Remarkable effects upon the treatment of relapsed/refractory (r/r) B-ALL have been observed by applying the CD19 × CD3 bispecific T cell engager (BiTE) Blinatumomab or anti-CD19 chimeric antigen receptor (CAR) T cell products such as Tisagenlecleucel [10,11]. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.