CD274 and neoplasm: Interestingly, despite previous evidence of increased expression of PD-L1 and an immunosuppressive TME in high-grade meningiomas [51,55], this study found no significant correlation between PD-L1 expression in pre- and post-treated the meningioma samples and either PFS-6 rate or tumor growth curve stabilization, likely suggesting that other factors come into play at the level of TME [46].