CD274 and cholangiocarcinoma: However, another study found that MSI-H (N = 15) was not an independent protective factor (P = 0.162) in refractory CCA with PD-L1 positivity (CPS≥ 1 or tumor proportion score (TPS) ≥ 1%) and treated with pembrolizumab, indicating that PD-L1 expression is also another important confounding factor [58].