CTLA4 and central nervous system cancer: To date, immunotherapeutic targets have been identified mainly in the CTLA-4 and PD-1/PD-L1 axis, and related treatments have exhibited antitumor efficacy by activating components of the immune system [5], nevertheless, due to the existence of glioma special microenvironment, the immunotherapy targeting PD-1/PD-L1 is not encouraging in glioma [6].