1. Introduction
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Biomarkers are indicators that measure normal processes or disease processes in the body. This might include an individual’s response to a medicine.
For example body temperature is measured to indicate a fever. The concept of biomarkers is not new. Some examples of biomarkers are:
- Biological substances (‘biochemicals’), such as enzymes or hormones - these may be found in the blood or in tissue samples (biopsies).
- Gene changes.
- Images from Magnetic Resonance Imaging (MRI).
Biomarkers can be any measurements that can reliably be made and that can tell us something about a person’s health or disease state. This might include the persons’ response to a therapy. It has to be considered that levels of specificity and sensitivity of a given marker may vary widely.
- Specificity – this is the proportion of ‘negatives’ which are correctly identified.
- Sensitivity – this is the proportion of ‘positives’ which are correctly identified.
In other words, the accuracy of biomarkers varies and therefore not all markers are suitable for drug development. Even more challenging is the use of biomarkers for regulatory purposes (see below).
The main focus of this topic is molecular biomarkers in medicines development. There is a special emphasis on recent genomic technologies, i.e. those that look at genes.