To date, five antibodies that target the PD1/PDL1 axis have been approved by the FDA (Figure 2) for advanced or unresectable melanoma and NSCLC, and pembrolizumab (an anti-PD1 antibody) induces a better response than ipilimumab (an anti-CTLA4 antibody)24. This evidence concerns the gene CTLA4 and melanoma.