CD8A and glioblastoma: The rapid progression of glioblastoma often leads to the fact that patients seek specialized care when the tumor has a significant size and an immunosuppressive microenvironment, characterized by a decrease in CD4+ T helper cells, cytotoxic activity, and proliferation of CD8+ T lymphocytes as well as increased levels of Tregs and other non-tumor cells in the microenvironment [6, 7].