Analysis of Epidermal Growth Factor Receptor Mutations in Serum Among Japanese Patients Treated With First-Line Erlotinib for Advanced Non-Small-Cell Lung Cancer

Analysis of serum to detect EGFR (epidermal growth factor receptor) mutations may be an alternative to using tumor tissue. Scorpion-ARMS was used to detect serum EGFR mutations in the single-arm Japanese JO22903 erlotinib study. Serum EGFR mutations (exon 19 deletions or L858R) were detected in 26.3% of patients analyzed; agreement between tumor and serum results was 96.2%. As sensitivity was low, further validation of serum-based EGFR analysis is needed. Background: Obtaining tumor samples for epidermal growth factor receptor (EGFR) mutation analysis during treatment can be difficult; therefore, serum samples may be a convenient alternative. We analyzed serum EGFR mutations in the Japanese phase 2 JO22903 study in chemotherapy-naive non-small-cell lung cancer patients with tumor EGFR mutations. Materials and Methods: Serum samples were analyzed by Scorpion-ARMS to detect EGFR mutations before and after erlotinib administration. Agreement between serum and tumor EGFR mutations and time course changes of EGFR mutations were evaluated. Results: A total of 95 of 103 patients consented to examination of serum samples; baseline serum EGFR mutations (exon 19 deletions or L858R) were detected in 25 patients (26.3%). The agreement rate between tumor and serum samples was 96.2%. Among 65 serum samples taken at 190 days after treatment initiation, EGFR mutations were detected in 5 patients (7.7%). Of the serum samples taken at progression (n = 71), EGFR mutations were detected in 16 patients (22.5%). Patients with baseline serum EGFR mutations had a median progression-free survival of 9.7 months; those without baseline serum mutations had a median progression-free survival of 15.2 months. Conclusion: The sensitivity of these analyses was not enough to draw firm conclusions; however, the results suggest that serum EGFR mutations correlate with disease activity. (C) 2016 The Authors. Published by Elsevier Inc.