PDCD1LG2 and neoplasm: The HDACi Panobinostat also enhanced the expression of immune checkpoint ligands on the surface of tumor cells, including PD-L1 and PD-L2, and of checkpoint receptors (CTLA-4, PD-1) on the surface of tumor-infiltrating lymphocytes (TILs), thus affecting the efficacy of immune checkpoint blockade therapy [10].