Epidermal growth factor receptor (EGFR) is their downstream factor, and its inhibition facilitates CD8+ T cell infiltration, reduces myeloid cells, and sensitizes pancreatic tumors to combination immunotherapy (CD40 agonist, programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade). Here, PDCD1 is linked to pancreatic neoplasm.