Viruses are hijackers, wreaking infectious havoc by taking over a cell’s machinery and using it to replicate. But their wily ways may not be all bad. Yale professor of neurosurgery Anthony van den Pol, Ph.D., is harnessing their destructive power to develop a novel treatment for glioblastoma, the most common and aggressive form of brain cancer.

Glioblastoma strikes about 7,000 Americans each year, and most patients live just a year after diagnosis. Although it can be treated with surgery, radiation and chemotherapy, said van den Pol, the cancer usually comes back.

The idea of unleashing viruses to destroy tumor cells is beginning to gain validity, not just for brain cancers but also for ovarian, prostate and other kinds of tumors. When this line of research began two decades ago, scientists feared that the viruses would spread to healthy cells, so they genetically altered them to prevent them from replicating. But those inactivated viruses kill relatively few brain tumor cells. The Yale team hypothesized that a replicating virus would be much more effective.

Van den Pol and his colleagues bred several generations of vesicular stomatitis virus on glioblastoma cells, selecting for strains with the highest tumor-killing capacity. Then they tested the virus and saved those strains that did not infect normal cells. In a study published in the Journal of Virology in May, the researchers reported that the strain they developed selectively killed glioblastoma cells in vitro, and was able to infect and kill whole tumors in mice.

The results are promising, but van den Pol stressed that they are still preliminary. The team plans to expose the virus to different types of cells found in the brain to make sure that it will not infect them. “This is a high-risk strategy,” he said, “but we’re dealing with a disease for which at present there is no cure.”