Medical researchers in the US have weaponized a mutated form of the Zika virus in the hopes of defeating a common, tenacious and highly aggressive form of brain cancer with some highly promising initial results.

“We showed that Zika virus can kill the kind of glioblastoma [brain cancer] cells that tend to be resistant to current treatments and lead to death,” said Michael S. Diamond, Professor of Medicine at Washington University School of Medicine and the study’s co-senior author.

Glioblastoma is the most common form of brain cancer and is both highly lethal and highly resistant to surgery, radiation, and chemotherapy treatments, with a median survival rate of less than two years following diagnosis. Its self-regenerating cells that spread out from the initial site of the tumor are what make it so hard to kill.

In a paper published in the Journal of Experimental Medicine on Tuesday, the joint team from Washington University School of Medicine and the University of California San Diego School of Medicine unveiled its results from tests conducted on adult mice and donated adult human brain cells in the laboratory.

In the tests, conducted on adult mice, the modified Zika virus preferentially infected and killed the cancer stem cells as opposed to the other cells within the tumor or the healthy cells within the test subjects’ brains, unlike the West Nile virus, which is indiscriminate in which cells it attacks.

The weaponized Zika and a saltwater placebo were injected into 18 and 15 mice respectively. The tumors in the Zika-infected mice shrank dramatically and they survived "significantly longer than the ones given saltwater."

Bringing #Zika back: Florida's 1st sexual transmission of virus in 2017 https://t.co/JJyuwhKxDE — RT America (@RT_America) August 2, 2017

While the Zika virus is incredibly damaging to infants in the womb, leading to microcephaly and other brain malformations in some babies, its effects on adult humans are generally far less severe, with cases of meningoencephalitis rare.

Infant brains have far more stem cells, specifically neuroprogenitor cells, than adult brains, which may explain why the treatment is so promising for adult cancer patients.

Approximately 12,000 people are diagnosed with glioblastoma in the US each year, reports the Washington University of Medicine in St. Louis, among them is US Senator John McCain, who was diagnosed in July.

“We’re going to introduce additional mutations to sensitize the virus even more to the innate immune response and prevent the infection from spreading,” Diamond, a professor of molecular microbiology, added.

“Once we add a few more changes, I think it’s going to be impossible for the virus to overcome them and cause disease.”

A controlled infection with a modified version of Zika in combination with chemotherapy-radiation could one day be used in tandem to defeat this particularly aggressive form of cancer.

“We see Zika one day being used in combination with current therapies to eradicate the whole tumor,” said co-author Milan Chheda, an assistant professor of medicine and neurology, as cited by The Washington University School of Medicine.