ACE-083 is a follistatin-based therapeutic agent designed for localized activity that increases muscle mass by binding myostatin and related muscle-regulatory factors, and although ACE-083 demonstrated consistent muscle volume increases across multiple clinical trials, its lack of functional improvement in phase II facioscapulohumeral muscular dystrophy studies led to discontinuation of its development for FSHD.

In preclinical mouse models of Duchenne muscular dystrophy (mdx) and Charcot-Marie-Tooth (CMT) disease, intramuscular injection of ACE-083 results in dose-dependent hypertrophy strictly limited to the injected muscle (e.g., tibialis anterior). No muscle growth is observed in contralateral untreated muscles, confirming its localized pharmacological profile. In these animal models, administration of the substance is associated with a measurable increase in Total Muscle Volume (TMV) at the site of injection [1].