Instead of bacteria and viruses burdening us with disease, what if we flipped the script and used their natural talents to give dangerous tumors an infection as a way of fighting cancer?
Microbes come in an incredible variety, armed with a wide range of biochemical tools. Some can home in on tumors, others can kill cancer cells directly. Scientists are beginning to uncover the tricks certain bacteria and viruses have that could help us fight cancer, and even better, these skills could be combined.
In a study from Columbia Engineering, published in Nature Biomedical Engineering, researchers pulled off exactly that: they tucked a cancer-fighting virus inside a tumor-seeking bacterium, smuggling it past the immune system to its final destination — the tumor.
Bacterial Trojan Horse for Cancer-Fighting Viruses
Because different bacteria and viruses are adapted to their own niches, each carries a unique set of biochemical abilities. Bioengineers can tap into these strengths, and sometimes, combining them can produce results greater than the sum of their parts. In fact, nature has already shown this in some infections where bacteria and viruses naturally interact to boost each other’s performance.
The Columbia team wanted to go further, deliberately pairing microbes to create a precision cancer-killing system.
“By bridging bacterial engineering with synthetic virology, our goal is to open a path toward multi-organism therapies that can accomplish far more than any single microbe could achieve alone,” said co-author Zakary S. Singer in a press statement.
The oncolytic (cancer-killing) virus they chose was a senecavirus, known for efficiently infecting certain cancer cells. What it needed was a delivery service, something that could navigate directly to the tumor while evading the body’s virus-neutralizing defenses. That’s where Salmonella typhimurium came in. This bacterium naturally gravitates toward the low-oxygen, nutrient-rich environment inside tumors.
“We programmed the bacteria to act as a Trojan horse by shuttling the viral RNA into tumors and then lyse themselves directly inside cancer cells to release the viral genome, which could then spread between cancer cells,” Singer explained in the release.
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Bacteria Keep the Virus on a Leash
The tricky part with using live viruses in therapy is making sure they don’t spread where they’re not wanted. Fortunately, the researchers’ system, called Coordinated Activity of Prokaryote and Picornavirus for Safe Intracellular Delivery (CAPSID), builds safety right in.
They engineered the virus so it can only replicate if it gets a specific protein from the bacteria. Since the bacteria stay almost exclusively in tumors, they act like a leash, preventing the virus from wandering elsewhere in the body.
“It is systems like these — specifically oriented towards enhancing the safety of these living therapies — that will be essential for translating these advances into the clinic,” Singer added.
Developing a Toolkit of Viral Therapies
This study marks a major step toward bringing bacteria–virus therapy into future cancer treatments. According to the press statement, the researchers believe their work, which was validated in mice, is the first example of a deliberately engineered partnership between bacteria and cancer-targeting viruses.
Co-lead author Jonathan Pabón, a physician-scientist, emphasized in the press release that efforts are already underway to move this technology out of the lab and toward clinical trials. The team is also expanding its approach to target a wider variety of cancers, testing different tumor types, mouse models, etc. The ultimate aim is to develop a “toolkit” of viral therapies that interacts with different conditions inside cancer cells.
Besides expanding the viral-side of things, they’re also exploring how to combine their system with bacterial strains that have already proven safe in human trials — a step that could bring these living medicines much closer to real-world use.
This article is not offering medical advice and should be used for informational purposes only.
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