Liquid biopsy to detect brain tumour biomarkers

Friday 4 May 2018

A research team of engineers and physicians at Washington University have developed a way to identify brain tumour biomarkers through a blood test

Biomarkers (or indicators) are an integral part of clinical practice, as they inform prognoses and treatment strategies. A biomarker could be a change in the cancerous cell's genes or a molecule produced by the tumour.

In order to identify biomarkers, a biopsy needs to be conducted. A biopsy is surgical procedure that involves taking a small sample of tissue for examination. However, biopsies are associated with potential complications such as haemorrhage and infection. Such procedures may not be feasible for brain cancer, given the location of some tumours.

While liquid biopsies—identification of biomarkers through blood tests—are being used for other types of cancer, they have made limited progress for brain tumours. This could be attributed to the blood brain barrier, which is a collection of cells and blood vessels surrounding the brain which regulate the movement of substances in and out of the brain.

Whilst this natural barrier usually protects the brain from infections and harmful substances, it also prevents the movement of biomarkers into the bloodstream.

To overcome this, researchers led by Dr Hong Chen, a biomedical engineer, and Dr Eric C. Leuthardt, a neurosurgeon, at Washington University have devised a novel method to allow the biomarkers from a brain tumour to pass through the blood brain barrier into the bloodstream.

The researchers targeted ultrasound energy, which is a type of mechanical energy, at brain tumours in mice. They then injected microbubbles, which are tiny artificial bubbles made up of a mixture of protein and gas.

These bubbles travel through the blood and pop once they reached the target causing tiny ruptures of the blood brain barrier. The ruptures would allow the biomarkers from the brain tumour to pass through the blood brain barrier and enter the bloodstream. A blood test can then determine the biomarkers in the tumour.

"Once the blood–brain barrier is open, physicians can deliver drugs to the brain tumour," said Dr Chen. “Physicians can also collect the blood and detect the expression level of biomarkers in the patient. It enables them to perform molecular characterizations of the brain tumour from a blood draw and guide the choice of treatment for individual patients."

This technique would enable personalised medicine, as it would allow physicians to tailor treatment regimens to the individual's tumour.

While this technique has immense potential, it is still being optimised to be safe and effective to be used in patients.

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