CD4 and melanoma: Results showed that melanoma patients with lower frequencies of CD4+CD26high T cells (cut-off value of < 7.3%, identified by ROC curve) had significantly worse survival outcomes (p 0.010) (median survival > 25.77 months; HR 3.31; 95% CI 1.35 to 7.62) as compared with patients with higher CD4+CD26high percentages (median survival > 37.3 months; HR 0.32; 95% CI 0.13 to 0.76) (Fig. 3A).