CTLA4 and central nervous system cancer: For instance, miR-138 could target CTLA-4 and PD-1 to escape from immune checkpoint therapy in glioma [128], hence,circ_002136 may also has a potential immunotherapy target through sponging miR138 [107], IL-6R by circHIPK3-miR124 axis may affect gliomas immune response [80], circ_0076248 could participate in immune response by regulating expression of p53 and SIRT1 mediated by miR-181a [52], Furthermore, miR-34a overexpression remarkably weakened PD-L1-induced chemoresistance, supporting that miR-34a is a negative regulator of PD-L1 signaling in glioma [129].