Tumor-Melting Virus vs. Prostate Cancer
Reovirus Is Harmless -- Except to Many Kinds of Cancers
One way of overcoming this problem is by using reovirus together with chemotherapy. Chemo kills cancer cells, but also dampens antiviral immune responses. A recent human study shows this strategy can benefit patients with advanced head and neck cancer.
Another way to overcome the problem is to harness anti-reovirus immune responses to attack cancer cells.
"The virus only sticks to tumor cells, so it sort of directs the immune response to the tumor area," Morris says. "We have actually taken reovirus and injected it in combination with tumor antigens, so the immune system kills tumors pasted with the virus."
There's still a lot of work to do before reovirus in general, or Reolysin in particular, becomes an approved cancer treatment, says cancer expert Rameen Beroukhim, MD, PhD. Beroukhim was not involved in the Morris study.
"There is a long way between this interesting study and showing that reovirus is going to be beneficial to patients," Beroukhim says. "But the hope is that this treatment could be tweaked in some way to have a systemic anti-cancer effect."
Morris is the first to acknowledge that there's a lot more work to do. One major issue, he says, is that not every patient's cancer is susceptible to reovirus.
"In the majority of cancers, if you take specimens from different patients, not all cancers are killed. Maybe seven or eight of 10 patients' cancers are sensitive. So we need to find out what makes a cancer cell susceptible to reovirus," he says.
The Morris study was partially funded by Oncolytics Biotech, and the company funds his laboratory. But Morris says he has not been compensated by any companies in the oncology-virus field for the last five years. Although he is a patent holder on some indications for reovirus, he has signed away rights to financial gain.
Morris and colleagues report their findings in the March 15 issue of Cancer Research.