A liquid biopsy – often a blood test– offers a fast, minimally-invasive way to get detailed information about a person’s tumor. This diagnostic tool has a huge potential to accelerate precision medicine.
Precision medicine in cancer treatment
Cancer was the second leading cause of death globally in 2018 . And rates of the disease are growing at an alarming pace – estimates suggest that the global burden of the disease will rise from 17 million new cases per year in 2018 to 27.5 million new cases per year by 2040 . As well as effective prevention strategies, there is an urgent need to develop improved treatment strategies to address this public health issue.
Precision medicine is an approach that allows doctors to select the right treatments for a patient based on a detailed molecular understanding of their disease.
“We are moving away from the era of chemotherapy where everybody gets the standard treatment and some will benefit, but many will not, and they will experience its side effects,” says Professor Ilhan Celik MD, Senior Global Program Lead, Global Clinical Development at Merck KGaA, Darmstadt, Germany.
“We need a more precise approach – getting the right drug for the right patient at the right time.”
To deliver precision medicine, doctors need detailed molecular information about a person’s tumor – which is usually obtained by testing a tissue biopsy. But new so-called ‘liquid biopsies’ have great potential to transform cancer diagnostics.
DID YOU KNOW?
is the predicted number of new cases of cancer worldwide each year by 2040. 
working days is what it takes to process a liquid biopsy with the RAS liquid biopsy test. 
saw the launch of the world’s first RAS liquid biopsy test for metastatic colon cancer. 
Biomarkers are vital to delivering precision medicine
Biomarkers – biological molecules found in the blood, other body fluids or tissues that signal a normal or abnormal process or a disease - hold the key to precision medicine. Commonly, a biomarker test may involve measuring the levels of abnormal genes or proteins within a person’s tumor. A doctor will then use this information to help guide the best treatment strategy.
Biomarkers are also vital for accelerating drug development – enabling a better prediction of patient response and quicker assessment of whether a new cancer drug is hitting its desired target in clinical trials.
One day, it may even be possible to screen for cancer through a simple biomarker-based blood test – detecting the presence of disease even before any symptoms arise .
How are cancer diagnostics usually carried out today?
If a person has discovered a suspicious lump or growth somewhere in their body, their physician may suggest they undergo a biopsy procedure to remove a tissue sample - which will be sent to the laboratory for testing to confirm or exclude a cancer diagnosis.
Many biopsies are relatively easy to collect – such as from tissues like the mouth, skin or breast. But this often isn’t true for tumors that lie deep inside the body – such as in the lung, liver or pancreas. In these cases, taking a biopsy can be difficult or even impossible. Testing will usually involve the patient undergoing an invasive, sometimes painful and risky, procedure that may even require a general anesthetic. Additionally, getting the results on tumor mutations from a tissue biopsy, which can help inform the most appropriate treatment, may take several weeks — precious time for a person who is living with an aggressive form of cancer .
An alternative to conventional tissue biopsy that allows less invasive, less painful and faster testing, particularly for tumors that are difficult to access, has the potential to transform the way cancer is diagnosed and treated.
What is a liquid biopsy?
Research into using liquid
biopsies as a tool for cancer diagnostics has been steadily increasing over recent decades. The approach typically involves examining a bodily fluid, such as a blood sample, rather than a potentially invasive tissue biopsy procedure, to identify tumor biomarkers.
As a tumor grows, it starts to release materials – such as intact cancer cells or pieces of DNA – into the circulation. So far, researchers have mainly focused on the molecular analysis of cell-free DNA (cfDNA) as well as circulating tumor cells (CTCs), although other tumor-derived materials are available.
“The beauty of the liquid biopsy is the physician can simply utilize a blood sample, which is collected nearly every day in cancer treatment. The plasma is then isolated, and the analysis can be run to get the same information as would be received for tissue biopsy,” says Celik.
The approach is also applicable to other bodily fluids – such as urine, saliva or sweat. But for cancer, most of the focus is on blood or plasma as these offer the best representation of what’s going on inside the whole of a person’s body – especially if it’s not known where the tumor is or if there are metastases in different organs.
What are the advantages of liquid biopsy?
Liquid biopsies offer a much less invasive alternative to the standard tissue biopsy procedure – which means less pain, a lower risk of complications and more convenience for patients.
This type of test also offers opportunities for doctors to get results rapidly and more regularly, potentially enabling them to better monitor the tumor response and adapt a person’s treatment if necessary. Getting laboratory results from a liquid biopsy is much quicker than traditional biopsies.
As a cancer grows and spreads, it evolves. As a result, the molecular make-up of different metastatic tumors can vary greatly - and even different areas of the same tumor can have distinct gene alterations, leading to tumor variability.
Because of this tumor variability, a biomarker test based on a single tissue biopsy may provide an incomplete picture of a patient’s cancer. But liquid biopsies open the possibility to capture information about all of the tumors in a person’s body.
“A liquid biopsy provides a view of various metastases and DNA from the different areas of a tumor – and so you can better identify the presence of certain alterations and treat the patient accordingly,” explains Celik.
What progress has been made so far?
There has been significant progress in the field, with some liquid biopsy tests already reaching the clinic and benefiting patients – marking a major step forward in cancer diagnostics and precision medicine.
But challenges remain - including the need to develop tests that are reliable, accurate and sensitive enough to detect the often extremely low levels of cfDNA or CTCs relative to the other cells and molecules also in the blood or other bodily fluid.
Our scientists are actively pursuing cutting-edge research programs to find and validate liquid biopsy tests that can identify which cancer patients may benefit best from targeted drugs.
“It’s absolutely thrilling that we are in the situation to analyze a blood sample in a way that we can get hundreds of biomarkers with one sample,” says Celik. “Ten years ago, nobody would really believe that – it’s taken only one decade to be able to get a really detailed profile of a patient’s tumor and base the treatment decision on it.”
For further reading on the potential of liquid biopsy and our work in this area, learn more on our blog Vibrant Thoughts:
- Harnessing Liquid Biopsy for Cancer Precision Medicine, by Ilhan Celik
- A Worthy Ally for Tracking Tumors in Real-Time, by Dennis Merkle
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