Adhesion Blocker Stops Tumor Growth

A unique approach to blocking tumor growth has had dramatic results in treating human breast and ovarian tumors growing in mice, according to scientists at McGill University (Montreal), Georgetown University (Washington, DC), and the Weizmann Institute (Rehovot, Israel). While research is still in the animal-testing phase, the compound Exherin, which targets adhesion sites among blood vessel cells, has been found to stop tumor growth. This factor, discovered at McGill University ten years ago, is being tested by Adherex Technologies (Ottawa, ON, Canada).

Tumors depend on blood vessels for oxygen and other nutrients. However, tumor blood vessels apparently have weaker bonds between cells, which allows Exherin to disrupt tumor vessel adhesions without affecting normal blood vessels. In preliminary safety tests, no apparent side effects were observed in healthy mice treated with up to 50 times the therapeutic dose.

Targeting cell adhesion differs from current cancer therapies that seek to stop new blood vessel growth (anti-angiogenesis). In contrast, Exherin acts on both pre-existing tumor blood vessels as well as new vessels being formed. If successful, this anti-adhesive approach will be faster and may not require treatment over a long period of time.

"We are cautiously optimistic about our animal experiment data," said Orest Blaschuk, an associate professor at McGill University and chief scientist of Adherex, a company created specifically to develop therapies using cell adhesion.

"While this research is in the early stages, Exherin's consistent and efficient ability to stop human breast and ovarian tumor growth in mice is very impressive," he added.

The ability of cancer cells to develop resistance to traditional cancer drugs has been a major obstacle in developing effective therapies. "By targeting the blood vessels that feed the tumor rather than the tumor itself, we bypass the common problem of cancer cells developing resistance to the anti-cancer drugs," said Barbara Gour, Adherex's director of medicinal chemistry.

Adherex hopes to start clinical trials of Exherin with human cancer patients in late 2000. The ongoing testing of Exherin is being led by Blaschuk and Riaz Farookhi at McGill, Stephen Byers and Sandra McLeskey at Georgetown, and Benjamin Geiger and Michal Neeman at the Weizmann Institute.

Patent rights for Exherin are owned by McGill University and licensed to Adherex, which was formed as part of McGill's policy of encouraging commercialization of inventions originating from its researchers.

For more information: Orest Blaschuk, Adherex Technologies Inc., 600 Peter Morand Cres., Suite 340, Ottawa, ON, K1G 5Z3, Canada. Tel: 613-738-8000.