ACE-031
Evidence: B-/C+ — Meaningful Human EvidenceRepair / Tissue Healing
Evidence Snapshot
What this grade covers
A for molecular identity; B for short human pharmacodynamic studies; C/D for disease efficacy; E for approved therapy, bodybuilding, performance, or dosing claims.
Regulatory Context
Investigational activin receptor type IIB ligand trap; not FDA-approved. The clinical development program was terminated after safety findings.
Research Takeaway
ACE-031 (ramatercept) is a soluble activin receptor type IIB-Fc fusion protein designed to sequester myostatin and related TGF-beta-family ligands; it is not a short peptide and should not be classified as one.
Evidence boundary: This mechanism does not establish safe or effective muscle enhancement in healthy people.
See all 6 evidence claims →Quick Summary
ACE-031 (ramatercept) is a soluble activin receptor type IIB–Fc fusion protein studied as a broad ligand trap intended to increase skeletal muscle mass. Small human studies documented pharmacodynamic effects, but the Duchenne muscular dystrophy program ended early after vascular-type adverse findings.
Mechanism & Research Overview
ACE-031 is an engineered soluble form of activin receptor type IIB fused to an Fc domain. It binds multiple TGF-beta superfamily ligands, including myostatin, and reduces signaling that ordinarily restrains skeletal-muscle growth. This broader ligand binding distinguishes it from a myostatin-only inhibitor and may also contribute to off-target effects.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
ACE-031 (ramatercept) is a soluble activin receptor type IIB-Fc fusion protein designed to sequester myostatin and related TGF-beta-family ligands; it is not a short peptide and should not be classified as one.
Does not establish
Evidence boundary: This mechanism does not establish safe or effective muscle enhancement in healthy people.
Sources: A single ascending-dose study of muscle regulator ACE-031 in healthy postmenopausal volunteers; Gel Electrophoretic Detection of Black Market ACE-031
Supported
Human studies demonstrated pharmacodynamic increases in lean or muscle-volume measures after ACE-031 exposure.
Does not establish
Evidence boundary: Changes in muscle-volume biomarkers do not establish durable functional benefit or an approved enhancement indication.
Sources: A single ascending-dose study of muscle regulator ACE-031 in healthy postmenopausal volunteers; Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial
Supported
ACE-031 is not an FDA-approved drug, and its Duchenne muscular dystrophy clinical program was terminated after safety findings.
Does not establish
Evidence boundary: Termination of this program does not establish that all activin-pathway drugs share the same safety profile.
Sources: Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial; Study of ACE-031 in Subjects With Duchenne Muscular Dystrophy
Supported
Clinical development identified adverse findings including epistaxis and telangiectasias that contributed to termination of the Duchenne muscular dystrophy study.
Does not establish
Evidence boundary: These findings do not quantify risk from an unverified grey-market product whose identity may differ.
Sources: Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial; Study of ACE-031 in Subjects With Duchenne Muscular Dystrophy
Supported
Analytical testing of products sold on the black market as ACE-031 found major identity failures, including full-length activin receptor IIB rather than authentic ACE-031 Fc-fusion protein.
Does not establish
Evidence boundary: This does not prove every grey-market product is mislabeled, but it prevents assuming equivalence.
Sources: Gel Electrophoretic Detection of Black Market ACE-031
Supported
Only dosing explicitly reported in a named clinical trial may appear as Study/Trial Dosing; consumer dosing, cycling, reconstitution, or injection instructions are prohibited.
Does not establish
Evidence boundary: Historical trial exposure must not be converted into a performance-enhancement protocol.
Sources: A single ascending-dose study of muscle regulator ACE-031 in healthy postmenopausal volunteers; Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Safety Consideration
Epistaxis and telangiectasias were reported in the Duchenne muscular dystrophy program, which was stopped early.Safety Consideration
The ligand trap binds more than myostatin, so biological effects may extend beyond skeletal muscle.Safety Consideration
Human evidence is limited to small early-phase studies; long-term cardiovascular, vascular, reproductive, and other systemic risks remain uncertain.Safety Consideration
ACE-031 must not be conflated with ACE-083, follistatin, or myostatin itself.Safety Consideration
Because ACE-031 binds multiple TGF-beta-superfamily ligands rather than myostatin alone, unresolved concerns include reproductive and fertility effects, developmental and pregnancy risks, endocrine and metabolic effects, bone effects, hepatic and renal effects, neoplasm and proliferative-signaling uncertainty, thrombosis or bleeding beyond the observed epistaxis/telangiectasia findings, blood-pressure and cardiovascular effects, immunogenicity and anti-drug antibodies, Fc-related or aggregate-related immune effects, and unknown long-term or repeated-dose safety. Nonclinical/marketplace-product identity, glycosylation, aggregation, sterility, endotoxin, and potency are also uncertain. Increased muscle volume is not a safety endpoint.
Research Areas Being Studied
Research areas discussed on this page reflect the Repair / Tissue Healing category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial (2017):
- A single ascending-dose study of muscle regulator ACE-031 in healthy postmenopausal volunteers (2013):
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial | 2017 | Ambulatory boys with Duchenne muscular dystrophy | ACE-031 was studied in ambulatory boys with Duchenne muscular dystrophy. The program identified pharmacodynamic muscle effects but the trial was terminated after safety findings including epistaxis and telangiectasias.
| The trial/program was stopped after safety findings including epistaxis and telangiectasias. | |
| A single ascending-dose study of muscle regulator ACE-031 in healthy postmenopausal volunteers | 2013 | 48 healthy postmenopausal women | ACE-031, an activin receptor type IIB-Fc fusion protein, produced dose-dependent increases in lean body mass and thigh muscle volume after a single dose in healthy postmenopausal women. The study was primarily a safety, pharmacokinetic, and pharmacodynamic study and did not establish a therapeutic or performance-enhancement indication.
| Single-dose exposure and a small healthy-volunteer sample limit conclusions about repeated-use or long-term safety. |
Animal / Cell / Preclinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Gel Electrophoretic Detection of Black Market ACE-031 | 2025 | Testing of 14 black-market products sold as ACE-031 found major identity failures; 12 contained ACVR2B-immunoreactive material, but analyses indicated full-length activin receptor IIB rather than authentic ACE-031 Fc-fusion protein. | |||
| Administration of a soluble activin type IIB receptor promotes skeletal muscle growth independent of fiber type | 2010 | Rodent skeletal-muscle models | A soluble activin type IIB receptor ligand trap increased skeletal muscle growth across fiber types in preclinical models. | Animal findings do not establish clinical benefit or safety in humans. |
Regulatory Documents & Official Trial Registries
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| 2026 World Anti-Doping Code International Standard: Prohibited List (ActRIIB Competitors) | 2026 | The 2026 WADA Prohibited List explicitly includes activin receptor IIB competitors, such as decoy activin receptors, with ACE-031 given as a named example. Anti-doping prohibition is separate from FDA approval and clinical efficacy. | |||
| Extension study of ACE-031 in subjects with Duchenne muscular dystrophy | 2010 | Participants with Duchenne muscular dystrophy | Extension-study registry record; the study was terminated. | The extension was terminated following preliminary safety information from the development program. | |
| Study of ACE-031 in Subjects With Duchenne Muscular Dystrophy | 2010 | Boys with Duchenne muscular dystrophy | The registry documents the randomized DMD study and states that it was terminated based on safety data. Trial registration does not establish approval. | The registry reports termination based on safety information. | |
| Multiple ascending-dose study of ACE-031 in healthy postmenopausal women | 2009 | Healthy postmenopausal women | Official registry record for repeated exposure; registry data are not equivalent to a peer-reviewed outcome publication. | ||
| A safety, tolerability, pharmacokinetic and pharmacodynamic study of ACE-031 in healthy postmenopausal women | 2008 | Healthy postmenopausal women | Official registry for the single-ascending-dose phase 1 study. Registry status and posted details should be read separately from publication findings. |
Review Articles / Secondary Sources
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Myostatin Inhibitors: Panacea or Predicament for Musculoskeletal Disorders? | A review of myostatin/ActRIIB-pathway inhibitors situates ACE-031 as a broad soluble ActRIIB ligand trap distinct from selective myostatin-only antibodies, and summarizes that its Duchenne muscular dystrophy development program was discontinued after safety findings. The review does not establish that ACE-031, ACE-083, or other ActRIIB/myostatin-pathway agents are interchangeable or that any is approved or safe for human muscle-building use. |
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
Educational information only. This page summarizes published and official research and does not provide medical advice, a recommendation, or instructions for human use.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Content pending review. Last updated 2026-07-30.
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