Osimertinib in ResectedEGFR-Mutated Non–Small-Cell Lung Cancer

BACKGROUND: Osimertinib is standard-of-care therapy for previously untreated epidermal growth factor receptor (EGFR) mutation-positive advanced non-small-cell lung cancer (NSCLC). The efficacy and safety of osimertinib as adjuvant therapy are unknown. METHODS: In this double-blind, phase 3 trial, we randomly assigned patients with completely resected EGFR mutation-positive NSCLC in a 1:1 ratio to receive either osimertinib (80 mg once daily) or placebo for 3 years. The primary end point was disease-free survival among patients with stage II to IIIA disease (according to investigator assessment). The secondary end points included disease-free survival in the overall population of patients with stage IB to IIIA disease, overall survival, and safety. RESULTS: A total of 682 patients underwent randomization (339 to the osimertinib group and 343 to the placebo group). At 24 months, 90% of the patients with stage II to IIIA disease in the osimertinib group (95% confidence interval [CI], 84 to 93) and 44% of thosein the placebo group (95% CI, 37 to 51) were alive and disease-free (overall hazard ratio for disease recurrence or death, 0.17; 99.06% CI, 0.11 to 0.26; P