Biological marker

A characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.
Biomarkers may have the greatest value in early efficacy and safety evaluations such as in vitro studies in tissue samples, in vivo studies in animal models, and early-phase clinical trials to establish “proof of concept.”
Biomarkers have many other valuable applications in disease detection and monitoring of health status. These applications include the following:
- use as a diagnostic tool for the identification of those patients with a disease or abnormal condition (e.g., elevated blood glucose concentration for the diagnosis of diabetes mellitus)
- use as a tool for staging of disease (e.g., measurements of carcinoembryonic antigen-125 for various cancers) or classification of the extent of disease (e.g., prostate-specific antigen concentration in blood used to reflect extent of tumour growth and metastasis)
- use as an indicator of disease prognosis (e.g., anatomic measurement of tumour shrinkage of certain cancers)
- use for prediction and monitoring of clinical response to an intervention (e.g., blood cholesterol concentrations for determination of the risk of heart disease).
Synonym: Biomarker