Efficacy and predictors of immune checkpoint inhibitors in patients with gallbladder cancer

Immune checkpoint inhibitors (ICIs) have shown promising efficacy in multiple cancers including biliary tract cancers (BTCs). However, the data focusing on the efficacy of ICIs in patients with gallbladder cancer (GBC) is still limited. In this study, we aim to assess the efficacy of ICIs in GBC and explore the clinicopathologic and molecular markers associated with ICI benefit. We retrospective analyzed 69 GBC patients who had received ICI therapy between January 2016 and December 2020. Tumor samples were obtained for genomic sequencing and immunohistochemical analysis. The median progression-free survival (PFS) and overall survival (OS) was 4.4 months and 8.5 months, respectively. Multivariate analysis indicated that alcohol intake history, carcinoma embryonic antigen (CEA) level ≥100 U/mL, and cutaneous immune-related adverse events (irAEs) were independent prognostic factors for PFS. CEA level ≥100 U/mL and cutaneous irAEs were independent prognostic factors for OS. The objective response rate and disease control rate (DCR) were 15.9% and 37.7%, respectively. Patients with cutaneous irAEs, high CD8⁺ T cell infiltrated or immune inflamed GBCs had higher DCR. Patients with high CD8⁺ T cell infiltrated or immune inflamed GBCs also had a notably improved prognosis. These results suggest that ICIs were effective in patients with GBC. High CEA level, cutaneous irAEs, high CD8⁺ T cell infiltration, and immune inflamed phenotype could be useful for predicting the efficacy of ICIs in GBC.