CD19-specific chimeric antigen receptor T-cells (CD19 CAR T-cells) have demonstrated encouraging clinical efficacy for the treatment of relapsed or refractory (R/R) B-cell malignances, including B-cell acute lymphoblastic leukemia (B-ALL), non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) (1). This evidence concerns the gene CD19 and precursor B-cell acute lymphoblastic leukemia.