Biomarkers
A Biomarker is a diagnostic tool that is used
for the detection of various medical states in a patient. It can be any
measurement that reflects an interaction between a biological system and a
potential hazard that can be chemical, physical, or biological. The response
produced may be functional and physiological, biochemical at the cellular
level, or molecular interaction.
Biomarkers are considered to be surrogate
endpoints when they are used as outcomes in clinical trials, that is, they act
as substitutes for clinically meaningful endpoints. Biomarkers have also been
approved by the U.S Food and Drug Administration (FDA) regulation for use as
surrogate endpoints in the treatment development process.
Biomarkers can provide researchers interim
evidence about the safety and efficacy of treatments while more definitive
clinical data is collected. In some cases, it may be preferable to use
established biomarkers as surrogate endpoints to reduce the risk of harm to
subjects.
Biomarkers play a critical role in improving
the drug development process within the larger biomedical research enterprise.
Understanding the connections between measurable biological processes and
clinical outcomes can lead to the expansion of our arsenal for treatments for
diseases, and for deepening our knowledge of normal and healthy physiology.
Types of Biomarkers
Biomarkers are classified into various
categories such as characteristics, their applications, genetics, and molecular
biology methods, though they can be dual in nature or roles and befitting in
diverse classifications. As per characteristics, they can be of two basic
types: (1) imaging biomarkers and (2) non-imaging biomarkers.
Imaging Biomarkers
Imaging biomarkers are applied in identifying
or visualizing a lesion or a disease as in computed tomography, positron
emission tomography, or magnetic resonance imaging.
Non- Imaging Biomarkers
Non-imaging biomarkers are biochemical having
biophysical properties thus they can be measured in biological samples. They
include cellular structures or biophysical components, such as nucleic
acid-based biomarkers including gene mutations or polymorphisms and
quantitative gene expression analysis, peptides, proteins, lipids metabolites,
and other small molecules.
On the Basis of Methodology
According to genetics and molecular biology
methods, biomarkers can be categorized into three types, i.e.,
(1) Type 0, (2)
Type 1, and (3) Type 2.
Type 0 are natural history biomarker that helps in measuring the natural history of a disease and
correlate over time with known clinical indicators.
Type 1 are drug activity
biomarkers that indicate the effect of drug intervention.
Type 2 are the surrogate markers
and serve as a substitute for a clinical outcome of a disease. Type 2 also
helps to predict the effect of a therapeutic intervention.
Examples
Some examples of biomarkers are Oxidative
Stress, Malondialdehyde (MDA), Isoprostanes, Enzymatic Anti-oxidants, Blood
Urates, Alpha-Amylase, Chromogranin A (CgA), MicroRNAs (miRNAs), Heat Shock
Proteins (HSPs), Acute Phase Proteins, etc.
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