IDH1 and central nervous system cancer: The potential of PD-L1 as a therapeutic target was highlighted by the fact that it was expressed in 33 (73.3%) glioma cases overall (Figure 6). IDH1 (R132H) expression (Figures 7, 8) and PD-L1 were found to be inversely correlated (Figure 9) (Pearson's correlation, p < 0.05).