PDCD1 and melanoma: It has been reported that in combination studies, presence of a T-cell-inflamed tumor microenvironment correlates with clinical efficacy of immunotherapies, including anti-PD-1 or IFN-α neoadjuvant therapy [20, 28–31], and T cell infiltrates are prognostic of outcome in patients with primary melanoma as well as melanoma metastatic to regional lymph nodes [28, 32, 33].