Peptides
ACE-031
An activin-receptor fusion protein with early muscle-mass findings, a stopped Duchenne trial and important product-identity concerns.
Compound-specific research / important limitations
Also known as: ramatercept
Practical use
Applying the explained evidence
- Where it fits
- An activin-receptor fusion protein with early muscle-mass findings, a stopped Duchenne trial and important product-identity concerns.
- Put the information into practice
- Read the healthy-volunteer, disease-specific and product-analysis studies separately. Each supplies a different piece of the evidence.
- Check what was actually tested
- Match the exact molecule, formulation and study setting to the claim. A result for a related peptide, a cell model or an animal model does not establish the same result for a marketed human-use product.
- Keep this limit in view
- Small early study, selected population, short follow-up. Lean mass and MRI muscle volume are not automatically improved function or established long-term benefit.
Overview
ACE-031 combines part of activin receptor type IIB with an IgG1 Fc component. It binds myostatin and related ligands rather than acting as a muscle-specific switch.
Risks and limitations
The Duchenne trial stopped because of concerns including nosebleeds and visible small-vessel changes. Products sold under its name may not contain the studied fusion protein. Neither a promising muscle measurement nor a research label resolves those issues.
How to read this
Read the healthy-volunteer, disease-specific and product-analysis studies separately. Each supplies a different piece of the evidence.
Research explained
Early healthy-volunteer study
Who was studied
48 healthy postmenopausal women in a randomized double-blind placebo-controlled single-administration study.
What was found
At day 29, the highest-exposure group showed a 3.3% increase in total lean mass and a 5.1% increase in thigh muscle volume; both P=0.03. Reported mean half-life was 10–15 days.
What it cannot establish
Small early study, selected population, short follow-up. Lean mass and MRI muscle volume are not automatically improved function or established long-term benefit.
Read the original studyDuchenne muscular dystrophy trial
Who was studied
A randomized placebo-controlled ascending-dose trial in ambulatory boys with Duchenne muscular dystrophy.
What was found
The study was stopped after the second regimen because of potential safety concerns involving epistaxis and telangiectasias. Six-minute-walk and body-composition signals were trends; the walk-test difference was not statistically significant.
What it cannot establish
An encouraging trend must not be reported as proven efficacy. The published abstract distinguishes these safety concerns from serious or severe adverse events, which were not reported.
Read the original studyProducts marketed as ACE-031
Who was studied
Laboratory analysis of 14 black-market products; no human efficacy experiment.
What was found
Twelve contained an activin-receptor-reactive protein, but further analysis identified full-length receptor rather than the intended ACE-031 Fc-fusion protein. Additional proteins were also present.
What it cannot establish
A selected sample cannot estimate the failure rate of every vendor. It directly shows why a label or matching protein reaction alone does not establish product identity.
Read the original studyTargeting a pathway can affect more than muscle
The drug binds multiple negative regulators of muscle mass. The clinical program therefore has to assess effects outside muscle, rather than infer safety from a desired anabolic signal. The stopped trial illustrates why function and adverse events matter alongside imaging outcomes.
Supporting sourceComposition belongs in the evidence chain
If a marketed product differs from the material used in a trial, the trial’s results cannot simply be applied to it. Identity, purity and biological activity are separate questions; an assay that detects one protein feature does not settle all three.
Supporting sourceSources
Duchenne muscular dystrophy trial
Sources checked 2026-09-28.
General education; not a personal treatment plan.