Specifically, activated Treg cells destroy tumour immunity by enriching a series of costimulatory molecules (such as ICOS, CD27, 41BB, OX40, and GITR) and immune checkpoints (PD-1, CTLA-4, LAG3, and TIGIT) to promote tumour immune evasion (40–42). This evidence concerns the gene CTLA4 and neoplasm.