title: Total and mutated EGFR quantification in cell-free DNA from non-small cell lung cancer patients detects tumor heterogeneity and presents prognostic value.
abstract: Mutation analysis of epidermal growth factor receptor (EGFR) gene is essential for treatment selection in non-small cell lung cancer (NSCLC). Analysis is usually performed in tumor samples. We evaluated the clinical utility of EGFR analysis in plasma cell-free DNA (cfDNA) from patients under treatment with EGFR inhibitors. We selected 36 patients with NSCLC and EGFR-activating mutations. Blood samples were collected at baseline and during treatment with EGFR inhibitors. Wild-type EGFR, L858R, delE746-A750, and T790M mutations were quantified in cfDNA by droplet digital PCR. Stage IV patients had higher total circulating EGFR copy levels than stage I (3523 vs. 1003 copies/mL; p < 0.01). There was high agreement for activating mutations between baseline cfDNA and tumor samples, especially for L858R mutation (kappa index = 0.679; p = 0.001). In 34 % of advanced NSCLC patients, we detected mutations in cfDNA not previously detected in tumor samples and double mutations in 17 %. Patients with baseline total EGFR copy levels above the median presented decreased overall survival (OS) (341 vs. 870 days, p < 0.05) and progression-free survival (PFS) (238 vs. 783 days; p < 0.05) compared with those with total EGFR copy levels below the median. Patients with baseline concentrations of activating mutations above the median (94 copies/mL) had lower OS (317 vs. 805 days; p < 0.05) and PFS (195 vs. 724 days; p < 0.05). During follow-up, T790M resistance mutation was detected in 53 % of patients. Total and mutated EGFR analysis in cfDNA seems a relevant tool to characterize the molecular profile and prognosis of NSCLC patients harboring EGFR mutations.
authors.affiliation: Clinical Chemistry Department, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.|Department of Biochemistry and Genetics, Universidad de Navarra, Irunlarrea 1, 31008, Pamplona, Spain.|IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Alegre
authors.affiliation: Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: J P
authors.initials: JP
authors.lastname: Fusco
authors.affiliation: Clinical Chemistry Department, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.|IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Restituto
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Salas-Benito
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: M E
authors.initials: ME
authors.lastname: Rodríguez-Ruiz
authors.affiliation: Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: M P
authors.initials: MP
authors.lastname: Andueza
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Program in Solid Tumors and Biomarkers|, Centro de Investigación Médica Aplicada (CIMA), Av Pio XII, 55 31008, Pamplona, Spain.|Department of Histology, Universidad de Navarra, Irunlarrea 1, 31008, Pamplona, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Pajares
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Pediatrics and CIMA LAB Diagnostics, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Patiño-García
authors.affiliation: Department of Biochemistry and Genetics, Universidad de Navarra, Irunlarrea 1, 31008, Pamplona, Spain.|IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Program in Solid Tumors and Biomarkers|, Centro de Investigación Médica Aplicada (CIMA), Av Pio XII, 55 31008, Pamplona, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Pio
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Pathology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: M D
authors.initials: MD
authors.lastname: Lozano
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Gúrpide
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Lopez-Picazo
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Gil-Bazo
authors.affiliation: IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain.|Department of Oncology, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Perez-Gracia
authors.affiliation: Clinical Chemistry Department, Clínica Universidad de Navarra, Av Pio XII 36, 31008, Pamplona, Spain. agonzaleh@unav.es.|Department of Biochemistry and Genetics, Universidad de Navarra, Irunlarrea 1, 31008, Pamplona, Spain. agonzaleh@unav.es.|IdiSNA, Navarra Institute for Health Research, Irunlarrea 3, 31008, Pamplona, Spain. agonzaleh@unav.es.
authors.forename: A
authors.initials: A
authors.lastname: Gonzalez
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000145:classification / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D004252:DNA Mutational Analysis / Q000379:methods; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000145:classification / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009367:Neoplasm Staging; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D060888:Real-Time Polymerase Chain Reaction; D012189:Retrospective Studies; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; D047428:Protein Kinase Inhibitors; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: Cell-free DNA; Droplet digital PCR; EGFR mutation; Non-small cell lung cancer; Prognosis; Tumor heterogeneity