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09.10
2024

Blood, saliva and tears: what bodily fluids can tell us about our health through liquid biopsies

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.

You can think of a liquid biopsy as a blood test that comes with a map

How’s a liquid biopsy different to a blood test?

With a blood test, you’re assessing soluble markers in the blood. For instance, if there’s a rise in C-reactive protein (inflammatory marker), you know the patient has an active inflammation, but you don’t know where it is in the body or whether it’s caused by an infection, autoinflammatory disease or trauma. You can’t link the markers to where they were produced.

The big difference with a liquid biopsy is that the information you extract from fluids can be traced back to bodily tissue – so it can tell you about the status of a particular organ or cells. You’re looking at the specific biomarkers travelling in your fluids from that tissue. So you can think of a liquid biopsy as a blood test that comes with a map – and lots of other precise information.

What are the advantages of liquid biopsies?

The issue with solid tissue biopsies is that, of course, you need to take tissue from a patient. If this involves removing some skin, or tissue from the colon, it’s fairly straightforward but you can’t do it too often. It also gets more complicated if you need information about the health of a patient’s brain or heart. You can’t easily remove a piece of tissue from those parts of the body. Any solid tissue biopsy is an invasive procedure.

That’s where liquid biopsies come in. It’s much less intrusive and risky to collect fluids from the body than to perform a complex operation. It’s also an extremely useful way of tracking the progression of a disease, or how a patient is responding to treatment – especially in cases where a patient is too weak to handle surgery.

Liquid biopsies will make it easier and quicker to see how a patient is responding to treatment after just a few days. You don’t need to wait weeks or months for a clinical response – and you can then adapt the treatment if it isn’t working. You can also perform such tests much more frequently. This is groundbreaking as it will save precious time and allow us to intervene earlier. If we do that in the early stages of a disease, we can hugely improve patient outcomes. Liquid biopsies will be crucial as we move towards personalised medicine, as they’ll allow us to adapt and tailor treatment to each patient.

Liquid biopsies will be crucial as we move towards personalised medicine

How widespread is the use of liquid biopsies?

Research into liquid biopsies started back in the 1970s, but their use in hospitals is very new. Only a handful of liquid biopsy-based diagnostic tools have been approved by the FDA – and the oldest is just fifteen years old. Out of 500 clinical trials registered on clinicaltrial.gov, more than a third relate to oncology, and around a fifth to neurology.

That said, I think the market will become much more crowded in the next few years. Right now, liquid biopsies are mainly used for serious conditions, but their use will become more widespread in years to come – and increasingly, they will be used for prevention. My hope is that we’ll get to the point where, from a single blood sample, we’ll be able to detect a patient’s risk for a wide range of diseases and put prevention measures in place.

Are there any obstacles that stand in the way?

The biggest challenge is to standardise methods to extract information from fluids. This research field is very active and each lab has specific procedures but most of them can’t easily be transferred to hospital labs. If two different labs have different technology, will they get different results? How do we ensure a lab in Lausanne gets the same results as a lab in London? Those are the big challenges at the moment. It takes a long time to develop such robust test, which explains why so few tests have been approved by regulatory authorities so far.

Of course, there are ways of overcoming this. Many experts are working on it, so I’m optimistic that solutions will be found over the next few years.

It’s well worth overcoming these obstacles to reap the rewards the widespread use of liquid biopsies would offer. Ultimately, they have the potential to lower the cost of healthcare, offer safe and easy testing, and save many lives.

Sylvain Perriot
Founder of Lermed

Sylvain Perriot is the Founder of Lermed. Previously, he worked at the CHUV as a researcher in the field of neuroinflammation and neurodegeneration. Sylvain’s work has focused on how to better stratify patients within this therapeutic area to improve diagnosis and care. He developed several fully human cellular models and ex-vivo approaches to reach this end.

He holds a PharmD from the University of Grenoble, France and a PhD with a specialisation in neuroimmunology from the University of Lausanne.

Sylvain’s focus is on research that can be applied to medicine, as his ultimate aim is to contribute to changing the lives of patients for the better.

Lermed

Lermed is developing several approaches to improve diagnosis, prognosis and overall care for patients with neurodegenerative diseases. It leverages two proprietary platforms to generate in-vitro avatars of patients, thus reproducing disease states to conduct clinical trials in a dish, identify responders and devise companion tests for drug development. This groundbreaking approach has the potential to unlock personalised medicine in the field of neurodegeneration and dementia.

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