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phase 2Cognitive & Neuro

CNTF Peptide

Also known as: Ciliary Neurotrophic Factor peptide fragment, CNTF-derived neuropeptide, Axokine peptide fragment, CNTFAx15

CNTF peptide refers to bioactive peptide fragments derived from Ciliary Neurotrophic Factor, a 200-amino acid cytokine in the interleukin-6 family that plays critical roles in neuronal survival, differentiation, and repair. Full-length CNTF and its modified variant Axokine (CNTFAx15) have been tested in clinical trials for neurodegenerative diseases (ALS, Huntington's) and obesity, demonstrating potent neuroprotective effects but limited by systemic side effects. Peptide fragments derived from the active domains of CNTF aim to retain neuroprotective activity while improving tolerability and pharmacokinetics.

3 cited references·5 researched benefits

Quick Answer

CNTF peptide fragments are derived from Ciliary Neurotrophic Factor, a potent neurotrophic cytokine that promotes motor neuron survival, retinal ganglion cell protection, and neural progenitor differentiation. Full-length CNTF reached Phase II/III clinical trials for ALS and obesity. Peptide fragments aim to harness its neuroprotective effects while minimizing systemic side effects like weight loss and antibody formation. CNTF signals through the JAK/STAT3, MAPK, and PI3K pathways via the CNTFR-alpha/LIFR/gp130 receptor complex.

Key Facts

Mechanism
CNTF signals through a tripartite receptor complex consisting of CNTF receptor alpha (CNTFRalpha), leukemia inhibitory factor receptor (LIFR), and the shared signal transducer glycoprotein 130 (gp130). Binding to CNTFRalpha recruits LIFR and gp130, triggering receptor heterodimerization and activation of Janus kinase 1 and 2 (JAK1/JAK2). These kinases phosphorylate STAT3 (Signal Transducer and Activator of Transcription 3), which dimerizes and translocates to the nucleus to upregulate genes involved in neuronal survival, differentiation, and anti-apoptosis. Parallel activation of the MAPK/ERK and PI3K/Akt pathways provides additional pro-survival and neurotrophic signaling. In motor neurons, CNTF is one of the most potent survival factors identified, preventing axotomy-induced cell death and maintaining neuromuscular junction integrity. In the retina, it protects photoreceptors and retinal ganglion cells from degeneration. CNTF-derived peptide fragments targeting the receptor-binding domains seek to activate these pathways with improved tissue selectivity.
Research Status
phase 2
Half-Life
~2.9 hours (full-length CNTF, IV); peptide fragments vary
Molecular Formula
Variable (full-length CNTF: C₉₄₅H₁₅₀₅N₂₆₃O₂₈₃S₉, ~22.8 kDa)
Primary Use
Cognitive & Neuro
Table of Contents

Benefits

  • Motor neuron survival — one of the most potent motor neuron survival factors identified; prevents motor neuron death after axotomy and in neurodegenerative disease modelsstrong
  • Retinal neuroprotection — protects photoreceptors and retinal ganglion cells from degeneration in models of retinitis pigmentosa, glaucoma, and macular degeneration; Phase II trials for retinal diseases show promisemoderate
  • Neural progenitor stimulation — promotes differentiation and survival of neural stem/progenitor cells, potentially supporting neuroregeneration after brain injurypreliminary
  • Remyelination support — promotes oligodendrocyte progenitor differentiation and myelin repair in demyelinating disease models, relevant to multiple sclerosispreliminary
  • Metabolic regulation — CNTF/Axokine demonstrated significant weight loss effects in clinical trials through hypothalamic signaling, establishing CNTF pathway as metabolically activestrong

Dosage Protocols

RouteDosage RangeFrequencyNotes
Subcutaneous injection (clinical trial dosing for Axokine)0.3–1.0 mcg/kg dailyOnce dailyDosing based on Axokine (CNTFAx15) clinical trials for obesity. The ALS trials used 5–30 mcg/kg of recombinant human CNTF but were limited by side effects. Peptide fragment dosing has not been established in clinical trials.
Intravitreal injection (retinal applications)Encapsulated cell technology (sustained release)Implanted device providing continuous deliveryNeurotech Pharmaceuticals developed NT-501, an encapsulated cell technology implant that continuously secretes CNTF into the vitreous for retinal neuroprotection. This bypasses systemic side effects. Phase II trials for macular telangiectasia and retinitis pigmentosa have shown promising results.

Medical disclaimer

Dosage information is provided for educational reference only. Always follow your prescriber's instructions and consult a qualified healthcare provider before starting any peptide protocol.

Side Effects

  • Weight loss and anorexia — full-length CNTF potently suppresses appetite through hypothalamic signaling; this was dose-limiting in ALS trials where patients were already losing weightserious
  • Injection site reactions — pain, redness, and swelling at subcutaneous injection sites observed in clinical trialscommon
  • Cough and upper respiratory symptoms — reported in clinical trials, potentially related to systemic immune modulationcommon
  • Anti-CNTF antibody formation — approximately 70% of patients in the ALS trials developed neutralizing antibodies against CNTF, reducing efficacy over timeserious
  • Fever and flu-like symptoms — acute-phase response due to IL-6 family cytokine activity, reported in dose-finding studiesrare

Frequently Asked Questions

What happened with CNTF in ALS clinical trials?
Recombinant human CNTF was tested in two large Phase III trials for amyotrophic lateral sclerosis (ALS) in the 1990s conducted by Regeneron Pharmaceuticals and Synergen. Despite strong preclinical evidence that CNTF prevents motor neuron death, both trials failed to show significant clinical benefit. The failure was attributed to several factors: dose-limiting systemic side effects (severe weight loss, cough, fever) prevented adequate dosing; up to 70% of patients developed neutralizing antibodies; the short half-life required frequent injections; and the blood-brain barrier limited CNS penetration from systemic administration. These trials highlighted the challenges of translating neurotrophic factor biology into clinical therapy.
How do CNTF peptide fragments improve upon full-length CNTF?
Peptide fragments derived from CNTF's active binding domains aim to address several limitations of the full-length protein: reduced immunogenicity (smaller peptides are less likely to trigger antibody formation); improved blood-brain barrier penetration; potentially more selective receptor engagement (activating neuroprotective signaling without full cytokine-like systemic effects); easier manufacturing and formulation; and potential for alternative delivery routes including intranasal. However, the trade-off is that fragments may have reduced potency compared to the full-length protein and may not fully replicate the complex receptor interactions required for complete CNTF signaling.
What is the NT-501 implant for retinal diseases?
NT-501 is an encapsulated cell technology (ECT) device developed by Neurotech Pharmaceuticals that is surgically implanted into the vitreous humor of the eye. It contains genetically modified retinal pigment epithelial cells that continuously produce and secrete CNTF into the surrounding retinal tissue. This provides sustained local CNTF delivery while avoiding systemic side effects. It has been tested in Phase II trials for retinitis pigmentosa (where it slowed photoreceptor loss), macular telangiectasia type 2, and geographic atrophy (dry age-related macular degeneration), with encouraging results in preserving retinal structure.

References

  1. 1
    Ciliary neurotrophic factor (CNTF) — structure, function, and clinical applications in neurodegenerative diseases(1993)PubMed ↗
  2. 2
    CNTF-derived peptides and neurotrophic factor delivery strategies for retinal and motor neuron protection(2014)PubMed ↗
  3. 3
    Encapsulated cell intraocular CNTF delivery for macular telangiectasia type 2: Phase II results(2019)PubMed ↗

Latest Research

Last updated: 2026-02-19