A study, published in Science Transnational Medicine, reports that tissue-damaging bacteria have been successfully employed in individualized treatment of tumors in rats, dogs. While final results of the ongoing trials in humans are unknown, scientists say that more studies are needed to find out the response to bacteria in patients.
The microbe Clostridium novyi, found in oxygen-poor environments, was modified to remove some of its toxicity and then targeted on oxygen-starved tumour cells. In the experiment of its direct injection into 16 dogs’ soft-tissue tumours, 3 showed reduction in the size of tumour by 30%, and 6 showed anti-cancer response.
Additionally, a clinical trial was conducted on one patient with a tumor in the abdomen. The result displayed that tumor reduced significantly. The study has focused on soft tissue tumor as these are usually locally advanced and spread into normal tissue. The bacteria cannot survive in normal tissues and will home in on the oxygen-starved tumor cells.
Bacteria therapy was first tried in rats where it was seen that bacteria avoided healthy cells and attacked the tumor alone. The treatment also improved their survival, with treated rats surviving an average of 33 days after bacterial injection as opposed to 18 days in rats that were not treated.
Bacteria have been used in tumour treatment for decades. Earliest accounts are from an immunotherapy called Coley toxins following cancer remission in patients who contracted serious bacterial infections.
Intratumoral injection of Clostridium novyi-NT spores induces antitumor responses. Sci Transl Med,2014. 6(249): 249ra111