Comparative study of the loop-mediated isothermal amplification method and the QIAGEN therascreen PCR kit for the detection of EGFR mutations in non-small cell lung cancer

BACKGROUND: Epidermal growth factor receptor (EGFR) mutations are important biomarkers in the treatment of patients with advanced or metastatic diseases. The therascreen EGFR Rotor-Gene Q (RGQ) PCR Kit(®) (Qiagen, Inc.) is an approved diagnostic test for EGFR mutations in non-small cell lung cancer (NSCLC). This study aims to investigate the diagnostic capability of a loop-mediated isothermal amplification (LAMP) assay as an accurate, efficient, and cost-effective alternative to the therascreen assay. METHODS: EGFR mutations were investigated by LAMP and therascreen assays using tissue samples that were surgically resected or biopsied from 117 consecutive patients with NSCLC tumors. The EGFR status from the LAMP assay was compared with that of the therascreen assay. Next-generation sequencing (NGS) was performed to confirm EGFR status of tumors that did not match in both assays. To establish an optimal LAMP AUC value, receiver operating characteristics (ROC) curve analysis was performed within tumors with exon 19 deletion or L858R point mutation. RESULTS: Of the 117 tumors assayed, 45 tumors with EGFR mutations and 68 tumors with EGFR wild type were matched in both assays, four tumors having mismatched EGFR statuses. NGS further confirmed that two of the four discordant tumors had the same EGFR status that was determined by the LAMP assay. The AUC values were 0.973 (95% CI: 0.929–1.00) in exon 19 deletion, and 0.952 (95% CI: 0.885–1.00) in L858R point mutation. In exon 19 deletion, sensitivity, specificity, and accuracy were 89.3%, 98.9%, and 96.6%, respectively, and 94.7%, 95.9%, and 95.7%, respectively, in L858R using AUC value of 0.222. CONCLUSIONS: The LAMP assay compared favorably with the therascreen assay and has potential as an effective, simple, rapid, and low-cost diagnostic alternative. Based on these results, a liquid biopsy LAMP system should be developed for point-of-care testing of oncogenes in the near future.