KANG-YI SUTseng J.-S.Liao K.-M.Yang T.-Y.Chen K.-C.Hsu K.-H.PAN-CHYR YANGSUNG-LIANG YUChang G.-C.2020-06-172020-06-1720181932-6203https://scholars.lib.ntu.edu.tw/handle/123456789/502815Several ultra-sensitive methods for T790M in plasma cell-free DNA (cfDNA) have been developed for lung cancer. The correlation between mutation-allele frequency (MAF) cutoff, drug responsiveness, and outcome prediction is an unmet needs and not fully addressed. An innovative combination of peptide nucleic acid (PNA) and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was used to proof of concept for monitoring cfDNA T790M in EGFR-mutant patients. Mutant enrichment by PNA was optimized and the detection limit was evaluated through serial dilutions. The cut-off value was identified by receiver-operating-characteristic (ROC) curve analysis utilizing serial sampled plasmas of patients from EGFR-tyrosine kinase inhibitor (TKI) pretreatment to progressive-disease (PD). Results, comparisons, and objective response rate (ORR) were analyzed in 103 patients’ tumor and cfDNA T790M, with 20 of them receiving an additional COBAS test. The detection limit was 0.1% MAF. The cut-off for PD and imminent PD was 15% and 5% with an ROC area under the curve (AUC) of 0.96 and 0.82 in 2 ml plasma. Detection sensitivity of cfDNA T790M was 67.4% and overall concordance was 78.6%. ORR was similar in T790M-positive cfDNA (69.6%) and tumor samples (70.6%) treated with osimertinib. Among 65 T790M-positive tumors, 15 were negative in cfDNA (23.1%). Seven of 38 T790M-positive cfDNA samples were negative in the tumors (18.4%). PNA-MALDI-TOF MS had a higher detection rate than COBAS. In conclusion, identification of T790M cut-off value in cfDNA improves cancer managements. We provide a strategy for optimizing testing utility, flexibility, quality, and cost in the clinical practice. ? 2018 Su et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.[SDGs]SDG3circulating tumor DNA; epidermal growth factor receptor; epidermal growth factor receptor kinase inhibitor; methionine; osimertinib; peptide nucleic acid; threonine; cell free nucleic acid; epidermal growth factor receptor; osimertinib; peptide nucleic acid; piperazine derivative; protein kinase inhibitor; adult; aged; Article; blood sampling; cancer patient; clinical outcome; cohort analysis; controlled study; dilution; disease course; EGFR gene; female; human; human tissue; limit of detection; lung adenocarcinoma; major clinical study; male; matrix-assisted laser desorption-ionization mass spectrometry; mutant; mutational analysis; patient monitoring; prediction; proof of concept; receiver operating characteristic; treatment response; very elderly; adenocarcinoma; blood; chemistry; disease free survival; genetics; lung tumor; metabolism; middle aged; mutation; pathology; treatment outcome; Adenocarcinoma; Adult; Aged; Aged, 80 and over; Cell-Free Nucleic Acids; Disease-Free Survival; ErbB Receptors; Female; Humans; Limit of Detection; Lung Neoplasms; Male; Middle Aged; Mutation; Peptide Nucleic Acids; Piperazines; Protein Kinase Inhibitors; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Treatment Outcomejournal article10.1371/journal.pone.0207001304448752-s2.0-85056574938