An unlikely remedy for brain cancer: Zika virus
When
people think of treating brain cancer, or any other cancer for that matter,
most people think of chemotherapy, radiation, or surgery as standard treatment
options. There are very few people who would think to utilize a virus to treat
brain cancer, especially the Zika virus. However, a team of researchers have
now found that Zika virus can be used to treat cancer, more specifically,
glioblastoma. If glioblastoma sounds familiar, that is because Senator John
McCain was recently diagnosed with this type of cancer (Mohney, 2017). Glioblastoma
is the most common brain cancer in adults with a survival rate of only two
years (Roberts, 2017; Zhu et al., 2017). The glioblastoma is usually removed
with surgery; however, tumorous stem cells cause the cancer to grow back. In
addition, glioblastomas do not metastasize outside of the central nervous
system (CNS), meaning the cancer tends to stay localized (Zhu et al., 2017). It is for these reasons that researchers have
been hoping to utilize a virus, such as Zika, to fight the cancer (Mohney,
2017).
Zika
virus is an RNA virus of the flavivirus genus that also includes dengue, West
Nile virus, and yellow fever viruses (Zhu et al., 2017). Zika virus made
headlines for causing microcephaly in infants and was linked to birth defects
in 30 countries. The virus is spread through infected mosquitoes (Roberts, 2017). Zika primarily attacks the CNS, mainly
stem and progenitor cells, which are prominent in the developing infant brain (Zhu et al., 2017)
Because Zika targets the CNS, Zhu et al. (2017) wanted to study the effects of Zika virus on
glioblastoma stem cells in mice. The researchers found that Zika virus killed
glioblastoma stem cells but not normal cells. This is in contrast to the West
Nile virus that killed both tumor and normal cells. Furthermore, when mice were
inoculated with a mouse strain of Zika virus, they had significantly longer
survival rates compared to a wild-type virus. However, the researchers are
still unsure of the exact mechanisms by which the virus works.
Zhu et
al. (2017) point out that safety is still a concern with utilizing this virus
because of some of the unknown factors, but the results of the mouse studies
are promising for glioblastoma treatments. In addition, the researchers
acknowledge that the virus would be used with other conventional therapies.
There is also work being done on other viruses for treating glioblastomas. These
studies are exciting because they offer new therapies for patients with a type
of cancer that significantly reduces their life spans. These are also targeted
therapies that could potentially reduce unwanted side effects associated with
more conventional therapies. Although more studies need to be done, there is
progress being made in finding alternative treatments for patients with these
types of cancers.
References:
Mohney, G. (2017). Researchers Hope Zika Virus
Can Treat Deadly Brain Cancer. Retrieved September 23, 2017, from https://www.healthline.com/health-news/zika-virus-can-treat-brain-cancer
Roberts, M. (2017). Zika virus used to treat
aggressive brain cancer. Retrieved September 23, 2017, from http://www.bbc.com/news/health-41146628
Zhu, Z., Gorman, M. J., Mckenzie, L. D., Chai,
J. N., Hubert, C. G., Prager, B. C., . . . Chheda, M. G. (2017). Zika virus has
oncolytic activity against glioblastoma stem cells. The Journal of
Experimental Medicine,1-15. doi:10.1084/jem.20171093
Glioblastoma is a cancer that affects the astrocytes and oligodendrocytes (glial cells) in the brain, causing the stem cells to proliferate and thus causes a variety of symptoms. The Zika virus works against this cancer by targeting the problem stem cells in the CNS, as it would attack healthy stem cells in an unborn child. The virus has its effect on children because of their large number of stem cells. If the Zika virus was able to continue developing into a cancer treatment, how would differing ages (and thus differing stem cell counts) of patients diagnosed affect the treatment? In other words, would we have to create a specific Zika virus for each patient’s specific nervous system’s cell count in order for this treatment to be successful in humans? (the age range for glioblastoma is 45-70- http://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Glioblastoma-Multiforme)
ReplyDeleteThe idea of using the Zika virus was not the first virus used to fight cancer. The viruses used in previous cases have been extensively engineered for the purpose of fighting cancer, but not killing off normal, healthy cells.
ReplyDeleteHow is the Zika virus modified for cancer treatment? Is the Zika virus particularly useful because when it is normally in a host it doesn't attack normal, healthy cells to begin with?
It's also interesting because when the virus is introduced to the body, the body's immune system recognizes the cancer cells even more because the virus is now attacking the cancer cells as well.
I assume that the reason for furthering the development of this type of treatment is because it would be less invasive and aggressive, yet equally, if not more, effective. I am wondering since this appears to be working because of the particular genus that Zika belongs to, if other viruses that belong to that genus, like West Nile or Yellow Fever, would have similar effects. It would be really interesting to figure out what the mechanism is for this, because it would potentially lay the foundation for future cancer treatment development, at least for unregulated growth in the CNS.
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