The effect and safety of immune checkpoint inhibitor rechallenge in non-small cell lung cancer

Introduction: Immune checkpoint inhibitors (ICIs) have demonstrated long survival for the treatment of advanced non-small cell lung cancer (NSCLC). However, the effect and safety of ICI rechallenge have not been fully evaluated. The aim of this study was to investigate the efficacy and safety of ICI rechallenge in NSCLC patients. Methods: We defined 'rechallenge' as re-administration of ICIs for patients who were previously treated with ICIs and discontinued treatment for any reason, and received subsequent chemotherapy. We retrospectively analyzed the histories of 434 patients with advanced NSCLC who received ICIs from December 2015 to December 2017 at seven centers. Results: A total of 317 patients discontinued the ICI treatment, and 14 patients (4.4%) received ICI rechallenge. All 14 patients discontinued the first ICI due to disease progression. Eight patients received the same kind of ICIs, and six patients received different ICIs. Median progression-free survival and overall survival were 1.5 months [95% confidence interval (CI): 0.8-2.6] and 6.5 months [95% CI: 1.4-19.0], respectively. The objective response rate was 7.1%, and the disease control rate was 21.4%. Two of three patients who achieved at least a stable disease, received radiotherapy between the first and second ICIs. Adverse events were not significantly different compared with the first ICIs. Conclusions: In this study, the effect of ICI rechallenge was limited. Careful consideration of the administration of ICI rechallenge is necessary. This report involved a small number of cases, so further large prospective studies are warranted to confirm the efficacy of ICI rechallenge and to investigate predictive markers to identify a patient population in which ICI rechallenge is effective.