Cedars-Sinai Medical Center opens patient trial of virus that attacks brain ca...( LOS ANGELES (April 15 2008) A commo...),Health

LOS ANGELES (April 15, 2008) A common, naturally occurring virus that attacks cancer cells but appears to be harmless to normal cells is being studied as a possible treatment for malignant, highly aggressive and deadly brain tumors called gliomas. Researchers at Cedars-Sinai Medical Center are among a few in the United States evaluating this experimental therapy.

Over the course of a lifetime, most adults will be exposed to the virus in its natural state. It commonly infects the lungs and intestines but unlike most viruses causes few if any symptoms and is usually eliminated by the body within two weeks. But while the reovirus (respiratory enteric orphan virus) may be harmless to normal cells, it can specifically kill certain cancer cells.

Vulnerable cancer cells have a defect in a signaling pathway (the Ras pathway) that controls key cell functions. The reovirus is able to infect and kill cancer cells that have an activated Ras pathway, but the virus does not normally come into contact with cancer cells. Researchers at Oncolytics Biotech Inc., of Calgary, Canada, developed a therapeutic drug, REOLYSIN, from the reovirus and are conducting multicenter clinical trials for a variety of cancers. Cedars-Sinai is participating only in the study on recurrent gliomas, the most common and deadly brain cancers.

Based on the fact that many types of cancer cells have an activated Ras pathway, the company estimates that up to two thirds of all human cancers are susceptible to reovirus induced cell death .

Although not every glioma cell line has an activated Ras pathway, Ras activation is very common in these malignant brain cancers. In lab tests and animal studies, the reovirus appears to target Ras-activated tumor cells and leave normal cells alone, said neurosurgeon John S. Yu, M.D., director of Surgical Neuro-oncology at Cedars-Sinais Department of Neurosurgery. Yu is principal investigator of the REOLYSIN clinical trial at Cedar
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