Classification and application of different biomarkers
Biomarkers are any substance of biological origin, which is used as an indicator for certain medical conditions. Atkinson et al., (2001) defined the biomarker as:
“A characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention”.
The assessment stated that a factual biomarker definition includes almost any measurement imitating an interaction between a potential hazard (biological, chemical or physical) and a biological system. The response of biomarkers measure functional and cellular level physiological, biochemical or a molecular interaction.
Examples of biomarkers range from a simple molecule to a complex substance; from basics like blood pressure and pulse to a more composite lab tests of various body parts including blood and tissues. However, they are merely a medical sign like any other. It is one of the most objective and measurable clinical signs a modern laboratory can have.
Application of biomarkers
- Identification and prognosis of diseases
- target discoveries and its validation
- preclinical studies
- lead discoveries & optimization
- in clinical trials for its role related to a particular medical condition
- disease curing and identification such as cancer, osteoarthritis, pulmonary diseases, sepsis, systemic sclerosis etc.
One of the most important application is its role in the target’s discovery and validation. It helps to identify the target and decide the therapy (Chau et al., 2008). In preclinical studies, biomarkers are used for the development and validation of novel disease models. They are also used for assessing the toxicity and safety of a drug.
Moreover, during clinical trials it is used to assess the effectiveness of a drug. They help medical practitioners select an ideal drug combination for better therapeutic efficiency against a particular disease. It is also used for the better optimization of the doses and in scheduling. Most importantly, a biomarker is deployed for the development of novel surrogate endpoints which is of significant clinical importance (Arrowsmith and Miller, 2013).
Classification of biological markers
Biological markers are classified on the basis of various parameters, which include their characteristics, such as:
- biomarkers of imaging like magnetic resonance imaging (MRI),
- positron emission tomography (PET),
- computed tomography (CT) or the molecular biomarkers which refers to the non-imaging biomarkers.
Furthermore, molecular biomarkers have biophysical properties that enables them to be quantified in biological samples. The classification is depicted in the figure below.
Recent trends and discoveries
They have great potential to influence the rate of success of clinical trials, identifying novel drug targets and developing diagnostic tools for detection of disease in early stages. The increasing potential application of biomarkers reflects on the literature published during recent times. Over the last two decade the number of scientific publications has increased significantly.
The US FDA (Food & Drug Administration) classifies them into four different types;
The table below shows some of the current biomarkers submitted to FDA for approval along with its year of submission (FDA, 2017).
Proposed Utility and Qualification stage (QS)
|Total hip bone mineral density (BMD)||2016||Response||Efficacy response,
QS: consultation and advice
|Serum glutamate dehydrogenase (GLDH)||2016||Safety||Safety assessment,
QS: consultation and advice
|Plasma fibrinogen in COPD||2012||Prognostic||Patient selection,
Table 1: List of current biomarkers at FDA for approval
The current research areas of biomarkers have widened to include toxicology, drug discovery, clinical markers of therapeutic index and efficacy, diagnostic test development and environmental pollutants exposure.
Protein biomarkers help development and advancement in the field of proteomic techniques that lead to the detection of an extensive range of biomarkers. They also help in identification of particular modifications in post-translational protein which is quite evident in the state of disease (Vanarsa and Mohan, 2010). However, apart from proteomics new dimensions to the field of biomarkers are pharmacogenomics, bioinformatics, microbiome and others.
Biomarkers, accompanied by innovative treatment technology have the prospective to transform the way the medicine practiced. However, the best is yet to come as extensive research is being going in the field of biomarkers.
- Arrowsmith, J. and Miller, P. (2013) ‘Trial Watch: Phase II and Phase III attrition rates 2011-2012’, Nature Reviews Drug Discovery, p. 569. doi: 10.1038/nrd4090.
- Atala, A. and Allickson, J. G. (2014) Translational Regenerative Medicine, Translational Regenerative Medicine. doi: 10.1016/C2012-0-06956-6.
- Atkinson, A. J. et al. (2001) ‘Biomarkers and surrogate endpoints: Preferred definitions and conceptual framework’, Clinical Pharmacology and Therapeutics, pp. 89–95. doi: 10.1067/mcp.2001.113989.
- Chau, C. H. et al. (2008) ‘Validation of analytic methods for biomarkers used in drug development’, Clinical Cancer Research, pp. 5967–5976. doi: 10.1158/1078-0432.CCR-07-4535.
- FDA (2017) Current Biomarker Qualification Submissions. Available at: https://www.fda.gov/Drugs/DevelopmentApprovalProcess/DrugDevelopmentToolsQualificationProgram/BiomarkerQualificationProgram/ucm535881.htm (Accessed: 21 March 2018).
- Vanarsa, K. and Mohan, C. (2010) ‘Proteomics in rheumatology: the dawn of a new era.’, F1000 medicine reports, 2(December), p. 87. doi: 10.3410/M2-87.