A biomarker is an indicator that can be quantified to show whether a biological process is pathogenic, normal, or responding to an intervention or exposure. Regarding the basic definitions and concepts involved in their application in clinical practice and research, there is a great deal of misunderstanding. Therefore in the spring of 2015 at a joint leadership conference of the National Institutes of Health (NIH) and the U.S. Food and Drug Administration (FDA), a collaborative task force was established with the goal of creating shared definitions and disseminating to the general public via an online document known as "Biomarkers, EndpointS, and other Tools" (BEST), which is updated on a regular basis. The idea behind BEST is to increase collective capacity to match a biomarker with its appropriate use in order to be able to develop diagnostic and therapeutic technologies and strategies more quickly, efficiently, and precisely. This will also help with the creation and application of public health policies. [1]
When employed as endpoints in clinical trials, biomarkers and COAs acquire added complexity and a commensurate requirement for scientific rigor. An endpoint is a well-defined variable that is meant to represent a desired result that is statistically evaluated in order to answer a specific research question. Biomarkers can be obtained from molecular, histologic, radiographic, or physiological features and includes therapeutic actions. It is not the same as objective measurements of an individual's survival, feelings, or functioning—a type of measurement called a clinical outcome assessment (COA). A contextual linkage between a biomarker and its intended usage is provided by summarizing the biological, physiological, or pathological mechanism for the biomarker's association with the disease or condition of interest. This is referred as biological plausibility. This data aids in defining the ways in which different biomarkers may interact for a shared purpose (e.g., common biochemical pathways leading to a common biologic or clinical phenotype). Name, unique identification, acronym, source, kind, biological plausibility, and a specified testing method are used to identify a biomarker. For instance, it has been noted that the presence of drug-induced acute tubular kidney injury increases when a molecular biomarker called Kidney Injury Molecule 1, or KIM-1, is detected in urine (pg/mL) using ELISA testing. KIM-1 biomarker falls under predictive biomarkers since it forecasts the outcome of exposure to a medicinal medication. [2]
Similarly, based on their potential uses, biomarkers can be classified into several kinds. A diagnostic biomarker finds or validates the existence of a condition or disease of interest, or it pinpoints a person who has a certain disease subtype. Tumor markers that are examined by immunophenotyping and immunohistochemistry to aid in the diagnosis of cancer and the differentiation of various cancer types are the most commonly used diagnostic markers. For instance, blood and/or tumor analysis is used to identify BRCA1 and BRCA2 gene mutations for cancer types, such as breast, ovarian, pancreatic, and prostate cancers. This analysis aids in choosing the best course of treatment.[3]
A biomarker is a monitoring biomarker if it can be evaluated repeatedly to determine the state of a disease or medical condition, look for signs of exposure to a biological agent or medical product in the environment, or analyze the impact of a biological agent or medical product.HIV-RNA, for instance, can be utilized as a monitoring biomarker to assess and direct antiretroviral therapy (ART) or In drug addiction prevention and treatment trials, blood concentrations of addictive drugs can be employed as monitoring biomarkers to assess compliance and sobriety. Prostate-specific antigen (PSA) or cancer antigen 125 (CA 125) can be utilized as monitoring biomarkers to determine the disease burden or status in patients with prostate or ovarian cancer, respectively. [4]
Pharmacodynamic/surrogate end-point biomarkers are those whose levels alter in response to exposure to pharmaceuticals or environmental agents. These biomarkers are incredibly helpful for early treatment development as ...
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