Viruses may help cure cancer by killing cancer cells

CALGARY, Alberta, June 28 /PRNewswire/ -- Researchers are now investigating how to make cancer cells "terminally ill" by giving a common reovirus to patients with various types of cancers.

Already in clinical trials, the reovirus-based therapy called "Reolysin" will soon be administered to patients at the Montefiore Medical Center in New York in a phase I trial sponsored by Calgary-based Oncolytics Biotech.

"Patients with cancers that have spread beyond their original tumor sites (metastatic) will receive the therapy via systemic, or intravenous administration," according to Oncolytics Biotech's chief scientific officer, Dr. Matt Coffey.

"This discovery -- that a common virus, even though it does not cause illness, can kill cancer cells -- offers hope for a truly revolutionary approach to cancer therapy," says Dr. George M. Gill, Senior Vice President of Clinical and Regulatory at Oncolytics.

As described by Dr. Coffey in published scientific journals, including Science and The EMBO Journal, reoviruses are able to replicate only in cancer cells with an activated Ras pathway, without harming healthy cells. The Ras Pathway is instrumental in transferring growth signals to the nucleus of a cell, telling the cell when and how to grow-much like an "on-off" switch.

A cell with an activated Ras Pathway, which has lost its ability to "turn off," leads to uncontrolled cell growth. These mutations along the Ras pathway are found in approximately two-thirds of all human cancers.

The virus in Reolysin will invade Ras-activated cancer cells, where the virus is able to replicate until it kills the host tumor cell. When the cancer cell dies, thousands of progeny virus particles are released, which then proceed to infect and kill adjacent cancer cells.

Dr. Coffey explains the process is believed to continue until all infected cancer cells with activated Ras pathways have been infected and killed by the reovirus -- all without causing the nausea, hair loss and other side effects associated with radiation and chemotherapy.

"In clinical trials completed to date, patients have not suffered any serious adverse side effects. Novel therapies like Reolysin are beginning to expand treatment options," says Dr. Coffey.