Lacking Immunotherapy Biomarkers for Biliary Tract Cancer: A Comprehensive Systematic Literature Review and Meta-Analysis

Background: Immunotherapy has recently been incorporated into the spectrum of biliary tract cancer (BTC) treatment. The identification predictive response biomarkers is essential in order to identify those patients who may benefit most from this novel treatment option. Here, we propose a systematic literature review and meta-analysis PD-1, PD-L1, other immune-related biomarker expression levels with BTC. Methods: Prisma guidelines were followed for meta-analysis. Eligible studies searched on PubMed. Studies published between 2017 2022, reporting data PD-1/PD-L1 BTC, considered eligible. Results: A total 61 eligible identified. Despite great heterogeneity 39 PD-L1 expression, found mean percentage (by choosing lowest cut-off per study) 25.6% (95% CI 21.0 30.3) BTCs. percentages 27.3%, 21.3%, 27.4% intrahepatic cholangiocarcinomas (iCCAs—15 studies), perihilar–distal CCAs (p/dCCAs—7 gallbladder (GBC—5 respectively. Furthermore, 4.6% 2.38 6.97) 2.5% 1.75 3.34) BTCs could be classified as TMB-H MSI/MMRd tumors, Conclusion: From our analysis, was occur approximately 26% BTC patients, minimal differences based anatomical location. MSI molecular phenotypes occurred less frequently. We still lack reliable biomarker, especially mismatch-proficient must need make an effort conceive new prospective discovery studies.