CTLA4 and neoplasm: Notably, breast cancer patients treated with metformin exhibit lower cPD‐L1 expression, and combined treatment with a CTLA‐4 antibody effectively inhibited tumor growth.[110] NCL00017509, a type of NEK2 inhibitor, can inhibit cPD‐L1 phosphorylation at T194/T210, resulting in an unstable cPD‐L1 conformation and its degradation.[103] In addition, the expression level of cPD‐L1 is also regulated by other regulatory mechanisms, which influence anti‐tumor immunity.