When is a good time to get a virus? When you have metastatic cancer, apparently. Researchers at San Francisco-based biotech company Jennerex conducted an early-stage trial of 23 patients with metastatic cancer. Jennerex researcher injected the research participants with a genetically engineered, cancer-killing virus, reports Technology Review's Alla Katsnelson. The researchers, who recently published their work in Nature, found that the virus can thoroughly infect tumors while leaving healthy tissue alone. This work may be the beginning of the development of a new type of cancer medicine, Katsnelson adds. The researchers started with a strain of the vaccinia virus — also used in the smallpox vaccine — which they picked because it evades the immune system. They modified the virus with a gene encoding the GM-CSF protein, which triggers an immune attack against cancer cells and added another gene that produces the beta-galactosidase protein to track the virus' replication, Katsnelson says. The team administered the resulting vaccine, dubbed JX-594, in different doses to patients with different types of metastatic cancers, and biopsied tumor tissue from each patient after 10 days. They found that the virus was replicating itself in the tumors of seven of the eight patients that received the highest dose, she says, with no serious side effects. "Several weeks after the injection, tumors in about half of the patients seemed to stop growing, and shrunk in one patient," she adds. "While the study is not the first to test a cancer-killing viral therapy, it is the first to thoroughly document the behavior of the virus in patients' biopsy tissue. The results confirm that viruses can be used to selectively target these cells." Though there are still many questions to be answered, Jennerex was encouraged enough by the results to begin testing the therapy in larger trials. The company tells Katsnelson that it recently completed a trial in which JX-594 significantly improved survival rates of liver cancer patients.
A Pox on You, Cancer!
Sep 06, 2011