Parkinson's Disease Research Today is a free monthly online journal that collates and summarizes the latest research about Parkinson's Disease, including details on symptoms, treatment, genetics, medication.

Results from a phase I safety trial of hAADC gene therapy for Parkinson disease.

Eberling JL, Jagust WJ, Christine CW, Starr P, Larson P, Bankiewicz KS, Aminoff MJ

Department of Molecular Imaging and Neuroscience, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. jleberling@lbl.gov

BACKGROUND: In a primate model of Parkinson disease (PD), intrastriatal infusion of an adeno-associated viral (AAV) vector containing the human aromatic l-amino acid decarboxylase (hAADC) gene results in robust gene expression. After gene transfer, low doses of systemically administered l-dopa are converted to dopamine in the transduced striatal neurons, resulting in behavioral improvement without the side effects typically associated with higher doses of l-dopa. These studies led to the initiation of a phase I safety trial. Here we report the findings for the first cohort of five patients. METHODS: Patients with moderate to advanced PD received bilateral infusion of a low dose of the AAV-hAADC vector into the putamen. PET scans using the AADC tracer, 6-[18F]fluoro-l-m-tyrosine (FMT), were performed at baseline and at 1 and 6 months after infusion as an in vivo measure of gene expression. RESULTS: PET results showed an average 30% increase in FMT uptake (K(i)(c)) in the putamen after gene transfer. Preliminary analysis of clinical data indicates a modest improvement, but absence of a control and the nonblinded analyses make interpretation difficult. CONCLUSIONS: Thus far, this gene therapy approach has been well tolerated and shows PET evidence of sustained gene expression. These initial findings demonstrate the safety of the therapy; higher doses of adeno-associated viral vector containing the human aromatic l-amino acid decarboxylase gene in the next cohort of patients may further increase dopamine production in the putamen and provide more profound clinical benefit.

Published 20 May 2008 in Neurology, 70(21): 1980-3.
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