539. Biodistribution and Safety Profile of CERE-110 (AAV2-NGF) Delivered to the Rodent Brain
Authors: M. Landers, K. Kwok, E. Ketchum, C. Wilson, R. Lin, D. Gammon, M. Austin, L. Manlapaz, A. Wilson, J. Cunningham, D. Vacante, M. Gasmi, K. Bishop, M. Printz, R. Bartus
Journal: Molecular Therapy (2004)

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Parkinson's disease is a progressive debilitating disorder that leads to the selective degeneration of dopamine-producing neurons within the substantia nigra. These nigral dopaminergic neurons send their axons to the striatum via the nigrostriatal pathway, critical for the initiation and coordination of movement. Numerous published studies demonstrate the efficacy of GDNF family ligands to protect and/or enhance dopaminergic neuron survival. Injection of CERE-120 into the striatum delivers Neurturin (NTN) to these dopaminergic neurons by gene transfer. In this study, CERE-120 was delivered by stereotaxic bilateral injections into the striatum of male and female Sprague-Dawley rats at two doses: (1) 8|[times]|109 vg/animal and (2) 4 |[times]|1010 vg/animal. Rats tissue was analyzed 3, 28 and 90 days post-injection for vector biodistribution, transgene expression, immunogenicity and safety endpoints.

Vector biodistribution was analyzed by Q-PCR (sensitive to 10 copies/|[mu]|g of DNA) and transgene expression by RT-PCR. Results indicate that the majority of vector DNA remains localized to the target injection site at both doses. The mean vector load at the injection site was dose reponsive and decreased over time, though long term stable transgene expression persisted throughout the study. CERE-120 DNA was detected at low levels in the brain stem and cerebellum in both doses, while transgene expression was only detected in the brain stem. CERE-120 vector DNA and transgene expression observed in the brain stem are likely due to the presence of CERE-120 in the substantia nigra tissue within brain stem dissection samples. The substantia nigra is a natural target of the striatal neurons and lies in close proximity to the brain stem making its inclusion in the dissection sample likely.Vector DNA was not detected in systemic organs or fluids from animals recieving the low dose. Vector detected 3 days post injection in the liver and spleen of animals receiving the high dose did not persist 28 days post injection. Vector DNA was detected at quantifiable levels only in the cervical lymph nodes and CSF (quantifiable at 3 days only) of animals given the high dose, while no corresponding transgene expression was detected in the cervical lymph nodes.

Serum Ab responses to AAV2 and NTN were assessed by ELISA. Weak to moderate anti-AAV2 responses were detected in the high dose animals at 28 and 90 days while no response was detected in those animals given the low dose. No antibody response to the NTN protein was detected. No morbidity or mortality were observed and no treatment related toxic effects were observed by organ histopathology, serum chemistry or hematologic analyses. All animals gained weight as expected over the course of the study. Overall, the data presented suggest that when administered to the striatum of rats, CERE-120 is primarily localized to the target site, is stably expressed and has a favorable safety profile.