Next, single-cell analysis of T cells from four patient cohorts that received ICB therapy revealed that the proportion of CD8+CXCR6- are markedly elevated after anti-PD-1 therapy compared with CD8+CXCR6-, CD4+CXCR6+, CD4+CXCR6- T cells, which suggested CD8+CXCR6+ are major tumor-reactive T cells to ICB therapy and the CXCR6 expression on infiltrating CD8+ T cells are significantly increased after ICB treatment. This evidence concerns the gene PDCD1 and neoplasm.