In a phase 3 trial, Eli Lilly’s experimental drug retatrutide delivered an average 28.7% weight loss and reduced pain among adults with obesity or overweight and knee osteoarthritis.
The trial recruited 445 participants and divided them equally to receive retatrutide 9 milligrams, retatrutide 12 milligrams or a placebo for 68 weeks, according to a Dec. 11 news release. Eli Lilly said its drug candidate met all primary and key secondary endpoints.
Retatrutide is a glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and glucagon triple-hormone receptor agonist — a medication class that is only in development but has greater weight loss potential than GLP-1s like Wegovy or GLP-1-GIPs like Zepbound.
Trial participants who received 9 milligram retatrutide doses averaged 26.4% weight loss, those who received 12 milligram doses averaged 28.7% weight loss and the placebo group averaged 2.1% weight loss.
Using the Western Ontario and McMaster Universities Osteoarthritis Index pain score, the placebo group saw a reduction in pain by 2.4 points, while the two retatrutide cohorts averaged about a 4.5-point reduction.
Treatment discontinuation was 12.2% with the 9 milligram cohort, 18.2% with the 12 milligram group and 4% with the placebo. Compared to the placebo, retatrutide’s common adverse events were nausea, diarrhea, constipation, vomiting and decreased appetite.
Eli Lilly said additional trial results are expected in 2026.
