CD274 and esophageal squamous cell carcinoma: Analysis of peripheral blood mononuclear cells (PBMCs) from both PD-1 antibody-sensitive and resistant ESCC patients, led to the successful identification of important pathways (like PD-L1 and PD-1 checkpoint pathways and B-cell receptor signaling pathways) and gene signatures associated with immunotherapy resistance of ESCC patients [82].