PDCD1 and cancer: In addition, after intravenous administration, the can effectively penetrate the peritoneal cavity and remain in the intraperitoneal cavity for up to 72 hours.[12] Programmed cell death 1 (PD-1) is a t cell surface receptor that inhibits immune responses when bound to its ligand (PDL1 or PD-L2), which is present in normal human cells and cancer cells.