Chugai Pharmaceutical has announced that Roche will discontinue the clinical development of GYM329 (emugrobart), an investigational anti-latent myostatin sweeping antibody, for the treatment of Spinal Muscular Atrophy (SMA) and Facioscapulohumeral Muscular Dystrophy (FSHD).

The decision follows a comprehensive evaluation of data from the phase II/III MANATEE study in SMA and the phase II MANOEUVRE study in FSHD. While emugrobart demonstrated a favourable safety profile and successfully engaged its biological target by reducing mature myostatin levels, it failed to deliver consistent and meaningful functional improvements in muscle growth and patient outcomes. As a result, the data did not support progression into late-stage clinical development for these neuromuscular conditions.

Importantly, the discontinuation is not related to safety concerns. The drug was well tolerated across both studies, with no serious adverse events or treatment-related discontinuations reported.

Despite the setback in neuromuscular diseases, the development of emugrobart will continue in obesity, where its mechanism of action remains scientifically promising. Unlike SMA and FSHD, obesity is a metabolic disorder where muscle quality is not primarily compromised by neurodegenerative or myopathic processes, and higher levels of myostatin may provide a more suitable target for therapeutic intervention.

Chugai also clarified that the decision will not impact its consolidated financial forecast for the fiscal year ending December 2026, as previously announced.