SAFETY OF SINGLE-DOSE ADMINISTRATION OF AN ADENOASSOCIATED VIRUS (AAV)-CFTR VECTOR IN THE PRIMATE LUNG

Gene therapy for cystic fibrosis (CF) would ideally be accomplished wi th a vector capable of long-term expression of the cystic fibrosis tra nsmembrane conductance regulator (CFTR) in then absence of a host infl ammatory response. Recombinant adeno-associated virus (AAV)-CFTR vecto rs possess these characteristics in rabbits. Because the utility of AA V vectors as gene transfer agents has only been recognized recently AA V vector-mediated transduction has never been modeled in a primate hos t, which is an important step before its use in humans. In order to te st the safety and biological activity of AAV-CFTR, single doses of AAV -CFTR vector were administered by fiberoptic bronchoscopy to the poste rior basal segment of the right lower lobe (RLL) of the lungs of 10 rh esus macaques with four matched vehicle-treated controls. Animals were followed for 10, 21, 90 or 180 days following vector instillation. Ve ctor DNA transfer occurred in bronchial epithelial cells in the RLL of each animal that received vector as assessed by in situ DNA PCR. Vect or mRNA was detectable for 180 days after administration, as defected by RT-PCR and by RNase protection assay. Safety of vector administrati on was determined by measurements of pulmonary mechanics, arterial blo od gas analysis, chest radiographs, and bronchoalveolar lavage (BAL) f luid analysis including cell count and quantification of inflammatory cytokines. Gross and microscopic pathologic examination were also perf ormed. There was no evidence of inflammation or other toxicity althoug h vector DNA was found in extrapulmonary organs of some animals. These results indicate that transduction of the primate airway epithelium w ith the AAV-CFTR mediates long-term CFTR cDNA transfer and is relative ly safe.