CD274 and cancer: Tumor infiltrating T cells (TILs) and tumor associated macrophages (TAMs) are key components of cellular immune response in tumor microenvironment (Becht et al., 2016; Galdiero et al., 2013; Reiser & Banerjee, 2016), in addition, PD-1/PD-L1 is an important immune checkpoint pathway in mediating tumor cell evasion from immune surveillance, and immunotherapies targeting PD-1/PD-L1 signaling pathway has demonstrated great efficacy in multiple type of cancers (FDA, 2019; Le et al., 2015; Sharma & Allison, 2015).