CTLA4 and neoplasm: It was found that infiltration of CD8+ T cells was associated with prolongation of survival in tumor patients, but the inherent low immunogenicity of tumor cells with TME suppressed the immune activity of T lymphocytes, leading to a decrease in the anti-tumor capacity of T lymphocytes (98, 99) MiR-424 (322) regulates the PD-L1/PD-1 and CD80/CTLA-4 pathways in drug-resistant ovarian cancer (100), and restoration of its expression reverses the chemoresistance that accompanies PD-L1 immune checkpoint blockage (101).