Development and Validation of Molecular Assays for Liquid Biopsy Applications

CTC analysis has already been shown to have an important impact on the prognosis, treatment selection, and monitoring of cancer patients. In this chapter, we are focusing on the development and validation of molecular assays for CTC analysis and present the principles of the main technologies used for CTC enrichment, isolation, and detection. We focus on the main principles and applications of molecular assays used for CTC molecular characterization and describe the main technologies used for single-cell analysis of CTCs since it provides unique opportunities and challenges. We further present studies on the applications of molecular assays for CTC analysis in the clinical setting focusing on breast, prostate, and non-small cell lung cancer. Finally, we discuss the urgent need for standardization and quality control throughout all the steps of CTC analysis, from preanalytical sample handling till the final results on the molecular biomarkers detected in CTCs. Development of standards for quality control of CTC analysis and interlaboratory ring studies are urgently needed. Toward this a joint and well-coordinated effort of researchers, clinicians, and technology providers is highly needed. The establishment of international organizations focusing on the standardization of liquid biopsy analysis guarantees that we are in the correct direction to achieve this goal.