ACE-031
ACE-031 is a recombinant fusion protein of the activin type IIB receptor that binds myostatin and related ligands. Studied in myostatin-pathway research.
Mechanism of action
ACE-031 (ramatercept) is a lab-made fusion protein that joins the outer, ligand-binding part of activin receptor type IIB (ActRIIB) to the Fc tail of a human IgG1 antibody. It acts as a decoy: it binds myostatin, activin A and related TGF-beta family growth-signalling proteins so they cannot signal through ActRIIB on muscle cells, and treated mice and marmosets had greater muscle mass than controls (Cadena et al., 2010 and 2026). In people, its developer Acceleron Pharma ran a placebo-controlled single-dose study in 48 healthy postmenopausal women and a placebo-controlled trial in boys with Duchenne muscular dystrophy, which was stopped early over safety concerns about nosebleeds and small dilated blood vessels (telangiectasias) (Campbell et al., 2017).