CD4 and liver cancer: In liver cancer cohort, after clustering T cell population into CD4+CXCR6+, CD4+CXCR6-, CD8+CXCR6+ and CD8+CXCR6- T cell (Figure 11D; Additional file 1: Figure S12A), we found that CD8+CXCR6+ showed preferential enrichment in post-treatment samples compared with baseline samples (Figures 11D, E), which might suggest that CD8+CXCR6+ represented tumor-reactive T cells and CXCR6 were a potential marker for tumor-reactive T cells.