Acceleron Pharma Inc.’s ACE-083 drug trials are over.
According to a company press release, the drug “did not achieve statistically significant improvements in functional endpoints relative to placebo” with CMT patients, so it will no longer be developed.
Correction, October 10, 2026: The full results were more mixed than “no benefit.” In the placebo-controlled part of the phase 2 trial, ACE-083 significantly increased the volume of the injected muscle and showed a significant difference from placebo in ankle-dorsiflexion strength. Walking tests and quality of life, measured with the CMT Health Index, did not improve.1 On October 13, 2026, the title was changed from “ACE-083 Trials Show No Benefit” to match.
Jacob Bell at BioPharma Dive takes a deeper look. 🤿
According to researchers Barry Miller et al., ACE-083 is “a locally acting follistatin‐based therapeutic that binds myostatin and other muscle regulators.” Studies showed it to increase muscle mass and force in neuromuscular disease mouse models. (PubMed)
Unfortunately, it does not work on people well enough to improve quality of life for CMT patients and others experiencing muscle atrophy. The drug did significantly increase the volume of the injected leg muscles (13.5% more than placebo), but the published trial results show that, apart from ankle strength, the bigger muscles did not translate into better walking or other functional outcomes. 😔
Notes
- Thomas et al., “Randomized Phase 2 Study of ACE-083”; open access at PMC9202530. Registry results: Acceleron Pharma, “Study of ACE-083,” NCT03124459. ↩︎
Sources
- Acceleron Pharma. “Study of ACE-083 in Patients with Charcot-Marie-Tooth Disease.” ClinicalTrials.gov. Accessed October 14, 2026. https://clinicaltrials.gov/study/NCT03124459.
- Thomas, Florian P., Thomas H. Brannagan, Russell J. Butterfield, et al. “Randomized Phase 2 Study of ACE-083 in Patients with Charcot-Marie-Tooth Disease.” Neurology 98, no. 23 (2022): e2356-e2367. https://doi.org/10.1212/WNL.0000000000200325.
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