AB-1005 (REGENERATE-PD) GDNF Gene Therapy Trial

AB-1005 GDNF Gene Therapy Regenereate PD

Overview

AB-1005 (also known as AAV2-GDNF) is an adeno-associated virus serotype 2 (AAV2)-based gene therapy developed by a consortium of researchers, designed to deliver the Glial Cell Line-Derived Neurotrophic Factor (GDNF) gene directly to the putamen of patients with Parkinson's disease. This approach represents a novel disease-modifying strategy that aims to protect and potentially restore dopaminergic neurons through continuous local GDNF expression["@hovde2024"][@bartus2013].

AB-1005 GDNF Gene Therapy Regenereate PD

Overview

AB-1005 (also known as AAV2-GDNF) is an adeno-associated virus serotype 2 (AAV2)-based gene therapy developed by a consortium of researchers, designed to deliver the Glial Cell Line-Derived Neurotrophic Factor (GDNF) gene directly to the putamen of patients with Parkinson's disease. This approach represents a novel disease-modifying strategy that aims to protect and potentially restore dopaminergic neurons through continuous local GDNF expression["@hovde2024"][@bartus2013].

Unlike previous GDNF delivery methods that required continuous infusion devices, AB-1005 provides sustained GDNF expression through a single surgical procedure, potentially offering long-term neuroprotective effects with a favorable safety profile.

Trial Details

| Property | Value |
|----------|-------|
| Phase | Phase 2 |
| Status | Active, recruiting |
| Drug | AB-1005 (AAV2-GDNF) |
| Sponsor | Clinical consortium / Research institutions |
| ClinicalTrials.gov Identifier | NCT04815625 (REGENERATE-PD) |
| Study Name | REGENERATE-PD |
| Indication | Parkinson's Disease |
| Target Enrollment | Approximately 40-60 patients |

Mechanism of Action

AAV2 Vector Design

AB-1005 utilizes a recombinant AAV2 capsid to deliver the human GDNF transgene:

GDNF Expression and Signaling

Once delivered, the transduced cells produce and secrete GDNF protein:

• PI3K/Akt pathway (anti-apoptotic, cell survival)
• MAPK/ERK pathway (neuronal differentiation, outgrowth)
• PLCγ pathway (calcium homeostasis)

Neuroprotective Effects

The GDNF signaling cascade produces several beneficial effects:

• Dopaminergic Neuron Survival: Promotes survival of degenerating dopaminergic neurons in the substantia nigra
• Axonal Protection: Protects striatal nerve terminals from degeneration
• Functional Restoration: May restore dopamine release capacity in surviving neurons
• Oxidative Stress Protection: Enhances cellular defenses against oxidative damage

Surgical Delivery

Procedure Overview

AB-1005 is delivered via stereotactic neurosurgery:

Delivery Parameters

| Parameter | Specification |
|-----------|---------------|
| Target | Bilateral posterior putamen |
| Injection Volume | Approximately 2-4 mL per hemisphere |
| Infusion Rate | Slow convection-enhanced delivery |
| Procedure Duration | Approximately 4-6 hours |

Trial Design

Study Phases

The REGENERATE-PD trial is designed as a Phase 2, open-label study with the following components:

Primary Endpoints

• Safety: Incidence and severity of adverse events (primary)
• Tolerability: Assessment of surgical and vector-related complications

Secondary Endpoints

• Motor Function: Change in Unified Parkinson's Disease Rating Scale (UPDRS) Part III "Off" medication scores
• Quality of Life: PDQ-39 scores
• Biomarkers: CSF and blood biomarkers including:
• Neurofilament light chain (NfL)
• Alpha-synuclein species
• GDNF levels in CSF
• Imaging: DaTscan (dopamine transporter SPECT) to assess striatal integrity
• Levodopa Response: Assessment of levodopa responsiveness

Eligibility Criteria

Inclusion Criteria

• Age 40-75 years
• Diagnosis of idiopathic Parkinson's disease
• Disease duration 4-15 years
• Hoehn & Yahr stage 2-3 in "On" state
• Positive levodopa response (≥30% improvement in UPDRS Part III)
• Stable antiparkinsonian medication for ≥4 weeks
• MMSE score ≥26 (no significant cognitive impairment)
• Capable of undergoing neurosurgical procedure

Exclusion Criteria

• Atypical parkinsonism (PSP, MSA, CBD)
• Significant cognitive impairment (MoCA <24)
• Psychiatric contraindications (active psychosis, severe depression)
• Previous brain surgery (DBS, lesioning)
• Active infection or inflammatory condition
• Immunosuppressive therapy
• Prior AAV vector exposure
• Contraindications to MRI or anesthesia
• Active malignancy

Trial Sites

The REGENERATE-PD trial is being conducted at leading movement disorder centers:

• United States: Major academic medical centers with expertise in gene therapy and movement disorders
• Additional sites: International centers with established PD research programs

Clinical Significance

Advantages Over Previous GDNF Approaches

| Feature | Historical GDNF Infusion | AB-1005 Gene Therapy |
|---------|-------------------------|---------------------|
| Delivery | Continuous external pump | Single surgical procedure |
| Duration | Requires device maintenance | Long-term expression |
| Distribution | Limited by diffusion | CED improves distribution |
| Safety | Device-related risks | No external hardware |
| Patient Burden | High (device, frequent visits) | Lower (one-time procedure) |

Disease-Modifying Potential

AB-1005 represents a potentially disease-modifying approach because it:

Comparison to Other GDNF Approaches

Historical GDNF Trials

| Trial | Approach | Outcome |
|-------|----------|---------|
| 1995 (Intraventricular) | Direct brain infusion | Mixed results, discontinued |
| 2002-2004 (Phase I) | Putaminal infusion | Improved motor scores |
| 2006-2008 (Phase II) | Continuous putaminal infusion | Did not meet primary endpoint |

AB-1005 Differentiators

• Gene Therapy vs. Protein Delivery: Single procedure vs. continuous infusion
• Modern Delivery: Convection-enhanced delivery for better distribution
• Targeted Approach: Precision stereotactic placement
• Sustained Expression: Long-term GDNF production from transduced cells

Safety Considerations

Potential Risks

Monitoring

• Regular neurological examinations
• MRI imaging at specified intervals
• CSF biomarker sampling
• Immunogenicity assessments

Future Directions

The REGENERATE-PD trial represents a critical proof-of-concept for GDNF gene therapy in Parkinson's disease. Success could pave the way for:

See Also

• [Parkinson's Disease](/diseases/parkinsons-disease)
• [GDNF Therapy for Parkinson's Disease](/therapeutics/gdnf-therapy-parkinsons)
• [Dopaminergic Neurons](/cell-types/dopaminergic-neurons)
• [Gene Therapy](/therapeutics/gene-therapy)
• [Neurotrophic Factor Therapies](/therapeutics/neurotrophic-factor-therapy)
• [Alpha-Synuclein](/proteins/alpha-synuclein)
• [Substantia Nigra](/brain-regions/substantia-nigra)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving AB-1005 (REGENERATE-PD) GDNF Gene Therapy Trial discovered through SciDEX knowledge graph analysis: