Role of Biomarkers in Personalized Medicine

Abstract

A biological marker (biomarker) is simply a molecule that indicates an alteration in physiology from the normal. For example, any specific molecular alteration of a cancer cell either on DNA, RNA, or protein level can be referred to as a molecular marker. A biomarker is defined as a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. The topic of biomarkers has been discussed in a special report on this topic (Jain 2009f). The expression of a distinct gene can enable its identification in a tissue with none of the surrounding cells expressing the specific marker. Relation of biomarkers to other technologies and healthcare is shown in Fig. 3.1. Applications of biomarkers relevant to personalized medicine are: The biomarker would specifically and sensitively reflect a disease state and could be used for diagnosis, for predicting response to drug, and for disease monitoring during and following therapy. Biomarkers can be used as drug targets in drug development. Biomarkers might serve to integrate diagnostics and therapeutics.