CD274 and diffuse astrocytoma: Recent studies showed that tumor cells from Grade IV gliomas, anaplastic astrocytoma and GBM, present intense positive staining for PD-L1, which was reduced in oligodendroglioma and diffuse astrocytoma (Grade II and III gliomas), and no positive staining of PD-L1 was detected in the tumor-free CNS tissue [46, 63, 64].