RO7434656

RO7434656 (also known as GYM329 or RG6237) is a humanized monoclonal antibody developed by Chugai Pharmaceutical (a member of the Roche Group) that targets the latent form of myostatin (Growth Differentiation Factor 8, GDF-8). It is engineered using Chugai's proprietary 'sweeping antibody' technology, which enables pH-dependent antigen binding. This mechanism allows the antibody to bind latent myostatin in the neutral pH of the blood, transport it into the cell via FcRn-mediated endocytosis, and release it in the acidic environment of the endosome for lysosomal degradation. By actively clearing latent myostatin from circulation, RO7434656 reduces the precursor pool available for conversion into active myostatin, a protein that negatively regulates skeletal muscle growth. The drug is primarily being developed for the treatment of spinal muscular atrophy (SMA), where it is studied in combination with the SMN2 splicing modifier risdiplam to improve muscle mass and motor function in patients who have persistent muscle weakness despite treatment.