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Muscle growth researchNot approved (US)

ACE-031

Ramatercept

The extracellular portion of activin receptor type IIB is joined to IgG1-Fc to form a soluble ligand trap. Binding myostatin (GDF-8), activins and related ActRIIB ligands removes inhibition of muscle satellite-cell activation and muscle-fiber enlargement. Unintended binding of BMP9 can disrupt vascular remodeling and is implicated in the bleeding complications that stopped development.

Not medical advice. Educational reference only.

Typical dose
0.02–3 mg/kg in Phase 1 trials
Route
Subcutaneous injection
Storage
Keep refrigerated at 2–8 °C and use within 28 days.

What is ACE-031?

ACE-031, also called ramatercept, is a soluble fusion protein combining ActRIIB with Fc. It captures myostatin and other TGF-β superfamily ligands, releasing their restraint on muscle growth. In Phase 1 studies, healthy volunteers gained lean mass and thigh muscle volume. Phase 2 development investigated Duchenne muscular dystrophy.

Development ended after vascular adverse events, including nosebleeds and telangiectasias, associated with unintended BMP9 inhibition. ACE-031 has no FDA approval or established safe consumer dose. Its history of bleeding complications demands extreme caution.

Mechanism of action

The extracellular portion of activin receptor type IIB is joined to IgG1-Fc to form a soluble ligand trap. Binding myostatin (GDF-8), activins and related ActRIIB ligands removes inhibition of muscle satellite-cell activation and muscle-fiber enlargement. Unintended binding of BMP9 can disrupt vascular remodeling and is implicated in the bleeding complications that stopped development.

Targets: Myostatin (GDF-8) · Activins · BMP9

Research indications

  • Tissue Repair

    Most effective

    Research investigates faster wound closure and repair of damaged soft tissue.

  • Gut Health

    Effective

    Potential gastrointestinal effects include support for intestinal lining integrity and digestive function.

  • Joint Support

    Effective

    Joint-related research examines lower inflammation together with better mobility.

  • Muscle Recovery

    Moderate

    Possible benefits include quicker recovery from muscle strains and stress associated with exercise.

Research protocols

These are commonly discussed research protocols — not medical advice. Consult a healthcare provider before use.

GoalAmountFrequencyRoute
Phase 1 Trial Context (healthy volunteers)0.02–3 mg/kgSingle ascending dose / infrequentSubcutaneous injection

Interactions

  • Anticoagulants / antiplatelets

    Avoid

    Bleeding risk increases with anticoagulants or antiplatelet drugs.

  • Follistatin-344 / other myostatin inhibitors

    Avoid

  • NSAIDs (bleeding risk)

    Caution

    NSAIDs can add to the bleeding risk that halted clinical development.

  • IGF-1 LR3

    Caution

  • TB-500

    Monitor

  • BPC-157

    Compatible

How to reconstitute and inject

Diluent: Use bacteriostatic water only; avoid saline because it may cause precipitation.

  1. Take the ACE-031 vial out of the refrigerator and leave it for 15–20 minutes to reach room temperature.
  2. Disinfect the vial stopper with an alcohol swab. Wait until the alcohol has completely air-dried.
  3. Measure the calculated amount of bacteriostatic water into a sterile syringe. Use only bacteriostatic water; avoid saline because precipitation may occur.
  4. Add the water slowly along the inner wall of the vial. Keep the stream away from the powder itself.
  5. Rotate the vial gently to mix its contents. Never shake it vigorously, because this can degrade the peptide.
  6. Wait 2–3 minutes for the powder to dissolve completely. Check that the liquid is clear and has no color.
  7. Withdraw the calculated dose into an insulin syringe for administration beneath the skin.
  8. Inject into your abdomen, thigh or upper arm. Change the injection site each time to help prevent lipodystrophy.
  9. Refrigerate the mixed solution at 2–8 °C. Use it within 28 days after reconstitution.

What to expect

Week 1–2
Early anti-inflammatory effects may reduce pain and swelling around the affected tissue.
Week 2–4
Tissue mobility may improve as discomfort decreases and healing begins to progress more rapidly.
Week 4–8
Recovery may reach more substantial milestones, with better tissue repair and improved function.
Week 8–12
Later expectations include near-complete healing in many cases, increased strength and better tissue integrity. These intervals are research expectations, not established individual outcomes.

Side effects and safety

  • Nosebleeds and telangiectasias were bleeding complications that stopped clinical development.
  • Changes in blood-vessel remodeling are linked to unintended inhibition of BMP9.
  • Combining with anticoagulants, antiplatelet drugs or NSAIDs increases bleeding risk.
  • Redness, bruising or discomfort can occur at injection sites.

ACE-031: not approved in the US.

Regulatory status

  • US

    Not approved

    FDA — no approval; clinical development stopped after bleeding-related adverse events.

    Rx required
    No
    503A
    Allowed
    Telehealth
    N/A

Frequently asked questions

What is ACE-031?

Ramatercept is an engineered ActRIIB-Fc receptor trap that captures myostatin and related TGF-β ligands. Phase 1 trials in healthy volunteers found increased lean mass and thigh muscle volume after release of myostatin’s inhibition of growth. It has no FDA approval.

Why did development end?

Nosebleeds and telangiectasias raised bleeding concerns during clinical development. Off-target BMP9 inhibition contributed to altered vascular remodeling, and these safety signals appear in the Duchenne muscular dystrophy trial literature. Development stopped without an approved dose or established human safety.

Which schedules were investigated?

Phase 1 studies tested 0.02–3 mg/kg by infrequent subcutaneous administration, with lean-mass changes at low-mg doses. DMD trial context: protocol-specific mg doses were given subcutaneously every 2–4 weeks before development stopped; a numeric amount is unavailable. Evidence boundary: no consumer dose is approved or recommended. Do not self-titrate; restrict any work to a qualified laboratory or professional protocol. The approximate half-life is 10–15 days.

How does it differ from follistatin-344?

Both interfere with myostatin and the wider TGF-β superfamily. Follistatin is an endogenous glycoprotein isoform that sequesters myostatin and activins. ACE-031 is an engineered soluble receptor with human pharmacokinetic and pharmacodynamic trial data. Its vascular safety problems halted development. Neither has FDA approval for increasing muscle mass.

References

  1. A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers. (2013)

    PMID 23169607DOI 10.1002/mus.23539

  2. Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial. (2017)

    PMID 27462804DOI 10.1002/mus.25268

  3. Myostatin and its Regulation: A Comprehensive Review of Myostatin Inhibiting Strategies. (2022)

    PMID 35812316DOI 10.3389/fphys.2022.876078

  4. ACE-031 (ActRIIB-Fc) studies on ClinicalTrials.gov (2024)