PDCD1LG2 and metastatic malignant neoplasm: Imai et al. (2023) found the expression of PD-L2 to be higher in metastatic cancer cells (47%) compared to PD-L1 (11%), with no PD-L1 expression observed in tumor-infiltrating lymphocytes (TILs) (0%), whereas 64% of TILs expressed PD-L2 [49].