CD19-directed chimeric antigen receptor T (CAR-T) cells have shown unprecedented initial response rates in relapsed/refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL); however, relapse due to the loss or downregulation of the CD19 is an emerging threat to this innovative form of cellular immunotherapy [1, 2]. This evidence concerns the gene CD19 and B-cell acute lymphoblastic leukemia.