Waterloo Engineers Tumor-Eating Bacteria With Safety Switch
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- University of Waterloo researchers are engineering Clostridium sporogenes, a soil bacterium that thrives only without oxygen, to invade and consume solid tumors from the inside — exploiting the oxygen-free, nutrient-rich cores that standard therapies struggle to reach.
- Dr. Marc Aucoin, a chemical engineering professor at Waterloo, said the bacteria "start eating those nutrients and growing in size" inside the tumor, colonizing the central space and "essentially ridding the body of the tumor."
- The team inserted a gene from a related, more oxygen-tolerant bacterium so the engineered microbes can survive longer as they expand outward toward the tumor's oxygen-exposed edges.
- Researchers used quorum sensing — bacteria's natural chemical signaling — to ensure the oxygen-tolerance gene only switches on once enough microbes have accumulated inside a tumor, preventing the bacteria from dangerously growing in oxygen-rich areas like the bloodstream.
- Dr. Brian Ingalls described the control system as "an electrical circuit, but instead of wires we used pieces of DNA," and validated the quorum-sensing design in an earlier experiment by programming bacteria to produce green fluorescent protein at the intended moment.
- The next step is combining the oxygen-tolerance gene and the quorum-sensing control into a single bacterium, then evaluating it against tumors in pre-clinical trials, according to the team.
- The work, led by PhD student Bahram Zargar with collaboration from CREM Co Labs (a Toronto company Zargar co-founded), was published in ACS Synthetic Biology (DOI: 10.1021/acssynbio.5c00628).
Why it matters: Solid tumors resist chemotherapy and radiation at their oxygen-starved cores, and Waterloo's quorum-sensing design tackles the central safety problem: a self-destructing cancer therapy that can only turn on its oxygen tolerance once it has already swarmed a tumor, not in healthy tissue.
