Neurotrophic Factor Gene Therapy Programs

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Neurotrophic Factor Gene Therapy Programs

<table class="infobox infobox-therapeutic">
<tr>
<th class="infobox-header" colspan="2">Neurotrophic Factor Gene Therapy Programs — GDNF, CDNF, BDNF, Neurturin</th>
</tr>
<tr>
<td class="label">Program</td>
<td>Company/Lab</td>
</tr>
<tr>
<td class="label">AB-1005</td>
<td>AskBio/Bayer</td>
</tr>
<tr>
<td class="label">AAV2-GDNF (NIH)</td>
<td>NIH/NINDS</td>
</tr>
<tr>
<td class="label">AAV9-GDNF</td>
<td>Academic</td>
</tr>
<tr>
<td class="label">Program</td>
<td>Company/Lab</td>
</tr>
<tr>
<td class="label">AAV2-CDNF</td>
<td>Herantis Pharma</td>
</tr>
<tr>
<td class="label">CDNF protein</td>
<td>Herantis</td>
</tr>
<tr>
<td class="label">Program</td>
<td>Company/Lab</td>
</tr>
<tr>
<td class="label">CERE-120</td>
<td>Ceregene/Sangamo</td>
</tr>
<tr>
<td class="label">Next-gen NRTN</td>
<td>Academic</td>
</tr>
<tr>
<td class="label">Program</td>
<td>Company/Lab</td>
</tr>
<tr>
<td class="label">AAV-BDNF</td>
<td>Multiple academic</td>
</tr>
<tr>
<td class="label">TrkB agonist gene therapy</td>
<td>Academic</td>
</tr>
<tr>
<td class="label">Factor</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">MANF</td>
<td>ER stress/UPR, immune modulation</td>
</tr>
<tr>
<td class="label">Artemin (ARTN)</td>
<td>GFRα3/RET signaling</td>
</tr>
<tr>
<td class="label">CNTF</td>
<td>JAK/STAT, gp130 signaling</td>
</tr>
<tr>
<td class="label">FGF2/FGF20</td>
<td>FGFR signaling</td>
</tr>
<tr>
<td class="label">VEGF</td>
<td>Neuroprotection, angiogenesis</td>
</tr>
<tr>
<td class="label">Delivery Method</td>
<td>Vector</td>
</tr>
<tr>
<td class="label">Intraputaminal CED</td>
<td>AAV2</td>
</tr>
<tr>
<td class="label">Intracisternal (ICM)</td>
<td>AAV9</td>
</tr>
<tr>
<td class="label">Intrathecal</td>
<td>AAV9/rh10</td>
</tr>
<tr>
<td class="label">IV with engineered capsid</td>
<td>PHP.eB/CAP-B10</td>
</tr>
<tr>
<td class="label">FUS + AAV</td>
<td>Any serotype</td>
</tr>
<tr>
<td class="label">Ex vivo cell therapy</td>
<td>Encapsulated cells</td>
</tr>
<tr>
<td class="label">Criterion</td>
<td>Rationale</td>
</tr>
<tr>
<td class="label">Age 40-70</td>
<td>Surgical risk increases >75; younger patients may have more residual neurons</td>
</tr>
<tr>
<td class="label">Disease duration 4-12 years</td>
<td>Enough degeneration to benefit; too advanced = insufficient target</td>
</tr>
<tr>
<td class="label">Hoehn & Yahr 2-3</td>
<td>Preserved motor function baseline; too severe = poor outcomes</td>
</tr>
<tr>
<td class="label">Positive levodopa response (≥30%)</td>
<td>Confirms intact dopaminergic terminals that can receive neurotrophic support</td>
</tr>
<tr>
<td class="label">DAT scan positive</td>
<td>Confirms presynaptic dopaminergic deficit</td>
</tr>
<tr>
<td class="label">No cognitive impairment (MMSE ≥26)</td>
<td>Protects informed consent and reduces placebo effect</td>
</tr>
<tr>
<td class="label">No atypical parkinsonism</td>
<td>PSP/MSA/CBS have different pathology — not targetable by GDNF/CDNF</td>
</tr>
<tr>
<td class="label">Biomarker</td>
<td>Source</td>
</tr>
<tr>
<td class="label">Dopamine transporter (DaT)</td>
<td>SPECT imaging</td>
</tr>
<tr>
<td class="label">FDG-PET</td>
<td>PET</td>
</tr>
<tr>
<td class="label">Alpha-synuclein (total, p-S129)</td>
<td>CSF, blood</td>
</tr>
<tr>
<td class="label">Neurofilament light (NfL)</td>
<td>CSF, blood</td>
</tr>
<tr>
<td class="label">GDNF levels</td>
<td>CSF</td>
</tr>
<tr>
<td class="label">Anti-AAV2 antibodies</td>
<td>Blood</td>
</tr>
<tr>
<td class="label">Inflammatory cytokines</td>
<td>CSF</td>
</tr>
<tr>
<td class="label">Program</td>
<td>Expected Milestone</td>
</tr>
<tr>
<td class="label">AB-1005 REGENERATE-PD</td>
<td>Phase 2 interim analysis</td>
</tr>
<tr>
<td class="label">AB-1005 REGENERATE-PD</td>
<td>Phase 2 primary completion</td>
</tr>
<tr>
<td class="label">HER-096 (CDNF mimetic)</td>
<td>Phase 2 initiation</td>
</tr>
<tr>
<td class="label">AAV9-GDNF BBB-crossing</td>
<td>IND filing / Phase 1 start</td>
</tr>
<tr>
<td class="label">AAV-BDNF</td>
<td>First-in-human study</td>
</tr>
</table>

Overview

Neurotrophic factors (GDNF, CDNF, BDNF, neurturin) are among the most promising payloads for CNS gene therapy because they address the fundamental problem of neuronal survival. Unlike small molecules that modulate pathways, gene therapy can provide sustained local production of these proteins at therapeutic concentrations in target brain regions — overcoming the key limitation of protein infusion (poor tissue distribution, catheter complications, immune responses).

This page tracks all active gene therapy programs delivering neurotrophic factors for neurodegenerative diseases.

Active Programs

GDNF Gene Therapy

Key findings:

AB-1005 REGENERATE-PD: multicenter Phase 2, bilateral putaminal delivery, MRI-guided CED
NIH Phase 1 (NCT04167540): dose-escalation, 3-year follow-up shows sustained GDNF expression on PET
Long-term follow-up study: [NCT07081841](/clinical-trials/ab-1005-gdnf-long-term-follow-up-nct07081841) (5-year safety monitoring)
Historical: Ceregene CERE-120 (AAV2-neurturin) Phase 2 failed — insufficient tissue coverage, prompting shift to CED delivery

Deep dive: [GDNF Therapy for PD](/therapeutics/gdnf-therapy-parkinsons) | [GDNF Signaling Pathway](/mechanisms/gdnf-signaling-pathway-neurodegeneration) | [GDNF Protein](/proteins/gdnf-protein)

CDNF Gene Therapy

Key findings:

CDNF uniquely targets ER stress and unfolded protein response (UPR) — distinct from GDNF's RET receptor mechanism
Phase 1-2 protein infusion showed safety but limited efficacy → motivating gene therapy approach
Preclinical: AAV-CDNF protects DA neurons in 6-OHDA and MPTP models with effect sizes >50%
Herantis transitioned to HER-096 (subcutaneous small molecule CDNF mimetic) — Phase 1b completed October 2025, Phase 2 planned

Deep dive: [CDNF Therapy](/therapeutics/cdnf-therapy-parkinsons) | [ER Stress in Neurodegeneration](/mechanisms/er-stress-neurodegeneration)

Neurturin Gene Therapy

Lessons from CERE-120 failure:

Phase 1 (NCT00252850): safe, modest clinical improvement in open-label
Phase 2 (NCT00400634): FAILED primary endpoint — no significant difference vs sham surgery
Post-hoc analysis: poor anterograde transport of AAV2-NRTN from putamen to substantia nigra
Key lesson: delivery method matters more than payload; drove field toward CED and BBB-crossing capsids

Deep dive: [Neurturin Therapy](/therapeutics/neurturin-therapy-parkinsons) | [Neurturin Protein](/proteins/neurturin-protein)

BDNF Gene Therapy

Key considerations:

BDNF does not cross BBB and has poor pharmacokinetics as protein → gene therapy is the logical delivery
Concerns: BDNF overexpression can cause seizures, pain sensitization, and neuronal hyperexcitability
Solution: regulated gene expression (tetracycline-inducible, miRNA-detargeting) to control dosing
Alternative: deliver TrkB receptor agonists or downstream effectors instead of BDNF itself

Deep dive: [BDNF](/proteins/bdnf) | [Exercise-Induced BDNF](/therapeutics/exercise-induced-myokines)

Emerging Neurotrophic Payloads

Delivery Technology Comparison

CBS/PSP Relevance

Neurotrophic factor gene therapy has potential relevance to CBS/PSP through:

GDNF: supports surviving dopaminergic neurons (DA loss confirmed on patient's DAT scan)
CDNF: targets ER stress — elevated in 4R-tauopathies due to misfolded tau accumulation
BDNF: could enhance neuroplasticity and circuit resilience (complement exercise effects)

Key gap: No neurotrophic gene therapy trials specifically in CBS/PSP or 4R-tauopathies. All current programs target PD or AD. The cure roadmap should track when these programs could expand to atypical parkinsonism indications.

Cross-Links

[Neurotrophic Factor Therapies (overview)](/therapeutics/neurotrophic-factor-therapies)
[GDNF Therapy for PD](/therapeutics/gdnf-therapy-parkinsons)
[CDNF Therapy for PD](/therapeutics/cdnf-therapy-parkinsons)
[Neurturin Therapy](/therapeutics/neurturin-therapy-parkinsons)
[AAV Gene Therapy for Neurodegeneration](/therapeutics/aav-gene-therapy-neurodegeneration)
[AAV Vectors](/technologies/aav-vectors)
[Gene Therapy Overview](/technologies/gene-therapy)
[AB-1005 REGENERATE-PD Trial](/clinical-trials/ab-1005-gdnf-gene-therapy-regenerate-pd)
[GDNF Signaling Pathway](/mechanisms/gdnf-signaling-pathway-neurodegeneration)
[Cure Roadmap](/mechanisms/cbs-psp-cure-roadmap)

Patient Selection & Biomarkers

Ideal Candidate Profile

Gene therapy for neurotrophic factors requires careful patient selection to maximize benefit-risk:

Biomarker Monitoring

Key insight: NfL trends may serve as early surrogate endpoints — if neurotrophic factors slow neurodegeneration, NfL should decrease relative to natural history. This is being tracked in the 5-year follow-up study (NCT07081841).

Pre-existing AAV Immunity

A critical and underappreciated barrier:

~40-60% of adults have pre-existing neutralizing antibodies (NAbs) against AAV2 from natural exposure
NAbs can reduce transgene expression or cause inflammatory responses
Screening is now standard in all trials (exclusion threshold: NAb titer <1:10 or <1:20 depending on program)
Solution strategies:
Use alternative serotypes (AAV9, AAVrh10) with lower seroprevalence (~20-30%)
Engineering capsids to escape neutralization (AAV2.7m8, AAVHS)
Immunosuppression priming before administration

Pipeline Timeline

gantt
title Neurotrophic Gene Therapy Clinical Timeline
dateFormat YYYY-MM
axisFormat %Y

section GDNF
Intraventricular GDNF (1995) :done, 1995-01, 2y
Putaminal infusion Phase I-II :done, 2003-01, 5y
NIH AAV2-GDNF Phase I :done, 2019-01, 3y
AB-1005 REGENERATE-PD Phase 2 :active, 2021-03, 4y
AB-1005 5yr follow-up (NCT07081841) :active, 2025-01, 5y

section CDNF
CDNF protein Phase 1-2 :done, 2010-09, 6y
AAV2-CDNF Phase 1-2 :done, 2011-03, 4y
HER-096 small molecule Phase 1b :done, 2025-10, 1y
HER-096 Phase 2 :milestone, 2026-06, 2y

section NRTN
CERE-120 Phase 1 :done, 2005-01, 4y
CERE-120 Phase 2 FAILED :crit, done, 2008-01, 3y

section BDNF
AAV-BDNF preclinical (multiple) :active, 2020-01, 5y

Anticipated Milestones

Cross-Links

[Neurotrophic Factor Therapies (overview)](/therapeutics/neurotrophic-factor-therapies)
[GDNF Therapy for PD](/therapeutics/gdnf-therapy-parkinsons)
[CDNF Therapy for PD](/therapeutics/cdnf-therapy-parkinsons)
[Neurturin Therapy](/therapeutics/neurturin-therapy-parkinsons)
[AAV Gene Therapy for Neurodegeneration](/therapeutics/aav-gene-therapy-neurodegeneration)
[AAV Vectors](/technologies/aav-vectors)
[Gene Therapy Overview](/technologies/gene-therapy)
[AB-1005 REGENERATE-PD Trial](/clinical-trials/ab-1005-gdnf-gene-therapy-regenerate-pd)
[GDNF Signaling Pathway](/mechanisms/gdnf-signaling-pathway-neurodegeneration)
[Cure Roadmap](/mechanisms/cbs-psp-cure-roadmap)

From the [SciDEX Exchange](/exchange) — scored by multi-agent debate

[Epigenetic Memory Reprogramming for Alzheimer's Disease](/hypothesis/h-29ef94d5) — 0.55 · Target: BDNF, CREB1, synaptic plasticity genes
[Bacterial Enzyme-Mediated Dopamine Precursor Synthesis](/hypothesis/h-7bb47d7a) — 0.44 · Target: TH, AADC
[Hippocampal CA3-CA1 circuit rescue via neurogenesis and synaptic preservation](/hypothesis/h-856feb98) — 0.73 · Target: BDNF
[Hippocampal CA3-CA1 circuit rescue via neurogenesis and synaptic preservation](/hypothesis/h-856feb98) — 0.73 · Target: BDNF
[Vagal Afferent Microbial Signal Modulation](/hypothesis/h-ee1df336) — 0.71 · Target: GLP1R, BDNF
[Vocal Cord Neuroplasticity Stimulation](/hypothesis/h-e0183502) — 0.48 · Target: CHR2/BDNF
[CYP46A1 Overexpression Gene Therapy](/hypothesis/h-2600483e) — 0.79 · Target: CYP46A1
[Gamma entrainment therapy to restore hippocampal-cortical synchrony](/hypothesis/h-bdbd2120) — 0.77 · Target: SST

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Neurotrophic Factor Gene Therapy Programs — GDNF, CDNF, BDNF, Neurturin