Reoviruses are a family of RNA viruses that, while not usually causing any symptoms in adults, are responsible for many of colds and cases of childhood gastroenteritis. However, in addition to depleting the health of the youngest, it seems that these reoviruses, such as atonement, could also help combat some diseases associated with high mortality. In fact, a study led by researchers at the University of Leeds shows that reoviruses not only stimulate the human immune system to kill liver cancer cells, but by themselves are able to kill the Hepatitis C virus – the virus that presents as a common trigger of liver cancer.
As explained by Stephen Griffin, director of this research published in the journal “Gut”, “current treatments for liver cancer that can not be removed with surgery are mainly a palliative intention. In fact, chemotherapy aims to prolong survival rather than cure the tumor, and may have very significant side effects. And in this context, we believe that by simultaneously treating cancer and the hepatitis virus that is driving tumor growth we can offer a more effective therapy and improve the prognosis for patients”.
The study, carried out with cultures of human liver tumor cells, shows that reoviruses stimulate the release by the immune system of proteins called interferons are intended to destroy viruses and bacteria that invade the body. In addition, these interferons stimulate the release of killer cells or NK cells from the natural killer, a type of lymphocyte capable controlling and regulating the size of tumors and eliminating infected cells by HCV.
And does this benefit also occur in living organisms or is it limited to laboratory plaques? To find out, the authors used an animal model – mice – which, after inducing the development of liver cancer and infecting them with HCV, introduced a reovirus. And again, the results showed the benefit on cancer and HCV associated with reovirus administration, thus confirming possible use in immunotherapy against liver cancer. In fact, the authors are already designing a clinical trial to evaluate its efficacy and safety in humans.
This work establishes a completely new type of viral immunotherapy for the most common type of primary hepatic cancer, that is, hepatocellular carcinoma, whose prognosis in the advanced stages of the disease is, according to Alan Melcher, co-author of the research, certainly poor. Not surprisingly, our results show that reovirus therapy activates the immune system to attack cancer cells and suppresses HCV replication, which in turn is associated with many tumors. As Alan Melcher points out, “our findings also show that reovirus therapy could be used in the treatment of other cancers associated with viral infections, including, but not limited to, Epstein-Barr virus-associated lymphoma”.
Most primary hepatic cancers in which the original tumor appears in the liver and is not the result of invasion or “metastasis” of a tumor developed in another organ – appear after damage or scarring in the liver, usually following infection with hepatitis B or C viruses – and albeit at a much lower rate, for continued abuse of alcohol. One aspect to be taken into account given that, on the one hand, primary liver cancer is the third leading cause of death from any cancer disease and on the other according to the World Health Organization (WHO), There are more than 130 million people with chronic HCV infection all over the world.
And in this context, as Adel Samson, co-author of the research reports, “it is increasingly clear that one of the most powerful weapons to treat cancer is our own immune system”. However, tumors are formed by our own cells, so the immune system must strive to identify the subtle differences that distinguish tumor cells from healthy cells. And immunotherapy contemplates several strategies, such as the use of viruses as in our study, to start our immune system for better identification and fight against tumor cells.
And the use of viruses to treat cancer, is it new? No, the so-called “virotherapy” or use of oncolytic viruses – viruses genetically modified so that they can only replicate in tumor cells and not in healthy cells – is already being tested today in the treatment of different types of tumors. In fact, there is already an oncolytic virus approved for skin cancer therapy.