Recent studies have shown that overexpression of IL-7 and CCL19 or C-C motif chemokine 21 (CCL21) within CAR-T cells can facilitate immune cell infiltration into tumors and support the persistence of CAR-T cells in the tumor microenvironment (Adachi et al.2018; Luo et al.2020; Pang et al.2021). The gene discussed is CCL21; the disease is neoplasm.