CTLA4 and central nervous system neoplasm: These notions and the recent availability of effective immunotherapeutic agents [10, 11], including anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), anti- PD-1, and PD-L1 monoclonal antibodies (mAbs), have supported their use, also in patients with brain metastases, as well as in primary CNS tumors [12].