A groundbreaking new study suggests that bacteria found in the intestines of Japanese tree frogs could offer a powerful new way to fight colorectal cancer.
Researchers at the Japan Advanced Institute of Science and Technology (JAIST) discovered that the bacterium Ewingella americana may be more effective than traditional treatments. Unlike previous approaches, which focused on altering the gut microbiome or performing fecal transplants, this study—published in the journal Gut Microbes—tested specific bacterial strains directly by isolating, culturing, and administering them intravenously to target tumors.
Screening the intestines of Japanese tree frogs, fire belly newts, and grass lizards, scientists identified nine bacterial strains with antitumor properties. Among them, E. americana showed exceptional potency.
When tested in mouse models of colorectal cancer, a single IV dose of E. americana eliminated tumors entirely, achieving a 100% complete response rate. These results surpass the effectiveness of many standard cancer therapies, including chemotherapy and immunotherapy.
Colorectal cancer affects around 150,000 Americans each year, with uncontrolled cell growth in the colon or rectum. While traditionally considered a disease of older adults, diagnoses in younger populations are rising sharply. In 2019, 20% of cases occurred in people under 55—nearly double the 11% reported in 1995. In response, the US Preventive Services Task Force lowered the recommended starting age for average-risk adults from 50 to 45 in 2021.
The researchers say E. americana works in two ways: it attacks cancer cells directly and activates the immune system to trigger apoptosis, the body’s natural process of eliminating damaged cells, all without causing inflammation. Importantly, the bacteria concentrate in tumor tissue without spreading to other organs.
Compared with chemotherapy’s harsh side effects, E. americana appears extremely safe. The bacteria disappear from the bloodstream within 24 hours, and inflammatory responses return to normal within 72 hours.
“This study shows that untapped biodiversity may hold immense potential for medical innovation, offering hope for new treatments for patients with hard-to-treat cancers,” the researchers said.
Next steps will test whether E. americana can treat other cancers, like breast and pancreatic cancer, and explore improved delivery methods, including targeted injections and dosing strategies. Scientists also aim to determine whether the therapy can safely complement existing treatments.
The research comes at a critical time: by 2030, early-onset colorectal cancer is projected to become the leading cause of cancer-related death for people aged 20 to 49 unless major preventive measures are taken.