Liquid biopsy is a useful tool during longitudinal monitoring of NSCLC patients but requires highly sensitive and reliable technologies for accurate detection of genomic alterations. Circulating tumor DNA (ctDNA) analysis has clinical utility in EGFR mutant NSCLC, while Circulating tumor cells (CTCs) consist a unique source of information at the cellular level. Digital PCR (dPCR) is a valuable tool for accurate and valid analysis of gene mutations in liquid biopsy analysis. The scope of the present study was to evaluate the presence and estimate mutation allele frequencies (MAFs) of EGFR mutations in plasma cfDNA and corresponding CTC-derived gDNA using Crystal Digital PCR™, in a group of EGFR mutant NSCLC patients under osimertinib therapy at two time points (before treatment initiation and at progression of disease).
• Crystal Digital PCR™ allowed us to track tumor evolution through the detection of low abundance mutations in cfDNA and CTCs predictive for the treatment outcomes of NSCLC patients under osimertinib.
• Crystal Digital PCR™ exhibited high concordance rates in correlation with the FDA-cleared cobas technology
• In some cases, Crystal Digital PCR™ was more sensitive in detecting the T790M mutation which is the key resistance mutation found during treatment with 1st and 2nd EGFR TKIs.
• The presence of EGFR mutations in paired CTC-derived gDNA revealed discrepancies between CTCs and tumor or cfDNA genotyping.
• Crystal Digital PCR™ combines the unique benefits of sensitivity and accuracy for the detection and quantification of MAFs of multiple EGFR mutations in plasma cfDNA and corresponding CTCs of NSCLC patients.