Frog-Gut Bacterium Erases Colorectal Tumors in Mice After One Dose

A bacterium from frog gut bacteria erased colorectal tumors in every treated mouse after one IV dose, with no new tumors after later exposure, but human testing is still needed.

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Researchers have found a surprising cancer-fighting candidate in the gut of a Japanese tree frog. The bacterium, Ewingella americana, was one of several microbes collected from amphibians and reptiles and tested for anti-tumor activity. In a mouse model of colorectal cancer, a single intravenous dose completely eliminated tumors in every treated animal. When the mice were later exposed to tumor cells again, none developed new tumors, suggesting that the treatment may have triggered a lasting immune response. The researchers found that the bacterium rapidly concentrated inside tumors. Its amount in tumor tissue increased roughly 3,000-fold within 24 hours, while it was not detected in several healthy organs at that point. The proposed effect appears to involve two processes working together: the bacterium can directly damage tumor cells and can also stimulate immune cells involved in attacking tumors. The study is an early proof of concept, not a human cancer treatment. The experiments were performed in mice, and the safety and effectiveness of the approach in people remain unknown. Ewingella americana has also been associated with human infections, which makes careful safety testing especially important before any possible clinical use. More studies will be needed to reproduce the result, understand exactly why the bacterium targets tumors, and determine whether the striking mouse results can translate to human cancer care.

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