Medicine Wants to know: Can we re-forge yesterday's Big Bad Monster into a silver bullet to bag a demon from today? The Food and Drug Administration seems to think so.

The FDA has just assigned what it calls “breakthrough” status to a treatment that uses the once-dreaded polio virus to target aggressive forms of brain cancer, in the hope of speeding it to market. Researchers from the Preston Robert Tisch Brain Tumor Center at Duke University have, in fact, re-engineered the polio virus to cure brain tumors by removing a key genetic sequence.

“So cancers, all human cancers, they develop a shield or shroud of protective measures that make them invisible to the immune system,” said Dr. Matthias Gromeier, a professor of neurosurgery, molecular genetics, and microbiology at Duke. “And this is precisely what we try to reverse with our virus. So by infecting the tumor, we are actually removing this protective shield. And enabling the immune system to come in and attack.”

While using viruses such as HIV, smallpox, and measles to treat cancer is nothing new, the Duke team had the big idea to try polio. Happily, they discovered that the virus is capable of seeking and attaching itself to a receptor found on the surface of almost every solid tumor.

A crucial aspect of re-engineering the virus was to de-fang it sufficiently that it would not cause the incapacitating symptoms that had afflicted a generation of polio sufferers. Gromier and his team accomplished this by by removing a certain genetic sequence and replacing it with material from the common cold virus. But the re-tooling still enabled the virus to reproduce in cancer cells.

While the altered polio virus initiates the fight against the cancer cells, its ability to alert the immune system to the trouble is what often finishes off the virus.