Snippets of Science

Cancer Biology: Harmless bacteria to be used as frontline cancer therapy?

Clostridium sporogenes

Commercially available anti-cancer drugs typically cause numerous, painful side effects. These side effects stem from the fact that these drugs are often not able to fully discern cancer cells from other normal body cells. The drugs work by targeting and killing cells that undergo a high level of division. This feature is a hallmark of cancer cells, since cancer is caused by uncontrolled cell division, but also of cells such as those lining the small intestine or the cells of our hair follicles. As a result, anti-cancer drugs are usually associated with nausea or hair loss. However, researchers from the University of Nottingham and the University of Maastricht might just have come across an ideal drug-delivering vehicle that could ensure anti-cancer drugs only take effect against cancer cells, sparing the healthy ones.

The vehicle in question is a soil-dwelling bacteria known as Clostridium sporogenes. When used, this particular bacteria will only grow in solid tumors. Upon injection, the bacteria colonizes the tumor and produces a specific bacterial enzyme. The anti-cancer drug is then introduced into the patient in its pro-drug or inactive form. The specific bacterial enzyme will cleave and activate the pro-drug only within the tumor, sparing the normal cells.

The teams from Nottingham and Maastricht are hard at work, and have successfully introduced a more efficient gene into the C. sporogenes DNA. This gene allows the bacteria to produce the needed enzyme in much higher quantities, increasing the rate of pro-drug activation. The therapy is expected to enter human clinical trials in 2013.

Spearheading this research is Professor Nigel Minton, who has this to say about the bacteria at the heart of this research, “Clostridia are an ancient group of bacteria that evolved on the planet before it had an oxygen-rich atmosphere and so they thrive in low oxygen conditions. When Clostridia spores are injected into a cancer patient, they will only grow in oxygen-depleted environments i.e. the center of solid tumors…We can exploit this specificity to kill tumor cells but leave healthy tissue unscathed.”

The outcome of the 2013 clinical trial will be eagerly anticipated, as it may well present a safe and much-needed cure for solid tumors. This possible therapy could also negate the usage of surgery, especially for high-risk patients or for tumors located at difficult positions.


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