CD19 and acute lymphoblastic leukemia: T-BsAbs are also mostly known for their use in hematological malignancies similarly to CAR T cells, and blinatumomab (a CD3 × CD19 BsAb built on scFv framework) was FDA approved in 2014 and has been successful against relapsed or refractory acute lymphoblastic leukemia (ALL) [80,81].