Analytical performance of the cobas EGFR mutation assay for Japanese non-small-cell lung cancer

Introduction: Clinical outcomes in non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations have been reported to be correlated with the use of EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Therefore, it is essential to confirm the presence of EGFR mutations using highly sensitive testing methods. In this study, we compared the performance of the cobas(®) EGFR Mutation Test (cobas EGFR assay) and the therascreen(®) EGFR RGQ PCR Kit (therascreen EGFR assay) for use as an in vitro diagnostic (IVD) product.

Methods: We extracted DNA from 150 formalin-fixed, paraffin-embedded tissue samples from 150 patients diagnosed with NSCLC, and performed a comparative study of the cobas EGFR and therascreen EGFR assay methods. All discordant results were re-analyzed by direct sequencing.

Results: The concordance rate between the cobas EGFR assay and the therascreen EGFR assay was 98.0% (145/148). EGFR mutations were detected at a frequency of 40.9% (61/149) in NSCLC specimens using the cobas EGFR assay and 40.2% (60/149) using the therascreen EGFR assay. Three discrepant results were found in this study. Two double mutations were detected by the cobas EGFR assay but only one in the therascreen EGFR assay. No invalid results resulted from sample analysis by the cobas EGFR assay.

Conclusions: Our results show a high concordance rate (98.0%) of cobas EGFR assay with an existing IVD product, the therascreen EGFR assay. Since they are IVD diagnostic products, both assays proved to be simple, validated methods in detecting the most common, clinically significant EGFR mutations and proved to be helpful for appropriate treatment guidance for NSCLC patients.