Detection of Predictive Biomarkers Using Liquid Biopsies

Liquid biopsies have emerged as tools to predict response to therapy in real time, detect genomic alterations, and monitor disease resistance and tumor evolution in peripheral blood. The most well-studied components of liquid biopsies include circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). These highly dynamic biomarkers reflect cellular and genetic information from multiple primary and metastatic sites and are detected after tumors undergo necrosis, apoptosis, or via active secretion mechanisms. CTCs have demonstrated considerable promise as prognostic tools, and early evidence suggests the potential for monitoring micrometastatic disease. ctDNA can serve as a quantitative measure of tumor burden, reflect minimal residual disease, and enable serial monitoring of genomic alterations. Advances in CTC isolation techniques and next-generation sequencing have dramatically improved the detection of these components in blood. Future studies will utilize these assays to understand genetic and functional characteristics of single tumor cells and to explore the potential for liquid biopsies for early cancer detection.