Given the crucial role of T cells as harms of cancer immunotherapeutic agents, whose activity is influenced by co-expression of immune suppressive mediators and/or receptors, in this study we analysed the frequency of circulating CD8+ lymphocytes expressing CD73, PD-1 or both in metastatic melanoma patients treated with nivolumab, in comparison with healthy subjects. This evidence concerns the gene PDCD1 and cancer.