PDCD1 and cancer: Immune checkpoint molecules are expressed on immune cells as tolerance regulators to minimize the potential damage to normal tissues.56 This pathway becomes hijacked by cancer cells or other pathogens to evade T cell‐mediated immune surveillance or even “exhaust” T cells into nonfunctional states.57 Programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte antigen 4 are two well‐characterized immune checkpoints where antibodies that target these pathways have demonstrated robust therapeutic efficacy in treating multiple types of cancer.