Our bodily fluids can tell us a lot about our risk of disease and our current health. The best way to harness this information is through a process called liquid biopsy. Sylvain Perriot, Founder of Lermed, helps us understand how liquid biopsies work – and why they’ll be crucial as we enter the era of personalised medicine.
What’s a biopsy? And what’s the difference between a liquid biopsy and a solid tissue biopsy?
A biopsy is when you take tissue or fluid from the body for examination. Typically, when we talk of biopsies, people think of solid tissue biopsies, as they’re much more common and have been used in clinical settings for many years. This is when a piece of solid tissue is taken from the body and sent for analysis. For example, a suspicious tumour is removed from a patient and analysed to understand whether it’s malignant.
A liquid biopsy tests bodily fluids instead of solid tissue. The most common fluid used is blood, but you can also work with fluid from the brain, urine, saliva or even tears.
With both kinds of biopsy, the idea is not only to detect diseases, but also to find out whether a patient is at risk of a disease, or resistant to treatment, for instance. This allows for more personalised care as prevention measures or treatment are targeted to a patient’s needs.
Does a liquid biopsy give the same information as a solid tissue biopsy?
This is a burning question in the field and we don’t yet have the answer. The way a liquid biopsy works is by analysing ‘plasma circulating’ biomarkers that can be traced back to their tissue of origin. These can include cell-free (cf) DNA or RNA, circulating tumour cells or extracellular vesicles. I won’t go into too much technical detail, but basically, some of these methods give more information than others.
Currently the most common use for liquid biopsies is to look at circulating tumour cells (CTCs) and cf-DNA in the blood of cancer patients. With this method, if you have the right markers, you can isolate them and get the same level of genome analysis as with a solid tissue biopsy. This provides crucial information about the type of cancer someone has and whether there’s resistance to the drug.