Blinatumomab is a bispecific T-cell engager (BiTE®) antibody targeting CD19 on B-cells and CD3 on T-cells, designed to treat relapsed or refractory B-cell malignancies. It redirects T-cells to destroy tumor cells, achieving high response rates. The thesis focuses on the mechanism of action of blinatumomab in addition to the latest clinical trails and summarizes their reported results.