Biomarkers used for medicine, or precision medicine, are a part of a relatively new clinical toolset. They are categorized in 3 primary ways according to their clinical applications. They are classified as molecular biomarkers, cellular biomarkers or imaging biomarkers. All 3 types of biomarkers have a clinical role in narrowing or guiding treatment decisions and follow a sub-categorization of being either

• predictive,
• prognostic, or
• diagnostic.

Predictive

Predictive molecular, cellular, or imaging biomarkers that pass validation can serve as a method of predicting clinical outcomes. Predictive biomarkers are used to help optimize ideal treatments, and often indicate the likelihood of benefiting from a specific therapy. For example, molecular biomarkers situated at the interface of pathology-specific molecular process architecture and drug mechanism of action promise capturing aspects allowing assessment of an individual treatment response. This offers a dual approach to both seeing trends in retrospective studies and using biomarkers to predict outcomes. For example, in metastatic colorectal cancer predictive biomarkers can serve as a way of evaluating and improving patient survival rates and in the individual case by case scenario, they can serve as a way of sparing patients from needless toxicity that arises from cancer treatment plans

Common examples of predictive biomarkers are genes such as ER, PR and HER2/neu in breast cancer, BCR-ABL fusion protein in chronic myeloid leukaemia, c-KIT mutations in GIST tumours and EGFR1 mutations in NSCLC

Diagnostic

Diagnostic biomarkers that meet a burden of proof can serve a role in narrowing down diagnosis. This can lead to diagnosis that are significantly more specific to individual patients.

After a heart attack a number of different cardiac biomarkers can be measured to determine exactly when an attack occurred and how severe it was a biomarker can be a traceable substance that is introduced into an organism as a means to examine organ function or other aspects of health.

For example, rubidium chloride is used as a radioactive isotope to evaluate perfusion of heart muscle.

Prognostic

A prognostic biomarker provides information about the patients overall outcome, regardless of therapy

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Rebecca Pearson
Editorial Manager