In our previous study, we determined that OPN is a novel immune checkpoint which compensates for PD-L1 function to support tumor immune escape in the pancreatic tumor microenvironment [18], and the WDR5/MLL1-H3K4me3 epigenetic axis regulates both PD-L1 and OPN expression [18,19]. The gene discussed is SPP1; the disease is pancreatic neoplasm.