PDCD1LG2 and neoplasm: For example, the PDAC tumor microenvironment favors the expression of co-inhibitory ligands, PDL-1 and PDL-2, and inhibits HLA class I expression in tumor cells (10–12) while promoting the emergence of regulatory T cells (Treg) and tumor-associated macrophages (TAM) that secrete immunosuppressive cytokines (5, 13).