Full Breakdown
Bacterial Strain from Japanese Tree Frogs Eradicates Tumors in Mice
7/14/2026, 4:19:58 AM
Breakthrough Findings
Scientists at the Japan Advanced Institute of Science and Technology (JAIST) isolated 45 bacterial strains from the intestines of Japanese tree frogs, fire-belly newts and grass lizards. After screening, nine strains showed anticancer activity, and the facultative anaerobe Ewingella americana produced the strongest effect. In a colorectal-cancer mouse model, a single intravenous dose eliminated all detectable tumors, achieving a 100 % complete-response rate and outperforming both an anti-PD-L1 immune-checkpoint inhibitor and liposomal doxorubicin.
Study Design and Results
The researchers cultured each strain in the laboratory and delivered the selected bacteria intravenously. Within 24 hours, the bacterial population inside tumors expanded roughly 3,000-fold, directly damaging cancer cells while sparking an immune influx of T cells, B cells and neutrophils. The tumor-specific environment—low oxygen, leaky vasculature and high CD47 expression—facilitated bacterial colonisation exclusively in malignant tissue, leaving healthy organs untouched.
Safety and Tumor Specificity
Pharmacokinetic analysis showed the bacteria were cleared from the bloodstream with a half-life of about 1.2 hours, becoming undetectable after 24 hours. No colonisation was observed in the liver, spleen, lungs, kidneys or heart, and only mild, transient inflammation resolved within 72 hours. A 60-day observation period revealed no chronic toxicity.
Future Research Plans
The team intends to test the approach against additional solid tumours such as breast, pancreatic and melanoma, and to explore dose-fractionation, direct intratumoral injection, and combination with existing chemotherapy or immunotherapy. The study also underscores the broader potential of biodiversity-derived microbes as a source of novel cancer therapeutics.
Verbatim Quotes
- “americana completely eliminated tumors, producing a 100% complete response (CR) rate.” — the researchers
- “According to the researchers, the treatment outperformed standard therapies used for comparison, including immune checkpoint inhibitors (anti-PD-L1 antibody) and the chemotherapy drug liposomal doxorubicin.” — the researchers
- “No bacterial colonization was detected in healthy organs, including the liver, spleen, lungs, kidneys, or heart.” — the researchers
- “The findings also highlight the potential value of exploring biodiversity as a source of future medical treatments, offering the possibility of new therapeutic options for patients with cancers that are difficult to treat.” — the researchers
