Scientists Use Zika Virus to Kill Cancer Cells in Brain

The mosquito-spread Zika virus can give a strong boost to an immunotherapy drug that can ward off a recurrence of glioblastoma tumors for at least eighteen months, scientists say.       

A recent study with mice shows the Zika virus activates immune cells to destroy glioblastoma, which is an aggressive brain tumor.

Zika Virus can Kill Deadly Cancer Cells in Brain

These findings were published in JCI Insight, which explains that the virus might have a key to unlock the power of immunotherapy for glioblastoma, a lethal brain cancer that may result in death within two years.

Immunotherapy helps transform the body’s own immune system into a weapon to destroy cancer cells. This method has proved effective for skin, blood, and some other cancers. It has shown limited benefit for patients with glioblastoma.

 Co-senior author Milan G. Chheda, who is also an assistant professor of medicine and neurology at Washington University in St. Louis described, “Glioblastoma is a difficult disease because it progresses so quickly, and we don’t have any interventions that ultimately alter its course.”

It is possible to treat the initial tumor, but recurrence is immediate and inevitable. If we use the Zika virus, we can revive the immune system to respond to the virus otherwise it is ineffective immunotherapy, says Chheda. He added further, “This also sets the stage to prevent a recurrence, allowing us to overcome two major barriers to effective treatment.”

Glioblastoma is known as the most common and threatening form of brain cancer. Around 12,000 people have this cancer and are treated each year in the US. The survival period of this cancer is only fourteen months.

Chheda and co-senior author Michael S. Diamond, a professor of medicine proved that the Zika virus can destroy brain cancer stem cells, which is a type of cells that are most immune to standard treatments.

Simply put, the Zika virus acts against brain cancer. Hence, scientists transplanted brain cancer cells into mice’s brains. After one week, they injected the Zika virus into the mice tumors or sterile saltwater for comparison.

This treatment improved the animal’s survival chance from 10% to 63% for one cancer cell line and 0-37% for the other. Additional analysis showed that the virus had drawn a large number of immune cells of several types to the tumors, most particularly so-called cytotoxic T cells which is a type of immune cell that can kill cancerous cells.

The scientists reintroduced the tumor to another part of the mice’s brains, one and a half years after the original tumor. One of the mice killed the new tumor within some weeks.

Several tumors produce suppressive environments nearby themselves which control an effective immune response. The suppression is formed, in part, by so-called immune checkpoint molecules including PD-1 that help prevent immune cells that can destroy cancer cells. It is called cytotoxic T cells that turn off and are unable to combat.

The purpose of immunotherapy drugs is that they target PD-1 that is successfully used to treat blood, lung, skin, and other cancers.

Not only does glioblastoma help keep immune cells turned off but also helps keep most of them away. Stimulating immune cells is not sufficient to destroy a tumor. Chheda stated that the Zika virus has the ability to draw huge numbers of immune cells to the tumor. If it is combined with immunotherapy it helps to free them from suppression.

To find out, the scientists inserted cancer cells in mice’s brains and treated the animals with the Zika virus, which acts as an antibody that hinders PD-1. 

PD-1 inhibition alone and Zika virus therapy alone each improved survival from 30 -60 percent. This combination made the survival rate 90 percent.

The study outcomes are promising, but the Zika virus is well-known for causing brain impairment in fetuses. So any treatment that involves inserting the virus into people’s brains increases safety concerns. The scientists repeated the main experiments with a vulnerable form of the virus and discovered similar positive cancer-fighting results. They decided to perform further research to examine the safety and efficacy of the vulnerable virus as a therapy for glioblastoma patients.