title: Quantification of mutant alleles in circulating tumor DNA can predict survival in lung cancer.
abstract: OBJECTIVE
  We aimed to investigate the feasibility of droplet digital PCR (ddPCR) for the quantitative and dynamic detection of EGFR mutations and next generation sequencing (NGS) for screening EGFR-tyrosine kinase inhibitors (EGFR-TKIs) resistance-relevant mutations in circulating tumor DNA (ctDNA) from advanced lung adenocarcinoma (ADC) patients.
  
  
  RESULTS
  Detection limit of EGFR mutation in ctDNA by ddPCR was 0.04%. Taking the EGFR mutation in tumor tissue as the golden standard, the concordance of EGFR mutations detected in ctDNA was 74% (54/73). Patients with EGFR mutation in ctDNA (n = 54) superior progression-free survival (PFS, median, 12.6 vs. 6.7 months, P < 0.001) and overall survival (OS, median, 35.6 vs. 23.8 months, P = 0.028) compared to those with EGFR wild type in ctDNA (n = 19). Patients with high EGFR-mutated abundance in ctDNA (> 5.15%) showed better PFS compared to those with low EGFR mutated abundance (≤ 5.15%) (PFS, median, 15.4 vs. 11.1 months, P = 0.021). NGS results showed that 66.6% (8/12) total mutational copy number were elevated and 76.5% (26/34) mutual mutation frequency increased after disease progression.
  
  
  METHODS
  Seventy-three advanced ADC patients with tumor tissues carrying EGFR mutations and their matched pre- and post-EGFR-TKIs plasma samples were enrolled in this study. Absolute quantities of plasma EGFR mutant and wild-type alleles were measured by ddPCR. Multi-genes testing was performed using NGS in 12 patients.
  
  
  CONCLUSIONS
  Dynamic and quantitative analysis of EGFR mutation in ctDNA could guide personalized therapy for advanced ADC. NGS shows good performance in multiple genes testing especially novel and uncommon genes.
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Minglei
authors.initials: M
authors.lastname: Zhuo
authors.affiliation: Asia and Emerging Markets Innovative Medicine of AstraZeneca R & D, Shanghai, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Bai
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Asia and Emerging Markets Innovative Medicine of AstraZeneca R & D, Shanghai, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Tongtong
authors.initials: T
authors.lastname: An
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Jianchun
authors.initials: J
authors.lastname: Duan
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Meina
authors.initials: M
authors.lastname: Wu
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital and Institute, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000401:mortality* / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000401:mortality* / Q000556:secondary; D000074141:Circulating Tumor DNA / Q000235:genetics*; D004273:DNA, Neoplasm; D018450:Disease Progression; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000401:mortality* / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011379:Prognosis; D015996:Survival Rate
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D000074141:Circulating Tumor DNA; D004273:DNA, Neoplasm; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: circulating tumor DNA; droplet digital PCR; epidermal growth factor receptor; next-generation sequencing; non-small-cell lung cancer