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Purpose: To assess the utility of the cobas EGFR Mutation Test, with tissue and plasma, for first-line osimertinib therapy for patients with EGFR -mutated ( EGFR m; Ex19del and/or L858R) advanced or metastatic non-small cell lung cancer (NSCLC) from the FLAURA study (NCT02296125)., Experimental Design: Tumor tissue EGFR m status was determined at screening using the central cobas tissue test or a local tissue test. Baseline circulating tumor (ct)DNA EGFR m status was retrospectively determined with the central cobas plasma test., Results: Of 994 patients screened, 556 were randomized (289 and 267 with central and local EGFR test results, respectively) and 438 failed screening. Of those randomized from local EGFR test results, 217 patients had available central test results; 211/217 (97%) were retrospectively confirmed EGFR m positive by central cobas tissue test. Using reference central cobas tissue test results, positive percent agreements with cobas plasma test results for Ex19del and L858R detection were 79% [95% confidence interval (CI), 74-84] and 68% (95% CI, 61-75), respectively. Progression-free survival (PFS) superiority with osimertinib over comparator EGFR-TKI remained consistent irrespective of randomization route (central/local EGFR m-positive tissue test). In both treatment arms, PFS was prolonged in plasma ctDNA EGFR m-negative (23.5 and 15.0 months) versus -positive patients (15.2 and 9.7 months)., Conclusions: Our results support utility of cobas tissue and plasma testing to aid selection of patients with EGFR m advanced NSCLC for first-line osimertinib treatment. Lack of EGFR m detection in plasma was associated with prolonged PFS versus patients plasma EGFR m positive, potentially due to patients having lower tumor burden., (©2019 American Association for Cancer Research.)

Purpose: In the phase III FLAURA study, third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) osimertinib significantly improved progression-free survival (PFS) versus standard-of-care (SoC) EGFR-TKI (gefitinib or erlotinib) in patients with previously untreated EGFR (exon 19 deletion or L858R) mutation-positive advanced non-small cell lung cancer (NSCLC). Interim overall survival (OS) data were encouraging, but not formally statistically significant at current maturity (25%). Here we report exploratory postprogression outcomes., Patients and Methods: Patients were randomized 1:1 to receive osimertinib (80 mg orally, once daily) or SoC EGFR-TKI (gefitinib 250 mg or erlotinib 150 mg, orally, once daily). Treatment beyond disease progression was allowed if the investigator judged ongoing clinical benefit. Patients receiving SoC EGFR-TKI could cross over to receive osimertinib after independently confirmed objective disease progression with documented postprogression T790M-positive mutation status., Results: At data cutoff (June 12, 2017), 138 of 279 (49%) and 213 of 277 (77%) patients discontinued osimertinib and SoC EGFR-TKI, respectively, of whom 82 (59%) and 129 (61%), respectively, started a subsequent treatment. Median time to discontinuation of any EGFR-TKI or death was 23.0 months [95% confidence interval (CI), 19.5-not calculable (NC)] in the osimertinib arm and 16.0 months (95% CI, 14.8-18.6) in the SoC EGFR-TKI arm. Median second PFS was not reached (95% CI, 23.7-NC) in the osimertinib arm and 20.0 months (95% CI, 18.2-NC) in the SoC EGFR-TKI arm [hazard ratio (HR), 0.58; 95% CI, 0.44-0.78; P = 0.0004]., Conclusions: All postprogression endpoints showed consistent improvement with osimertinib versus SoC EGFR-TKI, providing further confidence in the interim OS data., (©2019 American Association for Cancer Research.)