Real-World Efficacy and Safety of Atezolizumab for Advanced Non-Small Cell Lung Cancer in Japan: A Retrospective Multicenter Analysis

<b>Background/Objectives:</b> Atezolizumab, an immune checkpoint inhibitor (ICI), was used in a phase III clinical trial, i.e., the OAK trial, of previously treated patients with non-small cell lung cancer. We aimed to evaluate the real-world efficacy and safety of atezolizumab in a non-selected population and identify the clinical characteristics that influence its efficacy. <b>Methods:</b> This was a multicenter, retrospective, single-arm observational study. Seventy-four patients with advanced non-small cell lung cancer, who received atezolizumab monotherapy at Keio University and affiliated hospitals in Japan between April 2018 and March 2019, were enrolled. The follow-up period was until 28 February 2024. The efficacy of treatment and adverse events were reviewed retrospectively. Statistical analyses using Pearson's χ² test, Fisher's exact test, log-rank test, and Student's <i>t</i>-test were performed. <b>Results:</b> The median age of patients was 70 (range, 45-85) years. The overall survival duration was 7.54 (95% confidence interval [CI], 5.14-11.3) months, and the median time to treatment failure (TTF) was 2.00 (95% CI, 1.75-2.54) months. Patients treated with atezolizumab as their first ICI had a longer TTF than those treated with atezolizumab as their second or subsequent ICI (<i>p</i> = 0.04). <b>Conclusions:</b> Atezolizumab may be more effective when used as the first ICI for previously treated patients and may be safely used in elderly patients with non-small cell lung cancer in real-world settings.