St. Louis Post-Dispatch
Posted with permission from Tribune Content Agency

ST. LOUIS — Scientists who study viruses have long tried to harness their power to cause illness in healthy cells, and engineer them to attack and destroy cancer cells.

Now researchers at Washington University say they have shown that the Zika virus can kill stem cells in brain tumors in the lab. Zika is a mosquito-borne virus that can cause severe brain damage in the developing fetus if the mother catches the virus when pregnant.

Since Zika affects stem cells in the fetus' brain, scientists theorized that it might be able to infect stem cells in brain tumors.

"We take a virus, learn how it works and then we leverage it," said Dr. Michael Diamond, a professor of molecular microbiology, pathology and immunology. "Let's take advantage of what it's good at, use it to eradicate cells we don't want. Take viruses that would normally do some damage and make them do some good."

Researcher Zhe Zhu thought that glioblastoma stem cells, which stubbornly resist chemotherapy and radiation to regrow in most patients, looked a lot like the stem cells in a fast-growing fetal brain. Since the Zika virus kills those fetal cells, maybe it would do the same to the tumor cells.

Instead of injecting Zika virus into the brain, the scientists engineered a designer version of the virus that would be better controlled by the immune system if it invaded healthy cells.

They tested the Zika virus on glioblastoma stem cells that had been surgically removed from patients. The virus killed the cancer stem cells, which are most resistant to standard therapies. The experiment also worked in mice with brain tumors. The tumors shrunk and the mice lived longer than those treated with a placebo. It's important to note that an experiment that works in a test tube, or works in a mouse, will not necessarily work in people.

The next step is to see if the virus could kill human tumor stem cells in mice. If successful, then a clinical trial for humans could be designed. Other viruses that are being studied to see if they can attack tumors include polio, herpes and the common cold.

Glioblastoma is the most common form of brain cancer. It affects about 12,000 people each year in the U.S., including Sen. John McCain, R-Ariz., who recently announced his diagnosis.

The research, a collaboration with the University of California, San Diego, was published in the Journal of Experimental Medicine.