While first-generation CARs were able to induce T cell activation and produce in vitro and in vivo antitumoral effects in tumor models such as ERBB2-expressing tumors and ovarian cancer, early clinical trials employing these receptors unfortunately showed little to no tumor response and limited in vivo persistence of CAR T cells, varying from one to nine weeks, with longest durability in patients stimulated with interleukin 2 (IL-2) (12–17). This evidence concerns the gene IL2 and neoplasm.