A Dangerous Virus
Zika virus and its devastating consequences to unborn babies made the headlines in 2015 when scientists first established a link between this mosquito-borne virus, microcephaly and Guillain-Barré syndrome in babies, two devastating neurological disorders. Extensive research in the past couple of years on this previously poorly-known virus led scientists to the conclusion that Zika acts by infecting a very specific type of brain cells in the developing brain. These cells belong to the family of stem cells because of their capacity to renew themselves constantly.
A Clever Idea
This key finding led to the innovative idea that Zika could be used as a weapon against brain cancer. Indeed, Glioblastoma, the most prevalent form of brain cancer is believed to be fuelled by these very same brain stem cells. Conventional chemotherapy and radiation treatments can destroy the bulk of a tumour, but the few remaining stem cells that may be left behind have the capacity to re-initiate tumour growth within 6 months. These stem cells can therefore explain the poor prognostic for this type of cancer which is currently less than 2 years’ median survival rate.
Using viruses to kill cancer cells is not new but a team of scientists from Washington University School of Medicine in St. Louis and the University of California San Diego School of Medicine shows that the Zika virus, unlike other viruses of the same family (West Nile virus) kills brain cancer stem cells, bringing hope for the development of future oncolytic virus therapies. Their initial results, published in September 2017 in the Journal of Experimental Medicine, are very promising, suggesting that one day they may be a cure for brain cancer. The authors tested whether the virus could kill stem cells in glioblastomas removed from patients at diagnosis. They infected tumours in petri dish with Zika virus and looked at which type of cells were infected. The virus spread through the tumours, only infecting and killing the cancer stem cells. Using mice to test the behaviour of the virus in a living organism, they could show that tumours were reduced in size and, as a result, increased the lifespan of the animals.
Promising Potential For Combination Therapy
If Zika virus were used in people as a therapy or a cure for brain cancer, it would have to be injected directly into the brain, most likely during surgery to remove a primary tumour or in combination with chemotherapy. This is to avoid the immune system of the patient from finding and destroying the virus before it could reach the brain. The focus of the research now is to assess the safety of such treatment. Adults infected with Zika, usually display symptoms that resemble those of the common cold such as mild fever, skin rash, conjunctivitis, muscle and joint pain, malaise or a headache. These symptoms normally last for 2-7 days. By genetically altering the virus, scientists aim to reduce these symptoms that are the results of the virus infecting healthy cells.
Many more steps are needed to translate these initial results into treatment but this innovative project shows how people’s creativity can turn a devastating biological agent into an ally to fight or even be a cure for brain cancer.
Zhu Z, Gorman MJ, McKenzie LD, Chai JN, Hubert CG, Prager BC, Fernandez E, Richner JM, Zhang R, Shan C, Wang X, Shi P-Y, Diamond MS, Rich JN, Chheda MG. Zika Virus Has Oncolytic Activity against Glioblastoma Stem Cells. The Journal of Experimental Medicine. Sept. 5, 2017.