CD4 and glioblastoma: For example, it has been reported that the accumulation of regulatory T (T reg) cells in glioblastoma (GBM) contributes to the suppression of anti-tumor immunity, and the combined blockade of IL-12 and CTLA-4 acts on CD4 (+) cells, resulting in the reduction of FoxP3 (+) T reg cells and increases in effector T cells, thereby inhibiting tumor growth (8).