Immunotherapy has recently become an important part of cancer treatment.8, 9 The most successful immunotherapy in solid human cancers is the administration of immune checkpoint inhibitors, including antibodies against cytotoxic T lymphocyte‐associated antigen 4 (CTLA4), programmed death 1 (PD‐1), and programmed death ligand 1 (PD‐L1). Here, CTLA4 is linked to cancer.