CD19-targeting chimeric antigen receptor (CAR) T-cells are now approved for treating specific relapsed/refractory (r/r) B-cell malignancies such as B-cell acute lymphoblastic leukemia (B-ALL), B-cell non-Hodgkin lymphoma (B-NHL) and B-cell chronic lymphocytic leukemia (B-CLL) (1–5). Here, CD19 is linked to acute lymphoblastic leukemia.