CD274 and glioblastoma: Interestingly, despite relatively high PD-L1 expression rates, which range from 6.1% to 88%.6 PD-L1/PD-1 inhibitors in GBM patients have yet to demonstrate a clear clinical benefit.28,29 The immunologically “cold” GBM phenotype likely limits their efficacy, suggesting that rational combinatorial therapies targeting immune suppression or enhancing BBB permeability may help convert “cold” tumors into “hot” ones, thereby improving the response to these drugs.