CD274 and lymphopenia: Possible etiologies of treatment failure may be systemic lymphopenia when recurrence, low PD-L1 expression rate in this cohort, poor drug penetration of the blood–brain barrier (BBB), antigen-specific T-cells heavily dysfunctional in this special immune microenvironment, no identification of discrepancies between different genomic subtypes in their response to PD-1/PD-L1 checkpoint blockades, or the presence of structural barriers preventing T-cell–antibody interactions.