ACE-031
A soluble activin receptor type IIB (ActRIIB) fusion protein that functions as a myostatin and activin A trap. Developed for treatment of muscle wasting diseases, including muscular dystrophy and cachexia. Acts by sequestering myostatin and activin A, negative regulators of muscle growth.
Research Status
Limited Clinical Data
For research purposes only. Not approved for human use. Not medical advice.
Research Areas
Side Effects
Observed in clinical trials. Likely due to activin A inhibition, which normally suppresses hepcidin and iron metabolism. Requires regular hematologic monitoring. May increase thrombotic risk if severe.
Observed in animal studies at high doses. Manifested as sensory neuropathy and neuronal degeneration. Human incidence unclear; clinical trials were paused partly due to this signal. Requires neurological assessment if symptoms develop.
Erythema, induration, or mild pain at injection site. Typical of SC protein therapeutics. Rotate injection sites to minimize.
Reported in clinical trials. Usually self-resolving. Monitor frequency and severity.
Reported in some trial participants. May be related to systemic effects of myostatin/activin inhibition or polycythemia.
Anecdotally reported in trials. Mechanism unclear; may relate to altered TGF-β signaling in connective tissue.
Isolated cases reported in clinical trials. Polycythemia and altered hemodynamics may increase thrombotic or ischemic risk. Requires baseline and periodic cardiovascular assessment.
Dosing Reference
| Parameter | Value |
|---|---|
| Dose range | 1-3 mg/kg |
| Frequency | Every 2 weeks |
| Timing | Administered by healthcare provider |
| Route | Intravenous, Subcutaneous |
Research compound. Clinical trials paused due to safety signals including cardiovascular concerns and dorsal root ganglion toxicity in animal studies. Not approved for human use outside clinical trials.
Research disclaimer
Figures drawn from published research literature and community logs. Not clinical recommendations. Consult a qualified professional. Research use only.
Reconstitution Guide
Do not use saline or bacteriostatic saline — use only bacteriostatic water for reconstitution
Do not shake the vial vigorously; gentle swirling prevents peptide degradation
Discard immediately if the solution appears cloudy, discolored, or contains visible particles
Use within 30 days of reconstitution when stored at 2–8°C
Do not freeze the reconstituted solution; freezing may denature the peptide
Use the PeptideVolt reconstitution calculator for your exact concentration
Molecular and Pharmacological Data
| Molecular weight | 110 kDa (approximately) |
| Half-life | 3-5 days (estimated from preclinical data; human half-life not definitively established due to trial discontinuation) |
ACE-031 is a soluble ActRIIB receptor ectodomain that acts as a ligand trap, binding and sequestering myostatin and activin A—two TGF-β superfamily members that negatively regulate muscle growth. By removing these inhibitory signals, ACE-031 permits increased muscle protein synthesis and hypertrophy, particularly in conditions characterized by elevated myostatin or activin A signaling.
Myostatin/Activin A Inhibition
ACE-031 binds myostatin and activin A with high affinity, preventing their interaction with ActRIIB on muscle cells. This blocks SMAD2/3 phosphorylation and downstream anti-myogenic signaling, allowing unopposed myogenic differentiation and protein synthesis.
Muscle Protein Synthesis Upregulation
Relief of myostatin-mediated inhibition permits increased mTORC1 signaling and protein translation in myocytes, leading to net muscle hypertrophy.
Satellite Cell Activation
Reduced myostatin signaling enhances satellite cell proliferation and differentiation, supporting muscle regeneration and repair.
- ACE-031 is a recombinant fusion protein, not a small-molecule drug or traditional peptide
- Preclinical studies in mdx mice (muscular dystrophy model) showed significant increases in muscle mass and strength
- Clinical development was halted after Phase IIb trials due to safety concerns, including increased hemoglobin and hematocrit, and potential dorsal root ganglion toxicity observed in animal studies
- Myostatin and activin A are both ligands for ActRIIB; ACE-031 traps both, distinguishing it from myostatin-specific inhibitors
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