PDCD1LG2 and cancer: Similar properties are shared by other cancer-derived soluble factors, including B7H3 (CD276, PD-L3), CTLA-4 (CD152), Lymphocyte-activation gene 3 (LAG3), PD-L2 (PDCD1LG2), and T-cell immunoglobulin and mucin domain protein 3 (TIM3)16–21.