Bispecific antibody and use thereof

A bispecific antibody, which is composed of two identical polypeptide chains bonded covalently to form a tetravalent homodimer,

• wherein each of the polypeptide chains has an amino acid sequence of SEQ ID NO:
• 20,
• wherein each of the polypeptide chains consists of an anti-BCMA scFv, a linker peptide L2, an anti-CD3 scFv, and an Fc fragment in series,
• wherein VH and VL within the anti-BCMA scFv and the anti-CD3 scFv are connected by (GGGGS)3 respectively,
• wherein the amino acid sequences of the VH and the VL of the anti-BCMA scFv are SEQ ID NO:
• 7 and SEQ ID NO:
• 8, respectively,
• wherein the amino acid sequences of the VH and the VL of the anti-CD3 scFv are SEQ ID NO:
• 17 and SEQ ID NO:
• 18, respectively, and
• wherein the linker peptide L2 consists of a flexible peptide and a rigid peptide,
• wherein the flexible peptide is G2(GGGGS)3, and
• wherein the rigid peptide is SSSSKAPPPS.