Du and colleagues report high levels of PD-L1 mRNA which correlated to protein expression levels, in ~40% of grade I, 60% of grade II, and 77–88% of grade III meningiomas (55), while Everson and colleagues only identified PD-L1 in 25% of grade III cases, with no IHC expression detected in grade I or II cases (17). This evidence concerns the gene CD274 and meningioma.