CD4 and melanoma: In this context, the DCR of melanoma patients under treatment of nivolumab at 12 months (patients with CR, PR, and SD vs. PD) was significantly correlated with a higher pre-treatment median proportion of circulating CD4+CD26high T cells (8.85 [5.72; 11.33]) in patients with CR, PR, and SD than median occurring in patients with PD (5.80 [3.51; 8.00]) p 0.014, (Fig. 5A).