摘要：Genotyping epidermal growth factor receptor (
EGFR) is an essential process to indicate lung adenocarcinoma patients for the most appropriate treatment. Liquid biopsy using circulating tumor DNA (ctDNA) potentially complements the use of tumor tissue biopsy for identifying genotype-specific mutations in cancer cells. We assessed the performance of a high-fidelity sequencing method that uses molecular barcodes called the nonoverlapping integrated read sequencing system (NOIR-SS) for detecting
EGFR L858R-mutated alleles in 33 advanced or recurrent patients with L858R mutation-positive lung adenocarcinoma revealed by matched tissue biopsy. We compared NOIR-SS with site-specific droplet digital PCR (ddPCR), which was taken as the reference, in terms of sensitivity and ability to quantify L858R variant allele fractions (VAFs). NOIR-SS and ddPCR had sensitivities of 87.9% (29/33) and 78.8% (26/33) for detecting L858R alleles, respectively. The VAFs measured by each assay were strongly correlated. Notably, one specimen was positive with a VAF of 30.12% for NOIR-SS but marginally positive with that of 0.05% for ddPCR because of a previously poorly recognized mechanism: two-base substitution-induced L858R (c.2573_2574delinsGA). These results indicate that NOIR-SS is a useful method for detecting ctDNA, potentially overcoming a limitation of ddPCR which highly depends on the binding ability of primers to specific targeting sequences.
