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Localized virus can be used to treat liver cancer and hepatitis C.
The so-called reovirus usually causes mild cases of respiratory infections, especially in children. Researchers now found that the virus could be used as an immunotherapy to fight liver cancer and hepatitis C. This form of therapy could lead to improved treatment in many people around the world.
An international team of scientists found that a common virus could be used as a treatment for liver cancer and hepatitis C. The experts published the results of their study in the acclaimed medical journal "BMJ".
A widespread and harmless virus could enable more effective treatment of liver cancer in the future. Physicians achieved promising results in experiments with this new form of therapy. (Image: blueringmedia / fotolia.com) Three quarters of liver cancer diseases are caused by HCV or HBV
Viruses cause about twenty percent of all cancers. A particular problem is viruses in diseases caused by liver cancer, about three quarters of cases are caused either by the hepatitis C virus (HCV) or the hepatitis B virus (HBV).
Researchers force the immune system to fight tumors and HCV infection
These viruses cause a long-lasting infection within the liver. In some people, the infections then lead to the formation of tumors, explain the experts. However, the results of the latest study show that our immune system can be forced to fight both the tumor and the growth-promoting HCV infection.
Type of treatment could also be effective in other virus-driven malignancies
"We have, so to speak, the immune system by the administration of a benign reovirus convinced that both the tumor and the underlying HCV infection must be combated," explain the doctors. In mice with liver cancer caused by hepatitis C, it could be observed that the animals react very well to this type of therapy. This type of treatment could also be applied to other virus-driven malignancies, including blood cancer caused by the so-called Epstein-Barr virus, the researchers say.
Advanced liver cancer is very difficult to treat
Liver cancer is the third highest cause of cancer death worldwide. The disease alone killed about 745,000 people in 2012, the authors explain. Nevertheless, liver cancer is only the tenth most common form of cancer. This reflects the difficulties that the treatment of this tumor makes in advanced stages.
Many treatments only prolong the life of the patient
In about 90 percent of cases where surgery is not an option, the treatments used tend to prolong patients' lives instead of fighting the tumor, explain the physicians. HCV and HBV cause about 30 and 50 percent of these tumors, respectively. HCV is the leading cause of liver transplant surgery in developed countries, the researchers report.
Human immune response is a powerful weapon to fight cancer
The results show that one of the strongest weapons for fighting cancer is our own immune response. This approach can take various forms, including the deactivation of so-called immune control points. Alternatively, we can use strategies to "hyper-stimulate" immunity, the experts explain. So the immune system also recognizes and responds to targets that are usually ignored.
Oncolytic viruses enable the treatment of cancer
One such strategy involves the use of viruses. But only viruses that do not cause human disease, explain the authors. These cancer-fighting viruses (oncolytic viruses) are increasingly being used in clinical trials. For example, a drug was recently licensed to treat skin cancer.
Reovirus enhances the immune response
The current study focused on a specific oncolytic virus. "We already knew from the reovirus that it could reach tumors in the liver after an injection into the bloodstream," say the scientists. The virus enhances both the immune response of the liver, as well as within the cancers. This effect is particularly important because the underlying HCV infection affects the entire organ, just the tumor itself.
Interferon triggers an accelerated immune response
The trigger of the accelerated immune response was a substance called interferon. This is released by the body when an aggressive reaction to infections and cancer occurs.
Reovirus-stimulated interferon is extremely effective
Using primary human liver tissue and mice, we were able to show that interferon stimulated by the reovirus acts in two ways, the experts explain. First, it directly eliminates HCV in liver or tumor cells. Second, it activates specific immune cells, which are colloquially known as so-called killer cells. These cells destroy virus-infected cells and cancer cells, the researchers add.
Reovirus therapy also works on HBV liver cancer and Epstein Barr blood cancer
The result of the so-called reovirus therapy was the simultaneous elimination of HCV and the direct destruction of liver cancer cells. This culminated in reduced tumor growth within mouse models, the researchers explain. The same approach also worked in models of HBV liver cancer and Epstein Barr blood cancer.
Further clinical studies on the effects of similar strategies are necessary
Since the reovirus is already in a clinically useful form, our next step is to evaluate clinical trials early on the effect of these or similar strategies for the treatment of multiple tumors, the authors explain. Hopefully, the results can greatly improve the future treatment for cancer patients, the researchers said. (As)