“Omics” Enabled Technology: BriefIntroduction to Biomarkers
Biomarkers are clinically relevant substances used as indicators of a biologic state (Shaffer, 2006; DePrimo, 2007). Detection or concentration change of abiomarker may indicate a particular disease state (e.g., the presence of an antibody may indicate an infection), physiology, or toxicity. A change in expression or state of a protein biomarker may correlate with the risk or progression of a disease, with the susceptibility of the disease to a given treatment, or the drug’s safety profile. Implemented in the form of a medical device, a measured biomarker becomes an in vitro diagnostic tool (Williams et al., 2006). While it is well beyond this chapter to provide a detailed discussion of biomar-kers, it is important to note that omics technologies including omics-enabled technologies such as micro-arrays are being developed as clinical measuring devices for biomarkers. Biomarkers enable character-ization of patient population undergoing clinical trials or drug therapy, and accelerate drug development. Modern drug discovery often simultaneously in-volves biomarker discovery and diagnostic develop-ment (Frank and Hargreaves, 2003; Pien et al., 2005).
A “Theranostic” is a rapid diagnostic, possibly a microarray, measuring a clinically significant biomar-ker, which may identify patients most likely to benefit or be harmed by a new medication (Warner, 2004). Bundled with a new drug (and likely developed in parallel with that drug), the theranostic’s diagnosis of the requisite biomarker (e.g., the over-expression of the HER2 gene product in certain breast cancer patients) influences the physician’s therapeutic deci-sions [i.e., prescribing the drug trastuzumab (Herceptin) for HER2 receptor positive breast cancer patients]. Thus, the diagnostic and the therapy are distinctly coupled ¼ theranostic. The theranostic predicts clinical success of the drug. This example used to introduce the concept of a theranostic, is possibly the best example of personalized medicine, achieving the best medical outcomes by choosing treatments that work well with a person’s genomic profile, or with certain characteristics.