Trevogrumab

What Is Trevogrumab?

Trevogrumab, developed under the code REGN1033, is a fully human monoclonal antibody that specifically and potently blocks myostatin, a protein that limits skeletal muscle growth.^[1]

In mice, the antibody increased muscle fiber size, muscle mass and force production, and it prevented muscle loss in several models of atrophy.^[1] Early clinical interest focused on muscle wasting: REGN1033 was presented at the 2013 Cachexia Conference and reviewed in 2014 as an investigational biologic for cancer cachexia.^[2][3]

More recent reviews discuss trevogrumab as a possible adjunct to weight-loss drugs. Because a large share of the weight lost with incretin-based therapy comes from fat-free mass, researchers are testing whether blocking myostatin can help preserve lean tissue during weight loss.^[4][5] One review noted that incretin receptor agonists can achieve weight loss of 15% to 25% in many patients, and that accompanying losses of muscle and bone can compromise physical function and metabolic rate, especially in older adults.^[4]

Chemical Structure and Molecular Identity

Trevogrumab is a fully human monoclonal antibody, a large glycoprotein, so it has no PubChem compound record and no formula, molecular weight or CAS number is listed here. Its identity is defined by its target, myostatin, and by its antibody format.^[1]

The original characterization paper tested the antibody’s binding by surface plasmon resonance (Biacore) and measured its blocking activity in cell-based Smad2/3 signaling assays, which read out the main pathway myostatin activates. On that basis the authors described REGN1033 as a specific and potent myostatin antagonist. Its effects on muscle were then examined with messenger RNA sequencing, immunohistochemistry and ex vivo force measurements.^[1]

The “-umab” ending of the generic name follows international nonproprietary naming conventions for fully human monoclonal antibodies.

Research History and Development

Trevogrumab moved from preclinical muscle studies in the early 2010s to investigation as a drug candidate, first for muscle wasting and more recently alongside weight-loss drugs. A 2014 conference report listed the myostatin antagonist REGN1033 among drugs showing potential for treating wasting disorders, alongside the ghrelin receptor agonist anamorelin and the selective androgen receptor modulator enobosarm. The same meeting emphasized new biomarkers for wasting, including myostatin and growth differentiation factor-15, and new ways to measure muscle mass such as the D3-creatine dilution method.^[2]

A 2014 review of investigational biologics for cancer cachexia covered REGN1033 alongside agents such as bimagrumab. That review defined cancer cachexia as ongoing skeletal muscle loss leading to progressive functional impairment, and grouped candidate biologics into those targeting inflammatory pathways and those targeting the myostatin/activin type II receptor pathway. The authors identified two challenges for the field: the lack of a clinically meaningful definition of cachexia, and the tendency to identify and treat cachexia only at a late stage.^[3]

The full preclinical characterization appeared in 2015, followed in 2016 by a proteomic study comparing antibody blockade with genetic myostatin deletion.^[1][6] By 2024 to 2026, reviews grouped trevogrumab with bimagrumab and garetosmab as pipeline agents that inhibit myostatin or activin signaling to protect muscle during weight loss.^[4][5]

Mechanisms Studied in Research

Trevogrumab works by neutralizing myostatin so that it cannot activate Smad2/3 signaling in muscle, removing a brake on muscle growth.^[1]

Its selectivity distinguishes it from other agents in the pathway. Reviews describe bimagrumab as an activin type II receptor inhibitor and garetosmab as an activin A inhibitor, while trevogrumab targets myostatin.^[5] Researchers place all three within a myostatin-activin-follistatin-inhibin system in which activins and myostatin promote muscle breakdown and follistatins oppose them.^[4]

Blocking myostatin after development differs from lacking it from birth. In a mouse proteomics study, myostatin knockout mice had twice the muscle mass of wild-type mice and a greater than 1.5-fold change in 12.0% of 1,137 quantified muscle proteins, including changes consistent with a slow-to-fast fiber type switch. Mice treated with REGN1033 for two weeks gained about 20% muscle mass but showed minimal proteome change, 0.7% of 1,510 proteins, close to the 0.5% seen as normal biological variation.^[6]

The authors suggested these molecular differences may help explain why genetic myostatin deficiency produces greater hypertrophy than post-developmental blockade.^[6]

Key Findings From Published Studies

Most direct published evidence on trevogrumab comes from mouse studies; findings relevant to people are available mainly through reviews of weight-loss adjunct research.

Animal studies

• Chronic treatment of mice increased muscle fiber size, muscle mass and force production.^[1]
• The antibody prevented muscle loss caused by limb immobilization, glucocorticoid (dexamethasone) treatment and hindlimb unweighting.^[1]
• It increased the regain of muscle mass during recovery from pre-existing atrophy.^[1]
• In aged mice undergoing exercise training, it increased muscle mass and strength and improved treadmill performance.^[1]
• Two weeks of treatment raised muscle mass by about 20% with minimal change to the muscle proteome.^[6]

Reviews of weight-loss adjunct research

A 2026 review of drugs for preserving lean mass during GLP-1 receptor agonist weight loss reported that myostatin and activin A inhibitors, naming trevogrumab and garetosmab, showed effects similar to bimagrumab, which preserved or increased lean body mass while reducing fat mass. The review drew on both preclinical and clinical studies. Adverse events across the agents reviewed were generally mild and reversible, but long-term data remain limited and larger controlled trials are needed.^[5]

A 2024 review similarly described trevogrumab as showing promise in preventing muscle loss while promoting fat loss, and noted that more than 25% of weight lost through surgery or drug therapy typically comes from fat-free mass. It called for well-designed studies and noted that advanced age and prefrailty may affect candidate selection.^[4]

Muscle function remains an open question. In the 2026 review, the selective androgen receptor modulator enobosarm was singled out as also improving physical function, a result the review did not report for the myostatin and activin pathway inhibitors.^[5]

As a large monoclonal antibody, trevogrumab's identity is typically verified with SDS-PAGE, size-exclusion HPLC and mass spectrometry data on a certificate of analysis.

Regulatory and Research Status

Trevogrumab is an investigational antibody and has not been approved as a medicine; the cited reviews describe it as a pipeline compound still under investigation.^[4][5]

Reviews stress that the evidence base is preliminary. Larger controlled trials are needed to confirm efficacy and safety before clinical use, and long-term data are limited.^[5] In cachexia research, the lack of a clinically meaningful cachexia definition has complicated the evaluation of agents like REGN1033.^[3] Reviewers describe the combination of myostatin-pathway inhibition with incretin-based drugs as a strategy that may enhance fat loss while preserving muscle and bone, but one that still needs long-term evidence.^[4]

For researchers, the practical status is that trevogrumab is characterized mainly by preclinical mouse data and by review-level summaries of clinical work. In sport, myostatin-neutralizing antibodies fall within section S4 of the World Anti-Doping Agency Prohibited List, which covers agents that inhibit myostatin signaling.