Research from Japan showed that a combination of two naturally occurring bacteria eliminated tumours in mice, even without the assistance of the immune system. 

Modern immunotherapy advances, such as CAR T-cells, have largely relied on activating immune responses in patients, often immunocompromised due to other treatments like chemotherapy and radiotherapy.  

The concept of using bacteria to treat cancer dates back to the 19th century, but new research from the Japan Advanced Institute of Science and Technology (JAIST) revived that hypothesis.  

Scientists developed a microbial consortium named AUN, comprising two naturally occurring bacteria: Proteus mirabilis (‘A-gyo’), which resides in tumours and can damage them from within, and Rhodopseudomonas palustris (‘UN-gyo’), a photosynthetic bacterium that helps control the other bacterium’s growth and improves its ability to target tumour tissue specifically. 

When injected into the bloodstream of mice, the bacteria travelled directly to tumours and multiplied. Together, they blocked the tumour’s blood supply, triggering clotting in its blood vessels and causing cancer cells to die.  

This approach worked in several cancer types in mice – colorectal, ovarian and pancreatic cancers – and was even effective in mice with no functioning immune system, an important discovery for treatment of immunocompromised patients. 

“To accelerate the social implementation of this research, we are preparing to launch a startup and aim to begin clinical trials within six years,” said Eijiro Miyako from JAIST, lead author of the study published in Nature Biomedical Engineering. “A new chapter in bacteria-based cancer therapy, pursued for over 150 years, is finally beginning.”