Reovirus Shows Potential for Treating Prostate Cancer

A recent paper reported the results of a study designed to test the potential for using an oncolytic reovirus to treat prostate cancer.

Reoviruses (respiratory, enteric, orphan virus) are double-stranded RNA viruses that often cause mild gastroenteritis in humans with the most prominent type being Rotavirus. In addition, these viruses are able to exploit aberrant signaling pathways, which allow them to be selectively cytotoxic for several different types of cancer including lymphoid, ovarian, breast, pancreatic, and high-grade glioma.

In the current study, investigators at the Tom Baker Cancer Center (Calgary, AB, Canada) evaluated the potential for using reoviruses to attack prostate cancer using a combination of tissue culture, mouse xenografts, and a small cohort of prostate cancer patients.

They reported in the March 9, 2010, online edition of the journal Cancer Research that after exposure to replication-competent reovirus, the human prostate carcinoma cell lines PC-3, LN-CaP, and DU-145 showed evidence of infection as illustrated by viral protein synthesis, cytopathic effect, and release of viral progeny. This oncolytic effect was found to be manifested through apoptosis. In the mouse immunodeficient/nonobese diabetic xenograft model a single intratumoral injection of reovirus caused reduction in tumor size. Finally, intralesional reovirus injections into a cohort of six patients with clinically organ-confined prostate cancer resulted in minimal side effects and evidence of antitumor activity.

"The reovirus is a very common, ubiquitous virus that most people are exposed to. As far as we know, it does not cause any significant illness in humans, even though when someone is exposed to it, it manifests, at most, as a mild respiratory infection or mild diarrhea,” said senior author Dr. Don Morris, medical oncologist at the Tom Baker Cancer Center. "For the treatment of localized prostate cancer, we found that the reovirus is safe and has evidence of specific tumor vs. normal prostate cell efficacy. Our results are a stepping stone into future prostate cancer clinical trials with another category of cancer therapeutics.”

Related Links:
Tom Baker Cancer Center