PDCD1 and cancer: KEGG pathway enrichment identified significant associations with cancer‐related pathways, PD‐L1 expression and PD‐1 checkpoint pathways in cancer, apoptosis, chemokine signaling pathway, B cell receptor signaling pathway, Toll‐like receptor signaling pathway, T cell receptor signaling pathway, and NK cell mediated cytotoxicity (Figure S5D, Supporting Information).