As we demonstrate in our current study, the new triplebody anti-CD19/anti-CD3/anti-CD19 (19-3-19) is capable of activating resting T cells and of mediating redirected and serial lysis of tumor cells, both of established B-ALL cell lines and of primary cells isolated from the peripheral blood of patients suffering from different types of B cell malignancies. The gene discussed is CD19; the disease is acute lymphoblastic leukemia.