The reovirus, a cold virus, has potential as a therapeutic cancer vaccine, as well as having anticancer activity in its own right. The University of Leeds (U.K.) and the Institute of Cancer Research are carrying out clinical trials of the virus as cancer therapy, and have found that it can hide from the immune system (which would otherwise neutralize it as a foreign antigen) and also can "home in" on cancer cells, allowing it to treat hidden tumors and tumors deep in the body. In a trial of patients with advanced and metastatic bowel cancer due to have surgery, the virus was active in tumor cells but not healthy cells. According to University of Leeds' researcher Professor Alan Melcher: "It seems that reovirus is even cleverer than we had thought. By piggybacking on blood cells, the virus is managing to hide from the body's natural immune response and reach its target intact. This could be hugely significant for the uptake of viral therapies like this in clinical practice." Press release | Abstract