CD274 and primitive neuroectodermal tumor: However, the combination of anti-VEGFR2 and anti-PD-L1 did not improve the survival rate of patients with glioblastoma (7), which could be attributed to the low formation rate of high endothelial venules (HEVs) in these tumors—contrary to the findings in breast cancer and primitive neuroectodermal tumor (PNET) models.