Blinatumomab (MT103, AMG103) is a CD19 × CD3 targeting the bispecific T-cell-engager (BiTE) [Figure 1], currently approved for the treatment of CD19-positive R/R or MRD-positive B-cell-precursor acute lymphoblastic leukaemia (B-ALL) [93]. This evidence concerns the gene CD19 and precursor B-cell acute lymphoblastic leukemia.