The Zika virus can target and kill a particular type of brain tumour cell in the lab, according to US scientists.
Tests using the virus found it could kill stem cells that are thought to make glioblastoma particularly hard to treat.
The study, from scientists at Washington University School of Medicine in St. Louis, the University of California and San Diego School of Medicine, marks an important first step towards testing if a form of the virus could one day treat patients.
“We showed that Zika virus can kill the kind of glioblastoma cells that tend to be resistant to current treatments,” said Dr Michael S. Diamond, the study’s co-lead.
Zika can cause serious birth defects in the developing brain such as microcephaly, as seen in the 2015 epidemic in the Americas. This is because the virus specifically targets and kills specialised stem cells in a developing brain. These stem cells resemble those found in brain tumours.
Glioblastomas are the most common type of brain tumour in adults. They are also the most difficult to treat. Patients have surgery and chemotherapy but this only kills the bulk of the tumour and often leaves the stem cells intact.
Experts believe that the stem cells left behind are responsible for the tumour coming back.
The study, published in The Journal of Experimental Medicine, tested whether the virus could be used to kill stem cells in glioblastomas removed from patients.
The team infected tumour samples with one of two modified strains of the Zika virus. Both strains successfully infected and killed the tumour stem cells in the lab, while avoiding healthy tissues.
One of these modified viruses also shrank tumours in mice with glioblastoma.
Two weeks after injection, the tumours in 18 Zika-infected mice were smaller than in 15 mice not treated with the virus. The mice treated with Zika also survived longer.
The researchers claim that these findings suggest that Zika infection might help people with glioblastoma when combined with standard treatment. But this now needs testing in further studies.
Dr Harry Bulstrode, a Cancer Research UK-funded neurosurgeon at the University of Cambridge, is also looking at the effects of the Zika virus on glioblastoma.
Bulstrode said: “This study is very exciting. It shows, as predicted, that the virus is highly selective for glioma stem cells. It also suggests that infecting mice, who have glioblastoma, with the Zika virus can increase their survival.”
“Our work in Cambridge will undoubtedly complement this new study and hopefully we’ll see results sooner because of it,” he adds.
— Cancer Research UK (@CR_UK) September 6, 2017
Dr Colin Watts, a Cancer Research UK-funded brain tumour expert, agreed this study is an important first step in working out whether the Zika virus could help treat glioblastoma.
But he added that “there is still a long way to go before we know if it will work in patients.”
Zhu, Z., et al. (2017) Zika virus has oncolytic activity against glioblastoma stem cells. JEM. DOI: 10.1084/jem.20171093