Researchers in the USA have trialled a new form of cancer treatment in mice – using a mutation of the mosquito-borne Zika 

Though it causes life-changing brain damage if unborn babies are infected, new research suggests that the virus can also selectively target and destroy certain adult brain cancer cells.

The Zika virus made headlines when it spread rapidly throughout South America in 2016. In some cases, the Zika virus can present with mild symptoms or no symptoms at all. However, if a pregnant woman is infected, it can have severe effects on the unborn child, including microcephaly (reduced brain and head growth), brain malformations, and other birth defects.

Scientists hope that the same mechanism that makes the virus such a threat to the brains of developing babies could present a new hope for cancer treatment in adults. In infants, the Zika virus targets the brain’s stem cells which are crucial to growth and normal development – causing the microcephaly and other brain deformities. However, researchers believe that in adults, the Zika virus targets only glioblastoma stem cells, while leaving any normal stem cells intact.

Glioblastomas are a mutated form of brain stem cell found only in adults, and are notoriously difficult to treat, as they spread quickly and widely throughout the brain. This makes it difficult to tell what is tumour and what is healthy tissue, making it harder to target the cancer through surgery or radiation.

The groundbreaking new study, carried out by scientists from Washington University School of Medicine and the University of California San Diego School of Medicine, showed that mice injected with Zika virus had significant tumour shrinkage without damage to normal brain cells. If this effect were to be replicated in humans, it would represent a huge step towards treating a previously tricky form of brain cancer – prolonging the lives of those with a disease described by one researcher as “uniformly fatal”.

Scientists have used viruses to treat cancer before – immunotherapy treatments such as using the herpes virus to treat skin cancers have shown promise, and many other avenues of virus research are being explored. A follow-up to the Zika virus study is planned at the University of Cambridge, and there are hopes that human trials could begin as soon as 18 months away.

In the meantime, medical researchers are focusing on modifying the Zika virus to make it less dangerous to adults, while retaining its ability to attack glioblastomas.

Read the full report at the Journal of Experimental Medicine.

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