The main purpose of this study is to test the safety and efficacy (how well it works) of an investigational product called VY-AADC02 on the severity of PD. VY-AADC02 involves placing a gene in the brain that programs brain cells to produce an enzyme (protein) called AADC (aromatic amino acid decarboxylase).
Genes are what make up our genetic code, aka DNA – the chemical structure carrying all the information that determines many human traits and characteristics such as the color of your eyes or hair. Each gene can be read by your cells (the building blocks of the human body) as a set of instructions to make a specific protein.
AADC is a naturally occurring protein found in the brain that converts levodopa (one of your current PD medications) to dopamine. Dopamine is a chemical “messenger” that allows the brain cells to communicate with each other and is involved with the normal function of movement control centers in the brain. As PD worsens, the amount of AADC in the brain decreases, and, in turn, this decrease reduces the amount of dopamine that is produced from each dose of levodopa that you take.
In order to deliver the AADC gene into the brain cells, the gene is delivered inside a transporter called adeno-associated viral vector (AAV). To explain this, think about the AADC gene like a letter that carries the information that the brain will read. The AAV acts as the envelope that contains this information, and the combined AADC and AAV can be thought of as the complete package (the letter and envelope that the brain will receive). AAV is used because it is not known to cause disease or spread to others. The combined package of AADC and AAV will be referred to as the “study product” in the remainder of this document. The study product will tell the brain cells to make more AADC, which may increase dopamine levels in your brain when you take levodopa. An increase in dopamine levels may provide improvement in the movement areas in the brain and may help with your PD symptoms.
The investigators hope to learn more about the delivery and distribution of the study product, including the delivery device used in the surgery (called a cannula), the imaging substance (gadolinium) used to visualize the infusion of the study product during the surgery, and how the body reacts to the study product over time using PET (positron emission tomography) scans to determine the change in the level of the AADC gene in your brain. Gadolinium is routinely used for the purpose of imaging, in this study it is considered experimental as it is infused directly into the tissue of the brain, and not through a vein.
- Diagnosis of PD, consistent with United Kingdom Brain Bank Criteria
- Motor responsiveness to dopaminergic therapy, demonstrated by improvement in MDS-UPDRS III score
- Disease duration from diagnosis of ≥4 years
- Atypical or secondary parkinsonism, including but not limited to symptoms believed to be due to trauma, brain tumor, infection, cerebrovascular disease, other neurological disease, or to drugs, chemicals, or toxins, as determined by the Investigator
- MoCA score <26
- New or unstable psychiatric conditions (psychosis, depression) within 1 year of screening
While you are in the study, you will have approximately 17 visits to the study center. If you choose to participate in this study, and if you meet all study requirements, you will be involved in this study for approximately 12 months. As a participant, it is requested you complete all study activities and assessments.
- Blood drawing (venipuncture): You will be asked to give a blood sample for laboratory tests. Approximately 1 tablespoon of blood will be drawn by inserting a needle into a vein in your arm for these tests.
- Electrocardiogram: You will have an electrocardiogram (ECG), which is used to measure the rate and regularity of heartbeats, as well as the size and position of the heart chambers, and the presence of any damage to the heart.
- Chest X-ray: You will have an X-ray of your chest done, once at the beginning of the study in order to check the condition of organs and structures of the chest such as the heart and lungs.
- Brain MRI: You will have a magnetic resonance imaging (MRI) exam of your brain with an intravenous (IV) contrast product. For the MRI exam, you will lie down on a narrow bed which will then be moved into a tunnel that is open at each end. You will lie there quietly for about 1 hour, during which time there will be a noise generated by the MRI machine. You may feel warm during this procedure.
- F-Dopa PET Scan
- The positron emission tomography (PET) scan is a type of nuclear medicine imaging. It is a noninvasive and painless medical test that uses a small amount of a radioactive material injected into a vein in your arm. A PET scan using [F-18] DOPA (F-Dopa), is a way of determining the level of AADC gene expression in your brain after delivery of the study product.
- You will be required to undergo three F-Dopa PET scans during this study. The first will be during the baseline visit, on a separate day from your OFF-ON Visit. The second will be at approximately 45 days after surgery, and the third will be at the end of the study, approximately 12 months after surgery.