CTLA4 and central nervous system cancer: Preclinical studies have demonstrated early successes for the use of immunotherapy against glioma, including antibody-mediated blockade of checkpoints including anti-programmed death-1 (anti-PD-1), anti-cytotoxic T lymphocyte antigen-4 (anti-CTLA-4), and anti-4-1BB, particularly in combination with radiotherapy [5, 6].