A human bispecific T-cell engager antibody composed of a fixed-light-chain (FLC) arm targeting the CD3 antigen found on T-lymphocytes and a heavy-chain-only (HCO) arm targeting the B-cell-specific membrane protein CD19, with potential immunostimulating and antineoplastic activities. Upon administration, surovatamig binds to both the CD3 antigen on cytotoxic T-lymphocytes (CTLs) and the CD19 antigen expressed on malignant B-cells. This activates and redirects CTLs to CD19-expressing tumor cells, resulting in CTL-mediated killing of tumor cells. CD19 is a membrane antigen that is widely expressed during B-cell development, from pro-B-cell to early plasma cell stages. The FLC arm weakly activates CD3. The HCO arm has a high affinity anti-CD19 moiety.