Detection of activating and acquired resistant mutation in plasma from EGFR-mutated NSCLC patients by peptide nucleic acid (PNA) clamping-assisted fluorescence melting curve analysis

// Chang Gon Kim 1, 2 , Hyo Sup Shim 3 , Min Hee Hong 1 , Yoon Jin Cha 3 , Su Jin Heo 1 , Hyung Soon Park 1 , Jee Hung Kim 1 , Jin Gu Lee 4 , Chang Young Lee 4, * , Byoung Chul Cho 1, 5, * and Hye Ryun Kim 1, * 1 Division of Medical Oncology, Department of Internal Medicine, Yonsei Cancer Center, Seoul, Korea 2 Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea 3 Department of Pathology, Yonsei University College of Medicine, Seoul, Korea 4 Department of Thoracic and Cardiovascular Surgery, Yonsei University College of Medicine, Seoul, Korea 5 JE-UK Institute for Cancer Research, JE-UK Co., Ltd., Gumi, Kyungbuk, Korea * These authors contributed equally to this work Correspondence to: Hye Ryun Kim, email: nobelg@yuhs.ac Byoung Chul Cho, email: cbc1971@yuhs.ac Chang Young Lee, email: cyleecs@yuhs.ac Keywords: non-small cell lung cancer, epidermal growth factor receptor mutation, first-generation epidermal growth factor receptor-tyrosine kinase inhibitors, liquid biopsy, peptide nucleic acid clamping-assisted fluorescence melting curve analysis Received: January 04, 2017 Accepted: April 16, 2017 Published: May 10, 2017 ABSTRACT This study was designed to prospectively examine whether peptide nucleic acid clamping-assisted fluorescence melting curve analysis (PANAMutyper™) is feasible for the detection of activating and acquired resistant epidermal growth factor receptor ( EGFR ) mutation in plasma. Patients with non-small cell lung cancer harboring activating EGFR mutations who were scheduled to undergo EGFR-tyrosine kinase inhibitors (EGFR-TKIs) were enrolled between September 2011 and March 2015. A total of 102 patients with EGFR-mutated lung cancer were enrolled, 53 had available plasma samples at disease progression, and 28 underwent serial plasma sampling during EGFR-TKI treatment. EGFR-TKI-sensitizing and T790M mutations were detected in the plasma of 68.6% (70/102) at baseline and 30.2% (16/53) at disease progression, respectively. The concordance rates for matched tissue and plasma samples were 80.4% and 90.2% for E19del and L858R mutations at baseline and 56.3% for T790M mutation at disease progression. The sustained presence of plasma EGFR mutations four weeks after EGFR-TKI predicted a poor objective response rate (30.0% vs. 87.5%, P = 0.025), as well as worse progression-free survival (hazard ratio [HR], 4.381) and overall survival (HR, 5.475). Longitudinal analysis could detect T790M mutations earlier than disease progression based on imaging study (median time from appearance of T790M in plasma samples to progression at imaging scan, 103 days). In conclusion, PANAMutyper™ is reliable for detecting activating and acquired resistant EGFR mutation in plasma, and predicts responses to EGFR-TKI via longitudinal monitoring of EGFR mutation during treatment.