ACE-031
Also known as
Soluble activin type IIB receptor fusion protein studied for lean mass and metabolic health. One Phase I RCT showed increased lean mass in postmenopausal women; remaining evidence is preclinical. Flagged status, elevated risk.
Evidence
Small or single human study
Risk band
Serious AEs reported or theoretical
Research goals
Summary
ACE-031 is a soluble activin type IIB receptor (ActRIIB) fusion protein that acts as a ligand trap for multiple negative regulators of skeletal muscle, including myostatin [2,3]. In a single-ascending-dose Phase I randomized controlled trial of 48 healthy postmenopausal women, ACE-031 was generally well tolerated (injection-site erythema was a noted adverse event) and produced statistically significant increases in total body lean mass (3.3%) and thigh muscle volume (5.1%) at the highest dose, along with biomarker changes suggesting effects on bone and fat metabolism [4]. Supporting preclinical work in marmosets showed increased body weight, lean mass, muscle fiber cross-sectional area, and contractile force, supporting its potential for treating myopathies [2,3]. The human evidence is limited to one early-phase pharmacodynamic study with no functional efficacy endpoints, so its therapeutic value remains unproven [4].
Sources
- 2. ACE-031, a Soluble Activin Type IIB Receptor, Increases Muscle Mass and Strength in the Common Marmoset (Callithrix jacchus) bioRxiv : the preprint server for biology, 2025.
- 3. ACE-031, a soluble activin type IIB receptor, increases muscle mass and strength in the common marmoset (Callithrix jacchus) PloS one, 2026.
- 4. A single ascending-dose study of muscle regulator ACE-031 in healthy volunteers Muscle & nerve, 2013.
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