PDCD1LG2 and neoplasm: ICIs could activate T cells and NK cells from priming by antigen-presenting cells (APCs) via mediating the ligand–receptor pairs such as CTLA-4-CD80/86 and PD-1-PD-L1/PD-L2 in order to induce tumor regression (Dyck and Mils., 2017) (Leone et al., 2021).