CD8A and glioblastoma: To improve the antitumor immune response, Treg depletion therapy has been attempted in GBM models through combinatorial anti-CXCR4 and anti-PD1 immunotherapy, which have improved survival rates via decreased levels of Tregs and MDSCs, improved CD4+/CD8+ ratios, and increased levels of pro-inflammatory cytokines (Wu et al., 2019).