CTLA4 and melanoma: Ipilimumab, an anti-CTLA4 antibody, and nivolumab and pembrolizumab, antibodies directed against PD-1, have demonstrated significant clinical activity in advanced melanoma including improvements in PFS and OS and induction of durable responses (Hodi et al, 2010; Robert et al, 2014; Larkin et al, 2015; Robert et al, 2015).