Osimertinib in Elderly Patients with Epidermal Growth Factor Receptor T790M‐Positive Non‐Small‐Cell Lung Cancer Who Progressed During Prior Treatment: A Phase II Trial

LESSONS LEARNED. Non‐small‐cell lung cancer (NSCLC) represents 85% of lung cancer in elderly patients. In the present study performed in the 36 elderly subjects with epidermal growth factor receptor (EGFR) T790M mutation‐positive NSCLC, osimertinib 80 mg demonstrated statistically significant improvement in the objective response rate, which was comparable to those in the nonelderly population. Osimertinib appears to be an effective and safe treatment option in elderly patients with advanced NSCLC with EGFR mutation; further research in larger scale is warranted. BACKGROUND. Previous findings suggest the possibility of relatively safe use of osimertinib for patients with T790M‐positive non‐small‐cell lung cancer (NSCLC), with few serious adverse events for the elderly in comparison with conventional endothelial growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and with an antitumor effect. METHODS. This phase II study was performed to prospectively investigate the efficacy and safety of osimertinib for elderly patients aged ≥75 years with ineffective prior EGFR TKI treatment or with recurrence in T790M EGFR TKI resistance mutation‐positive NSCLC. RESULTS. A total of 36 patients were included in the analyses. Among the 36 subjects, 63.9% were female, with mean age of 79.9 years. The objective response rate (ORR) was 58.3% (95% confidence interval [CI], 42.2%–72.9%), demonstrating statistically significant efficacy of osimertinib (p = .0017). The median duration of response (DOR) was 27.9 weeks (95% CI, 21.1–82.0). Complete response (CR) and partial response (PR) were 2.8% and 55.6%, respectively. Disease control rate (DCR) was 97.2%. A waterfall plot revealed that 33 (91.6%) subjects exhibited tumor shrinkage during treatment, including 12 of 14 subjects who had stable disease (SD). All adverse events were not reason for discontinuation of the study drug. CONCLUSION. Osimertinib may be an effective and safe treatment option in elderly patients with advanced NSCLC with EGFR mutation.