In turn, PD1 is increased in Melan-A-reactive CD8 T cells with progression of melanoma, although the prognostic value of PD1 on CD8 T cells is less clear, with no association to overall survival in melanoma or a positive prognostic value in other types of cancers such as HPV-induced head and neck cancer (50, 51). This evidence concerns the gene CD8A and head and neck cancer.