Short answer: In the Phase 2 COURAGE trial, adding trevogrumab to GLP-1S reduced lean-mass loss at 52 weeks. By DXA, lean mass fell 4.2% with trevogrumab 75 mg versus 7.3% with GLP-1S plus placebo, which Regeneron calculates as 42.5% preserved (Regeneron release, Oct. 1, 2026). Regeneron issued that release on October 1, 2026; the data were presented at EASD and are in press at The Lancet. Trevogrumab is an antibody, not a peptide, and it is investigational.
This is adjacent-competition coverage. Trevogrumab is not a research peptide, but it targets a question now shaping obesity-drug competition: how much of GLP-1 weight loss is muscle, and can it be prevented?
What changed, and when
Regeneron announced the full results on October 1, 2026, with the trial presented in an EASD scientific symposium and in press at The Lancet (Regeneron release). EASD in Milan ran Sept. 28 to Oct. 2 (News-Medical). Secondary roundups on October 2 repeated the results (BioMed Nexus; BSR). Those are the dates readers should cite: October 1 for the company release, October 2 for the end of EASD and follow-on coverage.
Two trial portions: which doses are which
Earlier wire coverage mixed up doses, and the release clarifies why. COURAGE ran two independent portions (Regeneron release; BioMed Nexus):
- Higher-dose portion: trevogrumab 200 mg or 400 mg with GLP-1S 2.4 mg for 26 weeks, then trevogrumab versus placebo for another 26 weeks after GLP-1S was stopped. A GLP-1S-trevogrumab-Activin-A inhibitor arm was also included, with results previously presented.
- Lower-dose portion: trevogrumab 25 mg or 75 mg with GLP-1S 2.4 mg versus GLP-1S alone for 52 weeks. The 52-week primary endpoint figures below come from here.
News-Medical reports 975 enrolled participants, with 376 in the 52-week portion and an exploratory MRI substudy of 76 (News-Medical).
The 52-week numbers
All values are from the lower-dose portion, versus placebo plus GLP-1S. Preservation percentages are Regeneron's own calculations against the GLP-1S-plus-placebo arm (BioMed Nexus; Regeneron release).
| Measure | GLP-1S + placebo | Trevogrumab 25 mg | Trevogrumab 75 mg |
|---|---|---|---|
| DXA lean mass, week 26 | -6.7% | -4.7% (29.9% preserved) | -3.3% (50.7% preserved) |
| DXA lean mass, week 52 | -7.3% | -5.8% (20.5% preserved) | -4.2% (42.5% preserved) |
| MRI muscle volume, week 52 (absolute change) | -1.03 | -0.29 (71.8% preserved) | -0.32 (68.9% preserved) |
Two details matter for accuracy:
- The DXA result is dose-dependent. The published-paper summary reports the week-52 difference versus placebo as +3.1% for 75 mg (statistically significant) and +1.5% for 25 mg (not statistically significant) (News-Medical). The 25 mg arm should not be treated as a clean win.
- The ~72% MRI figure belongs to the 25 mg arm, not 75 mg. At 75 mg, MRI preservation was 68.9% at week 52 (Regeneron release). Some summaries say "over 70%" for 75 mg (BSR); the release's own table does not support that for week 52, though it does report 72.7% for 75 mg at week 26.
The MRI data come from participants with evaluable scans, and News-Medical describes the substudy as exploratory (News-Medical). The 75 mg DXA preservation also faded between week 26 (50.7%) and week 52 (42.5%), a decay that the MRI numbers do not show as clearly.
Weight loss did not improve
Regeneron states that lower-dose trevogrumab did not meaningfully enhance the weight loss achieved with GLP-1S alone (Regeneron release). That sets the pitch: the product being tested is composition (the company calls it quality), not more kilograms lost. Whether payers or patients value that is not answered by a body-composition trial.
Safety signals, and the garetosmab caveat
In the lower-dose portion, 77% of trevogrumab participants had at least one adverse event versus 82% on placebo; nausea, constipation, diarrhea and vomiting were the most common events at 10% or higher (Regeneron release).
The higher-dose portion's triplet arm, with the Activin-A antibody garetosmab, was different. It had substantially higher serious adverse events and discontinuations, muscle spasms in 41% (61/149) versus 5% (7/151) on GLP-1S plus placebo, and two deaths; a causal link was not identified (News-Medical). The authors say the triplet was not well tolerated. Reports that trevogrumab alone looked tolerable should not be read across to that triplet.
Sarcopenia subgroup and the next trial
A pre-specified analysis of participants with low baseline lean mass, defined with the imaging component of the FNIH sarcopenia definition, found greater lean-mass loss on GLP-1S alone and numerically more preservation with trevogrumab (Regeneron release). "Numerically" is the operative word. The people in that subgroup averaged 53 years versus 46 years for the others (News-Medical).
Regeneron plans a Phase 2 trial combining trevogrumab with GLP-1-based therapies in older adults with obesity and decreased muscle mass or strength (Regeneron release). BioMed Nexus notes that this is the population in which functional outcomes, rather than scans, would decide whether muscle preservation becomes a reimbursable claim (BioMed Nexus). That is an analyst's framing, and the trial has been planned, not started.
What the evidence cannot say yet
- Body composition is not function. The authors write that whether muscle preservation translates into better physical function, metabolic health and clinical outcomes requires further investigation (News-Medical).
- It is a sponsor-run trial. Regeneron sponsored COURAGE (News-Medical), and the preservation percentages are the company's calculations against the placebo arm (BioMed Nexus). The Lancet paper was described as in press, so independent readers should check the final version.
- No regulator has judged it. Regeneron says trevogrumab's safety and efficacy have not been evaluated by any regulatory authority (Regeneron release).
- Exercise comparisons are not head-to-head. The authors say trevogrumab showed greater lean-mass preservation than reported with GLP-1 plus moderate-to-vigorous exercise, but trial design differences preclude direct comparison (News-Medical).
- The "~30% of weight lost is lean mass" figure is background. The BSR briefing cites studies indicating roughly 30% of GLP-1S weight loss is lean mass (BSR). That is not a COURAGE result, and the briefing does not detail the underlying studies.
PeptidePrices analysis: why this matters for the obesity-drug market
This is our interpretation, not a source finding. The field has so far competed on how much weight a drug removes. BioMed Nexus's weekly readout framed the contrast: a survodutide dual agonist landed at 13.1% weight loss while COURAGE opened composition as a new axis of differentiation (BioMed Nexus). COURAGE is the first Phase 2 dataset in this pack to quantify, at 52 weeks, how much of GLP-1S's lean-mass loss an add-on antibody can blunt. The caution is that it is one sponsor trial with one backbone, and a modest-sized MRI substudy.
For readers following muscle-targeted antibody biology more broadly, our coverage of apitegromab's FDA approval in spinal muscular atrophy is a separate indication and a different regulatory situation. For the GLP-1S side of the question, see STEP Young and the peptide index. Delivery alternatives to weekly injection are covered in our Fractyl Rejuva explainer.
Research-use boundary
Trevogrumab is not available as an approved product, and nothing here is guidance on obtaining or using it. This article is for general informational purposes only and is not medical advice. Talk to a licensed clinician about personal medical decisions. PeptidePrices does not sell peptides or give dosing advice.
Continue your research
Sources
- Regeneron Pharmaceuticals via GlobeNewswire (Oct. 1, 2026): Phase 2 COURAGE Trial Confirms Trevogrumab Prevents Lean Mass and Muscle Loss
- News-Medical: Trevogrumab cuts GLP-1S-induced lean mass loss by half
- BioMed Nexus (Oct. 2, 2026): Regeneron's Trevogrumab Preserved Muscle Lost on GLP-1S at 52 Weeks
- BSR: EASD 2026 Peptide Pipeline