Clinical Validation of the Unparalleled Sensitivity of the Novel Allele-Discriminating Priming System Technology–Based EGFR Mutation Assay in Patients with Operable Non–Small Cell Lung Cancer

Abstract

Purpose Recently, we developed allele-discriminating priming system (ADPS) technology. This method increases the sensitivity of conventional quantitative polymerase chain reaction up to 100 folds, with limit of detection, 0.01%, with reinforced specificity. This prospective study aimed to develop and validate the accuracy of ADPS epidermal growth factor receptor (<i>EGFR</i>) Mutation Test Kit using clinical specimens.Materials and Methods In total 189 formalin-fixed paraffin-embedded tumor tissues resected from patients with non–small cell lung cancer were used to perform a comparative evaluation of the ADPS <i>EGFR</i> Mutation Test Kit versus the cobas <i>EGFR</i> Mutation Test v2, which is the current gold standard. When the two methods had inconsistent results, next-generation sequencing–based CancerSCAN was utilized as a referee.Results The overall agreement of the two methods was 97.4% (93.9%-99.1%); the positive percent agreement, 95.0% (88.7%-98.4%); and the negative percent agreement, 100.0% (95.9%-100.0%). <i>EGFR</i> mutations were detected at a frequency of 50.3% using the ADPS <i>EGFR</i> Mutation Test Kit and 52.9% using the cobas <i>EGFR</i> Mutation Test v2. There were 10 discrepant mutation calls between the two methods. CancerSCAN reproduced eight ADPS results. In two cases, mutant allele fraction was ultra-low at 0.02% and 0.06%, which are significantly below the limit of detection of the cobas assay and CancerSCAN. Based on the <i>EGFR</i> genotyping by ADPS, the treatment options could be switched in five patients.Conclusion The highly sensitive and specific ADPS <i>EGFR</i> Mutation Test Kit would be useful in detecting the patients who have lung cancer with <i>EGFR</i> mutation, and can benefit from the EGFR targeted therapy.