CTLA4 and neoplasm: To balance the immune response and protect normal host tissues, T-cell inhibitory ligands, such as CD80 and CD86 of the B7 family and PD-L1 as well as regulatory T cells (Tregs), are correspondingly upregulated in tumour cells to bind coinhibitory receptors, including PD-L1 and CTLA4 (19, 65) (Figure 3A).