High CCR7 expression of CAR-T cells exposed to IL-7 and IL-15 facilitates homing to secondary lymphoid organs. (A) Equal numbers of CAR-T cells expanded either with IL-2 or IL-7 and IL-15 were subjected to migration assay toward CCL21 (n = 4). (B) NSG mice were subcutaneously implanted with EBV-LCL and then infused with CAR-T cells. CD45⁺CD3⁺ cells were numerated by flow cytometry in blood and spleen 3 days after T-cell infusion (n = 5). (C-D) Expression of CD45RA and CCR7 in CAR-T cells in vivo. Data summarize 3 mice per group from 2 independent experiments. (E) Expression of other chemokine receptors by CAR-T cells. Data shown are representative of 3 independent experiments. (F-G) Detection of CAR-T cells at the tumor sites in vivo. Data are obtained from 3 mice per group from 2 independent experiments.