Neurologix’s 12-patient, dose-escalating phase I trial is the world’s first study to use a viral vector (the non-pathogenic adeno-associated virus, or AAV) for the treatment of an adult neurological disease.
The vector was injected into a specific target site in the brain in order to transfer a gene to treat Parkinson’s disease. The gene encodes glutamic acid decarboxylase (GAD), an enzyme which synthesizes the major inhibitory neurotransmitter in the brain, (gamma)-aminobutyric acid (GABA).
Patients with advanced Parkinson’s disease received unilateral (one side of the brain) infusion of AAV-GAD via a hair-thin catheter into the subthalamic nucleus (STN), a deep brain structure known to function abnormally in Parkinson’s patients.
According to the interim findings, Neurologix’s treatment appears to be safe and well-tolerated in advanced Parkinson’s disease, with no evidence of adverse effects or immunologic reaction related to the study treatment. Furthermore, patients in the trial, at one year, exhibited a statistically significant improvement in motor function on the side of their body correlating to the treated part of the brain, as measured by the Unified Parkinson Disease Rating Scale.
In contrast, the untreated side evidenced no significant improvement. Also, activities of daily living, another standard measure of Parkinson’s severity which is recorded by the patients themselves, showed a strong trend toward statistical improvement.
In addition, fluorodeoxyglucose (FDG)-PET scans at one year revealed that the treated side of the brain exhibited a statistically significant decrease in abnormal metabolism, while the untreated side showed a further increase in abnormal metabolism. The imaging results were considered similar to those achieved with STN Deep Brain Stimulation, an FDA-approved treatment which currently represents the preferred surgical approach for advanced Parkinson’s disease.