CD274 and cholangiocarcinoma: For example, a 2024 large-cohort study of 887 CCA patients found that MSI-H tumors had a median TMB of ~41.7 mut/Mb (versus ~3.1 mut/Mb in MSS) and a higher PD-L1 positivity (37.5% vs. 11.9%), and those patients experienced significantly longer OS and progression-free survival (PFS) under PD-1 inhibitor-based therapy (179).