Cancer is a mixture of diseases characterised by complex genomic changes. For example, in melanoma, patients who carry specific genetic signatures respond better to certain drugs. The cancer genomes evolve in response to treatment and patients often developed drug resistance. Monitoring of these changes are crucial but current methods depended heavily on tumour biopsies which are often risky and complicated by spatial and temporal heterogeneity.
Non-invasive biomarkers like circulating tumour DNA (ctDNA) has shown promises for more comprehensive and real-time monitoring of cancer therapy. This presentation will summarise the recent development of state-of-the-art technologies for the analysis of ctDNA, including cost-effective targeted-sequencing methodology for de novo identified of somatic point mutations, and high-resolution whole-genome or whole-exome sequencing approaches for assessing structural rearrangement or copy number changes. Clinical cases will be presented to illustrate the potential clinical utility of ctDNA, including non-invasive molecular stratification in a targeted therapy setting, monitoring of tumour response, identification of acquired resistance and alternative actionable targets, using examples in breast cancer and lung cancer, to demonstrate the potential of plasma DNA analysis as a new paradigm for personalised therapies and stratfied medicine.