Bugging tumors

Abstract

The effects of bacteria on patients with cancer have been observed for at least two centuries. Recent studies in animal models of cancer have shown effi cacy of both anaerobic bacteria such as Clostridia and Bifi dobacteria and facultative anaerobes such as Salmonella. In this issue of Cancer Discovery, Flentie and colleagues have identifi ed fi ve Salmonella promoters that are specifi cally stimulated by cancer cells as well as by acidic pH, a property of most tumors. One of these promoters (STM1787) was linked to a Shiga toxin gene and inserted in a wild-type Salmonella typhimurium strain, which showed in vivo antitumor effi cacy. Approaches to further improving the effi cacy of S. typhimurium with the use of tumor-targeting mutations are discussed. Because the barriers to effi cacy of standard therapy of cancer appear to be opportunities for bacterial cancer therapy, the future of bacterial therapy of cancer appears bright. © 2012 American Association for Cancer Research.