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AAV-GAD

Phase 1

Parkinson's Disease | Gene therapy | Neurology |MeiraGTx Holdings plc|Last Updated: Sep 1, 2026

Target and mechanism

Molecular targetGAD1/2
ModalityGene therapy

Also known as AAV-GAD Low Dose

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindNO_TREATMENT_CONTROLLEDDMC
Total Trials2
Total Enrollment27

FDA Designations

RMAT

Clinical trial landscape

AAV-GAD · 2 trials · 1 indication

Phase 1 2
NCT05894343Long-term Follow-up of Glutamic Acid Decarboxylase (GAD) Gene Transfer in Parkinson's DiseaseParkinson's Disease
ACTIVE NOT_RECRUITING13 Analytics
NCT05603312A Double-blind Study to Evaluate the Safety of Glutamic Acid Decarboxylase Gene Transfer in Parkinson's ParticipantsParkinson's Disease
COMPLETED14 Analytics
PHASE1ACTIVE NOT_RECRUITING
Long-term Follow-up of Glutamic Acid Decarboxylase (GAD) Gene Transfer in Parkinson's Disease
Parkinson's DiseaseUnlock trial analytics
PHASE1COMPLETED
A Double-blind Study to Evaluate the Safety of Glutamic Acid Decarboxylase Gene Transfer in Parkinson's Participants
Parkinson's DiseaseUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of participants with study drug-related adverse events and serious adverse events
From study start until Month 60 post treatment
Incidence of Adverse Events Related to the Treatment
Baseline to Week 26

The primary outcome measure is the safety of treatment with AAV-GAD, assessed by the absence of IMP-related treatment-emergent adverse events.

Incidence of Serious Adverse Events Related to the Treatment
Baseline to Week 26

The primary outcome measure is the safety of treatment with AAV-GAD, assessed by the absence of IMP-related serious treatment-emergent adverse events.

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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Follow-up groupNO_INTERVENTIONParticipants who were randomized to immediate treatment in Study MGT-GAD-025 will transition directly to a long-term follow-up schedule to complete an additional 54 months of follow-up. All study participants are to be followed for 60 months after vector administration.
Active treatment groupEXPERIMENTALParticipants who were randomized to sham surgery in Study MGT-GAD-025 will transition to an active treatment schedule, including open-label bilateral treatment, upon confirmation of continued eligibility. Upon completion of the treatment period, participants will enter the long-term follow-up schedule to complete a total of 60 months of follow-up.
AAV-GAD Low DoseEXPERIMENTALEligible participants received bilateral infusion of AAV-GAD low dose into the STN
AAV-GAD High DoseEXPERIMENTALEligible participants received bilateral infusion of AAV-GAD high dose into the STN
Sham SurgerySHAM_COMPARATOREligible participants underwent a sham surgical procedure

Interventions

NameTypeDescription
AAV-GADGENETICBilateral infusion of AAV-GAD
AAV-GAD Low DoseGENETICBilateral infusion of AAV-GAD low dose
AAV-GAD High DoseGENETICBilateral infusion of AAV-GAD high dose
Sham SurgeryPROCEDURESham infusion
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Eligibility Criteria

Age Range25 Years to 86 Years
SexALL
Healthy VolunteersNo
Study Sites6

Inclusion Criteria: * Previously enrolled in Study MGT-GAD-025. Exclusion Criteria: * None

Countries:United States
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Recent Changes (Last 90 Days)

LOWSep 1, 2026NCT05894343lastUpdatePostDate: changed
LOWSep 1, 2026NCT05894343lastUpdatePostDate: changed

Frequently asked questions about AAV-GAD

What is AAV-GAD used for in Parkinson's Disease?

AAV-GAD is an investigational gene therapy being developed for Parkinson's disease. It delivers the gene for glutamic acid decarboxylase into the brain with the goal of restoring GABA production in the affected neural circuits. It is not approved and remains in Phase 1 clinical development.

What does AAV-GAD target?

AAV-GAD targets GAD1 and GAD2, the genes encoding glutamic acid decarboxylase, the enzyme that converts glutamate into GABA. By introducing these genes via an adeno-associated viral vector, the therapy aims to increase GABA synthesis in the subthalamic region and rebalance the excitatory and inhibitory signaling that is disrupted in Parkinson's disease.

Who is developing AAV-GAD?

AAV-GAD is being developed by MeiraGTx Holdings plc, which trades on the Nasdaq under the ticker MGTX. The company holds an RMAT designation from the FDA for the program, which covers the gene therapy in Parkinson's disease.

What phase is AAV-GAD in?

AAV-GAD is in Phase 1 clinical development. It is an investigational gene therapy and has not been approved by the FDA. Two Phase 1 trials have been conducted in Parkinson's disease, one completed and one active but no longer recruiting, with a combined enrollment of 27 participants.

What clinical trials is AAV-GAD in?

AAV-GAD has been studied in two Phase 1 trials. NCT05603312 was a double-blind, no-treatment-controlled study of glutamic acid decarboxylase gene transfer in Parkinson's participants, and it is completed. NCT05894343 is a long-term follow-up study of GAD gene transfer in Parkinson's disease and is active but not recruiting.

Is AAV-GAD the same as AAV-GAD Low Dose?

Yes, AAV-GAD Low Dose is another name used for AAV-GAD. Both refer to the same MeiraGTx gene therapy program for Parkinson's disease, which uses an adeno-associated viral vector to deliver the glutamic acid decarboxylase gene. The low dose label distinguishes the dose level studied in the clinical program.