Abstract
BACKGROUND: Atezolizumab is a programmed death-ligand 1 (PD-L1) targeted monoclonal antibody that inhibits PD-L1 interacting with its receptors PD-1 and B7-1, thereby enhancing anticancer immunity. Some real-world efficacy and safety studies of anti-PD-1 antibody have been previously reported. However, there have been no reports investigating the efficacy of atezolizumab monotherapy in clinical practice which have focused on performance status and previous anti-PD-1 antibody treatment. METHODS: We retrospectively reviewed consecutive advanced NSCLC patients who received atezolizumab monotherapy between April 2018 and February 2019 at eight institutions. A total of 152 patients with NSCLC were enrolled in this study. RESULTS: A total of 38 patients (25%) had already been treated with anti-PD-1 treatment (nivolumab or pembrolizumab) before atezolizumab. The median OS and TTF was 384 days (12.8 months) (95% confidence interval [CI]: 206-424), and 42 days (1.4 months) (95% CI: 27-56) in all patients, respectively. ECOG PS 0 had significantly longer OS (median OS; not reached, p < 0.0001) and TTF (median TTF; 63 days, p = 0.012) compared with PS 1 or 2-3. Most retreated patients were unable to continue atezolizumab for a longer period, but seven patients (18.4%) were able to continue atezolizumab over four months as an ICI retreatment. CONCLUSIONS: In previously treated advanced NSCLC patients, atezolizumab monotherapy demonstrated good efficacy and safety regardless of heavily treated patients in real-world clinical practice, and ECOG PS 0 was a favorable predictive factor. The efficacy of retreatment with atezolizumab was limited but was well tolerated in patients treated with prior anti-PD-1 antibody.