However, studies also show that PD-L1 expression on macrophages may have no impact on anti-PD therapy—for example, in the early stage of lung cancer, PD-L1 expression on most tumor-associated macrophages (TAM) does not affect the tumor cell killing by tumor-specific T cells (30), which only plays a role in regulating the interaction between TAM and homologous effector T cells and protecting TAM from being killed by T cells. Here, CD274 is linked to lung cancer.