A few years later, trials with antibodies inhibiting the PD-1 pathway demonstrated superiority to chemotherapy in Ipilimumab-refractory melanomas, resulting in the approval of Pembrolizumab and Nivolumab for the treatment of refractory unresectable or metastatic melanoma in 2014 [6,7,8,9,10]. Here, PDCD1 is linked to melanoma.