By Staff Reports
(DGIwire) – Harnessing the immune system to fight cancer, long a medical dream, is becoming a reality. As The New York Times showed in a major article on immunotherapy in July 2016, this form of cancer treatment—either alone or combined with other treatments—is now the subject of hundreds of clinical studies for nearly every type of cancer.
The Times profiled patients whose cancers dramatically improved following immunotherapy. But the article also examined the challenges faced by researchers who are trying to create a specific class of immunotherapy drug. These drugs free immune cells to fight cancer by blocking a mechanism—called a checkpoint—that cancer uses to shut down the immune system. These so-called checkpoint inhibitors, which allow the immune system to work at full strength to attack cancer cells, can be astonishingly effective, but they do not work for all patients—and researchers don’t know exactly why.
According to the Times, some researchers suspect that checkpoint inhibitors might work better if combined with other treatments that kill tumor cells. Studies are underway to test checkpoint drugs in combination with cell-killing treatments like chemotherapy and radiation.
One potential tool with significant potential in treating various forms of cancer when combined with immunotherapy or standard chemotherapy is called virotherapy or oncolytic virus therapy. This involves the conversion of viruses into cancer-fighting agents by reprogramming them to attack cancerous cells, while healthy cells remain relatively undamaged. Specifically, viruses can be harnessed to infect, multiply within and subsequently destroy cancer cells; the drug targets the tumor and protects normal tissue.
“As excitement about the potential of immunotherapy has grown, researchers have taken a closer look about how its benefits could be enhanced in tandem with other approaches,” says Brad Thompson, Ph.D., president and CEO of Oncolytics Biotech Inc. “These may go beyond traditional options such as chemotherapy and radiation to include advances made with the reovirus, one particular type of oncolytic virus.”
The reovirus is a non-enveloped virus with a double-stranded, segmented RNA genome. It preferentially replicates in cancer cells that have an “activated Ras pathway,” which is caused by mutations in certain genes. The reovirus leaves normal cells unharmed. This makes it intrinsically tumor-selective without the need for any genetic manipulation. With no known associated disease, the reovirus replicates in the cytoplasm and therefore does not integrate into the cell’s DNA. It is found commonly in nature and has been isolated from untreated sewage, river and stagnant waters. Exposure to the reovirus is common in humans, with half of all children by the age of 12 having been exposed and up to 100 percent testing positive by adulthood.
Oncolytics’ lead product, REOLYSIN®, is a proprietary formulation of the human reovirus. It has been utilized in nearly 30 clinical studies in a range of cancers, including ovarian, pancreatic, prostate, colorectal, non-small cell lung and breast cancers.
“Additional studies are likely to enhance our understanding of which combination therapies show the most promise in addressing specific cancers,” adds Thompson.