Adherex Issued New Patent Which Further Strengthens Anti-Cancer Portfolio - Intracellular Catenin Inhibition: A New Approach to Tumor Vascular Targeting.

Business Editors/Health/Medical Writers

OTTAWA, Ontario--(BUSINESS WIRE)--June 11, 2003

Adherex Technologies Inc. (TSX: AHX), an Ottawa-based biopharmaceutical company, today announced it was issued a new US patent that significantly strengthens its anti-cancer drug candidate portfolio.

Therapeutic approaches that target and destroy a tumor's blood supply are being increasingly recognized as an important area for new cancer research and drug development. A key aspect of Adherex's latest patent is the protection for the structure of drugs that inhibit intracellular catenin molecules. Catenins are critical in the cell-to-cell binding process and play an important role in the maintenance of the structural integrity of a tumor's blood vessels. Inhibiting catenins may offer a novel approach to attacking and destroying a tumor's blood supply.

Dr. Orest Blaschuk, Chief Scientist and a scientific founder of Adherex explains, "Adherex's prior intellectual property has focused on cadherin-based cell adhesion mechanisms on the surface of cells. This patent, Adherex's 25th issued in the US, targets a distinct family of molecules inside cells called catenins and opens up the possibilities of a new realm of further therapeutic applications and a completely novel way to attack and destroy the blood vessels that feed a tumor."

"Adherex is a clear leader in the new field of tumor vascular targeting, which is the targeted destruction of the blood vessels inside tumors," said Dr. William Peters, Chief Executive Officer and Vice Chairman of Adherex. "Our latest patent covers a new application and novel direction in this therapeutic approach and contributes to what we believe is the most comprehensive portfolio of intellectual property for this exciting new area of medical research. Our first vascular targeting agent, Exherin(TM), which entered clinical trials in December of 2002, is based on the cadherin platform, as are our pre-clinical development programs relating to N-cad and VE-cad angiolytics, and our research with OB-cad and cancer metastasis." A selection of these pre-clinical compounds and drug candidates from the new catenin inhibitor family are scheduled to be evaluated for their anti-cancer effects and vascular targeting capabilities as part of the recently announced agreement with the US National Cancer Institute.

Adherex's expanded vascular targeting platform is now based on two families of cell adhesion molecules. A fundamental aspect of cell-to-cell adhesion and intracellular signaling is the interaction between the two intracellular proteins, alpha and beta catenin. These two catenins bind as a complex to cell surface adhesion molecules called cadherins. The cadherin molecules form the actual binding to neighboring cells, but cannot promote cell adhesion unless the two catenins are bound to them. This patent protection compliments and strengthens Adherex's vascular targeting portfolio by adding an important intracellular approach to its cadherin based extracellular cell adhesion platform. As a result, the company's vascular targeting platform now has strong patent protection from both intracellular and extracellular modes of action.

About Adherex Technologies Inc.

Adherex Technologies is an Ottawa-based biopharmaceutical company with a broad portfolio of products under development. Four products will be in clinical trials during 2003 including Exherin(TM), which works to destroy the blood vessels that feed a cancerous tumor and STS a drug that protects against severe hearing loss that is often produced by platinum-based anti-cancer agents. For more information, please visit Adherex's Web site at www.adherex.com.

This news release shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

Certain information contained in this news release is forward-looking and is subject to unknown risks and uncertainties. The actual results, performance or achievements of the company may differ materially from the results, performance or achievements of the company expressed or implied by such forward looking statements.