Researchers use salmonella to attack deadly brain cancer tumors

Researchers with Duke University have detailed a new project in which salmonella was successfully tapped to target cancerous brain tumors. According to the university, biomedical engineers set their sights on a solution for one of the deadliest forms of brain cancer, the glioblastoma. Patients have only a 10-percent chance of surviving five years following their diagnoses of this cancer, but a potential new treatment may double those numbers.

Glioblastomas are difficult to treat due to a proactive sheath around the brain called the blood-brain barrier — while great at protecting the brain, it also inhibits any potential drug-based treatments. This leaves patients with only surgery as the best treatment option, but surgical tumor removal often leaves behind minuscule bits of tumor tissue that eventually grow into new tumors.

Researchers with Duke University have decided to tackle the issue, and they turned to an unlikely place: salmonella typhimurium bacteria. According to the university, the scientists ‘tweaked’ the bacteria’s genes and turned it into a ‘cancer-seeking missile.’

The team used a strain of salmonella that has been detoxified, and that is also lacking an enzyme called purine, something found in large quantities in tumors. Because of the bacteria’s deficiency, it seeks the purine-rich tumors and ‘flocks’ to them.

Thanks to the researchers’ work at genetically modifying the bacterium, the salmonella produces a couple of substances after swarming to the tumors. These substances — p53 and Azurin — essentially instruct the tumor cells specifically to commit suicide. The destructive nature of the salmonella, though, has more than one fail-safe mechanism to keep it from destroying non-cancerous cells.

In addition to seeking out purine-rich sources (tumors), the salmonella also only releases its two destructive compounds in low-oxygen environments, the kind found in tumors. It appears that, at least at this point, the salmonella is delivered to the patient’s brain via an injection — a scary sounding method that, in context, in much better than a full tumor-removing brain operation.

Though the salmonella isn’t the perfect cure for glioblastomas, it shows a better success rate than surgical removal, at least amongst the mice that were used in testing. The researchers noted a 20-percent survival rate among treated mice, twice that of current surgical survival rates, and for the duration of 100 days, which is said to be the mouse-to-human equivalent of 10 years.

SOURCE: Duke University