In combination, PD-1 blockade (nivolumab, pembrolizumab) and anti-CTLA-4 (ipilimumab) have achieved a 1 year survival rate of 85% as opposed to 63–69% for anti-PD-1 alone in metastatic melanoma, underscoring the potential for combination immunotherapies to improve patient outcomes [5]. This evidence concerns the gene PDCD1 and metastatic melanoma.