PD-1 was noted on over 46% and 35% of CD8+ and CD4+ T cells in HCC patients, respectively, but was much more heterogenous in PDA (5%-85% for CD8+ and 3%-75% for CD4+) and CCA (24%-80% for CD8+ and 10%-76% for CD4+) patients. Here, CD4 is linked to cholangiocarcinoma.