Locally acting follistatin fusion protein
ACE-083
Trial Discontinued development
What it is
ACE-083 is an engineered follistatin-based fusion protein designed to act locally at the injection site rather than systemically. It was developed for focal muscle weakness in facioscapulohumeral dystrophy (FSHD) and Charcot-Marie-Tooth disease, where strengthening a specific muscle matters more than whole-body exposure.
Benefits in plain language
What researchers and reference users usually mean when they talk about this compound. These are study themes and common claims — not a promise that it will do this in you.
- The idea was “grow this one muscle” — inject locally, get local growth, avoid whole-body effects.
- It is a follistatin relative, so it acts on the myostatin brake like follistatin-344 but with a shorter reach.
- Trials did not deliver the functional benefit developers hoped for, and the program was stopped.
- Its interest today is conceptual: it shows how hard local muscle targeting is to pull off.
If a branded, FDA-approved product exists, that label is the only dose that is actually authorized. Research-chemical vials are a different object.
Mechanism of action
Follistatin binds and neutralizes myostatin and activin A. ACE-083 was engineered with modifications intended to limit systemic spread after intramuscular injection, so the trap acts mostly on the muscle injected. In trials this produced measurable increases in muscle volume in some cohorts but did not translate into consistent functional gains.
Possible side effects / caveats
Reported trial issues included injection-site reactions and, at higher exposures, the familiar myostatin-pathway concerns around connective tissue and vascular effects. Development was discontinued. There is no approved product, and “ACE-083” sold as a research chemical is very unlikely to be the actual clinical molecule.
Protocol ranges
| Source tier | Amount | Frequency / duration | Notes |
|---|---|---|---|
| Trial | Dose-escalating, mg-level per muscle | Repeated intramuscular dosing | Supervised; program discontinued |
| Cited range | No accepted community protocol | — | Not a commercially viable research peptide |