CTLA4 and cancer: Cancer immunotherapy has shown great potential as a therapeutic paradigm in treating patients with advanced or metastatic cancer recurrence.[1] Immune checkpoint blockade (ICB) antibodies that target cytotoxic T‐lymphocyte‐associated protein 4 (CTLA4) or programmed cell death‐1/programmed cell death‐ligand 1 (PD‐1/PD‐L1) constitute an effective regimen and can generate complete and durable responses in cancer patients.