Indeed, CAR T cells that produce IL-7 and CCL19 to mimic T-zone function in lymphoid tissues have been reported to exhibit strong efficacy in animal solid tumor models, mastocytoma cell line–derived xenografts (CDXs), hepatocellular carcinoma (HCC) patient-derived xenografts (PDXs), and pancreatic carcinoma CDXs (32, 33). Here, IL7 is linked to mastocytoma.