Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.
The muscle chalone: a circulating brake on muscle growth, and the target every “myostatin inhibitor” is aiming at.
Also known as: GDF-8 · growth differentiation factor 8 · MSTN
Part of the Growth hormone & IGF peptides cluster
Overview
Myostatin (GDF-8) is a TGF-β-superfamily protein made by skeletal muscle that circulates and acts back on muscle to limit its growth, signalling through activin type II receptors (ACVR2B) and the SMAD pathway. Removing it causes marked muscle hypertrophy in animals, which is why antibodies and receptor blockers that neutralise it are in clinical trials for muscle-wasting diseases and, combined with semaglutide, for obesity.
Source & context
Biological / chemical source: Made by skeletal myofibres, with smaller amounts from myocardium and adipose tissue
Primary research or clinical context: Endogenous protein; the therapeutic target of investigational anti-myostatin antibodies and receptor blockers, not a product itself
What myostatin is
Myostatin, also called growth differentiation factor 8 (GDF-8), is a secreted growth and differentiation factor of the TGF-β superfamily, predominantly synthesised and expressed in skeletal muscle, where it limits muscle growth and promotes protein breakdown (Sharma et al., IUBMB Life 2015; Esposito et al., Advances in Clinical Chemistry 2022). It is made by skeletal myofibres, circulates in the blood, and acts back on myofibres to limit growth — the properties of a chalone, the term proposed decades ago for circulating tissue-specific growth inhibitors that control organ size (Lee, Annual Review of Physiology 2023).
Mechanism
Myostatin binds activin type IIB membrane receptors (ACVR2B) and activates the canonical SMAD2/SMAD3 pathway, plus non-canonical pathways (IUPHAR record; Knapp et al., Biomolecules 2023). Its expression is tightly regulated at epigenetic, transcriptional, post-transcriptional and post-translational levels, and extracellular binding proteins modulate its activity — each layer a potential point of intervention (Sharma et al., 2015). Beyond muscle, brown adipose tissue secretes myostatin to control skeletal muscle function (Kong et al., Cell Metabolism 2018), and transgenic overexpression reduces heart mass while removal increases it (Knapp et al., 2023).
Why it is a drug target
Inhibiting myostatin/ACVR2B signalling is a mechanistic target for drugs to combat muscle-wasting conditions (IUPHAR record). A human anti-ActRII antibody, bimagrumab, prevents ligand binding, enhances human myoblast differentiation, and prevents myostatin- or activin-A-induced atrophy by blocking SMAD2/3 phosphorylation (Lach-Trifilieff et al., Molecular and Cellular Biology 2014). A myostatin-specific antibody enhanced muscle strength in disease models (Muramatsu et al., Scientific Reports 2021). Alternative scaffolds such as the fibronectin-domain fusion talditercept alfa are also being investigated (IUPHAR record).
Clinical development of myostatin blockers
ClinicalTrials.gov lists 35 studies naming myostatin as of September 2026. Among the interventional programmes: apitegromab (Scholar Rock) in phase 3 long-term studies in spinal muscular atrophy (NCT05626855) and phase 2 in facioscapulohumeral muscular dystrophy (NCT07435129); trevogrumab alone or with garetosmab, given with semaglutide, in a phase 2 obesity trial (NCT06299098, Regeneron) — testing whether blocking myostatin preserves muscle during incretin-driven weight loss; and an AAV-follistatin gene therapy for age-related muscle decline (NCT07443826). Circulating myostatin is also under study as a prognostic marker, for instance in cirrhosis and acute-on-chronic liver failure (Ruiz-Margáin et al., JHEP Reports 2023).
“Myostatin inhibitor” peptides online
Products sold as myostatin inhibitors — follistatin fragments, “GDF-8 blockers”, or peptides with invented names — are not the antibodies in clinical trials, have no published human data, and are not approved anywhere. Myostatin itself is a folded, disulfide-linked protein of the TGF-β family, not a short synthetic peptide, and PubChem holds no compound record for it. This profile is educational and is not guidance on obtaining or using any product.
Related peptides on this site
Growth-hormone secretagogues (sermorelin, ipamorelin, CJC-1295) act on muscle through the GH/IGF-1 axis rather than by removing the myostatin brake; the two mechanisms are distinct and no trial has combined them. The semaglutide profile covers the incretin drug with which myostatin blockers are now being tested.
Structure & chemistry
Molecular identity & reference confidence
Reference mass unavailable
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Myostatin (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- IUPHAR/BPS source snapshot · 2026-09-07
- Receptors
- Activin type II receptor ACVR2B (also ActRIIA); canonical SMAD2/3 signalling plus non-canonical pathways
- Status
- Endogenous protein — a drug target, not a drug; anti-myostatin antibodies in phase 2–3 trials
- IUPHAR ligand: 5025
Chemistry values: curated profile, IUPHAR/BPS Guide to Pharmacology · fetched 2026-09-07.
Clinical development snapshot
ClinicalTrials.gov lists 35 registered studies with “Myostatin” as an intervention (snapshot 2026-10-01). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT07804719 | Possible Sarcopenia, Sarcopenia, and Functional Status in Patients With Primary Sjögren's Syndrome | — | active not recruiting | 2026-09-24 |
| NCT07047144 | A Study to Evaluate How Apitegromab Works in Subjects Who Are Less Than 2 Years Old and Have Spinal Muscular A | Phase 2 | recruiting | 2026-09-14 |
| NCT07435129 | Phase 2 Study Evaluating Apitegromab for the Treatment of FSHD | Phase 2 | recruiting | 2026-09-02 |
| NCT05626855 | Long-Term Safety & Efficacy of Apitegromab in Patients With SMA Who Completed Previous Trials of Apitegromab | Phase 3 | active not recruiting | 2026-09-01 |
| NCT06299098 | A Study to Test if Trevogrumab or Trevogrumab With Garetosmab When Taken With Semaglutide is Safe and How Well | Phase 2 | active not recruiting | 2026-09-01 |
| NCT07443826 | CALM-AF-AI: Counteracting Age-related Loss of Muscle With AAV-Follistatin Combined With Angiogenesis-Inducing | Phase 2 | recruiting | 2026-07-13 |
Change log
Dated observations from the data pipeline (registry flags, trial footprints, identifiers) and editorial reviews of this profile.
- IdentifiersCross-linked to IUPHAR ligand 5025.
- TrialsClinicalTrials.gov snapshot added: 35 registered studies, highest phase 3.
- EditorialProfile content reviewed and updated by the editorial team.
FAQ about Myostatin
What is Myostatin?+
Myostatin (GDF-8) is a TGF-β-superfamily protein made by skeletal muscle that circulates and acts back on muscle to limit its growth, signalling through activin type II receptors (ACVR2B) and the SMAD pathway. Removing it causes marked muscle hypertrophy in animals, which is why antibodies and receptor blockers that neutralise it are in clinical trials for muscle-wasting diseases and, combined with semaglutide, for obesity.
What Canadian product status is recorded for Myostatin?+
Canadian product status for Myostatin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Myostatin?+
Myostatin is not a classic amino-acid chain peptide in the same sense; see the profile for classification details.
What is myostatin?+
A TGF-β-family protein (GDF-8) made by skeletal muscle that circulates and limits muscle growth by activating activin type II receptors and SMAD signalling — a muscle chalone.
What happens if myostatin is blocked?+
In animals, removing or neutralising it produces strong muscle hypertrophy and protects against atrophy. Anti-myostatin and anti-ActRII antibodies are in phase 2–3 trials for muscle-wasting diseases and, with semaglutide, for obesity.
Is there an approved myostatin inhibitor?+
Not as of September 2026 in the packs reviewed here; apitegromab is in phase 3 for spinal muscular atrophy and bimagrumab and trevogrumab are in trials.
Are the “myostatin inhibitor peptides” sold online real?+
They are not the clinical antibodies, have no human data, and are unapproved. Myostatin is a protein, not a short peptide.
Related peptides
References & further reading
- 1.Lee (2023). Myostatin: A Skeletal Muscle Chalone. Annual Review of Physiology
- 2.Esposito et al. (2022). Myostatin: Basic biology to clinical application. Advances in Clinical Chemistry
- 3.Sharma et al. (2015). Myostatin: expanding horizons. IUBMB Life
- 4.Lach-Trifilieff et al. (2014). An antibody blocking activin type II receptors induces strong skeletal muscle hypertrophy and protects from atrophy. Molecular and Cellular Biology
- 5.Muramatsu et al. (2021). Novel myostatin-specific antibody enhances muscle strength in muscle disease models. Scientific Reports
- 6.Kong et al. (2018). Brown Adipose Tissue Controls Skeletal Muscle Function via the Secretion of Myostatin. Cell Metabolism
- 7.Knapp et al. (2023). Myostatin and the Heart. Biomolecules