Cross-Platform Comparison of Four Leading Technologies for Detecting <i>EGFR</i> Mutations in Circulating Tumor DNA from Non-Small Cell Lung Carcinoma Patient Plasma

Abstract

Analysis of circulating tumor DNA (ctDNA) is emerging as a powerful tool for guiding targeted therapy and monitoring tumor evolution in patients with non-small cell lung cancer (NSCLC), especially when representative tissue biopsies are not available. Here, we have compared the ability of four leading technology platforms to detect epidermal growth factor receptor (<i>EGFR)</i> mutations (L858R, exon 19 deletion, T790M and G719X) in ctDNA from NSCLC patients. Two amplification refractory mutation systems (cobas-ARMS and ADx-ARMS), a droplet digital polymerase chain reaction (ddPCR) and a next-generation sequencing (Firefly NGS) platform were included in the comparison. Fifteen <i>EGFR</i> mutations across twenty NSCLC patients were identified. Firefly NGS, cobas-ARMS and ddPCR all displayed superior sensitivity while ADx-ARMS was better suited for the qualitative detection of <i>EGFR</i> mutations with allele frequency higher than 1% in plasma and tissue samples. We observed high coincidence between the plasma and tissue <i>EGFR</i> mutational profiles for three driver mutations (L858R, exon 19 deletion and G719X) that are known targets of first generation EGFR-TKI therapies among patients who relapsed. Discrepancies between tissue and plasma <i>EGFR</i> mutational profiles were mainly attributable to spatial and temporal tumor heterogeneity, mutation inhibition due to therapy response and drug resistance (T790M). This study illustrates the challenges associated with selection of a technology platform for <i>EGFR</i> ctDNA analysis in the context of treatment evaluation and drug resistance detection.