PDCD1 and cancer: The interaction between PD‐L1 and PD‐1 inhibits T cell immune activation and effector responses.[20, 21] Disruption of the PD‐1/PD‐L1 axis and reactivation of TILs are considered promising targets for cancer immunotherapy.[22] Since PD‐L1‐negative cells are sensitive to T cell surveillance, PD‐L1‐positive cells are resistant even in the presence of the SASP.