Postprogression Outcomes for Osimertinib versus Standard-of-Care EGFR-TKI in Patients with Previously Untreated EGFR-mutated Advanced Non-Small Cell Lung Cancer.

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.