The Study Of The Detection Of EGFR Drive Mutation In Lung Cancer Patients By The Method Of CastPCR

Objectives:EGFR mutation status is an important predictive molecular marker for EGFR TKIs treatment in non-small cell lung cancer (NSCLC) patients. Therefore, it is necessary to detect EGFR mutation status in patients with lung cancer before clinical treatment, for it would guide the personalized treatment, reduce the financial burden and maximize the efficiency of EGFR TKIs. Besides, real-time monitoring of the EGFR mutation status during treatment would be useful to evaluate the early-time efficacy and predict the prognosis. While the key to achieve the above goal is to establish a stable and efficient molecular detecting platform. In this study, Purpose: Investigated the EGFR mutation status in tumor tissue samples of treatment-naive adenocarcinoma patients and the correlation between EGFR mutation status and their clinical characteristics; Evaluate the value of castPCR detection method which we employed in EGFR mutation in NSCLC patients. Since it is difficult to obtain suitable tumor tissue samples in some advanced cancer patients, and it is unpractical to monitor the EGFR mutation statues with repeated biopsy during the EGFR TKIs treatment, the peripheral serum/plasma free nucleic acid which contains rich biological information has attracted extensive attention. The preliminary analysis of this study has demonstrated the sensitivity of castPCR method for detecting EGFR mutations, which has set the foundation for detecting EGFR mutation statues with serum/plasma free nucleic acid.Methods:1. We collected 103 lung adenocarcinoma patients’clinical pathologic data, formalin-fixed paraffin-embedded (FFPE)tissues and their paired blood samples before treatment in The Affiliated Drum Tower Hospital of Medical School of Nanjing University from November 2010 to December 2014. The castPCR method was employed to detect the EGFR mutation statues (exon 19,2235-2249 and 2236-2249; exon 20 T790M; exon 21 L858R) of 103 treatment-naive FFPE tissues samples. Discuss the relationship between tumor tissues EGFR mutation status and their clinical biological behavior.2. According to certain proportion of EGFR-mutated cell DNA diluted to wild type EGFR cell DNA, we demonstrated the sensitivity of castPCR method.Results:54 out of 103 lung adenocarcinoma patients were detected with at least one site of EGFR mutations (mutation rate 52.43%). There were 45 (43.69%) patients carrying sensitive mutation (exon 19 and/or exon 21) and 11 people (10.68%) carrying exon 20 mutation. We also found some patients harbored complex mutations:2 carried exon 19 and 20 mutations,4 carried exon 19 and 21 mutations, and 1 carried exon 20 and 21 mutation. Our cell experiment showed that the sensitivities of castPCR method detecting the EGFR gene mutation in exon 19 and 21 were both 0.1%, while the sensitivity detecting exon 20 mutation was 1%.Conclusions:In this study, the castPCR method was proved to be with high sensitivity and specificity, and we have also demonstrated the clinical feasibility of utilizing the castPCR method to detect the EGFR mutation statues from tumor tissue of lung cancer patients. Moreover, we have demonstrated the potential of the castPCR method detecting the EGFR mutation statues from peripheral blood mutant DNA. This method has probably found a new testing platform for serum/plasma circulating DNA, which can play the role as a tumor marker for the "real time" individualized treatment.