ABSTRACT
This chapter focuses on some of the critical challenges currently facing biomarkers and precision medicine. A biomarker and its assay is a complementary process: No good biomarker is without a good assay, and no useful assay is without a good biomarker. Despite all the potential benefits of using biomarkers to advance pharmaceutical research and development, discrepant results can pose a threat to development programs by triggering false go/no-go decisions or enrolling the wrong subjects in targeted therapy. Listing a biomarker as exploratory on a study protocol is usually automatically misunderstood by a study operational team as an “optional.” Pre-analytical errors can occur at any time between the test order and the analytical phase, and may affect sample integrity and its suitability for biomarker testing. Biomarker assays range from exploratory type of assays performed on a fit-for-purpose basis to rigorously validated assays when a biomarker is used as a surrogate end point or for patient selection or randomization.
