A bacterium found in Japanese tree frog intestines completely eliminated colorectal tumors in mice with just one intravenous dose — outperforming both chemotherapy and immunotherapy in the study. The microbe works by multiplying inside oxygen-deprived tumors and simultaneously rallying the immune system to attack cancer cells. Researchers say the findings offer a promising new direction for treating hard-to-beat solid tumors.
Scientists at Japan's JAIST have discovered that Ewingella americana — a bacterium naturally found in the intestines of Japanese tree frogs — can completely eliminate colorectal tumors in mice with a single intravenous dose. Unlike conventional microbiome research that tweaks gut bacteria composition, this approach delivers living bacteria directly into the bloodstream to target tumors.
The bacterium pulls off a two-pronged attack: it thrives in the low-oxygen environment inside tumors (multiplying ~3,000-fold within 24 hours) while simultaneously triggering an immune response that floods the tumor with T cells, B cells, and neutrophils. Crucially, it stays out of healthy tissue — cleared from the bloodstream within 24 hours with no colonization of organs like the liver, lungs, or kidneys.
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Why it matters: If these results translate to humans, bacterial cancer therapy could offer a targeted, low-toxicity alternative — or complement — to chemotherapy and immunotherapy, especially for solid tumors that are notoriously difficult to treat.
