Detection of Epidermal Growth Factor Receptor (EGFR) Mutations in Circulating Cell-Free DNA in Two Phase III Studies (LUX-Lung 3 and LUX-Lung 6) of Afatinib vs Platinum-Based Chemotherapy in Patients With Advanced Non-Small Cell Lung Cancer

Detection of gene mutations in circulating cell-free DNA (cfDNA) isolated from blood is an emerging minimally invasive methodology for identifying cancer patients eligible for targeted treatments. During the phase III LUX-Lung 3 (LL3; 345 patients) and LUX-Lung 6 (LL6; 364 patients) trials, blood samples were prospectively collected from randomized patients with NSCLC with confirmed EGFR mutation in the tumor at baseline. cfDNA samples were isolated from serum (LL3; QIAamp DNA Blood Mini Kit, Qiagen, Manchester, England) or plasma (LL6; QIAamp Circulating Nucleic Acid Kit, Qiagen). A standardized allele-specific quantitative real-time polymerase chain reaction kit (Therascreen EGFR 29; Qiagen), with a 1% detection threshold, was employed to detect EGFR mutations in tumor and paired serum/plasma samples. Of 287 serum (LL3) and 334 plasma (LL6) samples analyzed, detection rates of EGFR …