Tumors often do not respond to chemotherapy because they contain large poorly vascularized areas that limit the efficacy of radiation and chemotherapeutic drugs. In November 27 Proceedings of the National Academy of Sciences early edition, Long Dang and colleagues from The Johns Hopkins School of Medicine show that administration of anaerobic bacteria in addition to chemotherapy can efficiently destroy large tumors.

Dang et al. created a strain of anaerobic bacteria (Clostridium novyi-NT) lacking a lethal toxin gene. They found that intravenously injected C. novyi-NT spores germinated within the avascular regions of tumors in mice and destroyed surrounding viable tumor cells. When the bacteria were administered in combination with chemotherapy, extensive hemorrhagic necrosis of the tumors resulted in significant and prolonged antitumor effects (Proc Natl Acad Sci USA 2001, DOI:10.1073/pnas.251543698).

This strategy, called 'combination bacteriolytic therapy (COBALT)', has the potential to add a new dimension to the...