Efficacy and safety of a triple combination of atezolizumab, bevacizumab plus GEMOX for advanced biliary tract cancer: a multicenter, single-arm, retrospective study

BACKGROUND: Anti-programmed cell death ligand 1/vascular endothelial growth factor inhibition, coupled with chemotherapy, may potentiate antitumor immunity leading to enhanced clinical benefit, but it has not been investigated in advanced biliary tract cancer (BTC). OBJECTIVES: We investigated the efficacy and safety of atezolizumab, bevacizumab, and gemcitabine plus oxaliplatin (GEMOX) in advanced BTC and explore the potential biomarkers related to the response. DESIGN: Multicenter, single-arm, retrospective study. METHODS: Advanced BTC patients, who received a triple combination therapy at three medical centers between 18 March 2020 and 1 September 2021, were included. Treatment response was evaluated via mRECIST and RECIST v1.1. Endpoints included the overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety. The whole exome sequencing of pathological tissues was conducted for bioinformatic analysis. RESULTS: In all, 30 patients were enrolled. The best ORR was 76.7% and the DCR was 90.0%. The median PFS was 12.0 months, and the median OS was not reached. During the treatment, 10.0% (3/30) of patients suffered from ⩾grade 3 treatment-related adverse events (TRAEs). Furthermore, fever (73.3%), neutropenia (63.3%), increased aspartate transaminase and alanine aminotransferase levels (50.0% and 43.3%, respectively) are the most common TRAEs. Bioinformatics analysis revealed patients with altered ALS2CL had a higher ORR. CONCLUSION: The triple combination of atezolizumab, bevacizumab, and GEMOX may be efficacious and safe for patients with advanced BTC. ALS2CL may be a potential predictive biomarker for the efficacy of triple combination therapy.