for joint replacements. Additionally, further research is necessary to understand the drug’s effects on individuals who are not overweight, as the current studies did not involve them.
Participants’ pain was evaluated using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) Pain index, complemented by pain logging through a mobile application.
