Natural Sciences Active Updated Sep 21, 2026
Can a gut bacterium be used to attack tumors?
A gut bacterium that hunts tumors
Where it stands as of Sep 4, 2026
A team at the Japan Advanced Institute of Science and Technology screened 45 bacterial strains from the guts of tree frogs, newts and lizards and found one, Ewingella americana, that cleared colorectal tumors in mice. A single intravenous dose produced a 100 percent complete response rate, beating both a checkpoint-inhibitor drug and the chemotherapy used for comparison. It has been tested in mice, in one cancer type, and no person has received it.
Researchers at the Japan Advanced Institute of Science and Technology isolated dozens of bacterial strains from the intestines of frogs, newts and lizards and found one that eliminates tumors from the inside by multiplying in the oxygen-starved core of a tumor while recruiting the immune system's own cells. The arc will run as the approach, tested only in mice so far, moves toward safety and efficacy testing beyond a single animal model.
The story so far
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Sep 21, 2026 Latest
ScienceAlert reported that a separately engineered probiotic wiped out 43 percent of colorectal tumors in mice, a second bacterial approach targeting the same cancer type as the Ewingella americana work.
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Jul 13, 2026
The Japan Advanced Institute of Science and Technology team said Ewingella americana came from screening 45 bacterial strains taken from the intestines of tree frogs, fire belly newts and grass lizards, and reported the bacterium was undetectable in the bloodstream at 24 hours, showed zero colonization in healthy organs, and caused no chronic toxicity over 60 days of observation. The team plans to test it next against breast cancer, pancreatic cancer and melanoma.
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Jul 11, 2026
A single intravenous dose of the bacterium Ewingella americana, isolated from a Japanese tree frog's gut, produced a 100 percent complete response rate eliminating colorectal tumors in mice, beating both a checkpoint-inhibitor drug and chemotherapy used for comparison, while the bacterium multiplied about 3,000-fold inside the tumor's oxygen-starved core within 24 hours.
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Jul 3, 2019
Researchers engineered a harmless strain of E. coli to multiply inside tumors and then rupture, releasing a small protein that strips cancer cells of a signal they use to fend off the immune system. In mice the treatment drove lasting tumor regression, and it also shrank distant, untreated tumors by waking the body's defenses more widely. The design joined synthetic biology to immunotherapy in a single living dose.
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Jul 20, 2016
Bioengineers gave a tumor-seeking strain of bacteria a genetic clock, so the colony would grow and then burst in unison once it hit a set density, spilling a cancer-fighting payload before a few survivors began the cycle again. In mice the self-clearing bacteria slowed tumors, and paired with chemotherapy they lengthened survival. A microbe had been turned into a controllable, self-dosing delivery system.
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Jan 1, 2002
In one of the first clinical tests of the idea, 25 patients with advanced melanoma received intravenous doses of VNP20009, a strain of Salmonella genetically stripped of much of its toxicity and tuned to seek out tumors. The bacteria were tolerated at a set dose and settled into some tumors, but none of the cancers shrank. The trial showed both the appeal of a living cancer drug and how hard it is to make one work.
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