AbstractBackgroundImmune checkpoint inhibitors (ICIs) are effective for advanced hepatocellular carcinoma (HCC). However, there are few reports on the correlation between the clinical efficacy of ICIs and the development of immune-related adverse events (irAEs) in patients with HCC. The aim of this study was to investigate the association between irAE development and survival in patients with HCC treated with atezolizumab plus bevacizumab.Patients and MethodsWe enrolled 150 patients with advanced HCC treated with atezolizumab plus bevacizumab between October 2020 and October 2021 at 5 territorial institutions. We compared the efficacy of atezolizumab plus bevacizumab between patients who experienced irAEs (irAE group) and those who did not (non-irAE group).ResultsThirty-two patients (21.3%) developed irAEs of any grade. Grade 3/4 irAEs were observed in 9 patients (6.0%). The median progression-free survivals (PFS) in the irAE and non-irAE groups were 273 and 189 days, respectively (P= .055). The median overall survivals (OS) in the irAE and non-irAE groups were not reached and 458 days, respectively (P= .036). Grade 1/2 irAEs significantly prolonged PFS (P= .014) and OS (P= .003). Grade 1/2 irAEs were significantly associated with PFS (hazard ratio [HR], 0.339; 95% confidence interval [CI], 0.166-0.691;P= .003) and OS (HR, 0.086; 95% CI, 0.012-0.641;P= .017) on multivariate analysis.ConclusionThe development of irAEs was associated with increased survival in a real-world population of patients with advanced HCC treated with atezolizumab plus bevacizumab. Grade 1/2 irAEs were strongly correlated with PFS and OS.