Trevogrumab is a human monoclonal antibody that neutralizes myostatin, the brake on muscle growth. It is being tested with semaglutide to keep lean mass while accelerating fat loss. It is an injectable biologic used in supervised trials, not a SARM, not a peptide, and not a practical or legal physique drug today.
What Trevogrumab is (and what it is not)
Trevogrumab, also known as REGN1033, is a fully human IgG4 class antibody that binds myostatin and prevents it from signaling. That makes it a targeted myostatin inhibitor, similar in strategic goal to apitegromab, but from a different company and used in different clinical settings. It is not a SARM and not a short peptide.
Why lifters care, dialing back myostatin can increase muscle size in animals and can reduce the amount of lean mass lost during aggressive weight loss in humans. The new development is that Trevogrumab is being paired with GLP-1 drugs, with the goal of higher quality weight loss.
How it is given, dose patterns, half life
Route, subcutaneous or intravenous injection, administered on a schedule inside a clinical study.
Dose patterns seen publicly
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In older sarcopenia and method patents, subcutaneous REGN1033 regimens included 100 to 400 mg every 2 weeks, and 200 to 400 mg every 4 weeks, typically for 12 weeks. These were research regimens, not approved dosing.
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In the 2025 obesity study known as COURAGE, Trevogrumab arms were described as 200 mg and 400 mg dose levels when combined with semaglutide 2.4 mg during the 26 week weight loss phase.
Half life
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A Trevogrumab specific terminal half life has not been disclosed in peer reviewed form at the time of writing. As an IgG class monoclonal, an expected class half life is roughly 2 to 4 weeks, which explains the every 2 weeks or every 4 weeks schedules that appear across early programs.
What this means for bodybuilders, it behaves like a long acting biologic. Think infrequent clinic injections and slow pharmacokinetics, not day to day modulation.
What the human data shows so far
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Muscle preservation with GLP-1 cutting
The mid 2025 interim and September 2025 26 week readouts from the COURAGE Phase 2 program reported that adding Trevogrumab to semaglutide preserved about half of the lean mass that is usually lost on semaglutide while increasing fat loss. A higher dose and a triplet that adds an anti activin A antibody were explored. Triplet arms improved fat loss further, although tolerability was tighter and discontinuations were higher. -
Earlier human signals
Earlier healthy volunteer and sarcopenia programs evaluated REGN1033 as a single agent, focused on changes in lean body mass and thigh muscle volume. These studies established the dose ranges and the feasibility of modulating lean mass endpoints over weeks using an antibody that targets the myostatin pathway. -
Takeaway for lifters
The near term value is about protecting muscle during aggressive cuts, especially when GLP-1 medications are in the mix. This is not positioned as a mass cycle for healthy athletes. It is a quality of weight loss play.
Mechanism, how this differs from other approaches
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Trevogrumab binds myostatin itself.
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Garetosmab, which sometimes appears in combination, binds activin A.
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Bimagrumab, a different program, binds the activin receptor type II and tends to drive powerful fat loss with lean mass preservation.
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Apitegromab targets the activation of latent myostatin rather than binding the mature ligand.
For athletes, the common thread is pushing body composition toward more lean and less fat without relying on androgens. The differences are which node in the pathway is targeted and the balance of efficacy and side effects that follow.
Practical implications for physique goals
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Cutting with less collateral damage, the headline use case is to pair a strong fat loss drug with a muscle preservation agent so you lose more fat and less muscle. If this holds up in Phase 3, it rewires cutting phases for clinical populations first.
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Recomp and rehab potential, outside of weight loss, trevogrumab class agents could prove useful in preserving or regaining muscle after immobilization or catabolic stress, which is closer to the day to day reality of athletes who get injured.
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Training still matters, resistance training remains additive in virtually all body composition studies that test it. Expect the best outcomes when lifting and protein intake are on point.
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This is not a gray market play, this is a regulated biologic in clinical trials with no approved bodybuilding use.
Safety frame for athletes
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Unknowns in healthy users, long term tendon and connective tissue balance, strength to size ratios, cramping risk, and off target pathway effects need more data in non patient populations.
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Anti doping, myostatin inhibitors are prohibited in sport. Detection methods for biologics are improving.
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Tolerability, the triplet regimen that adds garetosmab increased discontinuations in study updates. Expect safety to drive which combinations survive.
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Access and cost, clinic administered injections with trial oversight and cold chain handling keep this well outside black market copycats. Avoid any product marketed as Trevogrumab.
Comparison cheat sheet
| Modality | Target | Typical schedule in studies | Primary value prop | Reality check for lifters |
|---|---|---|---|---|
| Trevogrumab | Myostatin ligand | Injection every 2 or 4 weeks in trials, 200 to 400 mg dose levels reported | Preserve lean mass during GLP-1 driven weight loss, possible rehab support | Clinical only, anti doping prohibited, half life likely multi week, not a SARM or peptide |
| Apitegromab | Latent myostatin activation | IV every 4 weeks in trials for SMA | Functional gains in neuromuscular disease and proof that the pathway is druggable in humans | Regulatory path is active, not a physique drug |
| Bimagrumab | Activin type II receptor | IV, various schedules in trials | Strong fat loss with lean preservation | Different node, clinical only |
| SARMs | Androgen receptor | Oral, short half lives | Strength, lean mass, appetite effects | Variable quality, endocrine suppression, prohibited |
| Peptides (misc.) | Often GH axis, diverse | Subcutaneous, frequent | Recovery, appetite, sleep claims | Evidence thin for hypertrophy, QC issues |
Frequently asked questions
Is Trevogrumab a peptide or a SARM
Neither. It is a monoclonal antibody against myostatin.
How is it used and what are the doses
Used in clinical trials by injection on schedules such as every 2 weeks or every 4 weeks. Public sources describe 200 mg and 400 mg dose levels in the obesity study. Historic research regimens tested 100 to 400 mg subcutaneous, every 2 to 4 weeks, over about 12 weeks.
What is the half life
Class expectation for an IgG antibody is about 2 to 4 weeks. A Trevogrumab specific terminal half life has not been published in detail at the time of writing.
What results have been seen
In 2025 readouts, adding Trevogrumab to semaglutide preserved about half of the lean mass typically lost on semaglutide while increasing fat loss. Earlier work in healthy volunteers and sarcopenia focused on lean mass and thigh muscle volume endpoints to establish bioeffect and dose ranges.
Will this become a bodybuilding drug
No. Expect clinical use cases first, such as better quality medical weight loss and possibly rehab contexts. Anti doping rules prohibit myostatin inhibitors. Cost and access remain clinical.
Bottom line
Trevogrumab is part of a new strategy, protect muscle while you strip fat. For bodybuilders, the take home is to watch this space for how clinicians redesign cutting phases with GLP-1s plus muscle preservation agents. It is not a cycle compound, it is a signal that the composition war is shifting toward less fat with more muscle retained.
Sources and further reading
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26 week COURAGE Phase 2 results presented September 2025, semaglutide plus Trevogrumab preserved about half of GLP-1 associated lean mass loss and increased fat loss. Reuters+3GlobeNewswire+3Nasdaq+3
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Regeneron interim analysis June 2025 and study design details. Regeneron Newsroom
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COURAGE listing at ClinicalTrials.gov and Regeneron trials site. ClinicalTrials.gov+1
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Dose patterns referenced in patents and earlier sarcopenia programs, including 100 to 400 mg SC every 2 or 4 weeks. Google Patents+1
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Identification and class, Trevogrumab REGN1033, IgG4 myostatin antibody. PMC+1
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Preclinical and early translational work showing hypertrophy and anti atrophy effects with REGN1033. PMC+1
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General monoclonal antibody PK and half life ranges used for class context. ASCPT Onlinelibrary
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Media and trade coverage summarizing the lean mass preservation signal and triplet tolerability notes. PharmExec+1
