PDCD1 and hepatocellular carcinoma: However, targeted therapies in the form of inhibitors of vascular endothelial growth factor (VEGF) and its receptor (VEGFR), MET, RAF, platelet-derived growth factor receptors (PDGFR), programmed cell death protein 1 (PD-1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are now established as standard systemic therapy options in advanced HCC.