PDCD1 and intrahepatic cholangiocarcinoma: ICI, immune checkpoint inhibitor; SCLC, small cell lung cancer; NSCLC, non-small cell lung cancer; ICC, intrahepatic cholangiocarcinoma; N/A, not available; CR, complete response; PR, partial response; PD-L1, programmed cell death ligand 1; PD-1, programmed cell death protein 1.