CD8A and neoplasm: Some of these are represented by the challenging anatomical location, the tumor invasiveness with diffuse patterns of growth and infiltrating characteristics, the intra- and intertumoral heterogeneity, the blood-brain barrier (BBB), and the immunosuppressive nature of the tumor microenvironment (TME) [20,21] including dendritic cells, monocytes, CD4+ Tcell, CD8+ Tcell, tumor-associated neutrophils (TANs), tumor-associated macrophages (TAMs), microglia, myeloid-derived suppressor cells (MDSCs).