Of interest, the tumor-antigen specificities and TCR repertoires of the CD8+PD-1+ cells from peripheral blood and tumor tissues are similar [80], suggesting that the circulating CD8+PD-1+ T cells might be a novel noninvasive approach of adoptive cell therapy with neoantigen-reactive lymphocytes, or serve as a surrogate biomarker for adaptive immune resistance. This evidence concerns the gene CD8A and neoplasm.