Results obtained in early clinical studies with so-called first-generation CD19 CAR-T, which contained the ζ chain of the CD3/T-cell receptor (TCR) complex as the only signalling domain (Figure 1A), proved the feasibility of the CAR approach but could not demonstrate objective anti-tumour effects or the persistence of cells after infusion [for a review, see Boyiadzis et al. (50)]. This evidence concerns the gene CD19 and neoplasm.