During the onset of chronic infection or tumor growth, although some antigen-experienced activated CD8+ T cells exhibit features of early effectors (KLRG1HiCX3CR1+PD-1loTCF-1lo), the others become progenitor exhausted T cells (progenitor Tex cells) marked by high expression of Ly108, intermediate level expression of PD-1 and low expression of CX3CR1 and KLRG1 [3, 95]. This evidence concerns the gene CD8A and neoplasm.