EGFR Mutation Analysis of Circulating Tumor DNA Using an Improved PNA-LNA PCR Clamp Method
Introduction. Rebiopsies have become more crucial in non-small cell lung cancer (NSCLC). Instead of invasive biopsies, development of collecting biological data of the tumor from blood samples is expected. We conducted a prospective study to assess the feasibility of detection of epidermal growth factor receptor (EGFR) mutation in plasma samples.Method. NSCLC patients harboring EGFR activating mutations, who were going to receive EGFR-tyrosine kinase inhibitors (TKIs) as first-line treatment, were enrolled in this study. Plasma EGFR activating mutations and the T790M resistance mutation were analyzed by an improved PNA-LNA PCR clamp method, characterized by a 10-fold or more sensitivity compared with the original methods.Result. Six patients with wild-type EGFR and 24 patients with EGFR mutations were enrolled in this study. Pretreatment plasma samples achieved sensitivity of 79%. The 6 patients with wild-type EGFR were all negative for plasma EGFR mutations. At the time of disease progression, plasma T790M mutation was detected in 8 of 16 cases. Absence of T790M before and during TKI treatment and disappearance of activating mutations during TKI treatment were considered as predictors of EGFR-TKIs efficacy.Conclusion. We were able to detect EGFR mutations in plasma samples by using an improved PNA-LNA PCR clamp method.