Bispecific T cell engager (BiTE) as blinatumomab are a class of therapeutic antibodies that consist of two single-chain variable fragments (scFv) simultaneously targeting tumor antigens (e.g., CD19) on cancer cells and CD3 of the T cell receptor complex, hereby bringing target and effector cells into close proximity and activating the cytotoxic function of T cells. The gene discussed is CD19; the disease is cancer.