Other · 1mg × 10 vials
ActRIIB decoy receptor. Studied as a myostatin-pathway modulator of muscle mass in preclinical models.
ACE-031 (ramatercept) is a recombinant fusion protein built from the extracellular ligand-binding domain of the human activin receptor type IIB (ActRIIB) joined to the Fc region of human IgG1. It functions as a soluble decoy receptor for myostatin and related TGF-beta superfamily ligands. In normal physiology, myostatin (GDF-8), activin A, and several related ligands bind ActRIIB on muscle cells and trigger Smad2/3 signalling that limits muscle growth. ACE-031 circulates freely, presents the same binding surface as the membrane receptor, and sequesters these ligands before they reach the cell.
With the inhibitory ligands neutralised, Smad signalling falls, mTOR and Akt protein-synthesis pathways are released, and net anabolic balance rises. Preclinical models showed rapid increases in lean mass, muscle fibre cross-sectional area, and grip strength, with the largest effects in muscle-wasting models (mdx mice, Duchenne models, aged sarcopenia models). Acceleron's Phase 2 programme in Duchenne muscular dystrophy was halted after bleeding and vascular-leak adverse events. The most-cited mechanistic explanation is that ActRIIB also binds BMP9 and BMP10, which regulate vascular endothelial integrity, so trapping those ligands alongside myostatin disrupts vessel maintenance.
What the published studies measured.
Peer-reviewed studies and clinical guidelines - tap any to read the source.
single-dose lean mass increase, biomarker confirmation, first human safety signals
Read study ↗PubMedCampbell et al, Muscle Nerve 2017 - Phase 2 trial of ACE-031 in Duchenne muscular dystrophyfull Phase 2 outcome data, epistaxis and gum bleeding signals, vascular leak discussion, trial termination rationale
Read study ↗PubMedCadena et al, Sci Rep 2019 - administration of myostatin inhibitors and vascular adverse effectsmechanism discussion of BMP9/BMP10 sequestration and vascular leak
Read study ↗PubMedLee, Annu Rev Physiol 2023 - Targeting myostatin/activin pathway for sarcopenia and muscle wastingpathway biology, comparison of ACE-031 vs follistatin vs anti-myostatin antibodies, why the soluble decoy approach is mechanistically attractive but pharmacologically tricky
Read study ↗PubMedBogdanovich et al, Nature 2002 - Functional improvement of dystrophic muscle by myostatin blockadefoundational preclinical work in mdx mice that drove the ACE-031 program
Read study ↗Clinical guidelinesAcceleron Pharma Phase 2 termination press release (archived)](https://www.fiercebiotech.com/biotech/acceleron-shutters-program-after-second-trial-halt) - official program discontinuation, vascular and bleeding rationale
Read study ↗Storage: refrigerated, ~14 days after reconstitution (fusion proteins are less stable post-recon than small peptides). Pre-recon vials: refrigerated, freezer for long storage.