DURHAM, N.C. An experimental vaccine based on a virus that causes encephalitis in the wild appears to block tumor growth in some cases of advanced cancer, according to researchers at Duke University Medical Center. Scientists say the vaccine is able to stimulate an immune response, even in the face of profound immune system suppression, a condition most patients with advanced cancer experience.
Scientists removed the genes that enable the Venezuelan equine encephalitis virus - an alphavirus - to replicate itself, and replaced them with genes that make the biomarker CEA, present in many malignant colon, breast and lung cells.
"Alphaviruses have been used before in designing treatments for infectious diseases, but we believe this is the first time one has been used in patients with cancer," said Michael Morse, MD, associate professor of medicine at Duke and the lead author of the study appearing online in the Journal of Clinical Investigation.
The Phase I/II study included 28 patients with advanced cases of lung, colon, breast, appendix or pancreatic cancers who had already been treated with multiple courses of chemotherapy, but whose cancers kept coming back.
Cancer vaccines, unlike traditional vaccines, are designed to boost the body's own immune system to recognize and destroy tumors, not prevent disease. Scientists often use genetically altered viruses as vaccines, stripping the virus of any harmful parts and inserting genes related to their anticancer strategy. But in many cases, the immune system still sees the incoming virus as a foreign invader and springs into action, generating antibodies and T cells that destroy it before it has a chance to do any good.
Based on earlier research, investigators at Duke believed that by using the alphavirus for Venezuelan equine encephalitis as a carrier they might be able to thwart that response.
"The beauty of alphaviruses is that they are naturally att
|Contact: Michelle Gailiun|
Duke University Medical Center