CXCR5 and neoplasm: Both the co-expression and single expression of CXCR5 or CCR6 in HER2-CAR T cells resulted in a markedly higher positive staining for CD4 + and CD8 + CAR T cells in the tumor tissue compared to those in the HER2-CAR T cell and Control-T treatment groups (Fig. 6E and Fig. S9A).