Safety Study of AADC Gene Therapy (VY-AADC01) for Parkinson's Disease

Parkinson's disease is a neurodegenerative disorder involving loss of neurons that release dopamine in the striatum. To compensate for the loss of dopamine, patients are typically prescribed levodopa medication which is converted to dopamine by the enzyme Aromatic L-Amino Acid Decarboxylase (AADC). As Parkinson's disease progresses, levodopa therapy becomes less effective and is associated with motor fluctuations, involuntary movements and other complications. This study will primarily investigate the safety of increasing AADC levels in the striatum via AADC gene delivery. The hAADC gene is packaged into a gene transfer vector derived from a common, non-pathogenic virus (AAV2) to which \>90% of humans have been exposed. This investigational drug, termed VY-AADC01, will be injected directly into the striatum during a neurosurgical procedure that is performed with real-time MRI imaging to monitor delivery. Subjects will continue to take Parkinson's disease medications, including levodopa. The safety and potential clinical responses to VY-AADC01 will be assessed by repeated clinical evaluations of Parkinson's disease, cognitive tests, laboratory blood tests and neuroimaging. Clinical evaluations will be performed over a 3 year follow-up period. A test to specifically assess the clinical response to levodopa will be performed once before AADC gene delivery and approximately 6 months after.