CD274 and neoplasm: Generally, the efficacy of immunotherapy depends on the immunological tolerance developed by TME, mainly characterized by ineffective T-cell activation due to a lack of tumor-associated antigens (TAAs), lack of co-stimulatory signals, T-cell exhaustion, presence of immunosuppressive cells (MDSCs, Treg cell), and expression of programmed cell death 1 ligand 1 (PD-L1).