ACE-031

Myostatin inhibitor · Also known as ACVR2B-Fc, Soluble Activin Receptor Type IIB

What is ACE-031?

A soluble activin receptor decoy that traps myostatin and other TGF-beta family ligands, preventing them from signaling muscle growth inhibition.

ACE-031 is a fusion protein combining the extracellular domain of the activin type IIB receptor with the Fc portion of an antibody. It acts as a trap for myostatin, activin, and GDF-11, all of which normally limit muscle growth.

Key takeaway: ACE-031 showed rapid muscle gains in early trials but was discontinued for muscular dystrophy due to off-target effects on blood vessels. It remains of interest in research.

Benefits & evidence

Muscle growth Moderate confidence
Lean mass increase Moderate confidence

How it works

Myostatin is the body's natural brake on muscle growth. ACE-031 works as a decoy receptor that binds myostatin and related ligands before they can reach their actual receptors on muscle cells. With myostatin neutralized, muscle protein synthesis increases and muscle fibers grow larger.

In a Phase 2 trial for Duchenne muscular dystrophy, subjects gained an average of 1.7% lean body mass in just 4 weeks. However, the trial was halted due to minor nosebleeds and gum bleeding, likely from effects on blood vessel growth factors.

Dosing information

Typical dosing protocol
Starting dose

Not well established

Maintenance dose

Not well established


Clinical trials used IV infusions. No established subcutaneous dosing protocol.

Side effects

Most side effects tend to improve as your body adjusts.

Nosebleeds Moderate
Gum bleeding Moderate
Dilated blood vessels Moderate

Research (10 studies)

Gel Electrophoretic Detection of Black Market ACE-031. Drug testing and analysis · 2025
Combinatorial Inhibition of Myostatin and Activin A Improves Femoral Bone Properties in the G610C Mouse Model of Osteogenesis Imperfecta. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research · 2022
Skeletal Response to Soluble Activin Receptor Type IIB in Mouse Models of Osteogenesis Imperfecta. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research · 2018