CD19 and acute lymphoblastic leukemia: This innovative approach to cancer immunotherapy has borne fruit in the form of the CD3-CD19 cross-linking construct blinatumomab (Blincyto®) that was granted accelerated FDA approval in 2014 for use in Philadelphia chromosome-negative B-cell precursor acute lymphocytic leukemia (B-cell ALL), an indication that since has been expanded to include B-ALL patients with minimal residual disease (MRD) [79,80].