Detection of EGFR alterations in circulating cell-free DNA of lung tumor patients: Higher sensitivity obtained with plasma compared to serum.

e19046 Background: Detection of EGFR alterations is critical for predicting the response to tyrosine kinase inhibitors (TKI) in patients with non-small-cell lung cancer (NSCLC). In clinical practice, molecular testing is performed on tumor tissues when available. We investigated the use of circulating cell-free DNA for the detection of EGFR alterations in patients with NSCLC. Methods: Serum and plasma were obtained by centrifugation (10 min, 2,000 g, 20°C) performed within 3 hours following blood collection. Cell-free DNA was extracted using the QIAamp Circulating Nucleic Acid kit (Qiagen). Detection of EGFR alterations was performed using the approved Therascreen EGFR RGQ kit (Qiagen). Samples were tested positive for EGFR mutation when the ΔCt value (Ct of the mutation specific PCR – Ct of the control PCR) was lower than 12 for exon 19 deletions, and below 14 for L858R mutation. Results: No EGFR alteration was detected in samples collected from healthy donors (n=6), NSCLC patients with a wild type EGFR ...