Targeted Genetics Corporation announced the issuance of a patent covering additional approaches to manufacturing AAV (adeno-associated virus) vectors. The patent, U.S. #6,475,769 is titled "Methods and Cell Line Useful for Production of Recombinant Adeno-Associated Viruses" and covers the production of AAV vectors using stable cell lines. The patent was issued to the University of Pennsylvania and is exclusively licensed to Targeted Genetics.

Production of AAV vectors requires the introduction of several elements into a permissive cell -- the AAV vector and gene of interest, AAV rep and cap genes and a helper virus. Targeted Genetics has proprietary technologies for creating established cell-lines in which several of these elements are integrated into the cellular DNA. Non established cell-line approaches require introducing these elements on plasmid DNA via transfection during each production cycle. Transient transfections are not as amenable to scale-up because the cells must be grown on an adherent surfaces and transfection processes are not as efficient and robust.

"We believe that cell-line based manufacturing is the most cost-effective method for producing AAV vectors, particularly at large scale," said Vaughn Himes, Vice President, Manufacturing at Targeted Genetics. "Our intellectual property in this area is significant, and the addition of this patent further solidifies our leadership position in cell-line based approaches to AAV production. Targeted Genetics' capabilities related to AAV manufacturing cover both rapid production techniques as well as large scale manufacturing methods. To date these capabilities have been an important factor in our ability to attract world-class partners, and to undertake one of the largest and most advanced clinical development programs for AAV-based product candidates, and we believe that these capabilities will continue to be an important asset for the Company."

The patent covers methods of making AAV using a stable cell line and the stable cell line itself, which has at least five copies of the AAV rep and cap genes stably integrated into the cell's genome and the use of this cell line to produce recombinant AAV vectors. Targeted Genetics previously has established cell-lines in which several of the elements required for AAV vector production are integrated into the cellular DNA. These cell lines have been adapted to grow in suspension and can be used to manufacture AAV vectors via standard biopharmaceutical production methods used for the manufacture of therapeutic proteins, monoclonal antibodies and vaccines. The technology covered by the patent issued today complements and expands the Company's capabilities in the area of AAV vector production. These cell-lines can be used in the Company's Ad-AAV hybrid manufacturing process or can be integrated into the Company's existing manufacturing process.