New U.S. Patent Added To Inex's Intellectual Property Assets.

VANCOUVER, British Columbia--(BUSINESS WIRE)--Nov. 17, 1998-- INEX PHARMACEUTICALS (TSE:IEX.) (TSE:IEX.WT.A.) Inex Pharmaceuticals Corp. ("INEX", TSE: IEX) has been issued United States Patent No. 5,820,873 for a key component of the company's drug delivery technology that carries gene drugs to the interiors of cells at disease sites following intravenous administration.

Dr. Pieter R. Cullis, Senior Vice President of Research at INEX, said the patent covers PEG-ceramide, a fusion regulator and exchangeable polymer used in INEX's proprietary Transmembrane Carrier Systems (TCS).

PEG-ceramide consists of a ceramide lipid linked to an immunologically inert polymer, polyethyleneglycol (PEG) molecule. Its role is to stabilize the TCS formulation for a sufficient length of time to allow the accumulation at the disease site. During accumulation at the disease site, the PEG-ceramide dissipates from the formulation and promotes intracellular delivery of the gene drug.

Cullis said the PEG-ceramide patent confirms INEX's lead position in systemic delivery of lipid-based gene drug formulations.

"In order to treat metastatic cancer, physicians need a drug that can be administered into the blood circulation system and will seek out and enter tumour cells wherever they are in the body. Our work is the only lipid-gene drug formulation known to demonstrate efficacy at distal tumour sites following intravenous administration in pre-clinical models."

Currently, published reports on other gene delivery technologies, such as lipid complexes and viruses, indicate they are limited in their ability to carry genes beyond the lungs and liver after intravenous administration. These limitations have restricted the majority of gene therapy research for cancer to direct injection or local delivery of the gene to the tumour site, which represent niche commercial applications.

Earlier this year, INEX was awarded U.S. Patent Nos. 5,753,613 and 5,785,992 for its proprietary cationic lipid DODAC, which is used in its gene plasmid drugs. Also earlier this year, INEX was awarded US Patent No. 5,705,385 that protects the essential hydrophobic intermediate generated during the preparation of INEX's lead gene drug products.

INEX currently owns and holds licenses to 101 U.S. patents and patent applications covering technologies required for commercialization of its lead products. Approximately two-thirds of these patents and patent applications are specific for gene drug formulations.

INEX expects two of its gene drug product candidates to begin clinical trials before the year 2000. The most advanced of the product candidates is INXC-6295, an antisense drug which blocks the function of a gene that produces a cancer-causing protein. INEX expects to begin testing INXC-6295 in clinical trials in early 1999 following the filing in January of an Investigational New Drug (IND) application with the U.S. Food and Drug Administration or the Health Protection Branch of Canada.

A fourth INEX product candidate, Onco TCS, is already in Phase II clinical trials. Onco TCS is not a gene drug, but is a combination of the company's TCS and the off-patent conventional cancer drug vincristine. The TCS makes vincristine less toxic and more effective by carrying the drug to disease sites and into diseased cells in higher concentration and for a longer duration than if vincristine was administered without the TCS. INEX announced November 5th that Onco TCS has demonstrated in Phase II trials the capacity to shrink tumours in patients with advanced non-Hodgkin's lymphoma after standard chemotherapy treatments have failed.

INEX is a Canadian biopharmaceutical company commercializing drugs that utilize proprietary drug delivery systems to treat cancer and inflammatory diseases. The company is focused on gene-based drugs, such as antisense oligonucleotides, which regulate or block genes that produce an undesired disease-causing protein, and gene plasmids, which replace defective genes to achieve a therapeutic effect. The company has operations in Vancouver, British Columbia, and Hayward, California.