Overexpression of PD-L1 induces the development of an immunosuppressive TME in multiple cancers [39–41], including non-small-cell lung cancer (NSCLC) [42, 43], melanoma [44], renal cell carcinoma (RCC) [45], prostate cancer [46], breast cancer [47] and glioma [48]. This evidence concerns the gene CD274 and central nervous system cancer.