A novel, rapid point-of-care test for lung cancer patients to detect epidermal growth factor receptor gene mutations by using real-time droplet-PCR and fresh liquid cytology specimens.

ABSTRACT

Epidermal growth factor receptor gene (EGFR) mutations are associated with response to tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). We developed a novel, rapid EGFR mutation assay using a real-time droplet-polymerase chain reaction machine (EGFR d-PCR assay). The purpose of this study was to validate the performance of the EGFR d-PCR assay using fresh liquid cytology specimens. We analyzed three major EGFR mutations (L858R in exon 21, E746_A750del in exon 19 and T790M in exon 20) in 80 fresh liquid cytology specimens of adenocarcinoma (ADC) or NSCLC-not otherwise specified (NOS) via the EGFR d-PCR assay and conventional real-time PCR assay using the therascreen® EGFR RGQ PCR kit (Therascreen assay). In addition, we performed sensitivity assays using cell lines with EGFR mutations. The EGFR d-PCR assay detected 16 L858Rs, 8 E746_A750dels and 1 T790M mutation and the Therascreen assay detected 16 L858Rs, 11 deletions in exon 19 and 1 T790M mutation. The results were concordant between the two assays. The reaction time of the EGFR d-PCR assay was 8 min and 10 sec, but that of the Therascreen assay was 1 h and 45 min. Sensitivity, as assessed by the detection limit of the EGFR d-PCR assay was 0.5, 0.05 and 0.5% for L858R, E746_A750del and T790M, respectively. The EGFR d-PCR assay markedly reduced the detection time of major EGFR mutations with high sensitivity compared with the conventional Therascreen assay and is expected to expedite EGFR-TKI therapy for lung cancer patients, especially those in advanced stages.