Targeted Genetics Announces Issuance of Broad Patent for Lipid-Based Gene Delivery Systems for Use in Gene Therapy
07:49 a.m. Aug 18, 1998 Eastern

SEATTLE, Aug. 18 /PRNewswire/ -- Targeted Genetics Corporation (Nasdaq:TGEN) and the University of Pittsburgh today announced that they have received notification from the U.S. Patent and Trademark Office regarding the issuance of a patent which provides broad protection for a new class of lipid-based systems that can be used as vehicles for efficient gene delivery.

Specifically, the patent covers cationic lipid formulations, known as LPD vectors, comprised of cationic lipid, polycation (positively charged polymer molecule), and DNA/nucleic acid. These novel gene delivery systems are stable, capable of being produced at relatively high concentrations, and maintain biological activity over time. The patent also covers methods for the production of such LPD formulations, and protects against competitors employing the covered formulations or methods of production for any application. LPD formulations could be made using a wide variety of polycations and cationic lipids, and a majority of these possible combinations are broadly covered in this patent.

"The issuance of broad patent protection for LPD vectors represents a major strategic advantage for Targeted Genetics," said H. Stewart Parker, President and CEO for the Company. "Compared to currently available cationic liposome formulations, LPD formulations demonstrate significantly improved gene transfer efficiency in cells. This represents an approach that we and many of our competitors acknowledge as the next logical step in lipid mediated nucleic acid delivery. This patent and numerous others that are issued or pending have allowed the Company to amass a formidable intellectual property position in the gene and cell therapy arena."

Targeted Genetics researchers and their collaborators have successfully generated a variety of LPD formulations and tested their gene transfer efficiencies in cells. The Company currently is developing LPD formulations for direct intratumoral and intraperitoneal gene delivery of the Company's proprietary tumor inhibitor gene, E1A. The Company expects to initiate Phase II studies of E1A in head and neck cancer prior to the end of the year. Additional studies are underway to optimize gene transfection efficiencies of these formulations in the context of systemic in vivo delivery.

The issued patent (USSN 08/376,701) is exclusively licensed to Targeted Genetics. The technology covered by the patent was originally developed by Xiang Gao, Ph.D. and Leaf Huang, Ph.D. at The University of Pittsburgh. Dr. Huang is a pioneer in developing lipid-based gene delivery systems and is an exclusive collaborator to Targeted Genetics. Dr. Huang is a member of the Company's Scientific Advisory Board.

Background - LPD Vectors

Over the years, numerous studies have demonstrated the utility of using cationic lipids to deliver genes and nucleic acids to cells. Many cationic lipids have been described and characterized, but inefficient delivery has continued to be a concern in simple lipid-nucleic acid formulations.

In the approach described in the patent by Drs. Gao and Huang and as being developed by Targeted Genetics, DNA is condensed with polycations prior to the association with cationic lipids such as DC-Chol. The formulation produced by this method has uniformly small sized particles that retain physical stability and potency over a number of months. This represents a substantial improvement over current two-vial lipid-DNA formulations which tend to be much larger and less stable over time. Furthermore, the LPD formulations can have gene transfer activity much greater than the corresponding DNA-lipid vehicle.

Current evidence indicates that compacting DNA and nucleic acids with polycations protects them from enzymes present in cells that destroy foreign DNA and nucleic acids. This helps them to survive uptake by the cell, and may facilitate their transfer into the cell nucleus, commonly their site of action.

Targeted Genetics Corporation develops gene and cell therapy products for the treatment of certain acquired and inherited diseases. The Company has three lead product development programs targeting cystic fibrosis, cancer, and infectious disease, as well and an extensive technology platform.

This news release contains forward-looking statements that involve risks and uncertainties, including the timing and results of clinical trials and other product development risks. Risks associated with liquidity, capital resources and other risks are detailed in Targeted Genetics' filings with the U.S. Securities and Exchange Commission (SEC). SOURCE Targeted Genetics Corporation

Copyright 1998, PR Newswire 

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