The S. typhimurium A1-R mutant, which is auxotrophic for leu-arg to attenuate growth in normal tissue, and selected for high antitumor virulence, has been shown to be effective as monotherapy against human prostate, breast, pancreatic, and fibrosarcoma tumors. In the present study, we first administered A1-R to nude with subcutaneous murine colon cancer Colon-26 which expressed red fluorescent protein (RFP). S. typhimurium A1-R (1×107 cfu) was administered intravenously (i.v.) or intratumorally (i.t.) to the subcutaneous tumor as a positive control. The size of tumor was measured by weekly fluorescence imaging. Both i.v.- and i.t.-treated mice had smaller tumors and survived longer (p<0.05) compared to the control group treated with PBS. When S. typhimurium A1-R was administered orally to nude mice with orthotopically-transplanted Colon-26 RFP, tumor growth was inhibited (p<0.05) and animals survived longer than untreated controls (p<0.05). Furthermore, orally-treated mice had no observable side effects suggesting oral delivery of tumor-targeting S. typhimurium A1-R is a promising route for bacterial therapy of cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5547. doi:1538-7445.AM2012-5547