In the samples from the first operation, PD-1 and PD-L1 expression was found in only 3 (16.7%) and 5 (27.8%), respectively, of patients with low-grade glioma; in high-grade glioma cases, the corresponding numbers of were 6 (26.1%) and 9 (37.5%), respectively. This evidence concerns the gene CD274 and central nervous system cancer.