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What Is ACE-031? Benefits, Research & Safety
A myostatin/activin decoy receptor designed to promote muscle growth, researched for muscular dystrophy but development discontinued.
Also known as:
ActRIIB-Fc
Activin Receptor Type IIB Fusion Protein
Educational Content Only: This page provides research-based information for educational purposes. ACE-031 is not an approved medicine. This is not medical advice. Always consult a qualified healthcare professional.
Quick Facts
Category
Hormonal & Endocrine
Half-Life
Extended due to Fc fusion (approximately 10-14 days)
UK Status
Not approved. Development discontinued.
EU Status
Development discontinued. Not available.
Overview
ACE-031 is a soluble fusion protein consisting of the extracellular domain of activin receptor type IIB (ActRIIB) fused to human IgG1 Fc. It functions as a "decoy receptor" or "ligand trap," binding to and neutralising myostatin, activins, and other TGF-β family ligands that normally inhibit muscle growth.
By sequestering myostatin and related factors, ACE-031 was designed to remove the natural limits on muscle development, potentially offering benefit for conditions characterised by muscle wasting such as muscular dystrophy, cancer cachexia, and sarcopenia.
Acceleron Pharma developed ACE-031 specifically for Duchenne muscular dystrophy (DMD). Early trials showed promising increases in lean body mass. However, development was halted after safety signals emerged, including nosebleeds, gum bleeding, and telangiectasias (dilated blood vessels in skin).
Despite ACE-031's discontinuation, the approach of ActRIIB blockade continues to be researched. Related compounds and alternative myostatin inhibitors remain in development for various conditions.
ACE-031 represented an important proof-of-concept for myostatin inhibition approaches, even though it did not achieve clinical approval.
Discovery & History
The myostatin inhibition field began with Se-Jin Lee's discovery of myostatin in 1997 and the observation that myostatin-null animals developed massive muscle hypertrophy. This immediately suggested therapeutic potential for muscle wasting conditions.
Multiple approaches to myostatin inhibition were developed, including antibodies, propeptides, and decoy receptors. The ActRIIB decoy approach was attractive because it could neutralise not only myostatin but also other inhibitory ligands like activins.
Acceleron Pharma developed ACE-031 as a fusion of ActRIIB with an antibody Fc domain, providing good pharmacokinetic properties and allowing subcutaneous administration.
Phase I trials in healthy volunteers showed ACE-031 increased lean body mass, confirming proof of concept. Phase II trials in Duchenne muscular dystrophy patients began with encouraging early results.
However, in 2013, Acceleron announced discontinuation of ACE-031 development due to safety concerns. Patients experienced nosebleeds and telangiectasias, believed related to effects on BMP9, a ligand involved in blood vessel integrity that also binds to ActRIIB.
Acceleron continued developing related compounds with different ligand binding profiles. ACE-083 (local muscle administration) and other agents are being explored. The company's experience with ACE-031 informed development of luspatercept (approved for anemia), which is related but has different activity.
Mechanism of Action
ACE-031 functions as a soluble decoy receptor:
**Ligand Trap Mechanism**
ACE-031 binds to and sequesters multiple TGF-β family ligands:
- Myostatin: Primary target for muscle growth inhibition
- Activin A and B: Also inhibit muscle growth
- GDF11: Related to myostatin
- BMP9: Involved in vascular biology (associated with side effects)
**Effects on Muscle**
By neutralising inhibitory ligands:
- Removes brake on muscle protein synthesis
- Promotes satellite cell activation
- Increases muscle fiber size (hypertrophy)
- May also increase muscle fiber number (hyperplasia)
- Improves muscle strength proportional to mass gains
**Broader TGF-β Effects**
Effects beyond muscle due to activin and other ligand binding:
- Bone: Activin inhibition may affect bone metabolism
- Fat: Potential effects on adipose tissue
- Other tissues: Diverse effects possible
**Vascular Effects (Safety Concern)**
Binding to BMP9 disrupted endothelial function:
- BMP9 is important for blood vessel integrity
- Loss of BMP9 signaling led to telangiectasias
- Nosebleeds and gum bleeding resulted
- This led to development discontinuation
[Molecular Structure Diagram Placeholder]
Researched Benefits
Based on preclinical and clinical research findings:
- 1Significant increases in lean body mass (demonstrated in trials)
- 2Proof of concept for myostatin inhibition
- 3Potential for muscular dystrophy treatment (not realized)
- 4Increased muscle strength parallel to mass gains
- 5Informed development of related therapeutics
Theoretical Dosing & Protocols
⚠️ Educational Only: The following information is derived from research literature and is not a prescription or recommendation. No standardised human dosing exists. Always consult a qualified healthcare professional.
| Theoretical Dosage | Clinical trials used doses up to 3 mg/kg |
| Frequency | Every two weeks in trials |
| Duration | Development discontinued; no established protocols |
| Notes | ⚠️ ACE-031 development was discontinued due to safety concerns. It is not available for therapeutic use. This information is provided for educational purposes about the history of myostatin inhibition research. |
Administration Routes
Routes studied in research settings (educational only):
- Subcutaneous injection (clinical trials)
| Half-Life | Stability |
|---|---|
| Extended due to Fc fusion (approximately 10-14 days) | Standard protein handling requirements |
Safety Profile & Known Risks
Commonly Reported Side Effects
- Nosebleeds (epistaxis)
- Gum bleeding
- Telangiectasias (dilated blood vessels in skin)
- Injection site reactions
Rare Risks & Concerns
- Development discontinued due to vascular safety signals
- Long-term effects unknown
- Effects on other TGF-β pathways
Contraindications
- Development discontinued—not available for use
- History of bleeding disorders would have been concerning
UK & EU Regulatory Context
🇬🇧 United Kingdom
Not approved. Development discontinued.
🇪🇺 European Union
Development discontinued. Not available.
ACE-031 development was halted by Acceleron Pharma in 2013 due to vascular safety concerns. It never achieved regulatory approval. Related research continues with modified approaches.
Clinical Studies Summary
ACE-031 in Healthy Volunteers
Phase I trial showing increased lean body mass and reduced fat mass with ACE-031.
Clinical pharmacology journalsView on PubMed
ACE-031 in Duchenne Muscular Dystrophy
Phase II trial results before discontinuation.
Neuromuscular disease journalsView on PubMed
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