Preliminary findings published in PLOS One on July 25th point to the potential of turning the destructive power of the Zika virus against tumors. A team of researchers from Nemours Children’s Hospital in Florida led by Dr. Kenneth Alexander, chief of the Division of Infectious Diseases, and Dr. Tamarah Westmoreland, a pediatric surgeon, reported on Wednesday that the virus may be highly effective in killing most neuroblastoma cells ― the virus was only non-lethal in the case of one of several neuroblastoma cell lines exposed to it.
The seemingly benign Zika virus, which is spread by mosquitoes, was first discovered in 1947 but only came to mainstream attention in 2016 after a wave infections quickly spread throughout South and Central America. Adults are rarely affected in a serious way, however, if a woman contracts the virus during pregnancy, it may find its way into the developing brain of the fetus leading to birth defects, in particular, microcephaly (a small underdeveloped head).
Neuroblastoma affects neuroblasts, stem cells responsible for creating the nerve fibers that make up the central nervous system and therefore tends to form along the spine or in the adrenal glands. This is the most common type of cancer in children, usually only afflicting infants and very young children ― most are diagnosed under the age of five ― and survival rates can be as low as 40 percent. Typical treatments involve a harrowing and often ineffective combination of surgery, chemotherapy, and radiation. Results of these early laboratory investigations highlight the possibility of using the virus as a neuroblastoma treatment, perhaps in conjunction with surgery.
The team at Nemours Children’s Hospital in Orlando is just one of several research groups exploring the Zika virus as a potential cancer weapon and studies in both the US (2) and Brazil (3) have also demonstrated the potential of using the virus to destroy cancer cells, including highly aggressive glioblastoma cells, another form of cancer that mainly affects the brain and spinal cord.
The virus tends to attack cells that are dividing and differentiating, which may explain why it only affects the developing brains of fetuses and not the adult host’s tissue. Neuroblasts and other cancer cells are also rapidly dividing cells ― one reason cancer spreads so quickly ― and may also be why the Zika virus seems to have oncolytic (cancer-fighting) properties. Therefore, the idea that this virus would only attack cancer cells while leaving healthy tissues intact seems to be a realistic hypothesis.
The concept of using viruses to target and combat cancer is not new. Thus far, however, studies have only been performed in mouse models or using in vitro laboratory experiments and there are still a number of technical obstacles to overcome, including making the Zika virus safe enough to use in cancer treatment. Clinical trials may still be far off, however, these recent findings, as well as previously published studies, continue to bring to light how something negative ― like a virus ― can sometimes lead to new discoveries that positively impact humanity.
(1) Mazar J. et al. Zika virus as an oncolytic treatment of human neuroblastoma cells requires CD24. PLOS One (2018). DOI: 10.1371/journal.pone.0200358
(2) Zhu Z. et al. Zika virus has oncolytic activity against glioblastoma stem cells. Journal of Experimental Medicine (2017). DOI: 10.1084/jem.20171093
(3) Kaid C. et al. Zika Virus Selectively Kills Aggressive Human Embryonal CNS Tumor Cells In Vitro and In Vivo. Cancer Research (2017). DOI: 0.1158/0008-5472.CAN-17-3201