Multivalent binding molecules

1. A bispecific and tetravalent antigen-binding protein complex comprising:

a. a first dual binding module (DBM1) comprising a variable heavy chain (V H ) polypeptide and a variable light chain (V L ) polypeptide;

b. a second dual binding module (DBM2) comprising a variable heavy chain polypeptide and a variable light chain polypeptide; and

c. a homo- or hetero-dimerization domain (HDM) module comprising two polypeptides, wherein

the first HDM polypeptide is covalently linked to the variable heavy or light chain of DBM1 and comprises a first HDM dimerization domain, and the second HDM polypeptide is covalently linked to the variable heavy or light chain of DBM1 and comprises a second HDM dimerization domain, which specifically binds to the first HDM dimerization domain, wherein:

(i) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 17 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 18;

(ii) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 19 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 20;

(iii) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 21 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 22;

(iv) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 23 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 24;

(v) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 25 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 26;

(vi) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 27 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 28; or

(vii) the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 32 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 33.

2. The antigen-binding protein complex of claim 1 , further comprising at least one pharmaceutically active moiety and/or imaging molecule.

3. The antigen-binding protein complex of claim 2 , wherein the pharmaceutically active moiety is selected from the group consisting of a ligand and an effector molecule.

4. The antigen-binding protein complex of claim 3 , wherein

a. the ligand is selected from the group consisting of an antigen-binding molecule, scaffold protein, natural ligand, ligand-binding receptor fragment, and aptamer,

wherein the antigen-binding molecule is selected from the group consisting of a Fab fragment, a Fab′ fragment, a heavy chain antibody, a single-domain antibody (sdAb), variable domain of a heavy chain antibody, a single-chain variable fragment (scFv), a tandem scFv, a bispecific T-cell engager, a single-chain diabody, a triple body, a nanoantibody, and a fusion protein thereof; or

b. the effector molecule is selected from the group consisting of cytokine, chemokine, immune (co)-stimulatory molecule, immunosuppressive molecule, death ligand, apoptosis-inducing protein, kinase, prodrug-converting enzyme, RNase, agonistic antibody or an antigen binding antibody fragment thereof, antagonistic antibody or an antigen binding fragment thereof, toxins growth factor, hormone, coagulation factor, fibrinolytic protein, and a fusion proteins.

5. The antigen-binding protein complex of claim 2 , wherein the imaging molecule is selected from the group consisting of bioluminescent reagent, chemiluminescent reagent, fluorescent imaging reagent, photosensitizer, chelating reagent, and a radioactive moiety.

6. A method for treatment of EGFR and HER3, CD3 and HER3 or HER2 and HER3 expressing comprising administering to a subject in need thereof an amount effective of the antigen-binding protein complex of claim 1 .

7. A bispecific tetravalent diabody-Ig, wherein the diabody-Ig molecule comprises:

a. a first dual binding module (DMB1) comprising:

i. a first heavy chain polypeptide comprising a diabody in a VHA-VLB orientation, wherein said VHA and VLB are connected by a peptide linker (L1) of five amino acids in length to prevent binding of VHA and VLA to each other, fused to a dimerization domain, and an Fc comprising a CH2 and a CH3 domain, and

ii. a first light chain polypeptide comprising a VHB-VLA orientation fused to a dimerization domain; and

b. a second DMB module (DBM2) comprising:

i. a second heavy chain polypeptide comprising a diabody in a VHA′-VLB′ orientation, wherein said VHA′ and VLB′ are connected by a peptide linker (L1) of five amino acids in length to prevent binding of VHA′ and VLA′ to each other, fused to a dimerization domain, and an Fc comprising a CH2 and a CH3 domain, and

ii. a second light chain polypeptide comprising a VHB′-VLA′ fused to a dimerization domain;

wherein the dimerization domain is selected from the group consisting of CH1 and CL heterodimerization domain, a human IgE CH2 homodimerization domain (EHD2), a human IgM CH2 domain (MHD2), a EHD2 having C247S/C337S substitutions, and EHD2 having C337S/C247S substitutions, wherein:

a. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 17 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 18;

b. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 19 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 20;

c. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 21 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 22;

d. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 23 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 24;

e. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 25 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 26;

f. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 27 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 28; or

g. the variable heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 32 and the variable light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 33.

8. The bispecific tetravalent diabody-Ig of claim 7 , wherein the heavy chain polypeptide comprises the amino acid sequence of SEQ ID NO: 23 and the light chain polypeptide comprises the amino acid sequence of SEQ ID NO: 24; and wherein the heterodimerization domain comprises EHD2 having C247S/C337S substitutions (hetEHD2).