Emerging immunotherapies, including anti-PD-1 (PDCD1)/PD-L1 (CD274) antibodies, have been used effectively to treat several types of cancers, including non-small-cell lung cancer (NSCLC) and malignant melanoma [11,12]; however, these therapies lack efficacy in treating pancreatic cancers, partly due to their abundant stroma with an immunosuppressive microenvironment [2,3,4,5,6,7,8,9,10,13,14,15,16,17,18]. Here, PDCD1 is linked to cancer.