PDCD1 and intrahepatic cholangiocarcinoma: Considering the combined role of PD1 and PD-L1 in regulating T cell function, ICC patients with high expression of both PD1 and PD-L1 had the poorest prognosis among patients with high expression of only PD1 or PD-L1 and patients with low expression of both PD1 and PD-L1 (Figure 2E and F; OS, p = 0.023; cumulative recurrence rate, p = 0.003).