Trevogrumab
Trevogrumab (REGN1033) with garetosmab (REGN2477)
Also known as: REGN1033, Garetosmab, REGN2477
Regeneron's anti-myostatin antibody, alone or with the anti-activin antibody garetosmab, preserved 51% to 81% of lean mass during semaglutide weight loss in the COURAGE trial, at the cost of more adverse events.
Overview
The COURAGE Phase 2 tested semaglutide alone, with trevogrumab (blocks myostatin/GDF8), and with both trevogrumab and garetosmab (blocks activin A). Reported at EASD 2025, the dual add-on preserved about 51% of the lean mass normally lost, and the triple regimen preserved 80.9% while increasing fat loss by 27.3% over semaglutide alone. The triple arm also had more adverse events and two deaths that were not attributed to the drugs; full data were expected in 2026. Garetosmab separately has positive Phase 3 results in fibrodysplasia ossificans progressiva.
Mechanism of action
Trevogrumab neutralizes myostatin (GDF8); garetosmab neutralizes activin A. Both ligands restrain muscle growth, and activin A also promotes fat storage.
Key studies & citations
- Human2025
Results from Phase 2 COURAGE trial with semaglutide, trevogrumab and garetosmab
Triple regimen preserved 80.9% of lean mass with 27.3% more fat loss.
Regeneron press release - Human2025
Interim COURAGE results
Higher adverse-event rate in the triple arm.
Regeneron press release
Frequently asked questions
Is muscle preservation worth the added risk?
That is exactly what COURAGE cannot yet answer. The lean-mass numbers are the best seen with any GLP-1 add-on, but the safety findings mean the combination is far from ready for use.