Reovirus Could Lead to Immunotherapy for Liver Diseases

The virus that causes coughs and colds, reovirus, could potentially be used as an immunotherapy treatment for liver diseases, such as hepatitis C virus (HCV) and primary liver cancer, a recent study found.

The reovirus affects the respiratory system and causes upset stomachs in children, but the virus does not have these effects on adults, since they have typically been exposed to it earlier in life. Researchers found that this virus increases an immune system response that can kill cancer cells in the liver.

These findings are significant since liver cancer is the third leading cause of cancer-related deaths around the world, and treatment options are limited if surgical intervention is not possible, according to the study published by Gut.

“Ultimately we hope that by simultaneously treating the tumor, and the hepatitis virus that is driving the growth of the tumor, we may provide a more effective therapy and improve the outcomes for patients,” said study co-leader Stephen Griffin, PhD. “Current treatments for liver cancer that can't be removed by surgery are mainly palliative -- with chemotherapy only tending to prolong life, rather than cure -- and it can have significant side effects.”

In the study, researchers were able to successfully treat lab-grown liver cancer cells and cells removed from a patient with reovirus, and they discovered that the virus stimulates interferon, which activates natural killer white blood cells. Natural killer cells then eliminate the tumor and cells infected with HCV, according to the study.

This immunotherapy treatment could provide patients with both diseases an alternative option to chemotherapy and current HCV antiviral treatments.

"It is becoming increasingly clear that one of the most powerful weapons available to treat cancer is our own immune system. However, as cancers are formed from our own cells, the immune system frequently struggles to identify the subtle differences that differentiate cancerous cells from normal cells, without help,” said co-researcher Dr Adel Samson. “Immunotherapy involves various strategies -- such as a virus, as in our study -- to kick-start our immune system to better identify and fight cancer. These 'oncolytic' viruses show great promise in clinical trials, and the first such virus has recently been licensed as a medicine for the treatment of skin cancer.”

A majority of primary liver cancers are the result of liver damage from hepatitis infections, and are only sometimes caused by excess alcohol consumption. A significant amount of the 130 million patients with HCV will develop liver cancer, according to the study.

Immunotherapy has become the focus of many novel cancer treatments, and these findings suggest reovirus could be used an immunotherapy to even treat viral infections that may progress to cancer. Virus-driven cancers can present challenges for treatment, and novel strategies to treat the cause of the cancer is desperately needed.

Next steps include determining if these findings translate to humans, according to the study.

"Our study establishes a completely new type of viral immunotherapy for the most common primary liver cancer type, hepatocellular carcinoma, which has a very poor prognosis in its advanced form," said study co-leader Alan Melcher, BM BCh, PhD. "We also showed that reovirus therapy could be used to treat a range of other cancer types associated with viral infection, including Epstein Barr Virus-associated lymphoma."