ACE-031 | Pen

ACE-031 is a peptide positioned for controlled research settings where myostatin/activin pathway inhibition is being studied in relation to lean mass accrual, muscle strength and function endpoints, and bone and metabolic biomarkers.

Supports

1. ActRIIB-ligand trapping and myostatin pathway suppression (model-dependent)
2. Lean mass and muscle volume endpoints in controlled body-composition studies
3. Strength and functional performance readouts (contractility/6MWT-type endpoints)
4. Bone turnover and density marker modulation alongside muscle outcomes
5. Vascular-safety signal monitoring in broad ligand-trap inhibition (epistaxis/telangiectasia markers)

Description

ACE-031 (ramatercept) is an investigational ActRIIB (activin receptor type IIB) ligand-trap designed to sequester circulating ligands in the myostatin/activin family before they engage cell-surface receptors. In research models, this approach is used to explore how reducing negative regulators of muscle growth can shift anabolic signaling, muscle fiber morphology, and functional outcomes.

Unlike selective anti-myostatin antibodies, ActRIIB ligand traps can bind multiple related ligands. This broader binding profile is studied for its potential to drive larger changes in muscle and bone endpoints, while also introducing mechanism-linked safety considerations (e.g., effects tied to inhibition of ligands beyond myostatin, depending on binding spectrum).

ACE-031 has been evaluated across preclinical systems and early human studies measuring lean mass and related biomarkers, and it has also been investigated in neuromuscular disease contexts. All effects are endpoint- and model-dependent and should be interpreted within controlled experimental design.

Clinical Status

ACE-031 has been evaluated in controlled human studies for body-composition endpoints and in clinical research programs for Duchenne muscular dystrophy, alongside extensive preclinical characterization of ActRIIB-ligand trapping on muscle and bone measures. The clinical program highlighted both pharmacodynamic signals (lean mass and biomarker shifts) and vascular-related tolerability signals that are relevant to study design and monitoring.

Evidence type:
Human RCT ✔ | Observational ✔ | Animal ✔ | In vitro ✔ | Regulatory approval ☐

Mechanism of Action

ACE-031 is engineered as a soluble ActRIIB-based ligand trap that binds myostatin (GDF8) and related TGF-β superfamily ligands, reducing their availability to activate signaling through activin type II receptor complexes. In muscle-focused models, this is used to study derepression of growth constraints and downstream shifts in muscle fiber cross-sectional area, lean mass, and strength-related endpoints.

Because ActRIIB ligand traps can interact with multiple ligands (not only myostatin), mechanistic interpretation often extends to broader pathway biology (including activins and certain BMP family ligands). This broader biology is also used to explain observed changes in bone and metabolic biomarkers and to contextualize vascular-related adverse-event signals reported in clinical programs.

Benefits

• Lean mass accretion endpoints:
  Studied for increasing lean body mass and muscle volume measures in controlled human and animal research contexts.
• Muscle strength/function readouts:
  Evaluated using functional outcomes and contractility measures in preclinical systems and exploratory clinical settings.
• Muscle fiber morphology:
  Associated in animal studies with increased muscle fiber cross-sectional area and related structural remodeling markers.
• Bone biomarker modulation:
  ActRIIB-ligand trapping is investigated for concurrent effects on bone density/turnover markers alongside muscle outcomes.
• Metabolic biomarker exploration:
  Research programs examine fat mass shifts and metabolic marker changes as secondary endpoints in body-composition designs.
• Pathway deconvolution tool:
  Used to dissect myostatin/activin receptor biology and ligand redundancy in muscle regulation under controlled inhibition.

Research Data

Stack Suggestions

In extended experimental designs, ACE-031 is sometimes paired with:

• CJC-1295 (No-DAC) → to co-study GH/IGF-axis signaling markers alongside myostatin-pathway inhibition endpoints
• MGF → to explore early-phase regenerative signaling readouts in parallel with muscle hypertrophy markers
• SS-31 (Elamipretide) → to test mitochondrial stress and recovery markers alongside contractility outcomes

Stacks discussed are for experimental design only, not safety/efficacy guidance.

Possible Side Effects

Like any active substance, supplement, or medication, ACE 031 can cause some side effects. It is important that each user is informed and consults with a specialist before taking it. Here are some of the possible side effects:

Skin reactions: Some users have reported redness or mild irritation at the injection site.

Headache: In some cases, mild headaches may occur after taking ACE 031.

Muscle aches: Temporary muscle pains or weakness may occur, especially after the first doses.

Fatigue: Some users have reported fatigue after starting therapy with ACE 031.

Mild stomach discomfort has also been rarely associated with taking the peptide.

If you have doubts or experience symptoms, it is advisable to consult a specialist or stop taking the peptide.

Scientific References

• A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers — Human RCT
• Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: results of a randomized, placebo-controlled clinical trial — Human RCT
• Study of ACE-031 in Subjects With Duchenne Muscular Dystrophy (NCT01099761) — Clinical registry
• Myostatin inhibitors as pharmacological treatment for muscle wasting and muscular dystrophy — Review
• Impact of Genetic and Pharmacologic Inhibition of Myostatin in Musculoskeletal and Metabolic Biology — Review
• Challenges and Future Prospects of Targeting Myostatin for Muscle Wasting Disorders — Review
• ACE-031, a soluble activin type IIB receptor, increases muscle mass and strength in a nonhuman primate model — Animal
• A myostatin and activin decoy receptor enhances bone and muscle mass in mice — Animal
• Administration of an activin receptor IIB ligand trap protects bone in a model system and correlates bone–muscle gains — Animal
• Administration study of black market ACE-031 (Ramatercept) — Regulatory/Analytical

Cautions

• For educational and scientific context only; not intended to diagnose, treat, cure, or prevent any disease.
• If you are pregnant, nursing, have a medical condition, or use prescription medication, consult a qualified professional.
• Discontinue use if sensitivity occurs.