Bispecific antibody molecule

1. A recombinant bispecific antibody molecule consisting of a Fab fragment comprising a first binding site for a first antigen, a single chain Fv fragment comprising a second binding site for a second antigen and an immunoglobulin IgG1 CH2 domain,

wherein the Fab fragment and the single chain Fv fragment are linked via the CH2 domain,

wherein at least three amino acid residues of the CH2 domain that are able to mediate binding to Fe receptors are deleted or mutated by substitution with a different amino acid, thereby attenuating the binding of the CH2 domain to Fc receptors, wherein the at least three amino acid residues of the CH2 domain consist of sequence position 233 and at least two amino acids selected from the group consisting of sequence position 228, 230, 231, 232, 234, 235, 236, 237, 238, 265, 297, 327, and 330 (numbering of sequence positions according to the EU-index), and

wherein further the amino acid residues of sequence positions 226 and 229 are deleted or mutated by substitution with a different amino acid,

wherein either the first binding site or the second binding site binds a tumor associated antigen, and

wherein the other of the first binding site or the second binding site binds a T cell or NK (natural killer) cell specific receptor molecule.

2. The antibody molecule of claim 1 , wherein the tumor associated antigen is selected from the group consisting of CD10, CD19, CD20, CD21, CD22, CD25, CD30, CD33, CD34, CD37, CD44v6, CD45, CDw52, Fms-like tyrosine kinase 3 (FLT-3, CD135), c-Kit (CD117), CSF1R, (CD115), CD133, PDGFR-α (CD140a), PDGFR-β (CD 140b), chondroitin sulfate proteoglycan 4 (CSPG4, melanoma-associated chondroitin sulfate proteoglycan), Muc-1, EGFR, de2-7-EGFR, EGFRvIII, Folate binding protein, Her2neu, Her3, PSMA, PSCA, PSA, TAG-72, HLA-DR, IGFR, CD133, IL3R, fibroblast activating protein (FAP), Carboanhydrase IX (MN/CA IX), Carcinoembryonic antigen (CEA), EpCAM, CDCP1, Derlin1, Tenascin, frizzled 1-10, VEGFR2 (KDR/FLK1), VEGFR3 (FLT4, CD309), Endoglin, CLEC14, Tem1-8, and Tie2.

3. The antibody molecule of claim 1 , wherein the T-cell or NK cell specific receptor molecule is one of CD3, the T cell receptor (TCR), CD28, CD16, NKG2D, Ox40, 4-1BB, CD2, CD5 and CD95.

4. The antibody molecule of claim 3 , wherein the TCR is TCR (alpha/beta) or TCR (gamma/delta).

5. The antibody molecule of claim 1 , wherein the Fab fragment is linked to the CH2 domain via the heavy chain CH1 and VH domains of the Fab fragment or via the CL and VL light chain domains of the Fab fragment.

6. The antibody molecule of claim 5 , wherein the heavy chain domains of the Fab fragment or the light chain domains of the Fab fragment are arranged at the N-terminus of the antibody molecule.

7. The antibody molecule of claim 6 , wherein the CH2 domain is linked to the scFv fragment via the variable domain of the light chain (VL domain) of the scFv fragment that comprises the second binding site.

8. The antibody molecule of claim 6 , wherein the CH2 domain is linked to the scFv fragment via the variable domain of the heavy chain (VH domain) of the scFv fragment that comprises the second binding site.

9. The antibody molecule of claim 1 , wherein the Fab fragment that comprises the first binding site for the first antigen consists of the VL domain fused to the CH1 domain and the VH domain fused to the CL domain.

10. The antibody molecule of claim 9 , wherein the CH1 domain of the Fab fragment is fused to the CH2 domain.

11. The antibody molecule of claim 9 , wherein the VL-CH1 chain of the Fab fragment is arranged at the N-terminus of the antibody molecule.

12. The antibody molecule of claim 1 , wherein the first binding site binds a tumor associated surface antigen and the second binding site binds one of CD3, the T cell receptor (TCR), CD28, CD16, NKG2D, Ox40, 4-1BB, CD2, CD5 and CD95.

13. A pharmaceutical composition comprising an antibody molecule as defined in claim 1 .