Consequently, our study and others have demonstrated that tumor-specific and tumor-infiltrating CD8+ T-cell repertoires are enriched in the circulating CX3CR1+ CD8+ subset in preclinical models and patients (16, 21), and the frequency of peripheral blood (PB) CX3CR1+ CD8+ T cells increases after effective immunotherapy such as adoptive T-cell therapy, neoantigen/in situ vaccination, and ICI therapy (15, 17, 22, 23). This evidence concerns the gene CX3CR1 and neoplasm.