CTLA4 and cancer: During the last few years, cancer immunotherapy with immune checkpoint inhibitors (ICIs), such as anti-PD1/PD-L1 and anti-CTLA-4 monoclonal antibodies (e.g., nivolumab and ipilimumab, respectively), has allowed impressive restoration of T cell immunity against neoplastic cells, which commonly induce overexpression of PD-1/CTLA-4 ligands to foster T cell exhaustion/anergy and break anti-tumor immune surveillance.