Biomarkers are becoming an increasingly important component of biomedicine, particularly in the field of cancer detection and drug development. But what exactly is a biomarker, and how does it help scientists and physicians screen for and treat different diseases? Read on for answers to some of the most frequently asked questions about this key biomedical topic.
What is a biomarker?
A biomarker is defined by the US Food and Drug Administration as a characteristic that, when objectively measured and evaluated, can serve as an indicator of standard or typical biologic or pathogenic processes, or an indicator of pharmacologic responses to a treatment or therapeutic intervention. In other words, biomarkers are distinct biological indicators that give us critical, measureable information about a person’s biological or physiological state, and can help us make predictions about their future health. For example, some well-known, “everyday” biomarkers include things like your weight, blood pressure, and blood type. Each of these measurable characteristics are used regularly to provide important information about your health.
What are the qualities of an ideal biomarker?
While biomarkers can vary greatly as to their form and what role they fulfill, ideal biomarkers share a number of particular qualities. Specifically, they are both safe and easy to measure, meaning that a blood or urine sample, for example, is preferred over an internal organ biopsy, which is a more invasive procedure. Biomarkers are also cost-efficient and rapid in terms of follow-up—that is, they can provide results quickly, if not immediately, as well as inexpensively. Finally, they are modifiable with treatment, and they are consistent across ethnic and gender groups. In addition, the detection method for a reliable biomarker will be sensitive, specific, and highly reproducible among clinical laboratories, so that clinicians can be sure that biomarker detection is not affected by where the tests were performed.
What forms can biomarkers take?
Biomarkers can take a wide range of forms, from the simple to the highly complex. Biomarkers that are in common clinical use today include proteins or peptides; antibodies; cell types; metabolites; lipids, such as cholesterol; hormones; enzyme levels; physiological states like fever or blood pressure; and imaging studies of individual organs or organ systems. Furthermore, a biomarker can be an external substance introduced into the body to assess the functioning of internal organ systems. For example, when radioactive iodine is introduced into the body, it allows for the measurement of thyroid function.
How are biomarkers used?
The function and use of biomarkers can be broken down into three broad categories.
The first category contains those biomarkers that are used to give information on a person’s risk for a particular disease, or on the status of an existing disease. For example, prostate-specific antigen (PSA) has become a well-known biomarker used in prostate cancer screenings. PSA is a protein that is produced by cells in the prostate gland; elevated levels of PSA in the blood can indicate that a man is at risk for developing prostate cancer. PSA tests are also used to monitor the progression of prostate cancer in men who have already been diagnosed with the condition.
The second category encompasses biomarkers that are used to measure the effect of a drug, or another form of therapeutic intervention, on a particular biological process. It’s important to note that this use of biomarkers does not necessarily measure or provide information on whether a particular disease is being affected by the drug; it simply provides more details on how a drug is affecting or behaving within the body.
The third category, closely linked to the second, includes the use of biomarkers to measure a drug’s direct interaction with its target molecule or receptor. This allows clinicians to monitor a patient’s reaction to a particular drug, and helps them determine whether treatment is proving effective for the condition in question, and whether there are any adverse side effects or reactions. This use of biomarkers shows how valuable they could be to personalized medicine, in which treatments can be tailored to individuals to maximize their effectiveness and reduce the possibility of ineffective, or even harmful, therapeutic interventions. It can also play a key role in drug development by helping to discover new “druggable targets;” that is, new targets that medicines can act on in order to treat disease.
What does the future of biomarker research look like?
Many large-scale studies on biomarkers are currently underway, and one of the principal goals of this research is to allow us to move beyond looking at just one biomarker at a time. A single biomarker is not always conclusive because the same molecule or marker can be affected by different diseases. Instead, researchers are looking for ways to work with tens, hundreds, or even thousands of different biomarkers that correlate with disease state, and to use the pattern, or the full sum, of changes in such a group to gain a more detailed picture about a person’s underlying pathology.