CD4 and biliary tract cancer: Our findings of similar immune cellular populations in both sets of analysis (e.g., staging and ICI responsiveness) are consistent with those in patients with biliary tract cancers; when they were analyzed according to their immunotherapy response (44), but differ from those reported in other melanoma patients, in which a lower frequency of CD4+and CD8+T-cells, and a higher frequency of CD19−HLA-DR+myeloid cells at baseline was observed in responders compared to non-responders to ICIs (32).