Regeneron Pharmaceuticals announced Phase 2 trial results on October 1, 2026, showing that its experimental antibody trevogrumab reduced the loss of lean body mass in adults taking semaglutide for obesity over a full year. The findings address one of the most discussed concerns surrounding GLP-1 weight-loss therapies: the loss of muscle alongside fat.
At the 75 mg dose, participants receiving trevogrumab alongside semaglutide 2.4 mg experienced a 4.2% reduction in lean mass over 52 weeks, compared with a 7.3% reduction in those receiving semaglutide plus placebo. That difference represents approximately 42% less lean mass loss in the trevogrumab group. The full paper is in press with The Lancet.
What happened
The Phase 2 trial tested trevogrumab at two dose levels — 25 mg and 75 mg — administered alongside semaglutide 2.4 mg for 52 weeks in adults with a body mass index of 30 or higher. The primary lean mass finding reported by Regeneron came from the 75 mg dose group.
Trevogrumab works by blocking myostatin, a protein that naturally limits muscle growth. By inhibiting this pathway, the antibody is designed to preserve muscle tissue during periods of rapid weight loss, such as those induced by GLP-1 receptor agonists like semaglutide.
The results are Phase 2 findings, meaning the therapy has not yet been evaluated in larger, late-stage trials and has not received regulatory approval.
Why it matters
Lean mass preservation has emerged as a major clinical concern with GLP-1 weight-loss medications, which can cause significant muscle loss alongside fat loss. A therapy that meaningfully reduces this risk could expand the patient population willing to use these drugs and improve long-term outcomes for people treated for obesity. Trevogrumab’s myostatin-blocking mechanism represents a novel approach in obesity medicine.
The results are relevant to a wide range of stakeholders, including obesity medicine specialists, telehealth platforms prescribing GLP-1 therapies, compounding pharmacies producing semaglutide products, and investors focused on obesity and muscle-wasting therapeutics.
What to watch next
- Publication of the full peer-reviewed paper in The Lancet, which is expected to provide detailed efficacy and safety data.
- Any announcement from Regeneron regarding Phase 3 trial plans for trevogrumab in obesity.
- Broader industry interest in combining muscle-preserving therapies with GLP-1 weight-loss drugs.
Sources
Industry information only. Not medical or legal advice.
