Soluble activin receptor type IIB (ActRIIB) fusion protein — potent myostatin pathway inhibitor. Studied for Duchenne muscular dystrophy and muscle wasting. Dramatically increases lean mass in human trials before safety pause.
ACE-031 is a research compound that was developed to block a signaling pathway called ActRIIB, which normally limits muscle growth. It was studied primarily in the context of muscle-wasting diseases. Human trials were conducted but were halted early due to side effects, and development has not advanced further.
Muscle Wasting Disease Research
ACE-031 was studied in conditions like Duchenne muscular dystrophy and other diseases where muscle wasting is progressive. Phase 2 trials in children with Duchenne muscular dystrophy were initiated, examining whether blocking the myostatin pathway could preserve muscle.
Muscle Mass and Strength
In the adult healthy volunteer phase 1 trial, ACE-031 produced measurable increases in lean body mass over a short treatment period. Researchers were examining its potential to counter muscle loss in aging and chronic disease.
Bone Density
Because the ActRIIB pathway also influences bone metabolism, researchers observed effects on bone density markers in some trial participants, suggesting cross-tissue activity beyond just muscle.
Increases in lean body mass observed in a phase 1 trial in healthy adults.
Phase 2 trials in Duchenne muscular dystrophy patients were halted due to side effects including nosebleeds and vascular-related events.
Changes in bone density markers observed, indicating effects beyond muscle tissue.
Development was discontinued before trials could demonstrate meaningful clinical outcomes.
ACE-031 trials were stopped due to safety signals — specifically, bleeding events and changes to blood vessel-related markers in participants. Development has not continued, and there is no approved use or established safe dose for this compound. The halted trial history is an important piece of context for anyone researching this compound.
Muscle growth is partly regulated by a group of proteins that act as natural brakes on how big muscles can get. Myostatin is the most well-known of these, and it signals through a receptor called ActRIIB. ACE-031 was designed as a decoy receptor — a soluble version of ActRIIB that soaks up these brake signals before they reach muscle cells. In theory, this frees muscle cells to grow more than they normally would. The problem is that the same pathway regulates other tissues too, including blood vessels, which contributed to the side effects seen in trials.
Clinical trials of ACE-031 were halted due to adverse events including epistaxis (nosebleeds) and signs of vascular-related activity in participants. The safety concerns that ended development are an essential part of this compound's research history. It is not approved for any use and is not being actively developed as of the most recent published data.
Preliminary
Most evidence comes from preclinical studies and case reports. Human data is limited and more research is needed.
Published Research Ranges
1–3mg/kg monthly SC in phase 2 studies; dramatic lean mass gains at low doses
Research Context Only: These are ranges reported in published scientific studies for educational reference. They are not dosing recommendations. This is not medical advice. Always consult a qualified healthcare professional.
Sources listed here are from the platform research library. All links open the original publication. No citations are generated by AI.
ACE-031 (ACVR2B-Fc) Increases Muscle Mass in Healthy Men: Phase 2 Results
European Heart Rhythm Association (EHRA)/Heart Rhythm Society (HRS)/Asia Pacific Heart Rhythm Society (APHRS)/Latin American Heart Rhythm Society (LAHRS) Expert Consensus Statement on the state of genetic testing for cardiac diseases
Anti-Inflammatory and General Glucocorticoid Physiology in Skeletal Muscles Affected by Duchenne Muscular Dystrophy: Exploration of Steroid-Sparing Agents
Research Education Only: This profile is for educational purposes only. All information is sourced from published scientific literature. This is not medical advice. Not for human consumption. Consult qualified medical professionals for any health decisions.
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