ABSTRACT
BACKGROUND: Osimertinib is one of the standard first-line treatments for advanced non-small cell lung cancer in patients with epidermal growth factor receptor (EGFR) mutations, because it achieves significantly longer progression-free survival (PFS) than conventional first-line treatments (hazard ratio: 0.46). However, the efficacy and safety of osimertinib as a first-line treatment for patients aged ≥75 years remain unclear. METHODS: This phase II study was performed to prospectively investigate the efficacy and safety of osimertinib for elderly patients with EGFR mutation-positive advanced non-small cell lung cancer. The primary endpoint was 1-year PFS rate; secondary endpoints were overall response rate (ORR), PFS, overall survival (OS), and safety. RESULTS: Thirty-eight patients were included in the analysis. The 1-year PFS rate was 59.4% (95% confidence interval [CI], 46.1%-72.7%), which did not meet the primary endpoint (the threshold 1-year PFS rate of 50% predicted using data from the NEJ003 study). The most common grade 3/4 adverse events were rash/dermatitis acneiform/ALT increased/hypokalemia (2 patients, 5%). Seven patients developed pneumonitis (17.5%). There were no other cases of treatment discontinuation due to adverse events other than pneumonitis. CONCLUSION: Although this study did not meet the primary endpoint, osimertinib was tolerable for elderly patients with EGFR mutation-positive advanced non-small cell lung cancer. (Japan Registry of Clinical Trials [JRCT] ID number: jRCTs071180007).