CD19 and B-cell acute lymphoblastic leukemia: Following the clinical success of bispecific engagers such as blinatumomab, a CD3-CD19 bispecific antibody that engages CD3+ T cells and traffic them to CD19+ B cell acute lymphoblastic leukemia, several groups have developed multi-valent targeting molecules that specifically engage NK cells in close proximity to the target tumor to improve tumor killing (147).