What is a Biomarker?
A biomarker, or biological marker, is a measurable indicator of a biological state or condition. It is typically used in medical research and clinical practice to assess normal biological processes, pathogenic processes, or responses to therapeutic interventions.
Biomarkers can be molecules found in blood, other body fluids, tissues, or measured directly in the body. They provide valuable information about the current state of health or disease and can help predict future health outcomes.
Types of Biomarkers
Biomarkers can be categorized into several types based on their applications and the information they provide about the physiological or pathological processes in the body. Some common types of biomarkers include:
1.Diagnostic Biomarkers
These biomarkers are used to detect or confirm the presence of a disease or condition. They play a crucial role in early diagnosis, allowing for timely intervention and treatment. Examples include blood glucose levels for diabetes and genetic mutations such as BRCA1 and BRCA2 for breast cancer.
2.Prognostic Biomarkers
Prognostic biomarkers provide information about the likely course of a disease, including its progression and overall outcome. They help in assessing the severity of a condition and predicting patient survival. For instance, specific genetic mutations in cancer can indicate the aggressiveness of the tumor and guide treatment decisions.
3.Predictive Biomarkers
These biomarkers predict how well a patient will respond to a particular treatment or therapeutic intervention. They are essential for personalized medicine, allowing healthcare providers to tailor treatments based on individual patient characteristics. An example is the presence of EGFR mutations in lung cancer, which can predict responsiveness to targeted therapies.
4.Pharmacodynamic Biomarkers
Pharmacodynamic biomarkers are used to monitor the biological response to a drug, helping to assess its efficacy and safety during clinical trials and in clinical practice. C-reactive protein (CRP) levels, for instance, can indicate the inflammatory response to a treatment for autoimmune diseases.
5.Safety Biomarkers
Safety biomarkers are used to detect and monitor potential adverse effects of drugs and treatments. They help in identifying toxicities early and adjusting dosages or therapies to minimize harm. Examples include liver enzymes and renal function tests that monitor the impact of medications on the liver and kidneys.
Examples:
- Blood glucose (molecular)
- Grading and staging of cancers (histologic)
- Bone mineral density (radiographic)
- Blood pressure (physiologic)
Applications of Biomarkers
Biomarkers have many useful applications in health care, including disease prevention and detection, determination of individual disease risk, and disease monitoring. They can also be used to measure the safety or toxicity of a therapeutic regimen or certain environmental exposures.
| Applications of Biomarkers | ||
| Biomarker Application | Biomarker Examples | Disease state |
| Screening | Prostate specific antigen (PSA) | Prostate cancer |
| Faecal occult blood test | Colon cancer | |
| Susceptibility/Risk | Breast cancer genes 1 and 2 mutations (BRCA 1/2) | Predisposition to developing breast cancer |
| Factor V Leiden | Predisposition to developing thromboembolism | |
| Apolipoprotein C | Predisposition to developing Alzheimer’s disease | |
| Human papillomavirus (HPV) | Predisposition to developing cervical cancer | |
| Diagnostic | Troponin-I | Coronary ischemia |
| Sweat chloride | Cystic fibrosis | |
| Ejection fraction (EF) | Cardiomyopathy/congestive heart failure | |
| Glomerular filtration rate (GFR) | Chronic kidney disease | |
| Prognostic | BRCA 1/2 | Likelihood of second cancer in women with breast cancer |
| Chromosome 17p deletions and TP53 mutations | Likelihood of death in patients with chronic lymphocytic leukaemia | |
| Monitoring | Serum low-density lipoprotein (LDL) | Response to lipid lowering drugs |
| International Normalized Ratio (INR) | Efficacy of anticoagulant therapy | |
| Cancer antigen 125 (CA-125) | Ovarian cancer disease status or burden | |
| Haemoglobin A1C | Response to antihyperglycemic agents or lifestyle changes | |
| Viral load | Response to antiretroviral treatment for human immunodeficiency virus (HIV) | |
| Safety | Hepatic aminotransferases and Bilirubin | Hepatotoxicity |
| Serum creatinine | Nephrotoxicity | |
| Serum potassium | Hypo or Hyperkalaemia while taking diuretics, angiotensin converting enzyme inhibitors | |
| Corrected QT interval (QTc) | Assess potential for drugs to induce ventricular tachycardia | |
| Serum Bisphenol A (BPA) | Measured in pregnant women; predicts adverse birth outcomes such as preterm birth; has informed/improved public safety through BPA-free plastics. | |
Significance of Biomarkers
Biomarkers play a crucial role in various aspects of medical research and clinical practice, including:
- Early Detection and Diagnosis: Biomarkers enable the early detection and accurate diagnosis of diseases, improving the chances of successful treatment and better patient outcomes.
- Personalized Medicine: By identifying specific biomarkers, healthcare providers can tailor treatments to individual patients, enhancing the effectiveness of therapies and reducing the risk of side effects.
- Drug Development: Biomarkers are essential in the development of new drugs, helping to identify potential therapeutic targets, monitor drug efficacy, and assess safety during clinical trials.
- Disease Monitoring: Biomarkers allow for the continuous monitoring of disease progression and response to treatment, enabling timely adjustments to therapy and improving disease management.
Examples of Common Biomarkers
- Genetic Mutations: Such as BRCA1 and BRCA2 for breast and ovarian cancers, and EGFR mutations for lung cancer.
- Blood Glucose: Used to monitor and diagnose diabetes.
- Cholesterol Levels: Indicators of cardiovascular health and risk of heart disease.
- C-reactive Protein (CRP): A marker of inflammation that can indicate infection or chronic inflammatory conditions.
- Hemoglobin A1c (HbA1c): Reflects average blood glucose levels over the past three months, used in diabetes management.
Why Are Biomarkers Important?
They’re important because they can give your doctor a lot of information about different parts of your health. Your doctor can measure your biomarkers to tell how normal or abnormal a system in your body is.
They can tell doctors different things about your body. For example, in the case of cancer, biomarkers include proteins, genes, or other substances in your body. These can:
1.Help find some early-stage cancers.
Your doctor can use your biomarkers to catch things in your body that are not normal. Early detection of cancer is very important.
2.Predict how serious a cancer might be.
Biomarkers can also help your doctor understand how far along a cancer is in your body.
3.Look at how you might respond to a cancer treatment.
This can help your care team find a proper treatment for you. Biomarkers can also tell how well a treatment works for you over a period of time. Because of this, experts are looking at how biomarker testing can replace image-based tests like CT scans and MRIs.
4.Monitor how likely it is for cancer to come back.
In some cases, if you have a tumour, doctors will take cells from that tumour and look at biomarkers. They’ll give a recurrence risk score. This will tell you how likely it is that your cancer could come back.
Biomarker testing for cancer has many names, such as:
- Companion diagnostic test
- Genomic testing
- Genomic profiling
- Genome sequencing
- Molecular testing
- Molecular profiling
- Next-generation sequencing
- Somatic testing
- Tumor testing
- Tumor genetic testing
- Tumor marker testing
- Tumor subtyping
Biomarkers can also be very helpful to experts creating new medications for different conditions. During clinical trials, doctors can use biomarkers to measure how new drugs affect people. They’ll look into any changes a medication has on different biomarkers in your body.
REFERENCES
- Amur, S. (n.d.) Biomarker terminology: Speaking the same language. U.S. Food and Drug Administration online educational materials retrieved from https://www.fda.gov/files/BIOMARKER-TERMINOLOGY–SPEAKING-THE-SAME-LANGUAGE.pdf
- Califf RM. Biomarker definitions and their applications. Exp Biol Med (Maywood). 2018 Feb;243(3):213-221. doi: 10.1177/1535370217750088. PMID: 29405771; PMCID: PMC5813875.
- BEST (Biomarkers, EndpointS, and other Tools) Resource. May 2, 2018. FDA-NIH Biomarker Working Group. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK326791/pdf/Bookshelf_NBK326791.pdf
- Lou, E., Johnson M., Sima, C., Gonzalez-Espinoza, R., Fleisher, M., Kris, M., & Azzoli, C., (2014). Serum biomarkers for assessing histology and outcomes in patients with metastatic lung cancer. Cancer Biomarkers, 14(4). doi: 10.3233/CBM-140399
- Raby, B. (2023, September 6). Personalized Medicine. UpToDate. https://www.uptodate.com/contents/personalized-medicine
- Strimbu K, Tavel JA. What are biomarkers? Curr Opin HIV AIDS. 2010 Nov;5(6):463-6. doi: 10.1097/COH.0b013e32833ed177. PMID: 20978388; PMCID: PMC3078627.
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