CD19 and neoplasm: For B cell malignancies, CARs generally bind to CD19 targets and redirect the patient’s own cells to kill tumour cells in 3 main steps (Fig. 2): (1) the antigen-binding domain of CARs recognizes the CD19 antigen on the B cell; (2) the CD3ζ chain signalling domain induces T cell activation and secretion of cytokines; and (3) the co-stimulatory domains increase T cell activation and enhance the cytolytic function [4].