The National Institutes of Health (NIH) Biomarkers Definitions Working Group describes a biomarker or biological marker as “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes (causing disease), or pharmacologic (medication) responses to a therapeutic intervention.”
Because biomarkers are measurable, they can give an idea of what's going on inside the body, assess if any abnormalities are present, and look at how well the body is responding to medical treatment.
But what is considered a biomarker? A “biomarker” covers most healthcare tests and measurements from pulse and blood pressure to blood tests and imaging scans. In this article, we’ll cover the different types of biomarkers, their use in drug development, various cancer biomarkers, and more.
There are four main types of biomarkers: physiological, molecular, histological, or radiographic. Let's look at some examples of these different biomarkers.
Physiological biomarkers include:
Molecular biomarkers are body fluids and other tissues in the body from:
Histological biomarkers are microscopic cells and tissues from:
Radiographic (imaging) biomarkers are from:
Healthcare would be a very different place without these kinds of biomarkers. They are very important tools to have at our disposal, allowing healthcare practitioners to get an idea of what’s happening inside the body — often without having to perform invasive procedures such as surgery.
Biomarkers can assess whether someone has results within the expected “normal” or “healthy” range. However, results may not always correlate with how the patient appears clinically and is feeling. It’s important to consider the whole picture, including symptoms and examination, along with biomarkers. It’s also important to note that there may be differing ranges for normal biomarker results in different populations.
Biomarkers are measurable, objective, and reproducible — meaning the same test could be done again at that point in time and the same or very similar result should be found. They can be looked at as a stand-alone measure or as a trend over time. It can be useful to compare certain biomarkers such as blood tests to someone’s usual baseline. In this way, they can act as an early warning sign for certain diseases.
Biomarkers can be used to diagnose a range of conditions (diagnostic biomarkers) alongside someone's symptoms, such as cancers, neurological conditions like dementia (including Alzheimer's disease), and lung and cardiovascular diseases. They can also be used to monitor a condition and assess response to treatment.
Biomarkers are also used in clinical research and drug discovery, and to provide personalized treatments — an area that is still developing, with ongoing research.
In drug development, biomarkers can be used to measure the effects of the drug being trialed on the people in the clinical trials. This can include looking at the effects on their liver, kidneys, heart, and digestive system.
Currently, potential new drugs only have around a 1 in 10 chance of being approved for use by the FDA after the human stage of trials. This includes those that have passed the earlier stages, including animal studies. This is in part due to current biomarkers not always accurately predicting whether the treatment will work or whether it will have unwanted side effects or toxicity.
If newer, more precise biomarkers were found to better predict the success of potential new drugs or other interventions, this would lower the cost of clinical trials, which would then lower the cost of new treatments and encourage innovation in medicine.
Cancer biomarkers (or tumor markers) can be used to tailor treatment based on the unique biomarkers of someone’s cancer. These can be different substances such as genes or proteins. Cancer biomarkers can also be known as genomic sequencing or profiling. In the case of oncology (cancer) biomarkers, it’s the cancer cells being tested rather than the person’s own genes.
As well as tailoring treatment, cancer biomarkers can be used to diagnose, monitor cancer treatment, and assess likely prognosis (prognostic biomarker). With some cancers, biomarkers can also show if someone is at high risk of developing a particular cancer (their susceptibility). Predictive biomarkers can give the likelihood that someone will respond to a particular treatment.
Biomarkers might not be useful for all cancers, but they are particularly useful in some types of cancer. These include blood cancers (including leukemias and lymphomas) and solid tumors. Solid tumors, abnormal masses of tissues without any cysts or liquid, make up 90% of cancers.
Certain types of cancer treatments such as targeted therapy and immunotherapy might only work if the cancer cells have undergone particular gene changes or contain certain proteins. Some of these characteristics can be tested using biomarkers.
There is a range of biomarkers used in cancer treatment, which differ for each type of cancer, such as:
These are just some of the biomarkers currently available, and cancer research into biomarkers and other areas is ongoing. The hope is that many more new biomarkers will be discovered and help improve early diagnosis and treatment success.
Personalized or precision medicine means using an assessment of a person’s or a disease's genes to offer a diagnosis and treatment tailored to them. This area of medicine is already being used in areas such as cancer treatment, and biomarkers contribute to this ongoing research.
A key factor in making this possible is the human genome project, which sequenced the whole human genome for the first time. A human genome is the DNA instructions found in each cell of the body, providing the information the body needs to grow and function.
Currently, a patient is typically prescribed medication for their condition based on the usual "first line,” not their individual and unique genetic makeup. Personalized medicine may make treatment more effective for every individual.
Here’s an example of being able to offer a personalized treatment plan with the help of biomarkers: There are certain enzymes found in the body that metabolize medications. Some people’s metabolizing enzymes work better or worse than average. This means that the medication may not work as well for them if it is metabolized (and leaves the body) too quickly, or it could cause unwanted side effects if it stays in the body too long.
There are biomarkers that can show if someone has a difference in these enzymes from the typical range. As genomic sequencing becomes quicker and cheaper, a simple blood, saliva, or cheek swab (pharmacogenetic) test could become more widely used in the future. This could show if certain medications would be a good choice for someone on the first go — rather than using trial and error with different medications until a good match is found.
Other areas where personalized medicine can be applied are diagnosis, disease monitoring, predicting treatment response, drug development and other clinical trials, and cancer treatment.
Biomarkers cover a huge range of measurements and tests. They are used to diagnose, treat, and monitor medical conditions. Biomarkers also have a role in research, including drug discovery, and are integral in cancer treatment.
As technology and research advances, the scope for future biomarkers is endless. Until then, you can take a proactive role in your health by keeping an eye on your biomarkers, in partnership with your healthcare practitioner. Which biomarkers you monitor will be a personal choice, likely guided by your general health and goals.
One such imaging biomarker you could consider is Ezra’s Full Body MRI Scan which can help give you insight into your health with early detection — the best defense against conditions like cancer. You can also assess your general cancer risk using a free calculator. Check out which biomarkers the CEO of Ezra, Emi Gal, is tracking.
