Certain molecules on the surface of cancer cells are either unique or more abundant than those found on non-cancerous cells. These molecules, or antigens, can stimulate the immune system to mount an immune response against the tumor. It is hoped that when a vaccine containing cancer-specific antigens is administered to cancer patients, these antigens will trigger an immune response that targets cancer cells without harming normal cells. Although many cancer vaccine strategies have resulted in measurable immune responses when tested, tumor remission has been observed in only a minority of patients. The identification of new cancer antigens, delivery formulations and vectors is sorely needed.
Since disease-causing bacteria are well equipped to stimulate the immune system, researchers have started to examine the suitability of bacteria that have been genetically manipulated to strip them of their disease-causing ability as delivery vehicles for cancer vaccines. One such bacterium is Salmonella typhimurium, often the culprit in food poisoning in humans. In a study appearing online on June 22 in advance of print publication in the July issue of the Journal of Clinical Investigation, Sacha Gnjatic and colleagues from the Ludwig Institute for Cancer Research constructed an avirulent strain of Salmonella typhimurium endowed with the capacity to deliver the known tumor cell antigen NY-ESO-1. This approach was able to elicit NY-ESO-1specific CD8+ and CD4+ T cells from lymphocytes taken from cancer patients. Oral delivery of this vaccine to mice resulted in the regression of established NY-ESO-1expressing tumors. The results of the study suggest that delivery of a cancer vaccine using the Salmonella typhimuriumbased delivery system is a promising novel strategy for cancer vac
Contact: Brooke Grindlinger
Journal of Clinical Investigation