The expression of immune checkpoint genes such as programmed cell death 1 ligand 1 (PDL1 or B7-H1), programmed cell death 1 (PD1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) in stromal components plays an important role in down-regulation of the immune response to tumor by preventing the activation of T-cells. The gene discussed is PDCD1; the disease is neoplasm.