title: Quantification and dynamic monitoring of EGFR T790M in plasma cell-free DNA by digital PCR for prognosis of EGFR-TKI treatment in advanced NSCLC.
abstract: BACKGROUND
  Among advanced non-small cell lung cancer (NSCLC) patients with an acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI), about 50% carry the T790M mutation, but this frequency in EGFR-TKI-naïve patients and dynamic change during therapy remains unclear. This study investigated the quantification and dynamic change of T790M mutation in plasma cell-free DNA (cf-DNA) of advanced NSCLC patients to assess the clinical outcomes of EGFR-TKI therapy.
  
  
  METHODS
  We retrospectively investigated 135 patients with advanced NSCLC who obtained progression-free survival (PFS) after EGFR-TKI for >6 months for their EGFR sensitive mutations and T790M mutation in matched pre- and post-TKI plasma samples, using denaturing high-performance liquid chromatography (DHPLC), amplification refractory mutation system (ARMS), and digital-PCR (D-PCR). Real-time PCR was performed to measure c-MET amplification.
  
  
  RESULTS
  Detection limit of D-PCR in assessing the T790M mutation was approximately 0.03%. D-PCR identified higher frequency of T790M than ARMS in pre-TKI (31.3% vs. 5.5%) and post-TKI (43.0% vs. 25.2%) plasma samples. Patients with pre-TKI T790M showed inferior PFS (8.9 vs. 12.1 months, p = 0.007) and overall survival (OS, 19.3 vs. 31.9 months, p = 0.001) compared with those without T790M. In patients harboring EGFR sensitive mutation, high quantities of pre-TKI T790M predicted poorer PFS (p = 0.001) on EGFR-TKI than low ones. Moreover, patients who experienced increased quantity of T790M during EGFR-TKI treatment showed superior PFS and OS compared with those with decreased changes (p = 0.044 and p = 0.015, respectively).
  
  
  CONCLUSIONS
  Qualitative and quantitative T790M in plasma cf-DNA by D-PCR provided a non-invasive and sensitive assay to predict EGFR-TKI prognosis.
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Zhijie
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Shuhang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, 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), Beijing Cancer Hospital & Beijing Institute for Cancer Research, 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), Beijing Cancer Hospital & Beijing Institute for Cancer Research, 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), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Minglei
authors.initials: M
authors.lastname: Zhuo
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, 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), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Thoracic Medical Oncology, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Beijing Cancer Hospital & Beijing Institute for Cancer Research, 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), Beijing Cancer Hospital & Beijing Institute for Cancer Research, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000097:blood* / Q000235:genetics; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood* / Q000188:drug therapy; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000097:blood* / Q000235:genetics; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D047428:Protein Kinase Inhibitors; C512478:EGFR protein, human; D066246:ErbB Receptors