Further, comparative investigation of these cells and the PD-1 expression intensity, as recently reported [47], in corresponding tumor tissue and peripheral blood samples of melanoma patients and healthy donors will be warranted to learn more about potential migration patterns, functional and phenotypical characteristics and could help to understand why patients with low PD-1+CD56+ T-cell frequencies have better chances of benefiting from therapy. Here, NCAM1 is linked to melanoma.