Circulating tumour cell RNA characterisation from colorectal cancer patient blood after inertial microfluidic enrichment

The detection and molecular analysis of circulating tumour cells (CTCs) potentially provides a significant insight to the characterisation of disease, stage of progression and therapeutic options for cancer patients. Following on from the protocol by Warkiani et al. 2016, which describes a method of enriching CTCs from cancer patient blood with inertial microfluidics, we describe a method to measure the CTC RNA expression in the enriched fraction using droplet digital PCR and compare transcript detection with and without RNA pre-amplification. • Inertial microfluidics combined with droplet digital PCR is advantageous as it allows for CTC enrichment and subsequent RNA analysis from patient blood. This allows for patient tumour analysis with increased sensitivity and precision compared to quantitative Real Time PCR and enables the direct quantification of nucleic acids without the need for tumour biopsy. • This method demonstrates an efficient approach providing important insights into the analysis of colorectal cancer patients’ CTCs using a specific gene subset or biomarkers, an approach that may be tailored to tumour type or expanded to larger panels.