CD19 and acute lymphoblastic leukemia: Since Blinatumomab (MT103), the first CD19/CD3 BiTE approved by the United States Food and Drug Administration (FDA) in December 2014 for clinical use in patients with relapsed and/or refractory (R/R) non-Hodgkin lymphoma and R/R B cell precursor acute lymphoblastic leukemia (B-precursor ALL), this antibody format has seen a rapid development for the treatment of several malignancies [59].