The deadly polio virus may be the key to curing some cancers. By injecting a modified version of polio in two patients with glioblastoma brain tumors, a doctor has eliminated their tumors without infecting them with polio.

CBS’s “60 Minutes” followed the patients for 10 months during the trial and will release the full report Sunday. Matthias Gromeier, a molecular biologist at Duke University, has been researching the idea for 15 years, first beginning with studies, then animal trials and now human tests.

Patient Stephanie Lipscomb was 20 when she entered the experimental treatment. “They didn’t expect me to live more than two years, I don’t think,” Lipscomb told USA Today. In 2012, doctors injected the genetically modified version of the polio virus into her tumor. Now, three years later, there is no active cancer.

The modified polio virus is able to remove the shield human cancers put up against the immune system, which then allows the immune system to fight back, Gromier explained to CBS. It only took one dose for Lipscomb to become cancer free.

“This, to me, is the most promising therapy I have seen in my career, period,” Henry Friedman, a neuro-oncologist and deputy director of the Brain Tumor Center at Duke University, told CBS. Friedman has been researching a cure for glioblastoma for more than 30 years.

Polio is a life-threatening, infectious disease that leaves its victims paralyzed. But, the disease, for the most part, has been eradicated after the development and widespread use of the polio vaccine in the 1950s. Gromeier’s lab at Duke modified the virus by adding genetic information from the rhinovirus, a cause of the common cold.

According to CBS’s report, the polio virus appears to start the killing of the tumor and then allows the immune system to do the rest of the damage. During human trials, 11 of the 22 participants succumbed to their tumors. But in two patients, doctors have not detected any signs of the cancer three years after they started receiving the experimental treatment.

The full "60 Minutes" report will air Sunday at 7 p.m. EDT on CBS.