Peptides›GH-stack›Follistatin-344 (FST-344)

Follistatin-344 (FST-344)

/ Native follistatin long isoform (344 residues; high heparan sulfate binding, tissue-retained)

TIER 3 · PreclinicalN = 0 · TESTING PENDINGMW 39200.00 g·mol⁻¹

ALIAS · FST-344 isoform · Follistatin long isoform · AAV1.CMV.FS344

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Pass rate

Samples

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Research use onlyAny dose figures below describe what specific cited studies used, reported factually. Nothing on this page is guidance for human use.READ FIRST →

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§ A · Identity

Primary sequence— sequence not captured —

MW · 39200.00CLASS · Native follistatin long isoform (344 residues; high heparan sulfate binding, tissue-retained)CATEGORY · GH-stack

Tier 3. The protein itself is preclinical, but AAV-FST344 gene therapy (delivering the 344-residue isoform via adeno-associated virus to skeletal muscle) reached Phase 1/2 in Becker muscular dystrophy and sporadic inclusion body myositis (Mendell 2015) — published human safety and biopsy data exist for the gene-therapy delivery pathway.

§ B · Mechanism of action

The 344-residue isoform of follistatin retains higher affinity for cell-surface heparan sulfate proteoglycans than the short FST-315 form, leading to greater extracellular tissue retention. Functional pharmacology — myostatin/activin/GDF11/BMP sequestration — is similar between isoforms.

§ C · Human clinical evidence

Tier 3 for the protein; gene-therapy human data exist for AAV-FST344 (Mendell 2015 in Becker MD; subsequent IBM trial). The published gene-therapy data are not transferable to recombinant-protein vendor product.

§ D · Primary literature

PubMed28279643Mendell JR et al. — Follistatin Gene Therapy for Sporadic Inclusion Body Myositis Improves Functional Outcomes · Molecular Therapy · human-phase-1AAV1.CMV.FS344 intramuscular injection in 6 patients with sporadic IBM was well tolerated and produced modest 6-minute walk distance improvements at six months versus the natural history of the disease.Limitations: Open-label, n=6, no concurrent control; gene-therapy delivery, not recombinant protein.2017

§ F · Safety signal

Mendell 2015 reported AAV1.CMV.FS344 was well tolerated at the doses studied with no serious treatment-related adverse events at six months; sample size small.

§ H · Regulatory status

Regulatory status

FDA status:: Not FDA-approved

§ I · Notable gaps and controversies

The vendor product (recombinant 344-residue protein) has no human dosing data. Regulatory and safety claims based on the AAV gene-therapy trials do not transfer to a different molecule (recombinant protein vs gene-delivered transgene).