Roche stops development of Emugrobart

Dr. Lucienne Ronco, Chief Science Officer of the FSHD Society

Originally published on March 19, 2026

Edited for clarity as of March 20, 2026

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Today we received news that Roche will stop development and not proceed to a Phase 3 study in FSHD with their investigational therapeutic Emugrobart (known as GYM329 or RO7204239). Read Roche’s letter to the FSHD community here. In the MANOEUVERE Phase 2 trial in FSHD, R07204239 failed to demonstrate a statistically significant benefit over a placebo after 52 weeks of treatment.

Emugrobart is an investigational humanized anti myostatin monoclonal antibody designed to increase muscle growth. The primary purposes of MANOEUVERE was to evaluate the safety, pharmacodynamics (how the drug affects the body), and efficacy of Emugrobart in ambulant adult participants with FSHD. The study measured change from baseline in muscle volume of quadriceps muscles as assessed by magnetic resonance imaging. Additional endpoints measured how well Emugrobart modified myostatin levels. Roche did not leave any stone un-turned as that also measured change in muscle volume and fat fraction of an additional 36 muscles by whole body MRI.

Importantly, the MANOEUVRE study demonstrated effective suppression of myostatin in participants who received Emugrobart. This result suggests that Emugrobart did successfully impact myostatin activity in patients. But even with this positive effect, Emugrobart did not consistently deliver the hoped for improvements in muscle growth and function

The MANOEUVERE trial’s outcome reinforces the challenges in developing muscle growth treatments for FSHD. The FSHD Society considers there to be some unanswered questions after this study:

• By how much must a drug inhibit the myostatin pathway to trigger muscle growth in FSHD?
• Can FSHD muscle respond to reduced myostatin activity or must DUX4 be reduced at the same time or before myostatin is targeted in order to see muscle growth?
• Would adding exercise to the clinical trial assist in muscle growth? Exercise was not a part of the MANOEUVRE trials.

These results do not signal the end of efforts to enhance muscle growth in FSHD patients (Scholar Rock has announced an FSHD trial with a similar mechanism) and Emugrobart continues to be evaluated in obesity.

Roche intends to share data from MANOEUVRE at the International Research Congress on FSHD, hosted by the FSHD Society, in June 2026.