ACE-031

Muscle In trials Human trials

Also called Ramatercept, ActRIIB-Fc

A lab-made fusion protein that joins part of the activin type IIB receptor to an antibody fragment. It works as a decoy: myostatin and related signals that hold back muscle growth bind to it instead of to muscle. It was tested in Duchenne muscular dystrophy.

Evidence at a glance

Evidence: Human trials — Studied in people
Status: Reached clinical trials
Dosing: No human study has set a dose

Trials halted in 2011 over nosebleeds and gum bleeding from off-target effects on blood vessels.

What studies report

Increased lean muscle mass and bone density in early human trials
Raised muscle volume on MRI in boys with Duchenne muscular dystrophy

How it works

A decoy. It is the activin type IIB receptor fused to an antibody fragment, so myostatin and activin bind it in the bloodstream and never reach the receptors on muscle that would otherwise restrain growth.

Binds a receptor on the cell surface and signals inward

Where it acts

Skeletal muscle

The library groups this compound under Muscle. The diagram shows that target, not every tissue it reaches.

Illustrated

Transverse section of skeletal muscle showing polygonal muscle fibres and delicate surrounding connective tissue, macro view.

AI-generated subject illustration; not a depiction of the compound or evidence of its effects.

Why people take it

Muscle growthMuscular dystrophy research

Reasons people seek it out — not a list of proven effects.

In practice Unapproved use

Largely abandoned after the trial safety signal; rarely used now

Reported real-world use, not evidence and not a recommendation.

Status: Clinical trials were stopped in 2011 after nosebleeds and gum bleeding were seen. Not approved.

Route: Subcutaneous injection, from reconstituted lyophilised powder
Available as: 1 mg

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Educational information only. Nothing here is medical advice, a dosing protocol, or a recommendation to use any compound. Most entries describe substances not approved for human use. Talk to a licensed clinician before acting on anything you read here. How to read these entries.