The present invention relates to bispecific antibodies. In particular, the present invention provides a heterodimeric antibody comprising: a) a CD3 binding domain； b) a CD123 binding domain； and c) a first Fc domain and a second Fc domain； wherein said CD123 binding domain comprises a heavy variable domain comprising a VHCDR1 of SEQ ID NO:440, a VHCDR2 of SEQ ID NO:441, and a VHCDR3 of SEQ ID NO:442； and a variable light domain comprising a VLCDR1 of SEQ ID NO:444； a VLCDR2 of SEQ ID NO:445, a VLCDR3 of SEQ ID NO:446. In another aspect, the present invention provides a heterodimeric antibody comprising: a) a first monomer comprising: i) a first Fc domain； ii) a CD3 binding domain； b) a second monomer comprising: i) a heavy variable domain； and ii) a heavy chain constant domain comprising a second Fc domain； and c) a light chain comprising a variable light domain and a variable light constant domain； wherein said variable light domain comprises a VLCDR1 of SEQ ID NO:444； a VLCDR2 of SEQ ID NO:445, a VLCDR3 of SEQ ID NO:446； and wherein said heavy variable domain comprises a VHCDR1 of SEQ ID NO:440, a VHCDR2 of SEQ ID NO:441, and a VHCDR3 of SEQ ID NO:442. The antibodies of the invention are useful in the manufacture of a medicament for treating cancer including； hematopoietic malignancies, B cell lymphomas and leukemias, non-Hodgkin’s lymphoma (NHL), Burkitt’s lymphoma (BL), multiple myeloma (MM), B chronic lymphocytic leukemia (B-CLL), B and T acute lymphocytic leukemia (ALL), T cell lymphoma (TCL), acute myeloid leukemia (AML), hairy cell leukemia (HCL), Hodgkin’s Lymphoma (HL), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML).
