7 Types of Biomarkers

Author: Laura Pozzi Ph.D., Scientific Content Manager, Atlas Antibodies AB, Sweden

A biomarker is a protein, a chemical, its metabolite, or the product of an interaction between a chemical and some target molecule or cell that is measured in the human body. Using modern analytical technology it is now possible to measure a large number of biomarkers present in the human organism (in blood, tissues, urine, hair, etc.). Biomonitoring techniques are becoming, in fact, common tools for decision-makers in the health and environmental fields. There are 7 distinct categories of biomarkers. Curios? Read on!

1. Susceptibility/Risk Biomarkers

The first category is susceptibility/risk biomarkers. These biomarkers can predict an individual's likelihood of developing a particular disease or medical condition in the future. For example, a genetic test that identifies a predisposition to breast cancer can be considered a susceptibility/risk biomarker. 

Mutations in the BRCA1 and BRCA2 genes, for example, are associated with an increased risk of developing breast and ovarian cancer. Testing for these mutations can identify individuals who may benefit from increased surveillance, risk-reducing surgeries, or targeted therapies.

2. Diagnostic Biomarkers

The second category is diagnostic biomarkers, which are used to detect or confirm the presence of a disease or medical condition. Diagnostic biomarkers can also provide information about the characteristics of a disease. Here are some examples of disease biomarkers:

Prostate-specific antigen (PSA): PSA is a biomarker used in the diagnosis (and monitoring) of prostate cancer. High levels of PSA in the blood can indicate the presence of prostate cancer, while changes in PSA levels over time can be used to monitor disease progression or response to treatment.

C-reactive protein (CRP): CRP is a biomarker used to assess inflammation in the body. Elevated levels of CRP in the blood can be associated with various inflammatory diseases such as rheumatoid arthritis, lupus, and cardiovascular diseases.

3. Prognostic Biomarkers

The third category is prognostic biomarkers, which can predict the likelihood of a clinical event, such as disease recurrence or progression, in patients who already have the disease. Examples of prognostic biomarkers include:

Ki-67: This protein is a marker of cell proliferation and is commonly used as a prognostic biomarker in breast cancer, prostate cancer, and other cancers. High levels of Ki-67 are associated with more aggressive tumors and worse outcomes.

BRAF: is a gene that is frequently mutated in melanoma and other cancers. Testing for BRAF mutations can help predict the response to targeted therapies such as BRAF inhibitors. Patients with BRAF mutations may have a better response to these drugs and may benefit from earlier treatment with them.

4. Monitoring Biomarkers

The fourth category is monitoring biomarkers, which are measured repeatedly to assess the status of a disease or medical condition or to quantify exposure to a medical product or environmental agent. Monitoring biomarkers play an important role in disease management and treatment.

Examples of monitoring biomarkers include:
Hemoglobin A1c (HbA1c): HbA1c is a biomarker used to diagnose and monitor diabetes. HbA1c levels in the blood reflect the average blood glucose levels over the past three months and can be used to monitor disease progression or the effectiveness of diabetes treatments.

Brain natriuretic peptide (BNP): BNP is a biomarker used to monitor heart failure. BNP is released by the heart in response to increased pressure and volume, which are common in heart failure. Monitoring BNP levels can help assess the severity of heart failure and guide treatment decisions.

5. Predictive Biomarkers

The fifth category is predictive biomarkers, which are used to identify individuals who are more likely than others to experience a favorable or unfavorable effect from exposure to a medical product or environmental agent. Predictive biomarkers are linked to treatment decisions. An example of a predictive biomarker is the presence of the HER2 protein, which indicates that certain breast cancer patients may respond well to a specific targeted therapy.

HER2/neu status in breast cancer: HER2/neu is a protein that is overexpressed in some types of breast cancer. Testing for HER2/neu status can help predict the response to targeted therapies such as trastuzumab (Herceptin). Patients with HER2/neu-positive breast cancer may benefit from earlier treatment with trastuzumab, which can improve outcomes.

EGFR mutation status in non-small cell lung cancer: EGFR is a gene that is frequently mutated in non-small cell lung cancer (NSCLC). Testing for EGFR mutation status can help predict the response to targeted therapies such as gefitinib (Iressa) and erlotinib (Tarceva). Patients with EGFR mutations may have a better response to these drugs and may benefit from earlier treatment with them.

6. Pharmacodynamic/Response Biomarkers

The sixth category is pharmacodynamic/response biomarkers, which show that a biological response has occurred in an individual who has been exposed to a medical product or environmental agent. These biomarkers are often used in clinical trials to evaluate the effectiveness of new treatments.

An example of a pharmacodynamic/response biomarker is the measurement of tumor size in response to chemotherapy for cancer treatment. Other examples are:
LDL cholesterol level in response to statins: Statins are a class of drugs used to lower cholesterol levels in patients with high cholesterol. The pharmacodynamic/response biomarker in this case is the reduction in LDL (low-density lipoprotein) cholesterol levels that occurs in response to treatment with statins.

Blood pressure in response to antihypertensive drugs: Antihypertensive drugs are used to lower blood pressure in patients with hypertension. The pharmacodynamic/response biomarker in this case is the reduction in blood pressure that occurs in response to treatment with these drugs.

7. Safety Biomarkers

The seventh and final category is safety biomarkers, which indicate the likelihood, presence, or extent of toxicity as an adverse effect of exposure to a medical product or environmental agent. For example:

Liver function tests (LFTs): LFTs are a group of blood tests that measure the levels of enzymes and proteins produced by the liver. LFTs can be used as safety biomarkers to monitor liver function and detect drug-induced liver injury (DILI), a potential adverse effect of some medications.

Creatinine clearance: Creatinine clearance is a measure of kidney function that can be used as a safety biomarker to monitor the potential nephrotoxicity (toxicity to the kidneys) of certain medications, such as antibiotics or chemotherapy drugs. 

 

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