PDCD1 and neoplasm: The programmed death-ligand 1 (PD-L1) expression on tumor cells was also increased when tumor cells were infected with OV-OX40L, OV-IL12, or OV-OX40L/IL12 and cocultured with TILs, providing the rationale for the combination therapy of these OVs with programmed cell death protein 1 (PD-1) inhibitors (Figures 2A and 2B).