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Canadian Respiratory Journal
Volume 2016, Article ID 5297329, 7 pages
Research Article

EGFR Mutation Analysis of Circulating Tumor DNA Using an Improved PNA-LNA PCR Clamp Method

1Department of Respiratory Medicine, Miyagi Cancer Center, 47-1 Nodayama, Medeshima-Shiote, Natori 981-1293, Japan
2Division of Cancer Biology and Therapeutics, Miyagi Cancer Center Research Institute, Natori, Japan
3Molecular Genetic Research Department, LSI Medience Corporation, Tokyo, Japan
4Japan Anti-Tuberculosis Association, Tokyo, Japan

Received 15 May 2016; Revised 10 June 2016; Accepted 15 June 2016

Academic Editor: Elisa Giovannetti

Copyright © 2016 Kana Watanabe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.