CTLA4 and melanoma: Following this, many more agents to treat melanoma were approved by the United States Food and Drug Administration, including Interleukin-2 in 1998 (55), Ontak (Treg inhibition) in 1999 (56), Peginterferon α-2b (Peg-IFN) and Ipilimumab (Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) blockade) in 2011 (53, 57),, Nivolumab (Programmed cell death protein 1 (PD-1)/PD-1 ligand (PD-L1) blockade) in 2014 (58), and Talimogene laherparepvec as the first oncolytic virus therapy in 2015 (59).