CD274 and cancer: As CuP‐mediated cuproptosis up‐regulates PD‐L1 expression in cancer cells, CuP/Er‐mediated ferroptosis and cuproptosis synergize with ICB to elicit potent antitumor immunity, leading to regression of MC38 and 4T1 tumors and prevention of lung metastasis of 4T1 tumors.