Currently, cancer immunotherapy especially the immune checkpoint blockade (ICB) therapy, such as monoclonal antibodies (mAbs) against programmed death-1 receptor (PD-1) and its ligand (PD-L1), and cytotoxic T lymphocyte-associated antigen 4 (CTLA4), have shown promising therapeutic efficacy in various types of cancer. Here, CTLA4 is linked to cancer.