Heteromeric proteins comprising three heteromerization improving substitution, production, combinations and applications thereof

Abstract

The present invention generally relates to the production and use of antigen-binding proteins. The invention relates to heteromeric antigen-binding proteins, their production and their use. In particular the invention relates to the combination of an antigen-binding protein binding to a peptide according to SEQ ID NO: 57 or to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a peptide according SEQ ID NO: 58 or to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins. Furthermore, the invention relates to heteromeric antigen-binding proteins with improved heterodimerisation properties and correspondingly improved production properties. The invention also relates to co-expression of at least two heteromeric antigen-binding proteins. The invention further relates to heteromeric antigen-binding proteins for use in the treatment of diseases, in particular cancer, optionally wherein nucleic acids encoding said antigen-binding proteins are administered to the subject.

Description

The present invention generally relates to the production and use of antigen-binding proteins. The invention relates to heteromeric antigen-binding proteins, their production and their use. In particular the invention relates to the combination of an antigen-binding protein binding to a peptide according to SEQ ID NO: 57 or to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a peptide according SEQ ID NO: 58 or to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigenbinding proteins. Furthermore, the invention relates to heteromeric antigen-binding proteins with improved heterodimerisation properties and correspondingly improved production properties. The invention also relates to co-expression of at least two heteromeric antigenbinding proteins. The invention further relates to heteromeric antigen-binding proteins for use in the treatment of diseases, in particular cancer, optionally wherein nucleic acids encoding said antigen-binding proteins are administered to the subject. Proteins serve as the building blocks of life, orchestrating a multitude of physiological processes within the human body. Leveraging their inherent biological activity, researchers exploit protein-based therapeutics to intervene in disease pathways at the molecular level, offering promising solutions for conditions ranging from cancer and autoimmune disorders to metabolic diseases and infections. Bispecific proteins represent an emerging innovative class of protein-based therapeutics designed to simultaneously target two different epitopes or proteins, thereby offering enhanced therapeutic efficacy and versatility compared to traditional monospecific drugs. Bispecific proteins hold immense promise for treating a wide array of diseases, including cancer, autoimmune disorders, and infectious diseases. An example for bispecific molecules that hold tremendous potential to treat e.g. cancer is the so called T cell Engaging Receptor (TCER®) format developed by the applicant of the present invention; see e.g. WO 2019 / 012138 Al herein incorporated. TCERs® are off-the-shelf biologies that leverage the body's immune system by redirecting and activating T cells towards cancer cells presenting specific tumor antigens. These novel biologies are engineered to allow T cells in the body to become activated and attack the tumor, regardless of the T cells' intrinsic specificity. A TCER® contains two polypeptide chains harboring a T cell-recruiting antibody domain and a pHLA-binding TCR domain. Furthermore, each of the polypeptide chains contains a Fc domain. The development and utilization of such protein-based therapeutics is crucial for the field of immunotherapy. However, the full spectrum of effectiveness of these promising drugs has not yet been recognized. For example, highly effective combination therapies involving immunotherapy are still not standard. Accordingly, there is a need for means and methods for additional effective cancer treatments. Thus, the technical problem underlying the present invention is the provision of means and methods to treat cancer. The technical problem is solved and the above mentioned needs are addressed by the provision of the embodiments characterized in the claims and as provided herein below. The patent applications EP24174662.7, EP24199013.4, EP25151617.5, EP24213284.3 and EP25166821.6 the preliminary results of a Phase 1 first-in-human clinical trials that tests the efficiency and safety of the bispecific antigen-binding molecules PRAME-004 TCER® and MAG-003 TCER® as monotherapy. Said molecules show excellent anti-tumor activity with acceptable side effects against different cancer types. In the appended Examples of the present application the inventors found surprisingly and unexpectedly that a synergistic anti-cancer effect is observed when a MAG-003 targeting TCER® and a PRAME-004 targeting TCER® are combined (see Example 4). Accordingly, the present invention provides a combination of the powerful anti-cancer molecules PRAME-004 TCER® and MAG-003 TCER® to allow treatment of a wide range of cancer types. In particular the invention relates to an antigen-binding protein binding to a peptide according to SEQ ID NO: 57 or to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a peptide according SEQ ID NO: 58 or to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins for use as medicine, in particular for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. The above mentioned and herein described antigen-binding proteins may be produced separately and administered in combination to a patient in need thereof as produced proteins. The skilled person understands that "combination" does not necessarily mean that the antigen-binding proteins are combined into one pharmaceutical composition and administered as one pharmaceutical composition but that "combination" is used herein in the broadest sense and refers to at least two therapeutically active drugs or compositions which may be administered or co-administered, simultaneously, in either separate or combined formulations, or sequentially at different times separated by minutes, hours or days, but in some way act together to provide the desired therapeutic response. It can be desirable to administer the to be combined antigen-binding proteins not as separately produced proteins but encoded by nucleic acids. In other words, it may be beneficial to administerto the patient nucleic acid(s) encoding the antigen-binding proteins so that antigenbinding proteins are produced by the cells of the patient. However, expressing two or more heterodimeric antigen binding proteins in the same production system can present significant challenges. A primary concern is the potential for mispairing between subunits of different heterodimers, leading to the formation of non-native or dysfunctional complexes. This mispairing can compromise the quality, efficacy, and safety of the therapeutic product, posing substantial hurdles for clinical use. For example, WO2013 / 157953 and WO2013 / 157954 describe charge changing amino acid substitutions in antibody-derived CH3-domain that facilitate heterodimerisation of proteins harboring said domains. However, further improvements are required. Accordingly, there is a need for means and methods that allow the correct assembly of heteromeric proteins, in particular heterodimeric proteins. Thus, the present invention also provides means and methods that allow the correct assembly of heteromeric proteins, in particular heterodimeric proteins. Specifically, the inventors developed CH3-domains that convey excellent multimerization, in particular heterodimerisation properties to proteins comprising said domains. Accordingly, the present invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C. As illustrated in the appended Example the present inventors surprisingly and unexpectedly found that the combination of a disulphide bridge with certain charge changing amino acid substitutions improves yield and stability of a heterodimeric protein. Example 1 in combination with Table 3 shows that a heterodimeric antigen-binding protein comprising the claimed charge changing amino acid substitutions and the claimed artificial disulphide bridge provided increased yield, increased heterodimerisation and improved stability. Furthermore, Example 2 in combination with Table 4 shows that said molecule can be co-expressed with another heterodimeric protein without formation of incorrectly assembled dimers. This was unexpected because the introduction of a disulphide bridge in molecules having other charge changing amino acid substitutions even reduced yield and heterodimerisation (see e.g. the molecule TPP-8629 in Table 3). That was further confirmed in Example 3 where it is shown that even when a Strep-Tag II is used for purification (i.e. native purification) up to 96% of the coexpressed heterodimeric antigen-binding proteins are correctly assembled. Accordingly, it is made plausible herein that MAG-003 and PRAME-004 targeting antigen-binding proteins can be combined for anti-cancer therapy. Accordingly, the invention provides combinations of specific amino acid substitutions in CH3 domains that convey excellent properties to heteromeric proteins for production an coexpression. In the following, the invention is described in more detail. In particular, the invention relates to the following items. 1. An antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C;or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C. 2. The antigen-binding protein of item 1, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and the amino acid variant S354C;or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and the amino acid variant Y349C. 3. The antigen-binding protein of item 1 or 2, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant Y349C. 4. The antigen-binding protein of any one of items 1 to 3, wherein the first and second polypeptide specifically bind to each other. 5. The antigen-binding protein of any one of items 1 to 4, wherein the amino acids substituted in the first polypeptide interact with the substituted amino acids in the second polypeptide. 6. The antigen-binding protein of any one of items 1 to 5, wherein the antigen-binding protein is a bispecific, trispecific or multispecific antigen-binding protein, preferably a bispecific antigen-binding protein. 7.   The antigen-binding protein of any one of items 1 to 6, wherein the antigen-binding protein comprises a first binding domain and a second binding domain. 8. The antigen-binding protein of item 7, wherein the first binding domain specifically binds to a cell surface molecule of a human immune cell and / or the second binding domain specifically binds to an MHC-associated peptide epitope. 9. The antigen-binding protein of item 7 or 8, wherein the first and / or second binding domain comprises or consists of (an) antibody(ies) or (a) functional fragment(s) or derivative(s) thereof. 10. The antigen-binding protein of any one of items 7 to 9, wherein the first and / or second binding domain comprises or consists of (a) T cell receptor(s) (TCR) or (a) functional fragment(s) or derivative(s) thereof. 11. The antigen-binding protein of any one of items 7 to 10, wherein the first binding domain comprises or consists of an antibody antigen binding site (VD). 12. The antigen-binding protein of any one of items 7 to 11, wherein the second binding domain comprises or consists of a TCR antigen binding site (VR). 13. The antigen-binding protein of item 11 or 12, wherein one polypeptide comprises the antibody variable light chain domain (VL) of the antigen binding site (VD) and the other polypeptide comprises the antibody variable heavy chain domain (VH) of the antigen binding site (VD). 14. The antigen-binding protein of any one of items 11 to 13, wherein one polypeptide comprises the TCR alpha variable domain (Va) of the antigen binding site (VR) and the other polypeptide comprises the TCR beta variable domain (VP) of the antigen binding site (VR). 15. The antigen-binding protein of item 13 or 14, wherein one polypeptide comprises the antibody variable light chain domain (VL) and the TCR beta variable domain (VP) and the other polypeptide comprises the antibody variable heavy chain domain (VH) and the TCR alpha variable domain (Va). 16. The antigen-binding protein of item 13 or 14, wherein one polypeptide comprises the antibody variable light chain domain (VL) and the TCR alpha variable domain (Va) and the other polypeptide comprises the antibody variable heavy chain domain (VH) and the TCR beta variable domain (VP). 17. The antigen-binding protein of any one of items 1 to 16, wherein the first polypeptide further comprises a CH2 domain and / orthe second polypeptide further comprises a CH2 domain. 18. The antigen-binding protein of item 17, wherein in one polypeptide the CH2 domain and the CH3 domain form a Fc domain FC1 and / or in the other polypeptide the CH2 domain and the CH3 domain form a Fc domain FC2. 19. The antigen-binding protein of any one of items 1 to 18, wherein the first polypeptide and the second polypeptide are on separate polypeptide chains or are connected by a linker. 20. The antigen-binding protein of any one of items 13 to 19, wherein the first polypeptide comprises a structure represented by the formula: V1-V2         [I]; and the second polypeptide comprises a structure represented by the formula: V3-V4         [II]; wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. 21. The antigen-binding protein of any one of items 13 to 20, wherein the variable domains are connected by linkers. 22. The antigen-binding protein of any one of items 13 to 21, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2              [III]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4             [IV]; wherein LI and L2 are linkers and may be the same or different, wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. 23. The antigen-binding protein of any one of items 13 to 22, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1        [V]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2        [VI]; wherein LI and L2 are linkers and may be the same or different, wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. 24. The antigen-binding protein of any one of items 13 to 23, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-L3-FC1            [VII]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-L4-FC2             [VIII]; wherein LI, L2, L3 and L4 are linkers and may be the same or different, and wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. 25. The antigen-binding protein of any one of items 21 to 24, wherein the linkers LI, L2, L3 and / or L4 comprise or consist of SEQ ID NO: 16 (GGGSGGGG). 26. The antigen-binding protein of any one of items 18 to 25, wherein FC1 and / or FC2 further comprise a hinge region, preferably wherein the hinge region comprises or consists of SEQ ID NO: 15 (EPKSS) or SEQ ID NO: 92 (EPKSC). 27. The antigen-binding protein of any one of item 18 to 26, wherein the FC1 and / or FC2 comprises at least one effector function silencing mutation at a residue selected from positions 233, 234, 235, 236, 297 and 331, preferably wherein said effector function silencing mutation is generated by replacing at least one residue in position 233, 234, 235, 236, and 331 with the corresponding residue derived from lgG2 or lgG4. 28. The antigen-binding protein of any one of items 18 to 27, wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1, 39, 88 or 90 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 39, 88 or 90; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2, 40, 89 or 91 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2, 40, 89 or 91. 29. The antigen-binding protein of any one of items 13 to 28, wherein the antibody variable light chain domain (VL) and the antibody variable heavy chain domain (VH) associate to form a functional antibody antigen binding site (VD). 30. The antigen-binding protein of any one of items 14 to 29, wherein the TCR alpha variable domain (Va) and the TCR beta variable domain (VP) associate to form a functional TCR antigen binding site (VR). 31. The antigen-binding protein of any one of item 8 to 30, wherein the cell surface molecule is known to induce the activation of the immune cell, or is at least one selected from the group consisting of immune response-related molecules, CD3, such as the CD3y, CD36, and CD3e chains, CD4, CD7, CD8, CD10, CDllb, CDllc, CD14, CD16, CD18, CD22, CD25, CD28, CD32a, CD32b, CD33, CD41, CD41b, CD42a, CD42b, CD44, CD45RA, CD49, CD55, CD56, CD61, CD64, CD68, CD94, CD90, CD117, CD123, CD125, CD134, CD137, CD152, CD163, CD193, CD203c, CD235a, CD278, CD279, CD287, Nkp46, NKG2D, GITR, FceRI, TCRa / p, TCRy / 6, and HLA-DR. 32. The antigen-binding protein of any one of item 8 to 31, wherein the cell surface molecule is a TCR / CD3 complex, preferably an alpha / beta TCR / CD3 complex. 33. The antigen-binding protein of item 32, wherein the antigen-binding protein comprises: an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. 34. The antigen-binding protein of item 32 or 33, wherein the antigen-binding protein comprises: a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 11, and 12, respectively. 35. The antigen-binding protein of item 32, wherein the antigen-binding protein comprises: an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. 36. The antigen-binding protein of item 32 or 35, wherein the antigen-binding protein comprises: a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10,14, and 12, respectively. 37. The antigen-binding protein of any one of items 12 to 36, wherein the TCR antigen binding site (VR) specifically binds to a bacterial peptide, a viral peptide or a tumor associated antigen peptide, preferably bound to a major histocompatibility complex (MHC) protein. 38. A nucleic acid or separate nucleic acids encoding an antigen-binding protein according to any one of the preceding items. 39. A vector comprising the nucleic acid or the separate nucleic acids or separate vectors comprising the separate nucleic acids according to item 38. 40. A host cell comprising the antigen-binding protein, the nucleic acid or separate nucleic acids, or the vector or the separate vectors according to any one of the preceding items. 41. A method for producing an antigen-binding protein, wherein the method comprises (i) cultivating the host cell of item 40, (ii) producing the antigen-binding protein, and optionally (iii) harvesting the host cell, and preferably (iv) isolating the antigen-binding protein. 42. The protein as obtained or obtainable by item 41. 43. A pharmaceutical composition comprising the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell according to any one of the preceding items or the antigen binding protein as obtained by item 42. 44. The pharmaceutical composition, the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell according to any one of the preceding items or the antigen binding protein as obtained by item 42 for use in medicine. 45. The pharmaceutical composition, the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, or the host cell according to any one of the preceding items or the antigen binding protein as obtained by item 42 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. 46. A method of treatment of a disease or disorder comprising administering a therapeutically effective amount of the pharmaceutical composition, the antigenbinding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell according to any one of the preceding items or the antigen binding protein as obtained by item 42 to a patient in need thereof. 47. A method of mutating an antigen-binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cystein, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cystein; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cystein, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. 48. A method of increasing the heterodimerisation of an antigen binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. 49. A method of increasing the stability of an antigen binding protein, wherein the antigenbinding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. 50. A method of increasing the yield of an antigen binding protein, wherein the antigenbinding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. 51. A method of increasing the purity of an antigen binding protein, wherein the antigenbinding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. 52. A method for producing at least two different heteromeric antigen-binding proteins in a single host cell, comprising (i) cultivating the host cell, (ii) producing the antigen-binding proteins, and optionally (iii) harvesting the host cell, and preferably (iv) isolating the antigen-binding proteins, wherein the host cell comprises a nucleic acid encoding a first antigen-binding protein comprising at least one heteromerization improving amino acid substitution and a nucleic acid encoding a second antigen-binding protein comprising at least one heteromerization improving substitution. 53. The method of item 52, wherein the heteromeric antigen-binding proteins are heterodimers and the heteromerization improving amino acid substitutions are heterodimerization improving amino acid substitutions. 54. The method of item 53, wherein the first antigen-binding protein is an antigen-binding protein according to any one of the preceding items. 55. The method of item 54, wherein the heteromerization improving amino acid substitutions of the second antigen-binding protein are knob-into-hole amino acid substitutions or wherein the second antigen-binding protein is an antigen-binding protein according to any one of the preceding items. 56. The method of item 55, wherein the second antigen-binding protein comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid variant T366W and the other polypeptide comprises the amino acid variant T366S, L368A and Y407V. 57. The method of item 56, wherein of the second antigen-binding protein one polypeptide further comprises the amino acid variant S354C and the other polypeptide further comprises the amino acid variant Y349C. 58. The method of item 57, wherein the second antigen-binding protein comprises one polypeptide comprising the amino acid sequence according to SEQ ID NO: 17 and another polypeptide comprising the amino acid sequence according to SEQ ID NO: 18. 59. The method of any one of items 52 to 54, wherein the second antigen-binding protein comprises one polypeptide comprising the sequence according to SEQ ID NO: 19 and another polypeptide comprising the amino acid sequence according to SEQ ID NO: 20. 60. The method of any one of items 52 to 54, wherein the second antigen-binding protein comprises one polypeptide comprising the sequence according to SEQ ID NO: 21 and another polypeptide comprising the amino acid sequence according to SEQ ID NO: 22. 61. The antigen-binding proteins as obtained or obtainable by the method of any one of items 52 to 60. 62. A pharmaceutical composition comprising at least two of the antigen-binding proteins as defined in any one of the preceding items. 63. A pharmaceutical composition comprising a nucleic acid or separate nucleic acids encoding at least two of the antigen-binding proteins as defined in any one of the preceding items. 64. The pharmaceutical composition of item 62 or 63 for use in medicine. 65. The pharmaceutical composition of item 64 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. 66. A method of treatment of a disease or disorder comprising administering a therapeutically effective amount of the pharmaceutical composition of item 62 or 63 to a patient in need thereof. 67. An antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex(MHC) protein for use as medicine. 68. An antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. 69. A combination comprising an antigen-binding protein binding to MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigenbinding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 70. A pharmaceutical composition comprising an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 71. A pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding at least two antigenbinding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition and wherein one of the at least two antigenbinding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and another of the at least two antigenbinding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 72. An antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 73. An antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein. 74. A method of protein production in a cell population, wherein the method comprises contacting a cell population with a nucleic acid or nucleic acids encoding at least two antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid or nucleic acids under conditions such that an effective amount of the protein is produced in the cell population, wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 75. A method for inducing in vivo translation of at least two antigen-binding proteins in a subject in need thereof, comprising administering to the subject an effective amount of a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid or nucleic acids under conditions such that the nucleic acid(s) is / are localized into a cell of the subject and the antigen-binding proteins are capable of being translated in the cell from the nucleic acid(s), wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 76. A method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein. 77. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 67 to 76, comprising one or more further antigenbinding proteins. 78. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 67 to 77, wherein the antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and the antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) and optionally one or more further antigen-binding proteins act together to provide a desired therapeutic effect. 79. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 67 to 78, wherein the MAGEA4 / 8 derived peptide is a peptide according to SEQ ID NO: 57. 80. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 67 to 79, wherein the PRAME derived peptide is a peptide according to SEQ ID NO: 58. 81. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 79 to 80, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises a T cell receptor (TCR) alpha variable domain (Va) and a TCR beta variable domain (VP), wherein the Va domain comprises (i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 62, (ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 63, and (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 64; and wherein the VP domain comprises (i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 59, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 60, and (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 61, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. 82. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 79 to 81, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 54 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 54 and comprising the CDRal, CDRa2, and CDRa3 according to SEQ ID NOs: 62, 63, and 64, respectively; and a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 53 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 53 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQ ID NOs: 59, 60, and 61, respectively. 83. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 79 to 82, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. 84. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 79 to 83, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 11, and 12, respectively. 85. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 79 to 84, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises or consists of a first polypeptide chain comprising a structure represented by the formula: VL-L1-VP-FC1; and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2; wherein LI and L2 are linkers and may be the same or different and FC1 and FC2 are Fc-domains and may be the same or different. 86. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of item 85, wherein LI and / or L2 comprise or consist of an amino acid sequence according to SEQ ID NO: 16. 87. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of item 85 or 86, wherein FC1 comprises or consists of an amino acid sequence according to SEQ ID NOs: 1,17,19, 21 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 17, 19, 21 or 39 and / or FC2 comprises or consists of an amino acid sequence according to SEQ ID NOs: 2,18, 20, 22 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2, 18, 20, 22 or 40. 88. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 79 to 87, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 75, 79, 80 or 82 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76, 81 or 83. 89. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 80 to 88, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises a T cell receptor (TCR) alpha variable domain (Va) and a TCR beta variable domain (VP), wherein the Va domain comprises (i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 68, (ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 69, and (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 70; and wherein the VP domain comprises (i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 65, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 66, and (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 67, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. 90. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 80 to 89, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 56 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 56 and comprising the CDRal, CDRa2, and CDRa3 according to SEQ ID NOs: 68, 69, and 70, respectively; and a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 55 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 55 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQ ID NOs: 65, 66, and 67, respectively. 91. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 80 to 90, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. 92. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 80 to 91, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10,14, and 12, respectively. 93. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 80 to 92, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises or consists of a first polypeptide chain comprising a structure represented by the formula: VL-L1-VP-FC1; and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2; wherein LI and L2 are linkers and may be the same or different and FC1 and FC2 are Fc-domains and may be the same or different. 94. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of item 93, wherein LI and / or L2 comprise or consist of an amino acid sequence according to SEQ ID NO: 16. 95. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of item 93 or 94, wherein FC1 comprises or consists of an amino acid sequence according to SEQ ID NOs: 1,17,19, 21 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 17, 19, 21 or 39 and / or FC2 comprises or consists of an amino acid sequence according to SEQ ID NOs: 2,18, 20, 22 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2, 18, 20, 22 or 40. 96. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of items 80 to 95, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 71, 74, 84 or 86 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72, 85 or 87. As mentioned above the present inventors identified amino acid substitutions that improve heterodimerization of heteromeric proteins when combined with substitutions that introduce a disulphide bridge. In other words, the substitutions identified by the inventors facilitate the interaction of subunits of heteromeric proteins when combined with substitutions that introduce a disulphide bridge. Amino acid substitutions that improve heterodimerization of heteromeric proteins refer to changes in the amino acid sequence of a polypeptide that enhance its ability to selectively pair and form complexes with a specific, non-identical partner polypeptide, while minimizing interactions with itself (or other unintended polypeptides). For example, when a protein consists of two non-identical subunits it may be referred to as a heterodimeric protein. In this case it is envisaged in context of the invention that one subunit comprises the substitutions to negatively charged amino acids and the other subunit comprises the substitutions to positively charged amino acids. It is envisaged that due to repulsion of the same charge the interaction of the identical subunits is reduced. In contrast, due to attraction of different charges the interaction of two of the non-identical subunits is facilitated. It is in particular envisaged that the polypeptides that are supposed to interact comprise antibody derived CH3-domains. The CH3-domain is the third constant domain of the heavy chain of an antibody and is located in the Fc region. The CH3 domain contributes to the dimerization of the antibody's heavy chains and provides a structural platform for interactions with Fc receptors and complement proteins. This domain plays a critical role in antibody stability and its ability to elicit immune responses. It is envisaged that the described polypeptides are derived from humans. In particular it is envisaged that the IgG CH3 domains are human. The present inventors identified amino acid substitutions in the CH3-domain that improve heterodimerization of heteromeric proteins when combined with substitutions that introduce a disulphide bridge. The amino acid positions provided herein are positions according to the EU numbering system of antibodies. Accordingly, the skilled person understands that the disclosed amino acid positions are not necessarily the position in the molecule used but the position the residue would have in an antibody, preferably an IgG antibody, more preferably an IgGl antibody. For example, when it is referred herein to e.g. a T366K substitutions, for example in a TCER®, the threonine which has been substituted with lysine is not necessarily at position 366but it refers to the threonine which would be at position 366 in a IgG molecule. The skilled person is readily capable to determine which position the substitution in the antigen binding protein actually is. The skilled person may align the CH3-domain of an antibody with the antigen binding protein sequence and determine the actual position of e.g. threonine 366 of the antibody. Accordingly, it is envisaged that the inventive molecule comprises CH3-domains. It is envisaged that the inventive molecule comprises CH3-containing polypeptides. "CH3-containing polypeptides" and "CH3-domain-containing polypeptides" are used synonymously herein. In the first polypeptide of the molecule or protein of the invention the amino acid at position 351 may be substituted by a negatively charged amino acid. Also, in the first polypeptide the amino acid at position 368 may be substituted by a negatively charged amino acid. Furthermore, in the second polypeptide the amino acid at position 351 may be substituted by a positively charged amino acid. In addition, in the second polypeptide the amino acid at position 366 may be substituted by a positively charged amino acid. These substitutions may be combined with the amino acid variant Y349C in the first polypeptide and the amino acid variant S354C in the second polypeptide or the amino acid variant S354C in the first polypeptide and the amino acid variant Y349C in the second polypeptide. It is envisaged that the cysteine at position 354 30 in one polypeptide forms a disulphide bridge with the cysteine at position 349 in the other polypeptide. The terms "disulphide bridge", "cysteine bridge", "disulphide bond" or "cysteine bond" may be used synonymously herein and refers to a covalent bond formed by two thiol groups. The term "amino acid variant" as used herein may refer to a change in the sequence of amino acids in a protein, resulting from a substitution, insertion or deletion. For example, S354C means that the serine at position 354 in the CH3-domain of an antibody is exchanged / replaced by a cysteine. Preferably, the inventive molecule is an antigen-binding protein. "Antigen-binding protein" as used herein refers to a protein that specifically recognizes an antigen through its antigenbinding site(s). The term "antigen" or "target antigen" as used herein refers to a molecule or a portion of a molecule or complex that is capable of being bound by at least one antigen binding site of e.g. an antigen-binding protein. The terms "antigen" and "epitope" may be used interchangeably herein. However, "epitope" may also refer to a specific molecular structure on the antigen. The antigen or epitope is bound by the antigen-binding site or antigen-binding domain. Accordingly, the term "antigen-binding site" or "antigen-binding domain" as used herein refers to the structure in the antigen-binding protein that interacts with the antigen or epitope e.g. via hydrogen bonds, electrostatic interactions and hydrophobic interactions. The phrases "the antigen-binding protein specifically recognizes", "the antigen-binding protein is reactive with", "the antigen-binding protein binds" or "the antigen-binding protein specifically binds" may be used synonymously herein and refers to the ability of a protein to bind to another molecule, typically another protein / peptide, a specific region on a protein / peptide, a protein / protein complex or a protein / peptide complex, with high affinity and specificity. This recognition may occur through complementary molecular surfaces or structures, where specific interactions take place, such as hydrogen bonds, electrostatic interactions and hydrophobic interactions. Affinity refers to the strength of the interaction between two molecules. In the context of proteins, it typically describes how tightly a protein binds to another molecule, such as an antigen. Higher affinity implies a stronger binding interaction, while lower affinity suggests a weaker binding. Affinity is often quantified by the dissociation constant (Kd). Lower Kd values indicate higher affinity. Specificity refers to the selectivity of a molecular interaction, particularly the ability of a molecule (such as a protein) to discriminate between different ligands or binding partners. Thus, in the context of proteins, specificity may relate to the ability of a protein to bind selectively to its cognate ligand or binding partner, despite the high concentration of other molecules present in the corresponding environment. It is evident for the skilled person that in context of the present invention specificity may mean the ability of an antigen-binding protein to discriminate between different antigens and to bind selectively to its target antigen. Accordingly, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C. The invention also relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C. In particular it is envisaged in context of the invention that in the first polypeptide of the protein the amino acid at position 351 is substituted by a aspartic acid or glutamic acid. Also, in the first polypeptide the amino acid at position 368 may be substituted by aspartic acid or glutamic acid. Furthermore, in the second polypeptide the amino acid at position 351 may be substituted by lysine, arginine or histidine. In addition, in the second polypeptide the amino acid at position 366 may be substituted by lysine, arginine or histidine. These substitutions may be combined with the amino acid variant Y349C in the first polypeptide and the amino acid variant S354C in the second polypeptide or the amino acid variant S354C in the first polypeptide and the amino acid variant Y349C in the second polypeptide. Accordingly, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and amino acid variant S354C. Additionally, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and amino acid variant Y349C. In particular it is envisaged in context of the invention that in the first polypeptide of the protein the amino acid at position 351 is substituted by a aspartic acid. Also, in the first polypeptide the amino acid at position 368 may be substituted by glutamic acid. Furthermore, in the second polypeptide the amino acid at position 351 may be substituted by lysine. In addition, in the second polypeptide the amino acid at position 366 may be substituted by lysine. These substitutions may be combined with the amino acid variant Y349C in the first polypeptide and the amino acid variant S354C in the second polypeptide or the amino acid variant S354C in the first polypeptide and the amino acid variant Y349C in the second polypeptide. Accordingly, in a preferred embodiment the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C. In another preferred embodiment the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant Y349C. Again it is pointed out that it is evident for the skilled person that the amino acid positions provided above are not necessarily the positions in the described protein but refer to the corresponding position in a wildtype IgG antibody. Accordingly, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the CH3 domain of the first polypeptide has aspartic acid at the position corresponding to position 351 in an IgG antibody, glutamic acid at the position corresponding to position 368 in an IgG antibody, and cysteine at the position corresponding to position 349 in an IgG antibody; and the CH3 domain of the second polypeptide has lysine at the position corresponding to position 351 in an IgG antibody, lysine at the position corresponding to position 366 in an IgG antibody, and cysteine at the position corresponding to position 354 in an IgG antibody. In addition, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the CH3 domain of the first polypeptide has aspartic acid at the position corresponding to position 351 in an IgG antibody, glutamic acid at the position corresponding to position 368 in an IgG antibody, and cysteine at the position corresponding to position 354 in an IgG antibody; and the CH3 domain of the second polypeptide has lysine at the position corresponding to position 351 in an IgG antibody, lysine at the position corresponding to position 366 in an IgG antibody, and cysteine at the position corresponding to position 349 in an IgG antibody. It is envisaged that the first and the second polypeptide of the described antigen-binding proteins specifically bind to each other, preferably (inter alia) via their CH3-domains. Accordingly, the invention relates to antigen-binding proteins comprising two IgG CH3- containing polypeptides as described herein, wherein the first and second polypeptide specifically bind to each other. As mentioned above it is envisaged that the substituted amino acids facilitate the interaction of the polypeptides or in other words facilitate the binding of the polypeptides to each other e.g. by electrostatic attraction. Without necessarily bound by scientific theory, it is envisaged that aspartic acid at position 351 and glutamic acid at position 368 form electrostatic interactions with lysine at positions 351 and 366. In particular, it is envisaged that aspartic acid at position 351 and glutamic acid at position 368 form electrostatic interactions with lysine at positions 366. Accordingly, the invention relates to the herein described proteins, wherein the amino acids substituted in the first polypeptide interact with the substituted amino acids in the second polypeptide. It is envisaged that the antigen-binding proteins in context of the invention have more than one antigen-binding site. In other words, the antigen-binding protein in context of the invention may be a bispecific, trispecific or multispecific antigen-binding protein, preferably a bispecific antigen-binding protein. Accordingly, the invention relates to the herein described proteins, wherein the antigen-binding protein is a bispecific, trispecific or multispecific antigen-binding protein, preferably a bispecific antigen-binding protein. The term "bispecific" in connection with the herein described antigen-binding proteins refers to antigen-binding proteins with at least two valences and binding specificities for two different antigens and, thus, comprise at least two antigen-binding sites. The term "valence" refers to the number of binding sites of an antigen-binding protein, e.g. a bivalent antigenbinding protein relates to an antigen-binding protein that has two binding sites. It should be noted, that, the term valence refers to the number of binding sites, wherein those binding sites may bind to the same or different targets, i.e. a bivalent antigen binding protein may be monospecific, i.e. binding one target, or bispecific, i.e. binding two different targets. Targets may be antigens, such as (target) peptides. In the context of "bispecific" it is preferred herein that at least one specificity of the antigen binding sites is derived from a TCR, more particularly, that at least one antigen-binding site comprises the TCR derived CDRs as described herein. It may also refer that the at least two binding sites are derived from antibodies. In particular, the term "bispecific" in the context of the present invention may refer to an antigen-binding protein which combines at least one antigen-binding site comprising TCR derived CDRs, and at least one further antigen-binding site, wherein said at least one further antigen-binding site, may be derived from an antibody and thus comprises antibody CDRs, or from a further TCR and thus comprises the CDRs of a further TCR, preferably said further antigen binding site, is derived from an antibody and thus comprises antibody CDRs. As mentioned before, a preferred format is the TCER® format. However, it is envisaged that the herein provided modified CH3 domains may be comprised in any other antigen binding protein. When it is referred to a bispecific molecule it is, however, possible that e.g. the Fc part of said molecule has an additional binding partner e.g. FcRn. Thus, the the antigen-binding proteins in context of the invention may have a first binding domain / site and a second binding domain / site. Accordingly, the invention relates to the herein described proteins, wherein the antigen-binding protein comprises a first binding domain / site and a second binding domain / site. "Binding domain / site" and "antigen-binding domain / site" may be used interchangeably herein. It is envisaged that one antigen binding domain binds to a cell surface molecule of a human immune cell. It is envisaged that said surface molecule is known to induce the activation of the immune cell, or is at least one selected from the group consisting of immune response-related molecules, CDS, such as the CDSy, CD36, and CD3e chains, CD4, CD7, CD8, CD10, CDllb, CDllc, CD14, CD16, CD18, CD22, CD25, CD28, CD32a, CD32b, CD33, CD41 , CD41b, CD42a, CD42b, CD44, CD45RA, CD49, CD55, CD56, CD61, CD64, CD68, CD94, CD90, CD117, CD123, CD125, CD134, CD137, CD152, CD163, CD193, CD203c, CD235a, CD278, CD279, CD287, Nkp46, NKG2D, GITR, FceRI, TCRa / P, TCRy / 6, and HLA-DR. In particular, the cell surface molecule may be a TCR / CD3 complex, preferably an alpha / beta TCR / CD3 complex. Said antigen binding site may be antibody derived. Accordingly, a VH and VL may form an antigen-binding domain that specifically binds to a T cell receptor complex. Binding of the antigen-binding domain that specifically binds to a T cell receptor complex may activate the T cell. Corresponding variable domains and CDRs are described throughout this application. The domain may bind to any part or epitope of the alpha / beta TCR / CD3 complex. It is also envisaged that one binding domain specifically binds to an MHC-associated peptide or MHC-associated peptide epitope. MHC proteins are a set of cell surface proteins essential forthe acquired immune system to recognize foreign molecules in vertebrates, which interalia determines histocompatibility. The main function of MHC molecules is to bind to antigens derived from pathogens and tumor antigens and display them on the cell surface for recognition by the appropriate T cells. It is preferred that the MHC protein belongs to MHC class I. It is further preferred that the MHC protein is of the serotype group HLA-A, preferably HLA-A*24 or HLA-A*02. It is most preferred that the MHC protein is of the serotype HLA-A*02. The skilled person is well aware that HLA-A*02 can be further subdivided. A preferred serotype is HLA-A*02:01. The skilled person understands that when it is referred herein to HLA-A*02 the serotype HLA-A*02:01 is preferred. As described further herein it is in particular envisaged that the antigen-binding domain binding to an MHC-associated peptide comprises or consists of a T cell receptor (TCR) or a functional fragment or derivative thereof. Accordingly, it is envisaged that the herein described antigen-binding proteins comprises a first binding domain specifically binding to a cell surface molecule of a human immune cell and / or a second binding domain specifically binding to an MHC-associated peptide epitope. Accordingly, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and amino acid variant Y349C; and wherein the antigen-binding protein comprises a first binding domain specifically binding to a cell surface molecule of a human immune cell and a second binding domain specifically binding to an MHC-associated peptide epitope. Furthermore, it is envisaged that in the herein described antigen-binding proteins the first and / or second binding domain comprises or consists of an antibody or a functional fragment or derivative thereof. In an "antibody" also called "immunoglobulin" two heavy chains are linked to each other by disulfide bonds and each heavy chain is linked to a light chain by a disulfide bond. There are two types of light chain, lambda (I) and kappa (k). There are five main heavy chain classes (or 37 isotypes) which determine the functional activity of an antibody molecule: IgM, IgD, IgG, IgA and IgE. Each chain contains distinct sequence domains. The light chain includes two domains or regions, a variable domain (Vl) and a constant domain (Cl). The heavy chain includes four domains, a variable domain (Vh) and three constant domains (CHI, CH2 and CH3, collectively referred to as CH or Fc or Fc domain). The variable regions of both light (Vl) and heavy (Vh) chains determine binding recognition and specificity to the antigen. The constant region domains of the light (Cl) and heavy (Ch) chains confer important biological properties such as antibody chain association, secretion, trans-placental mobility, complement binding and binding to Fc receptors (FcR). The Fv fragment is the N-terminal part of the Fab fragment of an immunoglobulin and consists of the variable portions of one light chain and one heavy chain. The specificity of the antibody resides in the structural complementarity between the antibody combining site (synonym to antibody binding site) and the antigenic determinant. Antibody combining sites are made up of residues that are primarily from the hypervariable or complementarity determining regions (CDRs). CDRs refer to amino acid sequences that together define the binding affinity and specificity of the natural Fv region of a native immunoglobulin binding site. The light and heavy chains of an immunoglobulin each have three CDRs, that may be referred to as CDR1-L, CDR2-L, CDR3-L and CDR1-H, CDR2-H, CDR3-H, respectively or CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3, respectively. A conventional antibody antigen binding site, therefore, includes six CDRs, comprising the CDR set from each of a heavy and a light chain V region. In the context of the application, an antibody may be an IgM, IgD, IgG, IgA or IgE. "Antibody Framework Regions" (FRs) referto amino acid sequences interposed between CDRs, i.e. to those portions of immunoglobulin light and heavy chain variable regions that are relatively conserved among different immunoglobulins in a single species. The light and heavy chains of an immunoglobulin each have four FRs, designated FR1-L, FR2-L, FR3-L, FR4-L, and FR1-H, FR2-H, FR3-H, FR4-H, respectively. Accordingly, the light chain variable domain may thus be designated as (FR1-L)-(CDR1-L)-(FR2-L)-(CDR2-L)-(FR3-L)-(CDR3-L)-(FR4-L) and the heavy chain variable domain may thus be designated as (FR1-H)-(CDR1-H)-(FR2-H)-(CDR2-H)-(FR3-H)-(CDR3-H)-(FR4-H). CDR / FR definition in an immunoglobulin light or heavy chain, may be determined based on IMGT definition (Lefranc et al. Dev. Comp. Immunol., 2003, 27(l):55-77; www.imgt.org). In context of the present application it is preferred that CDR / FR definition in an immunoglobulin light or heavy chain are determined according to Kabat numbering (Kabat et al., 1992, Sequences of Proteins of Immunological Interest). Accordingly, amino acid sequences of the CDR1, CDR2 and CDR3 of a given variable chain of an antibody or antibody fragment are indicated according to said Kabat definition. Knowing the amino acid sequence of the CDRs of an antibody, a TCR or an antigen binding protein of the invention, one skilled in the art can easily determine the framework regions, such as the TCR framework regions or antibody framework regions. However, in cases where the CDRs are not indicated, the person skilled in the art can first determine the CDR amino acid sequences based on the IMGT definition for TCRs or the IMGT definition or Kabat definition for antibodies and then determine the amino acid sequences of the framework regions. As used herein, a "human framework region" is a framework region that is substantially identical (about 85%, or more, in particular 90%, 95%, 97%, 99% or 100%) to the framework region of a naturally occurring antigen-binding protein, such as a naturally occurring human antibody or human TCR. A functional fragment or derivative of an antibody refers to a modified form of the antibody molecule that retains some or all of its functional properties but may have altered characteristics such as size or structure. These modifications can be made to enhance the antibody's therapeutic potential, improve its stability, reduce immunogenicity or enable specific interactions with target molecules. Fragments of antibodies may comprise a portion of an intact antibody, in particular the antigen-binding region or variable region of the intact antibody. Examples of antibody fragments include Fv, Fab, F(ab')2, Fab', dsFv, (dsFv)2, scFv and sc(Fv)2. A fragment of an antibody may also be a single domain antibody, such as a heavy chain antibody (including nanobodies) or VHH. Furthermore, it is envisaged that in the herein described antigen-binding proteins the first and / or second binding domain comprises or consists of a T cell receptor (TCR) or a functional fragment or derivative thereof. A TCR is a heterodimeric cell surface protein of the immunoglobulin super-family, which is associated with invariant proteins of the CD3 complex involved in mediating signal transduction. TCRs exist in ap and y6 forms, which are structurally similar but have quite distinct anatomical locations and probably functions. The extracellular portion of native heterodimeric TCR and y6 TCR each contain two polypeptides, each of which has a membrane-proximal constant domain and a membrane-distal variable domain. Each of the constant and variable domains include an intra-chain disulfide bond. The variable domains contain the highly polymorphic loops analogous to the complementarity determining regions (CDRs) of antibodies. The term TCR herein denotes TCRs and fragments thereof, as well as single chain TCRs and fragments thereof, in particular variable alpha and beta domains of single domain TCRs, and chimeric, humanized, bispecific or multispecific TCRs. Fragments of a TCR comprise a portion of an intact or native TCR, in particular the antigenbinding region or variable region of the intact or native TCR. Examples of TCR fragments include fragments of the a, p, 6, y chain, such as Va- Ca or Vp- Cp or portions thereof, such fragments might also further comprise the corresponding hinge region or single variable domains, such as Va, Vp, Vg, VY, or single chain VaVP fragments. Fragments of a TCR may exert identical functions compared to the naturally occuring full-length TCR, i.e. fragments selectively and specifically bind to their target peptide. The TCR may also be a single chain TCR (scTCR). scTCR herein denotes a protein wherein the variable domains of the TCR, such as the Va and Vp orVg and VY are located on one polypeptide. Typically, the variable domains are separated by a linker, wherein said linker typically comprises 5 to 20, such as 5 to 15 amino acids. "Native" as used for example in the wording "native TCR" refers to a wildtype TCR. Native alpha-beta heterodimericTCRs have an alpha chain and a beta chain. The skilled person is well aware how the TCR chains are assembled by recombination of the corresponding genomic regions (Lefranc, (2001), Curr Protoc Immunol Appendix 1: Appendix 10; Folch and Lefranc, (2000), Exp Clin Immunogenet 17(1): 42-54; Scaviner and Lefranc, (2000), Exp Clin Immunogenet 17(2): 83-96; LeFranc and LeFranc, (2001), "T cell Receptor Factsbook", Academic Press). For more information on immunoglobulin antibody and TCR genes see the international ImMunoGeneTics information system®, Lefranc M-P et al (Nucleic Acids Res. 2015 Jan; 43 (Database issue):D413-22; and http: / / www.imgt.org / ). Each variable region, herein referred to as alpha variable domain and beta variable domain, comprises three Complementarity Determining Regions (CDRs) embedded in a framework sequence, one being the hypervariable region named CDR3. The alpha variable domain CDRs may be referred to as CDRal, CDRa2 and CDRa3 or CDRal, CDRa2, and CDRa3 and the beta variable domain CDRs may herein referred to as CDRbl, CDRb2 and CDRb3 or CDRpi, CDR|32, and CDR|33. A conventional TCR antigen binding site, therefore, includes, usually, six CDRs, comprising the CDR set from each of an alpha and a beta chain variable region, wherein CDR1 and CDR3 sequences are relevant for the recognition and binding of the peptide antigen that is bound to the HLA protein and the CDR2 sequences are relevant for the recognition and binding of the HLA protein. Analogous to antibodies, TCR framework regions (FRs) refer to amino acid sequences interposed between CDRs, i.e. to those portions of TCR alpha and beta chain variable regions that are to some extent conserved among different TCRs in a single species. The alpha and beta chains of a TCR each have four FRs, herein designated FRl-a, FR2-a, FR3-a, FR4-a, and FRl-b, FR2-b, FR3-b, FR4-b, respectively. Accordingly, the alpha chain variable domain may thus be designated as (FRl-a)-(CDRal)-(FR2-a)-(CDRa2)-(FR3-a)-(CDRa3)-(FR4-a) and the beta chain variable domain may thus be designated as (FRl-b)-(CDRbl)-(FR2-b)-(CDRb2)-(FR3-b)-(CDRb3)-(FR4-b). In the context of the invention, CDR / FR definition in an a or p chain is to be determined based on IMGT definition (Lefranc et al. Dev. Comp. Immunol., 2003, 27(l):55-77; www.imgt.org). Similarly, native gamma-delta heterodimeric TCRs have a gamma chain and a delta chain. The skilled person is well aware how the TCR chains are assembled by recombination of the corresponding genomic regions (Lefranc, (2001), Curr Protoc Immunol Appendix 1: Appendix 10; Folch and Lefranc, (2000), Exp Clin Immunogenet 17(1): 42-54; Scaviner and Lefranc, (2000), Exp Clin Immunogenet 17(2): 83-96; LeFranc and LeFranc, (2001), "T cell Receptor Factsbook", Academic Press). For more information on immunoglobulin antibody and TCR genes see the international ImMunoGeneTics information system®, Lefranc M-P et al (Nucleic Acids Res. 2015 Jan; 43 (Database issue):D413-22; and http: / / www.imgt.org / ). Also, CDR / FR definition in an y or 6 chain is to be determined based on IMGT definition (Lefranc et al. Dev. Comp. Immunol., 2003, 27(l):55-77; www.imgt.org). Accordingly, CDR / FR amino acid positions when related to TCR or TCR derived domains are indicated according to said IMGT definition. Accordingly, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; and wherein the antigen-binding protein comprises a first binding domain comprising or consisting of an antibody or a functional fragment or derivative thereof and a second binding domain comprising or consisting of a T cell receptor (TCR) or a functional fragment or derivative thereof. In the herein described antigen-binding proteins, the first binding domain may comprise or consist of an antibody antigen binding site (or a TCR antigen binding site) (VD). It is envisaged that one part of the antibody antigen binding site (VD) is on one CH3-containing polypeptide and the other part of the antibody antigen binding site (VD) is on the other CH3-containing polypeptide. Accordingly, in specific embodiments, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein one polypeptide comprises the antibody variable light chain domain (VL) of an antigen binding site (VD) and the other polypeptide comprises the antibody variable heavy chain domain (VH) of an antigen binding site (VD). Although evident for the skilled person it is pointed out that it is envisaged that the antibody variable light chain domain (VL) and the antibody variable heavy chain domain (VH) associate to form a functional antibody antigen-binding site (VD). Accordingly, in certain embodiments, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein one polypeptide comprises the antibody variable light chain domain (VL) of an antigen-binding site (VD) and the other polypeptide comprises the antibody variable heavy chain domain (VH) of an antigen-binding site (VD), wherein the antibody variable light chain domain (VL) and the antibody variable heavy chain domain (VH) associate to form a functional antibody antigen-binding site (VD). It is further envisaged that in the herein described antigen-binding proteins the second binding domain may comprise or consist of a TCR antigen binding site (VR). In further certain embodiments, the first and the second binding domain may be derived from antibodies, and may comprise fragments of antibodies, e.g. variable domains of antibodies. One part of the TCR antigen binding site (VR) may be on one CH3-containing polypeptide and the other part of the TCR antigen binding site (VR) may be on the other CH3-containing polypeptide. Accordingly, in such embodiments, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein one polypeptide comprises the TCR alpha variable domain (Va) of a TCR antigen-binding site (VR) and the other polypeptide comprises the TCR beta variable domain (VP) of a TCR antigen-binding site (VR). Although evident for the skilled person it is pointed out that it is envisaged that TCR alpha variable domain (Va) and the TCR beta variable domain (VP) associate to form a functional TCR antigen binding site (VR). Accordingly, in particular embodiments, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein one polypeptide comprises the TCR alpha variable domain (Va) of a TCR antigen-binding site (VR) and the other polypeptide comprises the TCR beta variable domain (VP) of a TCR antigen-binding site (VR), wherein the TCR alpha variable domain (Va) and the TCR beta variable domain (VP) associate to form a functional TCR antigen binding site (VR). Specifically, the invention relates to an antigen-binding protein comprising two of the herein described IgG CH3-containing polypeptides, wherein one polypeptide comprises an antibody variable light chain domain (VL) and a TCR beta variable domain (VP) and the other polypeptide comprises an antibody variable heavy chain domain (VH) and a TCR alpha variable domain (Va). Furthermore, the invention relates to an antigen-binding protein comprising two of the described IgG CH3-containing polypeptides, wherein one polypeptide comprises an antibody variable light chain domain (VL) and a TCR alpha variable domain (Va) and the other polypeptide comprises an antibody variable heavy chain domain (VH) and a TCR beta variable domain (VP). The herein described antigen-binding proteins may comprise further antibody-derived domains. In particular, it is envisaged that the herein described antigen-binding proteins further comprise a CH2 domain. The CH2-domain is the second constant domain of the heavy chain of an antibody and is located in the Fc region. The invention relates to an antigen-binding protein comprising two (of the described) IgG CH3-containing polypeptides, wherein the first polypeptide further comprises a CH2 domain and / or the second polypeptide further comprises a CH2 domain. It is envisaged that in the herein described antigen-binding proteins a CH2 domain and a CH3 domain form a Fc domain. Accordingly, in one polypeptide the CH2 domain and the CH3 domain may form a Fc domain FC1 and / or in the other polypeptide the CH2 domain and the CH3 domain may form a Fc domain FC2. Thus, the invention relates to an antigen-binding protein comprising two of the herein described IgG CH3-containing polypeptides, wherein in one polypeptide the CH2 domain and the CH3 domain form a Fc domain FC1 and / or in the other polypeptide the CH2 domain and the CH3 domain form a Fc domain FC2. The term "Fc domain" as used in the context of the present invention encompasses native Fc domains and Fc domain variants and sequences as further defined herein below. As with Fc variants and native Fc molecules, the term "Fc domain" includes molecules in monomeric or multimeric form, whether digested from whole antibody or produced by other means. The term "native Fc" as used herein refers to a molecule comprising the sequence of a nonantigen-binding fragment resulting from digestion of an antibody or produced by other means, whether in monomeric or multimeric form, and may contain the hinge region. The original immunoglobulin source of the native Fc is, in particular, of human origin and can be any of the immunoglobulins, preferably IgGl or lgG2, most preferably IgGl. Native Fc molecules are made up of monomeric polypeptides that can be linked into dimeric or multimeric forms by covalent (i.e., disulfide bonds) and non-covalent association. The number of intermolecular disulfide bonds between monomeric subunits of native Fc molecules ranges from 1 to 4 depending on class (e.g., IgG, IgA, and IgE) or subclass (e.g., IgGl, lgG2, lgG3, IgAl, and lgA2). One example of a native Fc is a disulfide-bonded dimer resulting from papain digestion of an IgG. The term "native Fc" as used herein is generic to the monomeric, dimeric, and multimeric forms. The "hinge" or "hinge region" or "hinge domain" refers typically to the flexible portion of a heavy chain located between the CHI domain and the CH2 domain. It is approximately 25 amino acids long, and is divided into an "upper hinge," a "middle hinge" or "core hinge," and a "lower hinge." A "hinge subdomain" refers to the upper hinge, middle (or core) hinge or the lower hinge. The skilled person understands at least when looking at the sequences described herein that FC1 and / or FC2 may comprise a hinge region, in particular the hinge region according to SEQ ID NO: 15 (EPKSS). Accordingly, FC1 and / or FC2 may be formed by a Fc domain and a hinge region, preferably wherein the hinge region comprises or consists of SEQ ID NO: 15 (EPKSS). Accordingly, in certain embodiments, the invention relates to the herein described antigenbinding proteins, wherein FC1 and / or FC2 further comprise a hinge region, preferably wherein the hinge region comprises or consists of SEQ ID NO: 15 (EPKSS). When it is referred herein to amino acid positions in the Fc domain, these amino acid positions or residues are indicated according to the EU numbering system as described, for example in Edelman et al., Proc. Natl. Acad. USA, 1969, 63, 78-85. The term "Fc variant" or "Fc domain variant" as used herein refers to a molecule or sequence that is modified from a native Fc but still comprises e.g. a binding site for the salvage receptor, FcRn (neonatal Fc receptor). Exemplary Fc variants, and their interaction with the salvage receptor, are known in the art. Thus, the term "Fc variant" can comprise a molecule or sequence that is humanized from a non-human native Fc. Furthermore, a native Fc comprises regions that can be removed because they provide structural features or biological activity that are not required for e.g. the bispecific antigen-binding proteins described herein. Thus, the term "Fc variant" comprises a molecule or sequence that lacks one or more native Fc sites or residues, or in which one or more Fc sites or residues have been modified, that affect or are involved in: (1) disulfide bond formation, (2) incompatibility with a selected host cell, (3) N-terminal heterogeneity upon expression in a selected host cell, (4) glycosylation, (5) interaction with complement, (6) binding to an Fc receptor other than a salvage receptor, or (7) antibody-dependent cellular cytotoxicity (ADCC). In particular, when the bispecific antigen-binding protein comprises two Fc domains, i.e. in the TCER® format described herein (such as FC1 and FC2), the two Fc domains may be of the same immunoglobulin isotype or isotype subclass or of different immunoglobulin isotypes or isotype subclasses, preferably of the same. Accordingly, FC1 and FC2, may be of the IgGl subclass, or of the lgG2 subclass, or of the lgG3 subclass, or of the lgG4 subclass, preferably of the IgGl subclass, or of the lgG2 subclass, more preferably of the IgGl subclass. The Fc domain may be a Fc domain variant and thus comprises one or more of the amino acid substitutions described herein below. The Fc domain may comprises or further comprise the "RF" mutation. The "RF mutation" typically refers to the amino acid substitutions of the amino acids HY into RF in the CH3 domain of Fc domains, such as the amino acid substitution H435R and Y436F in CH3 domain as described by Jendeberg et al. (Jendeberg et al., J. Immunological Meth., 1997, 201: 25-34) and is described as advantageous for purification purposes as it abolishes binding to protein A. In case the bispecific antigen binding protein comprises two Fc domains, the RF mutation may be in one or both, preferably in one Fc domain. The Fc domain on one or both, preferably both polypeptide chains of the antigen-binding protein may comprise one or more alterations that inhibit Fc gamma receptor (FcyR) binding. Such alterations may include L234A or L235A. With the inclusion of Fc-parts consisting of Hinges, CH2 and CH3 domains, or parts thereof, into antigen-binding proteins, more particularly into bispecific antigen-binding proteins the problem of unspecific immobilization of these molecules, induced by Fc:Fc-gamma receptor (FcgR) interactions may arise. FcgRs are composed of different cell surface molecules (FcgRI, FcgRIla, FcgRIlb, FcgRI 11) binding with differing affinities to epitopes displayed by Fc-parts of IgG-molecules. As such an unspecific (i.e. not induced by either of the two binding domains of a bispecific molecule) immobilization is unfavorable due to i) influence on pharmacokinetics of a molecule and ii) off-target activation of immune effector cells various Fc-variants and mutations to ablate FcgR-binding have been identified. In this context, Morgan et al. disclose the exchange of the residues 233-236 of human IgGl with the corresponding sequence derived from human lgG2, i.e. the residues 233P, 234V and 235A and wherein no amino acid is present at position 236, resulting in abolished FcgRI binding, abolished Clq binding and diminished FcgRIII binding (Morgan et al., Immunology., 1995, 86(2): 319-324). EP1075496 discloses antibodies and other Fc-containing molecules with variations in the Fc region (such as one or more of 233P, 234V, 235A and no residue or G in position 236 and 327G, 330S and 331S) wherein the recombinant antibody is capable of binding the target molecule without triggering significant complement-dependent lysis or cell mediated destruction of the target. Accordingly, the Fc region may comprise or further comprise one or more of the amino acids or deletions selected from the group consisting of 233P, 234V, 235A, 236 (No residue) or G, 327G, 330S, 331S, preferably, the Fc region comprises or further comprises the amino acids 233P, 234V, 235A, 236 (No residue) or G and one or more amino acids selected from the group consisting of 327G, 330S, 331S, most preferably, the Fc region comprises or further comprises the amino acids 233P, 234V, 235A, 236 (No residue) and 331S. It is also envisaged that FC1 and / or FC2 comprises at least one effector function silencing mutation / substitution at a residue selected from positions 233, 234, 235, 236, 297 and 331, preferably wherein said effector function silencing mutation / substitution is generated by replacing / substituting at least one residue in position 233, 234, 235, 236, and 331 with the corresponding residue derived from lgG2 or lgG4. The Fc domain may comprise or further comprise the amino acid substitution N297Q, N297G or N297A, preferably N297Q. The amino acid substitution "N297Q", "N297G" or "N297A" refer to amino acid substitutions at position 297 that abrogate the native N-Glycosylation site within the Fc-domain. This amino acid substitution prevents Fc-gamma-receptor interaction and decreases the variability of the final protein products, i.e. the bispecific antigen-binding proteins described herein, due to sugar residues as described for example in Tao and Morrison (Tao and Morrison, J Immunol., 1989, 143(8):2595-601). The described antigen binding proteins may further comprise L242C and K334C located in the same Fc-domain, either in the FC1 or FC2 of one or both polypeptides to form a intradomain C-C bridge. The skilled person is readily capable to determine whether the above described mutations / substitutions are present in the disclosed sequences. Accordingly, the skilled person knows that when it is referred herein to antigen-binding proteins via sequence identity to disclosed sequences said mutations / substitutions may need to be present in said antigenbinding proteins. In particular, it is evident forthe skilled person that when it is referred herein to the described FC1 and / or FC2 via sequence identity the described substitutions improving heteromerization need to be present. In the herein described antigen-binding proteins comprising at least two polypeptide chains the polypeptide chains may be connected by a linker. Accordingly, the invention may relate to an antigen-binding protein comprising two of the herein described IgG CH3-containing polypeptides, wherein the first polypeptide and the second polypeptide are on separate polypeptide chains or are connected by a linker. As mentioned above, the herein described antigen-binding domains may comprise an antigenbinding site derived from an antibody, wherein the antibody variable light chain domain (VL) and the antibody variable heavy chain domain (VH) are on different polypeptide chains and an antigen-binding site derived from a TCR, wherein TCR alpha variable domain (Va) and the TCR beta variable domain (VP) are on different polypeptide chains. Accordingly, the invention may relate to the herein described antigen-binding proteins, wherein the first polypeptide comprises a structure represented by the formula: V1-V2         [I]; and the second polypeptide comprises a structure represented by the formula: V3-V4         [II]; wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. Accordingly, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; wherein the first polypeptide comprises a structure represented by the formula: V1-V2         [I]; and the second polypeptide comprises a structure represented by the formula: V3-V4         [II]; wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. It is envisaged that in the herein described antigen-binding proteins the variable domains are connected by linkers. Accordingly, the invention may relate to the herein described antigen-binding proteins, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2              [III]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4             [IV]; wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. The invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2 [Hi]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4 [IV]; wherein LI and L2 are linkers and may be the same or different, wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. As mentioned above, it is envisaged that the described antigen-binding proteins comprise FC1 and / or FC2. Accorddingly, the invention relates to the herein described antigen-binding proteins, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1        [V]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2        [VI]; wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. Such an antigen binding protein is herein referred to as a TCER. It is further envisaged that the herein described beneficial CH3 domains can be comprised in or added to any other antigen binding protein, e.g. as single chain or Tandem diabodies, VHHs, ImmTACs, Anticalins, Nanobodies, BiTE®, a Fab, ankyrin repeat proteins or DARPINs, Avimers, a DART, otherTCR-like antibodies, Adnectins, Affilins, Trans-bodies, Affibodies, a TrimerX, MicroProteins, Fynomers, Centyrins or a KALBITOR®. The invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1        [V]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2        [VI]; wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. It is envisaged that also the variable domains and FC1 and / or FC2 are connected by linkers. Accordingly, the invention relates to the herein described antigen-binding proteins, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-L3-FC1            [VII]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-L4-FC2             [VIII]; wherein LI, L2, L3 and L4 are linkers and may be the same or different, and wherein             VI is Va, V2 is VH, V3 is VL, V4 is V0; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. The invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-L3-FC1            [VII]; and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-L4-FC2             [VIII]; wherein LI, L2, L3 and L4 are linkers and may be the same or different, and wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL. The skilled person is readily capable to choose suitable linkers. In particular the skilled person is readily capable to choose suitable linkers for LI, L2, L3 and / or L4 used herein. The term "linker" as used herein refers to one or more amino acid residues inserted between domains to provide sufficient mobility for the domains or elements, for example the variable domains of bispecific antigen-binding proteins to fold correctly to form the antigen-binding sites. In some embodiments, a linker consists of 0 amino acids meaning that the linker is absent. A linker, as long as it is not specified otherwise in the respective context, can be from at least 1 to 30 amino acids in length. A linker can be 2-25, 2-20, or 3-18 amino acids long. A linker can be a peptide of a length of no more than 14, 13, 12, 11, 10, 9, 8, 7, 6, or 5 amino acids. A linker can be 5-25, 5-15, 4-11, 10-20, or 20-30 amino acids long. A linker can also be about, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 amino acids long, preferably 8 amino acids long. A linker can be less than 24, less than 20, less than 16, is less than 12, less than 10, for example from 5 to 24, 10 to 24 or 5-10 amino acid residues in length. A linker may be equal to 1 or more amino acid residues in length, such as more than 1, more than 2, more than 5, more than 10, more than 20 amino acid residues in length, or more than 22 amino acid residues in length. Preferably, the linker is a glycine / serine linker, i.e. a linker consisting of or essentially consisting of glycine and serine residues. Preferably, the linker comprises or consists of SEQ ID NO: 16 (GGGSGGGG). Accordingly, the invention relates to the herein described antigen-binding proteins, wherein the linkers LI, L2, L3 and / or L4 comprise or consist of SEQ ID NO: 16 (GGGSGGGG). The antigen-binding proteins may comprise the FC1 and / or FC2 of antigen-binding proteins as used in the appended examples. In particular FC1 may comprise or consist of the amino acid sequence according to SEQ ID NO: 1. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 and comprise the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 and comprise the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant Y349C. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 and comprise the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C. It is pointed out that when it is referred herein to "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1" in particular the wording "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 and comprising the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C" is encompassed. FC1 may also comprise or consist of the amino acid sequence according to SEQ ID NO: 39. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39 and comprise the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39 and comprise the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant S354C. FC1 may comprise or consist of the amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39 and comprise the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C. It is pointed out that when it is referred herein to "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39" in particular the wording "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39 and comprising the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C" is encompassed. FC2 may comprise or consist of the amino acid sequence according to SEQ ID NO: 2. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 and comprise the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 and comprise the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and the amino acid variant S354C. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 and comprise the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C. It is pointed out that when it is referred herein to "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2" in particular the wording "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 and comprising the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C" is encompassed. FC2 may also comprise or consist of the amino acid sequence according to SEQ ID NO: 40. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40 and comprise the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and amino acid variant Y349C. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40 and comprise the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and amino acid variant Y349C. FC2 may comprise or consist of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40 and comprise the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C. It is pointed out that when it is referred herein to "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40" in particular the wording "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40 and comprising the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C" is encompassed. Accordingly, the antigen-binding protein according to the invention may comprise FC1 comprising or consisting of the amino acid sequence according to SEQ ID NO: 1 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1; and / or FC2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 2 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2. Furthermore, the antigen-binding protein according to the invention may comprise FC1 comprising or consisting of the amino acid sequence according to SEQ ID NO: 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39; and / or FC2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40. In particular, the invention relates to an antigen-binding protein, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2. The invention also relates to an antigen-binding protein, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40. As mentioned above, it is envisaged that an antigen-binding site / domain of the herein described antigen-binding domains binds to a cell surface molecule of an immune cell. In particular, it is envisaged that an antibody antigen-binding domain binds to a TCR / CD3 complex, preferably an alpha / beta TCR / CD3 complex. Said antigen-binding domain may also be referred to as T-cell recruiting part. It is in particular envisaged that said antigen-binding domain binding to a TCR / CD3 complex is the antigen-binding domain of the antibody BMA031 (V36) as described in WO2021 / 023657. SEQ ID NO: 42 (VL) of WO2021 / 023657 corresponds to SEQ ID NO: 3 in the present application and SEQ ID NO: 43 (VH) of WO2021 / 023657 corresponds to SEQ ID NO: 9 in the present application. Accordingly, it is envisaged that the herein described antigen-binding proteins comprise an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The invention relates to an antigen-binding protein, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1 or 39, or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2 or 40, or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40; and wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. In particular it is envisaged that the T cell recruiting domain comprises a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 3 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 3 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; It is evident for the skilled person that under certain conditions a glutamine amino acid residue may be converted into pyro-glutamate. In particular, N-terminal glutamine may be converted into pyro-glutamate. Accordingly, it is evident for the skilled person that the present application also encompasses the described antigen-binding proteins with pyro-glutamate at the N-terminus instead of glutamine. In other words, when an antigen-binding protein as described herein has a glutamine residue at the N-terminus also the corresponding amino acid sequence with pyro-glutamate instead of glutamine at the N-terminus is encompassed. For example, when in the described antigen-binding protein the VL having the amino acid sequence according to SEQ ID NO: 3 is at the N-terminus said VL may comprise or consist of the amino acid sequence according to SEQ ID NO: 4 (with pyro-glutamate at the N-terminus). Accordingly, the antigen-binding proteins according to the invention may comprise a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 4. The antigenbinding proteins according to the invention may also comprise a VL comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 4. The antigen-binding proteins according to the invention may comprise a VL comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 4 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively. For simplicity it is mostly referred to SEQ ID NO: 5 (encompassing glutamine and pyro-glutamate at the N-terminus) herein in context of the preferred VL. It is evident for the skilled person that SEQ ID NO: 5 and "SEQ ID NO: 3 or SEQ ID NO: 4" may be used interchangeably herein. In other words, when it is referred to SEQ ID NO: 5 it may also be referred to as "SEQ ID NO: 3 and SEQ ID NO: 4" or "SEQ ID NO: 3 or SEQ ID NO: 4". It is evident for the skilled person that the herein described antigen-binding proteins may be a mixture of molecules with pyro-glutamate at the N-terminus and molecules with glutamine at the N-terminus. Accordingly, when it is referred herein to an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 it is evident for the skilled person that it may be referred to a composition comprising an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 3 and optionally comprising an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 4. Similarly, when it is referred herein to an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 it is evident for the skilled person that it may be referred to a composition comprising an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 4 and optionally comprising an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 3. When it is referred herein to an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 it is evident for the skilled person that it may be referred to a composition comprising an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 3 and optionally comprising at least 50%, at least 60%, at least 70%, at least 80% or at least 90% of an antigen-binding protein comprising a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 4. Thus, the described antigen-binding proteins may comprise a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5. The described antigen-binding proteins may comprise a VL comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5. The described antigen-binding proteins may comprise a VL comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively. The described antigen-binding proteins may comprise a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9. The described antigen-binding proteins may comprise a VH comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9. The described antigen-binding proteins may comprise a VH comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10,11, and 12, respectively. Thus, the invention relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides as described, wherein the antigen-binding protein comprises: a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 11, and 12, respectively. The invention relates to an antigen-binding protein, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40; and wherein the VL comprises or consists of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprises the CDRL1, CDRL2, and CDRL3 according to SEQIDNOs:6, 7, and 8, respectively; and the VH comprises or consists of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprises the CDRH1, CDRH2, and CDRH3 according to SEQIDNOs:10, 11, and 12, respectively. Furthermore, it is envisaged that the antigen-binding domain binding to a TCR / CD3 complex is the antigen-binding domain of a version of the antibody BMA031 as described in WO2022 / 233957. SEQ ID NO: 2 (VL) of WO2022 / 233957 corresponds to SEQ ID NO: 3 in the present application and SEQ ID NO: 32 (VH) of WO2022 / 233957 corresponds to SEQ ID NO: 13 in the present application. Accordingly, it is envisaged that the herein described antigen-binding proteins comprise an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The invention relates to an antigen-binding protein, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40; and wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The T cell recruiting domain may also comprise a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13. Accordingly, the described antigen-binding proteins may comprise a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13. The described antigen-binding proteins may comprise a VH comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13. The described antigen-binding proteins may comprise a VH comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQIDNOs:10, 14, and 12, respectively. Accordingly, the described antigen-binding proteins may comprise a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 14, and 12, respectively. The invention further relates to an antigen-binding protein, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40; and the VL comprises or consists of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprises the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and the VH comprises or consists of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprises the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 14, and 12, respectively. It is envisaged that the TCR antigen binding site (VR) of the described antigen-binding proteins may specifically bind to a bacterial peptide, a viral peptide or a tumor associated antigen peptide, preferably bound to a major histocompatibility complex (MHC) protein. Preferably, the TCR antigen binding site (VR) of the described antigen-binding proteins may specifically bind to a tumor associated antigen peptide, preferably bound to a major histocompatibility complex (MHC) protein. A preferred tumor associated antigen that is bound by the antigen-binding proteins described herein is the MAGE-A antigenic peptide comprising or consisting of the amino acid sequence "KVLEHVVRV" (SEQ ID NO: 57), more particularly, the MAGE-A antigenic peptide comprising or consisting of the amino acid sequence "KVLEHVVRV" (SEQ ID NO: 57) in a complex with a MHC protein. "MAGE-A" or "melanoma associated antigen A" subfamily proteins were the first tumor associated antigens identified at the molecular level (van der Bruggen et al., Science. 1991; 254:1643-47). MAGE-A is a sub-family of 12 genes (MAGE-A1 to -A12) located in the q28 region of the X chromosome. Members of the MAGE-A subfamily proteins are normally expressed only in testis or placenta and their restricted expression suggests that they may function in germ cell development. MAGE-A proteins were also detected in the early development of the central nervous system, the spinal cord and brainstem, revealing that MAGE-A proteins may also be involved in neuronal development. The members of this family encode proteins with 50 to 80% sequence identity to each other and all MAGE proteins share the common MAGE homology domain, a highly conserved domain consisting of approximately 170 amino acids. The biological functions and underlying regulatory mechanism of MAGE-A proteins expression in cancer is still not fully understood. The "MAGE-A4" or "Melanoma-associated antigen 4" protein is a member of the MAGE-A gene family and has the Uniprot accession number P43358 (as available on September 2, 2024). MAGE-A4 localization has been described as cytoplasmic. However, MAGE-A4 staining has also been detected in nuclei, with differential distribution between nucleus and cytoplasm in well-differentiated versus less differentiated cancers (Sarcevic et. al., Oncology, 2003, 64, 443-449). MAGE-A4 is used as a male germ cell marker. It is not expressed in gonocytes, but expressed in pre-spermatogonia and mature germ cells (Mitchell et al., Mod. Pathol., 2014, 27, 1255-1266). Expression of the MAGE-A4 protein and mRNA has been linked to the development and prognosis of various cancers. The "MAGE-A8" or "Melanoma-associated antigen 8" protein is a member of the MAGE-A superfamily and has the Uniprot accession number P43361 (as available on September 2, 2024). The "MAGE-A4" and "MAGE-A8" proteins have a sequence identity of 72% as determined by a protein sequence alignment using the BLASTP 2.9.0 algorithm (Stephen et al., Nucleic Acids Res., 1997, 25:3389-3402). Furthermore, "MAGE-A4" and "MAGE-A8" both comprise the MAG-003 peptide, i.e. "KVLEHVVRV" (SEQ ID NO: 57). It is evident for the skilled person that it is in particular envisaged herein that cancer is treated that presents the peptide according to SEQ ID NO: 57 in complex with a MHC protein. Accordingly, it is envisaged that the herein described antigen-binding proteins may comprise a TCR antigen binding site (VR) that binds to the MAG-003 peptide. In line with the above, it is envisaged that the antigen-binding protein according to the invention may comprise a T cell receptor (TCR) alpha variable domain (Va) as part of a TCR antigen binding site (VR) that binds to the MAG-003 peptide. "Va" and "Va domain" may be used synonymously herein. The Va domain may comprise a CDRal comprising or consisting of the amino acid sequence according to SEQ ID NO: 62. The Va domain may comprise a CDRa2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 63. The Va domain may comprise a CDRa3 comprising or consisting of the amino acid sequence according to SEQ ID NO: 64. Said CDRs may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. Accordingly, the antigen-binding protein according to the invention may comprise a Va domain comprising a CDRal comprising the amino acid sequence according to SEQ ID NO: 62, a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 63 and / or a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 64. The antigen-binding protein according to the invention may comprise a Va domain comprising a CDRal consisting of the amino acid sequence according to SEQ ID NO: 62, a CDRa2 consisting of the amino acid sequence according to SEQ ID NO: 63 and / or a CDRa3 consisting of the amino acid sequence according to SEQ ID NO: 64. It is further envisaged that the antigen-binding protein according to the invention comprises a TCR beta variable domain (VP) as part of a TCR antigen binding site (VR) that binds to the MAG-003 peptide. "VP" and "VP domain" may be used synonymously herein. The VP domain may comprise a CDRpi comprising or consisting of the amino acid sequence according to SEQ ID NO: 59. The vp domain may comprise a CDRP2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 60. The vp domain may comprise a CDRP3 comprising or consisting of the amino acid sequence according to SEQ ID NO: 61. Said CDRs may comprise one, two orthree amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. Accordingly, the antigen-binding protein according to the invention may comprise a vp domain comprising a CDRpi comprising the amino acid sequence according to SEQ ID NO: 59, a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 60 and / or a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 61. The antigen-binding protein according to the invention may comprise a vp domain comprising a CDRpi consisting of the amino acid sequence according to SEQ ID NO: 59, a CDRP2 consisting of the amino acid sequence according to SEQ ID NO: 60 and / or a CDRP3 consisting of the amino acid sequence according to SEQ ID NO: 61. Accordingly, it is envisaged that that the antigen-binding protein according to the invention comprises a Va and a VP wherein the Va comprises (i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 62, (ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 63, and / or (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 64; and wherein the VP comprises (i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 59, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 60, and / or (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 61, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. Furthermore, it is envisaged that the antigen-binding protein according to the invention comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 54. It is envisaged that the antigen-binding protein comprises a Va comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 54. It is envisaged that the antigen-binding protein comprises a Va comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 54 and comprising the CDRal, CDRa2, and CDRa3 according to SEQIDNOs:62, 63, and 64, respectively. It is envisaged that the antigen-binding protein for use according to the invention comprises a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 53. It is also envisaged that the antigen-binding protein comprises a VP comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 53. It is also envisaged that the antigen-binding protein comprises a VP comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 53 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQIDNOs:59, 60, and 61, respectively. Furthermore, it is envisaged that the antigen-binding protein according to the invention comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 54 and a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 53. Furthermore, it is envisaged that the antigen-binding protein for use according to the invention comprises a Va comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 54 and comprising the CDRal, CDRa2, and CDRa3 according to SEQ ID NOs: 62, 63, and 64, respectively and a VP comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 53 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQ ID NOs: 59, 60, and 61, respectively. Another preferred tumor associated antigen that is bound by the antigen-binding proteins described herein is the the PRAME antigenic peptide comprising or consisting of the amino acid sequence "SLLQHLIGL" (SEQ ID NO: 58), more particularly, the PRAME antigenic peptide comprising or consisting of the amino acid sequence "SLLQHLIGL" (SEQ ID NO: 58) in a complex with a MHC protein. "PRAME" or "Preferentially Expressed Antigen In Melanoma" was first identified as an antigen that is overexpressed in melanoma (Ikeda et al Immunity. 1997 Feb;6(2): 199-208); it is also known as CT130, MAPE, OIP-4 and has the Uniprot accession number P78395 (as available on January 11, 2019). The protein functions as a repressor of retinoic acid receptor signaling (Epping et al., Cell. 2005 Sep 23; 122(6):835-47). PRAME belongs to the family of germline-encoded antigens known as cancer testis antigens. Cancer testis antigens are attractive targets for immunotherapeutic intervention since they typically have limited or no expression in normal adult tissues. PRAME is expressed in a number of solid tumors as well as in leukemia and lymphomas (Doolan et al., Breast Cancer Res Treat. 2008 May; 109(2):359-65; Epping et al., Cancer Res. 2006 Nov 15;66(22): 10639-42; Ercolak et al., Breast Cancer Res Treat. 2008 May; 109(2):359-65; Matsushita et al., Leuk Lymphoma. 2003 Mar;44(3):439-44; Mitsuhashi et al., Int. J Hematol. 2014; 100(l):88-95; Proto-Sequeire et al., Leuk Res. 2006 Nov;30(ll): 1333-9; Szczepanski et al., Oral Oncol. 2013 Feb;49(2): 144-51; Van Baren et al., Br J Haematol. 1998 Sep; 102(5): 1376-9). It is evident for the skilled person that it is in particular envisaged herein that cancer is treated that presents the peptide according to SEQ ID NO: 58 in complex with a MHC protein. Accordingly, it is envisaged that the herein described antigen-binding proteins comprise a TCR antigen binding site (VR) that binds to the PRAME-004 peptide. In line with the above, it is envisaged that the antigen-binding protein according to the invention comprises a T cell receptor (TCR) alpha variable domain (Va) as part of a TCR antigen binding site (VR) that binds to the PRAME-004 peptide. The Va domain may comprise a CDRal comprising or consisting of the amino acid sequence according to SEQ ID NO: 68. The Va domain may comprise a CDRa2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 69. The Va domain may comprise a CDRa3 comprising or consisting of the amino acid sequence according to SEQ ID NO: 70. Said CDRs may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. Accordingly, the antigen-binding protein according to the invention may comprise a Va domain comprising a CDRal comprising the amino acid sequence according to SEQ ID NO: 68, a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 69 and / or a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 70. The antigen-binding protein according to the invention may comprise a Va domain comprising a CDRal consisting of the amino acid sequence according to SEQ ID NO: 68, a CDRa2 consisting of the amino acid sequence according to SEQ ID NO: 69 and / or a CDRa3 consisting of the amino acid sequence according to SEQ ID NO: 70. It is further envisaged that the antigen-binding protein according to the invention comprises a TCR beta variable domain (VP) as part of a TCR antigen binding site (VR) that binds to the PRAME-004 peptide. The VP domain may comprise a CDRpi comprising or consisting of the amino acid sequence according to SEQ ID NO: 65. The VP domain may comprise a CDRP2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 66. The VP domain may comprise a CDRP3 comprising or consisting of the amino acid sequence according to SEQ ID NO: 67. Said CDRs may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. Accordingly, the antigen-binding protein according to the invention may comprise a VP domain comprising a CDRpi comprising the amino acid sequence according to SEQ ID NO: 65, a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 66 and / or a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 67. The antigen-binding protein according to the invention may comprise a VP domain comprising a CDRpi consisting of the amino acid sequence according to SEQ ID NO: 65, a CDRP2 consisting of the amino acid sequence according to SEQ ID NO: 66 and / or a CDRP3 consisting of the amino acid sequence according to SEQ ID NO: 67. Accordingly, it is envisaged that that the antigen-binding protein according to the invention comprises a Va and a VP wherein the Va comprises (i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 68, (ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 69, and / or (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 70; and wherein the VP comprises (i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 65, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 66, and / or (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 67, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. Furthermore, it is envisaged that the antigen-binding protein according to the invention comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 56. It is envisaged that the antigen-binding protein comprises a Va comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 56. It is envisaged that the antigen-binding protein comprises a Va comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 56 and comprising the CDRal, CDRa2, and CDRa3 according to SEQIDNOs:68, 69, and 70, respectively. It is envisaged that the antigen-binding protein according to the invention comprises a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 55. It is also envisaged that the antigen-binding protein comprises a VP comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 55. It is also envisaged that the antigen-binding protein comprises a VP comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 55 and comprising the CDR01, CDR02, and CDR03 according to SEQ ID NOs: 65, 66, and 67, respectively. Furthermore, it is envisaged that the antigen-binding protein for use according to the invention comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 56 and a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 55. Furthermore, it is envisaged that the antigen-binding protein for use according to the invention comprises a Va comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 56 and comprising the CDRal, CDRa2, and CDRa3 according to SEQ ID NOs: 68, 69, and 70, respectively and a VP comprising or consisting of an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 55 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQ ID NOs: 65, 66, and 67, respectively. It is envisaged that the antigen-binding proteins in context of the invention consist or comprise of amino acid sequences of the antigen-binding proteins as used in the appended examples. Accordingly, in particular embodiments, the invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 23 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 24. In particular, the invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 25 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 26. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 27 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 28. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 29 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 30. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 31 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 32. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 33 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 34. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 35 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 36. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 37 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 38. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 41 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 42. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 43 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 44. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 45 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 46. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 47 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 48. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 49 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 50. The invention relates to an antigen binding protein comprising a first polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 51 and a second polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO: 52. Although evident for the skilled person it is pointed out that also nucleic acids and / or vectors encoding the herein described antigen-binding proteins are encompassed by the invention. Additionally, nucleic acids and / or vectors encoding the herein described antigen-binding proteins may be also used for the herein described uses and methods. Thus, the polypeptides of the antigen-binding proteins may be encoded by nucleic acids and expressed in vivo, ex vivo or in vitro. The nucleic acid may be comprised in one nucleic acid molecule or may be separated into two or more nucleic acid molecules, wherein each nucleic acid molecule comprises at least one of the two or more sequences encoding the described antigen-binding proteins. One nucleic acid molecule may encode one part or monomer of an antigen-binding protein (for example one of two chains of a TCER®), and another nucleic acid molecule may encode another part or monomer of an antigen-binding protein (for example the other one of two chains of the TCER®). The nucleic acid may encode two or more antigen-binding protein polypeptide chains, for example, at least two polypeptides of a TCER®. Nucleic acids encoding multiple antigenbinding protein polypeptide chains may include a nucleic acid cleavage site between at least two chain encoding sequences, may encode a transcription or translation start site, such as an internal ribosomal entry site (IRES) between two or more chain sequences, and / or may encode a proteolytic target site between two or more antigen-binding protein chains. If two or more antigen-binding protein polypeptide chains are encoded on one nucleic acid molecule, the two or more antigen-binding protein polypeptide chains may be under the control of the same promoter or under the control of separate promoters. The term "nucleic acid" refers in the context of this invention to single- or double-stranded oligo- or polymers of deoxyribonucleotide or ribonucleotide bases or both. Nucleotide monomers are composed of a nucleobase, a five-carbon sugar (such as but not limited to ribose or 2'-deoxyribose), and one to three phosphate groups. Typically, a nucleic acid is formed through phosphodiester bonds between the individual nucleotide monomers. As used herein, the term nucleic acid includes but is not limited to ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) molecules but also includes synthetic forms of nucleic acids comprising other linkages (e.g., peptide nucleic acids as described in Nielsen et al. Science 254:1497-1500, 1991). Typically, nucleic acids are single- or double-stranded molecules and are composed of naturally occurring nucleotides. The depiction of a single strand of a nucleic acid also defines (at least partially) the sequence of the complementary strand. The nucleic acid may be single or double stranded or may contain portions of both double and single stranded sequences. Exemplified, double-stranded nucleic acid molecules can have 3' or 5' overhangs and as such are not required or assumed to be completely double-stranded over their entire length. The term nucleic acid is used herein in the broadest sense and comprises chromosomes or chromosomal segments. Unless otherwise indicated, a particular nucleic acid sequence comprises or encodes complementary sequences, in addition to any sequence explicitly indicated. Preferably, the nucleic acid is an isolated nucleic acid. The nucleic acid may be a recombinant nucleic acid. The nucleic acids may be present in whole cells, in a cell lysate, or may be nucleic acids in a partially purified or substantially pure form. A nucleic acid is "isolated" or "rendered substantially pure" when purified away from other cellular components or other contaminants, e.g., other cellular nucleic acids or proteins, by standard techniques. Nucleic acid molecules of the disclosure may be obtained using standard molecular biology techniques, including but not limited to methods of amplification, and reverse transcription of RNA. Once DNA fragments encoding, for example, variable chains are obtained, these DNA fragments may be further manipulated by standard recombinant DNA techniques, for example to convert the variable region genes to full-length chain genes. In these manipulations, a variant-encoding DNA fragment is operatively linked to another DNA molecule, or to a fragment encoding another protein, such as a constant region or a flexible linker. The term "operatively linked", as used in this context, is intended to mean that the two DNA fragments are joined in a functional manner, for example, such that the amino acid sequences encoded by the two DNA fragments remain in-frame, or such that the protein is expressed under control of a desired promoter. The isolated DNA encoding the variable region, e.g. the variable alpha region and / or variable beta region, can be converted to a fulllength chain gene by operatively linking the variable-encoding DNA to another DNA molecule encoding constant regions. The sequences of human constant region genes, e.g. for TCRs or antibodies, are known in the art and DNA fragments encompassing these regions can be obtained by standard PCR amplification. The described nucleic acids may be included in one or more suitable vectors. If two or more antigen-binding protein polypeptide chains are encoded on one vector, the two or more antigen-binding protein polypeptide chains may be under the control of the same promoter or under the control of separate promoters. The terms "vector", "cloning vector" and "expression vector" refers to a vehicle by which a DNA or RNA sequence (e.g. a foreign gene) can be introduced into a host cell, so as to transform the host and promote expression (e.g. transcription and translation) of the introduced sequence. Various expression vectors may be employed to express the polynucleotides encoding the antigen-binding proteins. Both viral-based and non-viral expression vectors may be used to produce the antigen-binding proteins described herein in a mammalian host cell. Non-viral vectors and systems include plasmids, cosmids, episomes, and artificial chromosomes. Such vectors may comprise regulatory elements, such as a promoter, enhancer, terminator and the like, to cause ordirect expression of said polypeptide upon administration to a subject. Examples of promoters and enhancers used in the expression vector for animal cell include early promoter and enhancer of SV40 (Mizukami et al. J Biochem., 1987, 101(5):1307-10), LTR promoter and enhancer of Moloney mouse leukemia virus (Kuwana et al. FEBS Lett., 1987, 219(2):360-4), promoter (Mason et al. Cell., 1985, 41(2):479-87) and enhancer (Gillies et al. Cell., 1983, 33(3):717-28) of antibody heavy chain and the like. Examples of plasmids include replicating plasmids comprising an origin of replication, or integrative plasmids, such as for instance pllC, pcDNA, pBR and the like. The term "viral vector" refers to a nucleic acid vector construct that includes at least one element of viral origin and has the capacity to be packaged into a viral vector particle and encodes at least an exogenous nucleic acid. The vector and / or particle can be utilized for the purpose of transferring a nucleic acid of interest into cells either in vitro or in vivo. Numerous forms of viral vectors are known in the art. Useful viral vectors include vectors based on retroviruses, lentiviruses, adenoviruses, adeno-associated viruses, herpes viruses, vectors based on SV40, papilloma virus, Epstein Barr virus, vaccinia virus vectors and Semliki Forest virus (SFV). Recombinant viruses may be produced by techniques known in the art, such as by transfecting packaging cells or by transient transfection with helper plasmids or viruses. Typical examples of virus packaging cells include PA317 cells, PsiCRIP cells, GPenv+ cells, HEK293 cells, etc. Detailed protocols for producing such replication-defective recombinant viruses may be found for instance in WO95 / 14785, WO96 / 22378, US 5,882,877, US 6,013,516, US 4,861,719, US 5,278,056 and WO94 / 19478. Accordingly, the invention relates to a nucleic acid or separate nucleic acids encoding an antigen-binding protein as described herein. In particular, the invention relates to a nucleic acid or separate nucleic acids encoding an antigen-binding protein, wherein the the antigen-binding protein comprises a FC1 comprising or consisting of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or a FC2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40. The invention further relates to a vector comprising the nucleic acid or the separate nucleic acids as described herein or separate vectors comprising the separate nucleic acids as described herein. In particular, the invention relates to a vector comprising a nucleic acid or separate nucleic acids, wherein the nucleic acid or the separate nucleic acids encode an antigen-binding protein, wherein the the antigen-binding protein comprises a FC1 comprising or consisting of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or a FC2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40. Also encompassed herein is a host cell comprising the described antigen-binding proteins, the described nucleic acid(s) or the described vector(s). The host cell may be transfected, infected, transduced or transformed, in particular with a nucleic acid and / or a vector as described herein. Accordingly, the invention relates to a host cell comprising the described antigenbinding protein, the described nucleic acid or separate nucleic acids, or the described vector or the separate vectors. It is pointed out that the invention also relates to an antigen-binding protein as described herein, wherein the antigen-binding protein is produced by any one of the herein described host cells. Accordingly, the invention also relates to an antigen-binding protein, wherein the antigen-binding protein is produced by a host cell transfected with (a) nucleic acid(s) or (a) vector(s) encoding the herein described antigen-binding proteins. Thus, the invention relates to an antigen-binding protein, wherein the antigen-binding protein is produced by a) providing a suitable host cell, b) transfecting said suitable host cell with (a) nucleic acid(s) or (a) vector(s) encoding an antigen-binding protein as described herein, c) producing the antigen-binding protein, optionally d) harvesting the host cell, and e) purifying or isolating the antigen-binding protein. The invention relates to an antigen-binding protein, wherein the antigen-binding protein is produced by a) providing a suitable host cell, b) transfecting said suitable host cell with (a) nucleic acid(s) or (a) vector(s) encoding the antigen-binding protein, c) producing the antigen-binding protein, optionally d) harvesting the host cell, and e) purifying or isolating the antigen-binding protein, wherein wherein the antigen-binding protein comprises a FC1 comprising or consisting of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or a FC2 comprising or consisting of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40. It is envisaged that the produced antigen-binding proteins are further formulate into a pharmaceutical composition Thus, the invention relates to an antigen-binding protein, wherein the antigen-binding protein is produced by a) providing a suitable host cell, b) transfecting said suitable host cell with (a) nucleic acid(s) or (a) vector(s) encoding the antigen-binding protein as described herein, c) producing the antigen-binding protein, optionally d) harvesting the host cell, e) purifying or isolating the antigen-binding protein, and f) formulating the antigen-binding protein into a pharmaceutical composition. It is evident that the invention also relates to the antigen-binding protein as obtained or obtainable by the herein described methods. The host cell is preferably a eukaryotic cell. The host cell may be a cultured cell or a primary cell, i.e., isolated directly from an organism, e.g., a human. The host cell can be an adherent cell or a suspended cell, i.e., a cell that grows in suspension. For purposes of producing a recombinant antigen-binding protein, for example a TCER®, the host cell is preferably a mammalian cell. The host cell for recombinant expression may be a Chinese Hamster Ovary (CHO) cell or a yeast cell. The host cell may also be a peripheral blood leukocyte (PBL) or a peripheral blood mononuclear cell (PBMC). The host cell may also be a lymphocyte, such as a T cell, a T cell progenitor or a NKcell. The invention also relates to pharmaceutical compositions. In particular the invention relates to pharmaceutical compositions comprising the herein described antigen-binding proteins. The terms "pharmaceutical composition" or "therapeutic composition" as used herein refer to a compound or composition capable of inducing a desired therapeutic effect when properly administered to a subject. The subject may also be referred to as patent. Preferably, the subject is a mammal, more preferably a human. Such therapeutic or pharmaceutical compositions may comprise a therapeutically effective amount of an antigen-binding protein, in admixture with a pharmaceutically or physiologically acceptable formulation agent, carrier or aqueous medium selected for suitability with the mode of administration. The antigen-binding protein will usually be supplied as part of a sterile, pharmaceutical composition which may include a pharmaceutically acceptable carrier. "Pharmaceutically" or "pharmaceutically acceptable" refers to molecular entities and compositions that do not produce an adverse, allergic or other untoward reaction when administered to a mammal, especially a human, as appropriate. A pharmaceutically acceptable carrier or excipient refers to a non-toxic solid, semi-solid or liquid filler, diluent, encapsulating material or formulation auxiliary of any type. A "pharmaceutically-acceptable carrier" may also be referred to as "pharmaceutically acceptable diluent" or "pharmaceutically acceptable vehicle" and may include solvents, bulking agents, stabilizing agents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like which are physiologically compatible. The carrier may be an aqueous carrier or an aqueous medium. The pharmaceutical compositions may be provided in a sealed container and may be provided as part of a kit. Such a kit would normally (although not necessarily) include instructions for use. In particular, the pharmaceutical compositions may contain vehicles, which are pharmaceutically acceptable for a formulation suitable for injection. These may be in particular isotonic, sterile, saline solutions (monosodium or disodium phosphate, sodium, potassium, calcium or magnesium chloride and the like or mixtures of such salts), or dry, especially freeze-dried compositions which upon addition, depending on the case, of sterilized water or physiological saline, permit the constitution of injectable solutions. To prepare pharmaceutical compositions, an effective amount of the antigen-binding protein may be dissolved or dispersed in a pharmaceutically acceptable carrier or aqueous medium. Accordingly, the invention relates to a pharmaceutical composition, wherein the herein described antigen-binding protein is dissolved or dispersed in a pharmaceutically acceptable carrier or aqueous medium. The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions; formulations including sesame oil, peanut oil or aqueous propylene glycol; and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases, the form must be sterile and must be fluid to the extent that administration via a syringe is possible. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms, such as bacteria and fungi. Solutions of the active compounds as free base or pharmacologically acceptable salts can be prepared in water suitably mixed with a surfactant, such as hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, and mixtures thereof and in oils. Under ordinary conditions of storage and use, these preparations may contain a preservative to prevent the growth of microorganisms. An antigen binding protein described herein may be formulated into a composition in a neutral or salt form using pharmaceutically acceptable salts. Sterile injectable solutions are prepared by incorporating the active compounds (antigenbinding proteins) in the required amount in the appropriate solvent with various of the other ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the various sterilized active ingredients into a sterile vehicle which contains the basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum-drying and freeze-drying techniques which yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof. The preparation of more, or highly concentrated solutions for direct injection is also contemplated, where the use of DMSO as solvent is envisioned to result in extremely rapid penetration, delivering high concentrations of the active agents to a small tumor area. It is pointed out that pharmaceutical compositions comprising the herein described nucleic acids, vectors and host cells are also encompassed. Accordingly, the invention relates to a pharmaceutical composition comprising the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell as described herein and / or the antigen binding protein as obtained or obtainable by the herein described methods. The invention also relates to the use of the described antigen-binding proteins nucleic acids, vectors, host cells and / or pharmaceutical compositions in the manufacture of a medicament. The invention also relates to the use of the described antigen-binding protein, nucleic acids, vectors, host cells and / or pharmaceutical compositions in the manufacture of a medicament for the treatment of cancer. The invention also relates to the described antigen-binding protein, nucleic acids, vectors, host cells and / or pharmaceutical compositions for use in medicine. The invention further relates to the described antigen-binding protein, nucleic acids, vectors, host cells and / or pharmaceutical compositions for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. In particular the invention relates to an RNA encoding the described antigen-binding proteins as well as a pharmaceutical composition comprising an RNA encoding the described antigenbinding proteins for use in medicine. Accordingly, the invention in particular relates to an RNA encoding the described antigen-binding proteins as well as a pharmaceutical composition comprising an RNA encoding the described antigen-binding proteins for use use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. Although evident for the skilled person it is pointed out that the disclosures in context of the methods described herein are disclosed as corresponding use mutatis mutandis. The disclosures in context of the use described herein are disclosed as corresponding methods mutatis mutandis. Accordingly, the invention relates to a method of treatment of a disease or disorder comprising administering a therapeutically effective amount of the described antigen-binding protein, pharmaceutical composition, nucleic acid or separate nucleic acids, vector or the separate vectors, the host cell and / or the antigen-binding protein as obtained or obtainable by the described methods to a patient in need thereof. The invention also relates to a pharmaceutical composition / formulation for use in a method of treating a condition or disease by producing an antigen-binding proteins in vivo, wherein the pharmaceutical composition / formulation comprises a nucleic acid encoding the two antigen-binding protein and wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition / formulation. Preferably, the nucleic acid is a mRNA. The invention also relates to a method comprising administering to a subject in need thereof a pharmaceutical composition comprising the herein described antigen-binding protein or a nucleic acid encoding the herein described antigen-binding protein. The invention also relates to a method of efficient protein production in a cell population, the method comprising contacting a cell population with a nucleic acid encoding the herein described antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid under conditions such that an effective amount of the antigen-binding protein is produced in the cell population. The invention also relates to a method for inducing in vivo translation of the described antigenbinding proteins in a mammalian subject in need thereof, comprising administering to the subject an effective amount of a nucleic acid encoding the herein described antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid under conditions such that the nucleic acid is localized into a cell of the subject and the antigen-binding proteins are capable of being translated in the cell from the nucleic acid. In addition the invention relates to a method of mutating an antigen-binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. As shown in the appended examples the described amino acid substitutions can increase / improve heterodimerisation, increase / improve the stability, increase / improve the yield and / or increase / improve the purity of the corresponding antigen-binding proteins. Accordingly, the invention relates to a method of increasing the heterodimerisation of an antigen binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. The invention also relates to a method of increasing the stability of an antigen binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. Additionally, the invention relates to a method of increasing the yield of an antigen binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. Furthermore, the invention relates to a method of increasing the purity of an antigen binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises: (i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or (ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, and substituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; and optionally isolating the antigen binding protein. The invention also relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 409 by aspartic acid and the substitution of the amino acid at position 392 by aspartic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 399 by lysine and the substitution of the amino acid at position 356 by lysine and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of the amino acid at position 409 by aspartic acid and the substitution of the amino acid at position 392 by aspartic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 399 by lysine and the substitution of the amino acid at position 356 by lysine and the amino acid variant Y349C. The invention further relates to an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 394 by aspartic acid, the substitution of the amino acid at position 395 by aspartic acid and the substitution of the amino acid at position 396 by aspartic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 395 by lysine, the substitution of the amino acid at position 396 by lysine and the substitution of the amino acid at position 397 by lysine and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of the amino acid at position 394 by aspartic acid, the substitution of the amino acid at position 395 by aspartic acid and the substitution of the amino acid at position 396 by aspartic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 395 by lysine, the substitution of the amino acid at position 396 by lysine and the substitution of the amino acid at position 397 by lysine and the amino acid variant Y349C. As also demonstrated in the appended Example 2 the herein described antigen-binding proteins can be excellently co-expressed with other heteromeric proteins, in particular other heterodimeric antigen-binding proteins. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, comprising (i) cultivating the host cell, (ii) producing the antigen-binding proteins, and optionally (iii) harvesting the host cell, and preferably (iv) isolating the antigen-binding proteins, wherein the host cell comprises a nucleic acid encoding a first antigen-binding protein comprising at least one heteromerization improving amino acid substitution and a nucleic acid encoding a second antigen-binding protein comprising at least one heteromerization improving substitution. The described methods relate to methods performed in vivo, ex vivo or in vitro. The methods may be used to recombinantly produce two antigen-binding proteins simultaneously e.g. in a fermenter. The skilled person understands that in this case steps (iii) and (iv) may be relevant. However, especially, it is envisaged that a nucleic acid encoding a first antigen-binding protein and a nucleic acid encoding a second antigen-binding protein are together administered to a patient and that the cells of said patient produce said two antigen-binding proteins. The skilled person understands that in this case steps (iii) and (iv) are not relevant. In particular, it is envisaged that the heteromeric antigen-binding proteins are heterodimers and the heteromerization improving amino acid substitutions are heterodimerization improving amino acid substitutions. It is envisaged that in the described methods one of the at least two antigen-binding proteins is an antigen-binding protein as described above. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein one of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C. In particular it is envisaged that in the described methods for producing at least two antigenbinding proteins one antigen-binding protein is an antigen-binding protein as already described above and the other antigen-binding protein is an antigen-binding proteins that also comprises two IgG CH3-containing polypeptides. It is envisaged that said other antigen-binding proteins comprising two IgG CH3-containing polypeptides comprises at least one heteromerization improving amino acid substitution, preferably in the CH3-domain. A "heteromerization improving amino acid substitution" refers to an amino acid substitution that facilitates the interaction of two polypeptides or in other words facilitates the binding of the polypeptides to each other. It is in particular envisaged that the heteromerization improving amino acid substitutions of said other antigen-binding protein are so-called "knob-into-hole" mutations (US5731168 and US8216805). However, it is also envisaged that the heteromerization improving amino acid substitutions of said other antigen-binding protein are the amino acid substitutions described herein. Example 3 demonstrates that also two of the described antigen-binding proteins can be co-expressed, preferably two antigen-binding proteins with different of the described heteromerization improving amino acid substitution. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein one of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; and the other of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein one of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; and the other of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C. In a preferred embodiment, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein one of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; and the other of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant S354C; and the other of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant S354C. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C; and the other of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C. In a preferred embodiment, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigenbinding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C; and the other of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant S354C. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1; and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39; and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40. In a preferred embodiment, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigenbinding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1; and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 39 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 40. As mentioned above and as also shown in the appended Examples the described amino acid substitutions can be combined with knob-into-hole amino acid substitutions for co-expression of two heteromeric proteins. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein one of the at least two antigen-binding proteins is an antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; and the other of the at least two antigen-binding proteins is an antigen-binding protein comprising knob-into-hole amino acid substitutions. The knob-into-hole substitutions usually are T366W (knob) in one polypeptide and T366S, L368A and Y407V (hole) in the other polypeptide. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the amino acid variant T366W and the second polypeptide comprises the amino acid variants T366S, L368A and Y407V. In the described methods the second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprising the knob-into-hole substitutions may further comprise additional heteromerization improving amino acid substitutions, e.g. introduced disulphide bridges. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the amino acid variant S354C and T366W and the second polypeptide comprises the amino acid variants Y349C, T366S, L368A and Y407V. The invention relates to a method for producing at least two different heteromeric antigenbinding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the amino acid variant S354C and T366W and the second polypeptide comprises the amino acid variants Y349C, T366S, L368A and Y407V. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the amino acid variant S349C and T366W and the second polypeptide comprises the amino acid variants Y354C, T366S, L368A and Y407V. Again it is pointed out that it is evident for the skilled person that the amino acid positions provided above are not necessarily the positions in the described protein but refer to the corresponding position in a (wildtype / native) IgG antibody. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the CH3 domain of the first polypeptide has aspartic acid at the position corresponding to position 351 in an IgG antibody, glutamic acid at the position corresponding to position 368 in an IgG antibody, and cysteine at the position corresponding to position 349 in an IgG antibody; and the CH3 domain of the second polypeptide has lysine at the position corresponding to position 351 in an IgG antibody, lysine at the position corresponding to position 366 in an IgG antibody, and cysteine at the position corresponding to position 354 in an IgG antibody; or the CH3 domain of the first polypeptide has aspartic acid at the position corresponding to position 351 in an IgG antibody, glutamic acid at the position corresponding to position 368 in an IgG antibody, and cysteine at the position corresponding to position 354 in an IgG antibody; and the CH3 domain of the second polypeptide has lysine at the position corresponding to position 351 in an IgG antibody, lysine at the position corresponding to position 366 in an IgG antibody, and cysteine at the position corresponding to position 349 in an IgG antibody; and a second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the CH3 domain of the first polypeptide has cysteine at the position corresponding to position 354 in an IgG antibody, and tryptophan at the position corresponding to position 366 in an IgG antibody, and the CH3 domain of second polypeptide has cysteine at the position corresponding to position 349 in an IgG antibody, serine at the position corresponding to position 366 in an IgG antibody, alanine at the position corresponding to position 368 in an IgG antibody, and valine at the position corresponding to position 407 in an IgG antibody. It is in particular envisaged that the second antigen-binding protein comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 17 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 17 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 18 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 18. It is pointed out that when it is referred to "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 17" also the wording "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ 99 ID NO: 17 and the amino acid variants S354C and T366W" is encompassed. Similarly, when it is referred to "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 18" also the wording "an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 18 and the amino acid variants Y349C, T366S, L368A and Y407V" is encompassed. The invention, thus, relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 17 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identitytoSEQID NO: 17 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 18 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 17 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identitytoSEQID NO: 17 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 18 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or 39 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 17 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: V1-L1-V2-FC1 and the second polypeptide comprises a structure represented by the formula: V3-L2-V4-FC2 wherein LI and L2 are linkers and may be the same or different, wherein             VI is Va, V2 is VH, V3 is VL, V4 is VP; VI is VL, V2 is Va, V3 is VP, V4 is VH; VI is VP, V2 is VL, V3 is VH, V4 is Va; VI is VH, V2 is Va, V3 is VP, V4 is VL; VI is Va, V2 is VL, V3 is VH, V4 is VP; VI is VL, V2 is VP, V3 is Va, V4 is VH; VI is VP, V2 is VH, V3 is VL, V4 is Va; or VI is VH, V2 is VP, V3 is Va, V4 is VL; and wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1 or 39; and / or FC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: V5-L5-V6-FC3 and the second polypeptide comprises a structure represented by the formula: V7-L6-V8-FC4 wherein L5 and L6 are linkers and may be the same or different, wherein             V5 is Va, V6 is VH, V7 is VL, V4 is VP; V5 is VL, V6 is Va, V7 is VP, V8 is VH; V5 is VP, V6 is VL, V7 is VH, V8 is Va; V5 is VH, V6 is Va, V7 is VP, V8 is VL; V5 is Va, V6 is VL, V7 is VH, V8 is VP; V5 is VL, V6 is VP, V7 is Va, V8 is VH; V5 is VP, V6 is VH, V7 is VL, V8 is Va; or V5 is VH, V6 is VP, V7 is Va, V8 is VL; and wherein FC3 comprises or consists of the amino acid sequence according to SEQ ID NO: 17 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 17; and / or FC4 comprises or consists of the amino acid sequence according to SEQ ID NO: 18 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC1 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2 ; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 53, FC1 comprises or consists of SEQ ID NO: 1 or 39; Va comprises or consists of the amino acid according to SEQ ID NO: 54, VH comprises or consists of the amino acid according to SEQ ID NO: 9 and FC2 comprises or consists of SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC1 ; and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2 ; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 55, FC1 comprises or consists of SEQ ID NO: 17; Va comprises or consists of the amino acid according to SEQ ID NO: 56, VH comprises or consists of the amino acid according to SEQ ID NO: 13 and FC2 comprises or consists of SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC1 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2 ; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 53, FC1 comprises or consists of SEQ ID NO: 17; Va comprises or consists of the amino acid according to SEQ ID NO: 54, VH comprises or consists of the amino acid according to SEQ ID NO: 9 and FC2 comprises or consists of SEQ ID NO: 18; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC1 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2 ; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 55, FC1 comprises or consists of SEQ ID NO: 1 or 39; Va comprises or consists of the amino acid according to SEQ ID NO: 56, VH comprises or consists of the amino acid according to SEQ ID NO: 13 and FC2 comprises or consists of SEQ ID NO: 2 or 40. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC2 ; and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FCl; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 53, FC1 comprises or consists of SEQ ID NO: 1 or 39; Va comprises or consists of the amino acid according to SEQ ID NO: 54, VH comprises or consists of the amino acid according to SEQ ID NO: 9 and FC2 comprises or consists of SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC1 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2 ; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 55, FC1 comprises or consists of SEQ ID NO: 17; Va comprises or consists of the amino acid according to SEQ ID NO: 56, VH comprises or consists of the amino acid according to SEQ ID NO: 13 and FC2 comprises or consists of SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC1 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2 ; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 53, FC1 comprises or consists of SEQ ID NO: 17; Va comprises or consists of the amino acid according to SEQ ID NO: 54, VH comprises or consists of the amino acid according to SEQ ID NO: 9 and FC2 comprises or consists of SEQ ID NO: 18; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC2 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FCl; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 55, FC1 comprises or consists of SEQ ID NO: 1 or 39; Va comprises or consists of the amino acid according to SEQ ID NO: 56, VH comprises or consists of the amino acid according to SEQ ID NO: 13 and FC2 comprises or consists of SEQ ID NO: 2 or 40. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC2 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FCl; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 53, FC1 comprises or consists of SEQ ID NO: 1 or 39; Va comprises or consists of the amino acid according to SEQ ID NO: 54, VH comprises or consists of the amino acid according to SEQ ID NO: 9 and FC2 comprises or consists of SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC2 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FCl; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 55, FC1 comprises or consists of SEQ ID NO: 17; Va comprises or consists of the amino acid according to SEQ ID NO: 56, VH comprises or consists of the amino acid according to SEQ ID NO: 13 and FC2 comprises or consists of SEQ ID NO: 18. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC2 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FCl; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 53, FC1 comprises or consists of SEQ ID NO: 17; Va comprises or consists of the amino acid according to SEQ ID NO: 54, VH comprises or consists of the amino acid according to SEQ ID NO: 9 and FC2 comprises or consists of SEQ ID NO: 18; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises a structure represented by the formula: VL-L1-VP-FC2 ; and the second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FCl; wherein LI and L2 are linkers and comprise or consist of the amino acid according to SEQ ID NO: 16, VL comprises or consists of the amino acid according to SEQ ID NO: 5, VP comprises or consists of the amino acid according to SEQ ID NO: 55, FC1 comprises or consists of SEQ ID NO: 1 or 39; Va comprises or consists of the amino acid according to SEQ ID NO: 56, VH comprises or consists of the amino acid according to SEQ ID NO: 13 and FC2 comprises or consists of SEQ ID NO: 2 or 40. The skilled person understands that in the described antigen-binding proteins comprising the knob-into-hole substitutions the cysteines forming a disulphide bridge may be exchanged / flipped between the CH3-domain containing polypeptides, i.e. the first polypeptide comprises the amino acid variant S349C and T366W and the second polypeptide comprises the amino acid variants Y354C, T366S, L368A and Y407V. In particularthe invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 41 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 42; and wherein a second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 49 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 50. In particular the invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 41 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 42; and wherein a second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 51 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 52. In particular the invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 43 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 44; and wherein a second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 47 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 48. In particular the invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 45 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 46; and wherein a second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 47 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 48. The invention also relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 25 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 26; and wherein a second antigen-binding protein of the least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 27 and the second polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO: 28. It is also envisaged that the Fc parts of the disclosed antigen-binding proteins are exchanged between the CH3-domain containing polypeptides. The skilled person is readily capable to determine the FC1 and / or FC2 in the disclosed antigen-binding proteins and knows that these regions may be exchanged between the CH3-domain containing polypeptides. In other words when a herein described antigen-binding protein comprises a first IgG CH3-containing polypeptide comprising FC1 and a second IgG CH3-containing polypeptide comprising FC2 also the antigen-binding protein with FC2 in first IgG CH3-containing polypeptide and FC1 in the second IgG CH3-containing polypeptide is disclosed. It is envisaged that the described antigen-binding proteins are combined with further antigenbinding proteins having further target antigens. In particular, it is envisaged that the described antigen-binding proteins targeting MAG-003 and / or PRAME-004 are combined with further antigen-binding proteins having further target antigens. Thus, the invention also relates to a method for producing at least three different heteromeric antigen-binding proteins in a single host cell, wherein one antigen-binding protein of the at least three different heteromeric antigen-binding proteins binds to MAG-003. The invention also relates to a method for producing at least three different heteromeric antigen-binding proteins in a single host cell, wherein one antigen-binding protein of the at least three different heteromeric antigen binding proteins binds to PRAME-004. The invention also relates to a method for producing at least three different heteromeric antigen-binding proteins in a single host cell, wherein one antigen-binding protein of the at least three different heteromeric antigen-binding proteins binds to MAG-003 and another antigen-binding protein of the at least three different heteromeric antigen-binding proteins binds to PRAME-004. Also antigen-binding proteins harboring other heteromerization improving amino acid substitutions are envisaged to be co-expressed with the above described antigen-binding proteins. Said other heteromerization improving amino acid substitutions may be those described in WO2009 / 089004. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the amino acid variants K409D and K392D and the second polypeptide comprises the amino acid variants D399K and E356K, optionally wherein the second antigenbinding protein comprises further artificial disulphide bridges as described herein. The invention, thus, relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C;or (ii) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant Y349C;and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 21 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 21 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 22 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 22. It is also envisaged that antigen-binding proteins harboring the heteromerization improving amino acid substitutions as described in WO2017 / 034770 are co-expressed with the above described antigen-binding proteins. Accordingly, the invention relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C; or (ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C; and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein the first polypeptide comprises the amino acid variant T394D, P395D and P396D and the second polypeptide comprises the amino acid variants P395K, P396K and V397K, optionally wherein the second antigen-binding protein comprises further artificial disulphide bridges as described herein. The invention, thus, relates to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell, wherein a first antigen-binding protein of the at least two different heteromeric antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein (i) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C;or (ii) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, and the second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant Y349C;and wherein a second antigen-binding protein of the least two different heteromeric antigenbinding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 19 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identitytoSEQID NO: 19 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 20 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 20. Although evident for the skilled person it is pointed out that the invention also relates to the antigen-binding proteins as obtained or obtainable by the above described methods. Similarly the invention relates to a pharmaceutical composition comprising at least two of the antigen-binding proteins as defined herein or as produced by the herein described methods. The invention also relates a pharmaceutical composition comprising a nucleic acid or separate nucleic acids encoding at least two of the antigen-binding proteins as defined herein. Again, it is mentioned that the invention also relates to the described pharmaceutical composition for use in medicine, in particular for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. Accordingly, the invention also relates to a method of treatment of a disease or disorder comprising administering a therapeutically effective amount of the described pharmaceutical compositions to a patient in need thereof. As mentioned above it is in particular envisaged that the described antigen-binding proteins are co-expressed in a patient, preferably a human. Accordingly, in further embodiments of the invention, all the methods described herein directed to a method for producing at least two different heteromeric antigen-binding proteins in a single host cell also refer to a method of treatment, wherein nucleic acids encoding said antigen-binding proteins are administered to a patient and the cells of the patient produce said antigen-binding proteins. The herein described antigen-binding proteins described herein a particularly useful for such application because the present inventors showed that said antigen-binding proteins have excellent heterodimerisation properties and do not form incorrectly assembled dimers when co-expressed. Accordingly the invention relates to a pharmaceutical composition / formulation for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition / formulation comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins and wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition / formulation. Preferably, the nucleic acid is a mRNA. For example, the invention relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition, wherein a first antigen-binding protein of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or 39 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 17 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 18. The invention also relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition, wherein a first antigen-binding protein of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 1 or 39 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 2 or 40; and wherein a second antigen-binding protein of the least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 17 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 18, and wherein one of the antigen-binding proteins binds to the peptide according to SEQ ID NO: 57 and the other antigen-binding proteins binds to the peptide according to SEQ ID NO: 58. In particular it is envisaged that the TCER® molecules of Table 1 targeting MAG-003 or PRAME-004, respectively, are combined in the herein described methods of treating. It is evident that in particularthe combination of TPP-9501 with TPP-9505 orTPP-9506 and the combination of TPP-9504 with TPP-9502 or TPP-9503 is envisaged. Accordingly, the invention also relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition, wherein a first antigen-binding protein of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 41 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 42; and wherein a second antigen-binding protein of the least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 49 or 51 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 50 or 52. The invention further relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition, wherein a first antigen-binding protein of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 47 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 48; and wherein a second antigen-binding protein of the least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 43 or 45 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 44 or 46. Target antigen of TCR variable domain T-cell Recruiting Domain Mutation sets "Disulphide" substitutions TPP # MAG-003 (R7P1D5-derived) SEQ ID NOs: 5 + 9 (BMA031(V36)) Knob-into-hole S354C / Y349'C TPP-9501 (SEQ ID NOs: 41 + 42) MAG-003 (R7P1D5-derived) SEQ ID NOs: 5 + 9 (BMA031(V36)) L351D:L368E / L351'K:T366'K Y349C / S354'C TPP-9502 (SEQ ID NOs: 43 + 44) MAG-003 (R7P1D5-derived) SEQ ID NOs: 5 + 9 (BMA031(V36)) L351D:L368E / L351'K:T366'K S354C / Y349'C TPP-9503 (SEQ ID NOs: 45 + 46) PRAME-004 (R11P3D3-derived) SEQ ID NOs: 5 + 13 (BMhanced) Knob-into-hole S354C / Y349'C TPP-9504 (SEQ ID NOs: 47 + 48) PRAME-004 (R11P3D3-derived) SEQ ID NOs: 5 + 13 (BMhanced) L351D:L368E / L351'K:T366'K Y349C / S354'C TPP-9505 (SEQ ID NOs: 49 + 50) PRAME-004 (R11P3D3-derived) SEQ ID NOs: 5 + 13 (BMhanced) L351D:L368E / L351'K:T366'K S354C / Y349'C TPP-9506 (SEQ ID NOs: 51 + 52) Table 1: MAG-003 and PRAME-004 targeting TCER®s partly with the herein described heterodimerisation improving substitutions in the CH3-domain. The disulphide substitutions may be exchanged between the polypeptide chains. Accordingly, also the amino acid sequences of the polypeptides with the exchanged disulphide substitutions are considered to be encompassed / disclosed herein. For example, SEQ ID NOs: 41 is disclosed with S354C but the same sequence with Y349C is also encompassed (i.e. the sequence with a serine at the position corresponding to position 354 and cysteine at the position corresponding to position 349). It is evident for the skilled person that the antigen-binding molecules of Table 1 contain a C-terminal Strep-Tag. Accordingly, it is evident for the skilled person that when said antigenbinding molecules are used in medical or therapeutic settings the antigen-binding molecules without Strep-Tag may be preferred. Table 1A shows the sequences of the antigen-binding proteins of Table 1 without Strep-Tag. Accordingly, it is evident for the skilled person that the antigen-binding proteins shown in Table 1A may be preferred for medical or therapeutic settings. Target antigen of TCR variable domain T-cell Recruiting Domain Mutation sets "Disulphide" substitutions SEQ ID NO MAG-003 (R7P1D5-derived) SEQ ID NOs: 5 + 9 (BMA031(V36)) Knob-into-hole S354C / Y349'C MAG-003 TCER® (SEQ ID NOs: 79 + 76) MAG-003 (R7P1D5-derived) SEQ ID NOs: 5 + 9 (BMA031(V36)) L351D:L368E / L351'K:T366'K Y349C / S354'C TPP-9502 untagged (SEQ ID NOs: 80 + 81) MAG-003 (R7P1D5-derived) SEQ ID NOs: 5 + 9 (BMA031(V36)) L351D:L368E / L351'K:T366'K S354C / Y349'C TPP-9503 untagged (SEQ ID NOs: 82 + 83) PRAME-004 (R11P3D3-derived) SEQ ID NOs: 5 + 13 (BMhanced) Knob-into-hole S354C / Y349'C PRAME-004 TCER® (SEQ ID NOs: 74 + 72) PRAME-004 (R11P3D3-derived) SEQ ID NOs: 5 + 13 (BMhanced) L351D:L368E / L351'K:T366'K Y349C / S354'C TPP-9505 untagged (SEQ ID NOs: 84 + 85) PRAME-004 (R11P3D3-derived) SEQ ID NOs: 5 + 13 (BMhanced) L351D:L368E / L351'K:T366'K S354C / Y349'C TPP-9506 (SEQ ID NOs: 86 + 87) Table 1A: MAG-003 and PRAME-004 targeting TCER®s partly with the herein described heterodimerisation improving substitutions in the CH3-domain. The disulphide substitutions may be exchanged between the polypeptide chains. Accordingly, also the amino acid sequences of the polypeptides with the exchanged disulphide substitutions are considered to be encompassed / disclosed herein. Accordingly, the invention also relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition, wherein a first antigen-binding protein of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 79 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 76; and wherein a second antigen-binding protein of the least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 84 or 86 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 85 or 87. The invention further relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition, wherein a first antigen-binding protein of the at least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 74 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 72; and wherein a second antigen-binding protein of the least two antigen-binding proteins comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acid sequence according to SEQ ID NO: 80 or 82 and the other polypeptide comprises the amino acid sequence according to SEQ ID NO: 81 or 83. The invention also relates to a method comprising administering to a subject in need thereof a pharmaceutical composition comprising at least two of the herein described antigen-binding proteins or nucleic acids encoding at least two of the herein described antigen-binding proteins. The invention also relates to a method of efficient protein production in a cell population, the method comprising contacting a cell population with nucleic acids encoding at least two of the herein described antigen-binding proteins or a pharmaceutical composition comprising said nucleic acids under conditions such that an effective amount of the protein is produced in the cell population. The invention also relates to a method for inducing in vivo translation of at least two (recombinant) antigen-binding proteins in a mammalian subject in need thereof, comprising administering to the subject an effective amount of (a) nucleic acid(s) encoding at least two of the herein described antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid(s) under conditions such that the nucleic acid(s) is / are localized into a cell of the subject and the antigen-binding proteins are capable of being translated in the cell from the nucleic acid(s). The invention also relates to kits comprising the described antigen-binding proteins, nucleic acids, vectors, host cells or pharmaceutical compositions / formulations. Suitable pharmaceutical compositions and modifications of the nucleic acids that allow treatment of patients by the above described uses and methods are described e.g. in WO2012 / 019168, WO2013 / 151663 or WO2013 / 151665 which are incorporated by reference in their entirety. As mentioned above, the invention also relates to an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins for use as medicine. The antigen-binding proteins may be administered or co-administered, simultaneously, in either separate or combined formulations, or sequentially at different times separated by minutes, hours or days, but in some way act together to provide the desired therapeutic response. The invention also relates to an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC), preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. The invention also relates to a combination comprising an antigen-binding protein binding to MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins. The invention also relates to a pharmaceutical composition comprising an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins. The invention also relates to a pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding at least two antigen-binding proteins, wherein the method comprises contacting a cell, tissue or organism with the pharmaceutical composition and wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein. The invention also relates to an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins. The invention also relates to an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins. "Co-administration", "administered in combination", "administration of a combination", "co-administration of a combination", "combined therapy" and / or "combined treatment regimen" is used herein in the broadest sense and refers to at least two therapeutically active drugs or compositions which may be administered or coadministered, simultaneously, in either separate or combined formulations, or sequentially at different times separated by minutes, hours or days, but in some way act together to provide the desired therapeutic response. Accordingly, the described antigen-binding proteins may be administered or co-administered, simultaneously, in either separate or combined formulations, or sequentially at different times separated by minutes, hours or days. Simultaneous administration means that the therapeutically active agents (the described antigen-binding proteins) can be administered at the same time. This can occur either by combining them into a single formulation / composition or by administering them separately but concurrently or concomitantly. The described antigen-binding proteins may be administered in separate formulations which means that the active agents may be provided in different formulations / compositions, meaning each drug or composition retains its own distinct form. Even though they are administered together or in close succession, they are not physically combined into one dosage form (e.g. pharmaceutical composition). Sequential Administration means that the described antigen-binding proteins are administered at different times. This could mean administering them minutes, hours or even days apart. Despite this staggered timing, the agents are considered part of a combined therapy because they interact or work in concert to achieve the desired therapeutic effect. The skilled person knows that the key aspect of these combined approaches is that, regardless of the timing or method of delivery, the active agents may act in synergy or complement each other in a way that contributes to the intended therapeutic outcome or therapeutic effect. Accordingly, the invention relates to the described antigen-binding proteins for use in the treatment of cancer, wherein the antigen-binding proteins are administered in combination, wherein the antigen-binding proteins are each present in an amount effective to achieve a synergistic therapeutic effect when administered in combination. The invention also relates to a method of protein production in a cell population, wherein the method comprises contacting a cell population with a nucleic acid or nucleic acids encoding at least two antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid or nucleic acids under conditions such that an effective amount of the protein is produced in the cell population, wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein. The invention also relates to a method for inducing in vivo translation of at least two antigenbinding proteins in a mammalian subject in need thereof, comprising administering to the subject an effective amount of a nucleic acid or nucleic acids encoding the at least two antigenbinding proteins or a pharmaceutical composition comprising said nucleic acid or nucleic acids under conditions such that the nucleic acid(s) is / are localized into a cell of the subject and the antigen-binding proteins are capable of being translated in the cell from the nucleic acid(s), wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein. The invention also relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein and an antigenbinding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein, preferably a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein and optionally one or more further antigen-binding proteins. Although evident for the skilled person it is pointed out that in the above described embodiments the antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and the antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) and optionally one or more further antigen-binding proteins act together to provide a desired therapeutic effect. In particular the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein may comprise a T cell receptor (TCR) alpha variable domain (Va) and a TCR beta variable domain (VP), wherein the Va domain comprises (i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 62, (ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 63, and (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 64; and wherein the VP domain comprises (i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 59, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 60, and (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 61, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein may also comprises a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 54 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 54 and comprising the CDRal, CDRa2, and CDRa3 according to SEQIDNOs:62, 63, and 64, respectively; and a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 53 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 53 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQIDNOs:59, 60, and 61, respectively. Furthermore, the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein may comprise an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein may further comprise a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 11, and 12, respectively. The antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein may comprises or consists of a first polypeptide chain comprising a structure represented by the formula: VL-L1-VP-FC1; and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2; wherein LI and L2 are linkers and may be the same or different and FC1 and FC2 are Fc-domains and may be the same or different. LI and / or L2 may comprise or consist of an amino acid sequence according to SEQ ID NO: 16. FC1 may comprise or consist of an amino acid sequence according to SEQ ID NOs: 1,17,19, 21 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 17, 19, 21 or 39 and / or FC2 may comprise or consist of an amino acid sequence according to SEQ ID NOs: 2, 18, 20, 22 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2,18, 20, 22 or 40. The antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein may comprise a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 75, 79, 80 or 82 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76, 81 or 83. The antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein may comprise a T cell receptor (TCR) alpha variable domain (Va) and a TCR beta variable domain (VP), wherein the Va domain comprises (i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 68, (ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 69, and (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 70; and wherein the VP domain comprises (i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 65, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 66, and (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 67, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein may comprise a Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 56 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 56 and comprising the CDRal, CDRa2, and CDRa3 according to SEQIDNOs:68, 69, and 70, respectively; and a VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 55 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 55 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQIDNOs:65, 66, and 67, respectively. The antigen-binding protein binding to a peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein may comprise an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises (i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6, (ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and (iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises (i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12; wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution. The antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein may comprise a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; and a VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 14, and 12, respectively. The antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein may comprise or consist of a first polypeptide chain comprising a structure represented by the formula: VL-L1-VP-FC1; and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2; wherein LI and L2 are linkers and may be the same or different and FC1 and FC2 are Fc-domains and may be the same or different. LI and / or L2 may comprise or consist of an amino acid sequence according to SEQ ID NO: 16. FC1 may comprise or consist of an amino acid sequence according to SEQ ID NOs: 1,17,19, 21 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1,17,19, 21 or 39 and / or FC2 comprise or consist of an amino acid sequence according to SEQ ID NOs: 2, 18, 20, 22 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2,18, 20, 22 or 40. The antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein may comprise a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 71, 74, 84 or 86 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72, 85 or 87. In a preferred embodiment, the invention relates to an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 for use as medicine. In another preferred embodiment, the invention relates to an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 and an antigen-binding protein comprising a polypeptide 128 comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. In another preferred embodiment, the invention relates to a combination comprising an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72. In another preferred embodiment, the invention relates to a combination comprising an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders. In another preferred embodiment, the invention relates to a pharmaceutical composition comprising an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72. In another preferred embodiment, invention relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72. In another preferred embodiment, the invention relates to an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72. In another preferred embodiment, the invention relates to an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76. The described antigen-binding proteins may be administered in doses as described in EP24174662.7, EP24199013.4, EP25151617.5, EP24213284.3 and EP25166821.6 which are incorporated herein by reference in its entirety. In particular, the antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 may be administered at a dose of about 10 pg, about 20 pg, about 30 pg, about 40 pg, about 50 pg, about 60 pg, about 80 pg, about 100 pg, about 120 pg, about 140 pg, about 150 pg, about 160 pg, about 180 pg, about 200 pg, about 250 pg, about 300 pg, about 350 pg, about 360 pg, about 400 pg, about 450 pg, about 500 pg, about 540 pg, about 550 pg, about 600 pg, about 800 pg, about 1200 pg, about 1500 pg, about 1600 pg, about 1800 pg, about 2500 pg, about 3000 pg, about 3500 130 Hg, about 4000 pg, about 4500 ng, about 5000 ng, about 5500 ng, about 6000 ng, about 7000 Hg, about 8000 ng, about 9000 ng, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg, about 15 mg, about 16 mg, about 17 mg, about 18 mg, about 19 mg, about 20 mg, about 21 mg, about 22 mg, about 23 mg, about 24 mg, about 25 mg, about 26 mg, about 27 mg, about 28 mg, about 29 mg, about 30 mg, about 31 mg, about 32 mg, about 33 mg, about 34 mg, about 35 mg, about 36 mg, about 37 mg, about 38 mg, about 39 mg, about 40 mg, about 41 mg, about 42 mg, about 43 mg, about 44 mg, about 45 mg, about 46 mg, about 47 mg, about 48 mg, about 49 mg or about 50 mg, preferably about 20 pg, about 60 pg, about 120 pg, about 360 pg, about 800 pg, about 1600 pg, about 3000 pg, about 3500 pg, about 4000 pg, about 4500 pg, about 5000 pg, about 5500 pg, or about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg, about 15 mg, about 16 mg, about 17 mg, about 18 mg, about 19 mg or about 20 mg, more preferably about 1600 pg, about 3000 pg, about 4000 pg, about 5000 pg, about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg or about 15 mg. In particular, the antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 may be administered at a dose of about 6.6 pg, about 10 pg, about 20 pg, about 30 pg, about 40 pg, about 50 pg, about 60 pg, about 80 pg, about 100 pg, about 120 pg, about 140 pg, about 150 pg, about 160 pg, about 180 pg, about 200 pg, about 250 pg, about 300 pg, about 350 pg, about 400 pg, about 450 pg, about 500 pg, about 540 pg, about 600 pg, about 1000 pg, about 1200 pg, about 1800 pg or about 2500 pg, about 5000 pg, or about 10 mg, preferably about 6.6 pg, about 20 pg, about 60 pg, about 180 pg, about 300 pg, about 540 pg, about 600 pg, about 1000 pg, about 1200 pg, about 1800 pg, about 2000 pg, about 2500 pg, about 5000 pg, or about 10 mg more preferably about 1200 pg, about 1800 pg, about 2000 pg or about 2500 pg, or about 1000 pg to about 2500 pg or about 1200 pg to about 2500 pg. Accordingly, the invention relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof (a combination of) an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 at a dose of about 6.6 pg, about 10 pg, about 20 pg, about 30 pg, about 40 pg, about 50 pg, about 60 pg, about 80 pg, about 100 pg, about 120 pg, about 140 pg, about 150 pg, about 160 pg, about 180 pg, about 200 pg, about 250 pg, about 300 pg, about 350 pg, about 400 pg, about 450 pg, about 500 pg, about 540 pg, about 600 pg, about 1000 pg, about 1200 pg, about 1800 pg or about 2500 pg, about 5000 pg, or about 10 mg, preferably about 6.6 pg, about 20 pg, about 60 pg, about 180 pg, about 300 pg, about 540 pg, about 600 pg, about 1000 pg, about 1200 pg, about 1800 pg, about 2000 pg, about 2500 pg, about 5000 pg, or about 10 mg more preferably about 1200 pg, about 1800 pg, about 2000 pg or about 2500 pg, or about 1000 pg to about 2500 pg or about 1200 pg to about 2500 pg and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 at a dose of about 10 pg, about 20 pg, about 30 pg, about 40 pg, about 50 pg, about 60 pg, about 80 pg, about 100 pg, about 120 pg, about 140 pg, about 150 pg, about 160 pg, about 180 pg, about 200 pg, about 250 pg, about 300 pg, about 350 pg, about 360 pg, about 400 pg, about 450 pg, about 500 pg, about 540 pg, about 550 pg, about 600 pg, about 800 pg, about 1200 pg, about 1500 pg, about 1600 pg, about 1800 pg, about 2500 pg, about 3000 pg, about 3500 pg, about 4000 pg, about 4500 pg, about 5000 pg, about 5500 pg, about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg, about 15 mg, about 16 mg, about 17 mg, about 18 mg, about 19 mg, about 20 mg, about 21 mg, about 22 mg, about 23 mg, about 24 mg, about 25 mg, about 26 mg, about 27 mg, about 28 mg, about 29 mg, about 30 mg, about 31 mg, about 32 mg, about 33 mg, about 34 mg, about 35 mg, about 36 mg, about 37 mg, about 38 mg, about 39 mg, about 40 mg, about 41 mg, about 42 mg, about 43 mg, about 44 mg, about 45 mg, about 46 mg, about 47 mg, about 48 mg, about 49 mg or about 50 mg, preferably about 20 pg, about 60 pg, about 120 pg, about 360 pg, about 800 pg, about 1600 pg, about 3000 pg, about 3500 pg, about 4000 pg, about 4500 pg, about 5000 pg, about 5500 pg, or about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg, about 15 mg, about 16 mg, about 17 mg, about 18 mg, about 19 mg or about 20 mg, more preferably about 1600 pg, about 3000 pg, about 4000 pg, about 5000 pg, about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg or about 15 mg. The invention also relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof (a combination of) an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 at a dose of about 1000 pg, about 1200 pg, about 1800 pg, about 2000 pg or about 2500 pg, or about 1000 pg to about 2500 pg or about 1200 pg to about 2500 pg and an antigenbinding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 at a dose of about 1600 pg, about 3000 pg, about 4000 pg, about 5000 pg, about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg or about 15 mg or about 1600 pg to about 5000 pg, about 5000 pg to about 8000 pg, about 8000 pg to about 12 mg, about 12 mg to about 20 mg, about 20 mg to about 30 mg or about 30 mg to about 50 mg, preferably about 5000 pg to about 8000 pg, about 8000 pg to about 12 mg or about 12 mg to about 20 mg. The invention also relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof (a combination of) an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 at a dose of about 1000 pg, about 1200 pg, about 1800 pg, about 2000 pg or about 2500 pg, or about 1000 pg to about 2500 pg, about 1000 pg to about 4000 pg or about 1200 pg to about 2500 pg and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 at a dose of about 1600 pg, about 3000 pg, about 4000 pg, about 5000 pg, about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg or about 15 mg or about 1600 pg to about 5000 pg, about 3000 pg to about 8000 pg, about 5000 pg to about 8000 pg, about 8000 pg to about 12 mg, about 12 mg to about 20 mg, about 20 mg to about 30 mg or about 30 mg to about 50 mg, preferably about 3000 pg to about 8000 ng, about 5000 ng to about 8000 ng, about 8000 ng to about 12 mg or about 12 mg to about 20 mg. The invention also relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof (a combination of) an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 at a dose of about 1000 pg, about 1200 pg, about 1800 pg, about 2000 pg or about 2500 pg, or about 1000 pg to about 2500 pg, about 1000 pg to about 4000 pg or about 1200 pg to about 2500 pg and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 at a dose of about 1600 pg, about 3000 pg, about 4000 pg, about 5000 pg, about 6000 pg, about 7000 pg, about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg or about 15 mg or about 1600 pg to about 5000 pg, about 3000 pg to about 8000 pg, about 5000 pg to about 8000 pg, about 8000 pg to about 12 mg, about 12 mg to about 20 mg, about 20 mg to about 30 mg or about 30 mg to about 50 mg, preferably about 3000 pg to about 8000 pg, about 5000 pg to about 8000 pg, about 8000 pg to about 12 mg or about 12 mg to about 20 mg. Also the concentrations used in the in vitro assay of Example 4 can be used to estimate the doses that may be used for the combination of the MAG-003 TCER® and the PRAME-004 TCER®. Doses can be calculated using the molecular weight of the respective TCER® molecule derived from the amino acid sequence and the assumption that ~10% of the Cmax patient plasma or serum TCER® concentration corresponds to the expected TCER® concentration at the tumor site. Cmax values may be derived from EP24174662.7, EP24199013.4, EP25151617.5, EP24213284.3 and EP25166821.6. The invention also relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof (a combination of) an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 at a dose of about 0.34 ng to about 34 mg, such as about 0.34 ng, about 3.4 ng, about 34 ng, about 340 ng, about 3400 ng or about 34 mg and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 at a dose of about 0.38 pg to about 38 mg, such as about 0.38 pg, about 3.8 pg, about 38 pg, about 380 pg, about 3800 pg or about 38 mg. The invention also relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof (a combination of) an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76 at a dose of about 34 pg to about 3400 pg, such as about 34 pg, about 340 pg or about 3400 pg and an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72 at a dose of about 380 pg to about 38 mg, such as about 380 pg, about 3800 pg, about 30 mg or about 38 mg. Step dosing of the antigen-binding proteins may be performed as described in EP24174662.7, EP24199013.4, EP25151617.5, EP24213284.3 and EP25166821.6 which are incorporated herein by reference in its entirety. The invention relates to a method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein the treatment comprises administration to the patient a)     at least one first dose of about 200 pg to about 1000 pg, such as 300 pg; b)    at least one second dose of about 400 pg to about 1000 pg, such as about 600 pg; c)     at least one third dose in the range of about 600 pg to about 6000 pg, such as about 1000 pg, about 1100 pg, about 1200 pg, about 1300 pg, about 1400 pg, about 1500 pg about 1600 pg, about 1700 pg, about 1800 pg, about 1900 pg, about 2000 pg, about 2100 pg, about 2200 pg, about 2300 pg, about 2400 pg, about 2500 pg, about 2600 pg, about 2700 pg, about 2800 pg, about 2900 pg, about 3000 pg, about 3100 pg, about 3200 pg, about 3300 pg, about 3400 ng, about 3500 ng, about 3600 ng, about 3700 ng, about 3800 ng, about 3900 ng, about 4000 ng, about 4100 ng, about 4200 ng, about 4300 ng, about 4400 ng, about 4500 ng, about 4600 ng, about 4700 ng, about 4800 ng, about 4900 ng, about 5000 ng, about 5100 ng, about 5200 ng, about 5300 ng, about 5400 ng, about 5500 ng, about 5600 ng, about 5700 ng, about 5800 ng, about 5900 ng or about 6000 ng or about 1000 ng to about 4000 ng, such as about 1000 ng to about 2500 ng or about 1200 ng to about 2500 ng of an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 79 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76; and a) at least one first dose in the range of about 40 pg to about 120 pg such as about 40 pg, about 50 pg, about 60 pg, about 70 pg or about 80 pg; b) at least one second dose in the range of about 120 pg to about 400 pg, such as about 120 pg, about 200 pg, about 300 pg or about 400 pg; c) optionally at least one third dose in the range of about 400 pg to about 2000 pg, such as 1600 pg or 2000 pg; and d) at least one further dose in the range of about 2000 pg to about 6000 pg or about 6000 pg to about 30 mg, such as about 4000 pg, about 5000 pg or about 8000 pg, about 9000 pg, about 10 mg, about 11 mg, about 12 mg, about 13 mg, about 14 mg, about 15 mg, about 16 mg, about 17 mg, about 18 mg, about 19 mg or about 20 mg of an antigen-binding protein comprising a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 74 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72. The described antigen-binding proteins may be administered intravenously. The subject or patient to be treated is preferably human. As mentioned above, it is envisaged that in particular cancer is treated by the herein described antigen-binding proteins, nucleic acids, vectors, host cells, uses and methods. The skilled person is readily capable to choose cancers that can be treated by the herein described means and methods. The cancer may also be selected from the group consisting of adrenocortical carcinoma, bladder cancer, preferably (urinary) bladder carcinoma or bladder urothelial carcinoma, brain tumor, in particular glioblastoma, primary brain cancer, or atypical meningioma, breast cancer, in parti...

Claims

1. An antigen-binding protein comprising two IgG CH3-containing polypeptides, wherein(i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant Y349C, andthe second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant S354C;or(ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by a negatively charged amino acid and the amino acid variant S354C, andthe second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by a positively charged amino acid and the amino acid variant Y349C.

2. The antigen-binding protein of claim 1, wherein(i) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant Y349C, andthe second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and the amino acid variant S354C;or(ii) the first polypeptide comprises the substitution of amino acids at position 351 and at position 368 by aspartic acid or glutamic acid and the amino acid variant S354C, andthe second polypeptide comprises the substitution of amino acids at position 351 and at position 366 by lysine, arginine or histidine and the amino acid variant Y349C.

3. The antigen-binding protein of claim 1 or 2, wherein(i) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant Y349C, andthe second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant S354C; or(ii) the first polypeptide comprises the substitution of the amino acid at position 351 by aspartic acid and the substitution of the amino acid at position 368 by glutamic acid and the amino acid variant S354C, andthe second polypeptide comprises the substitution of the amino acid at position 351 by lysine and the substitution of the amino acid at position 366 by lysine and the amino acid variant Y349C.

4. The antigen-binding protein of any one of claims 1 to 3, wherein the first and second polypeptide specifically bind to each other.

5. The antigen-binding protein of any one of claims 1 to 4, wherein the amino acids substituted in the first polypeptide interact with the substituted amino acids in the second polypeptide.

6. The antigen-binding protein of any one of claims 1 to 5, wherein the antigen-binding protein is a bispecific, trispecific or multispecific antigen-binding protein, preferably a bispecific antigen-binding protein.

7. The antigen-binding protein of any one of claims 1 to 6, wherein the antigen-bindingprotein comprises a first binding domain and a second binding domain.

8. The antigen-binding protein of claim 7, wherein the first binding domain specifically binds to a cell surface molecule of a human immune cell and / or the second binding domain specifically binds to an MHC-associated peptide epitope.

9. The antigen-binding protein of claim 7 or 8, wherein the first and / or second binding domain comprises or consists of (an) antibody(ies) or (a) functional fragment(s) or derivative(s) thereof.

10. The antigen-binding protein of any one of claims 7 to 9, wherein the first and / or second binding domain comprises or consists of (a) T cell receptor(s) (TCR) or (a) functional fragment(s) or derivative(s) thereof.

11. The antigen-binding protein of any one of claims 7 to 10, wherein the first binding domain comprises or consists of an antibody antigen binding site (VD).

12. The antigen-binding protein of any one of claims 7 to 11, wherein the second binding domain comprises or consists of a TCR antigen binding site (VR).

13. The antigen-binding protein of claim 11 or 12, wherein one polypeptide comprises the antibody variable light chain domain (VL) of the antigen binding site (VD) and the other polypeptide comprises the antibody variable heavy chain domain (VH) of the antigen binding site (VD).

14. The antigen-binding protein of any one of claims 11 to 13, wherein one polypeptide comprises the TCR alpha variable domain (Va) of the antigen binding site (VR) and the other polypeptide comprises the TCR beta variable domain (VP) of the antigen binding site (VR).

15. The antigen-binding protein of claim 13 or 14, wherein one polypeptide comprises the antibody variable light chain domain (VL) and the TCR beta variable domain (VP) and the other polypeptide comprises the antibody variable heavy chain domain (VH) and the TCR alpha variable domain (Va).

16. The antigen-binding protein of claim 13 or 14, wherein one polypeptide comprises the antibody variable light chain domain (VL) and the TCR alpha variable domain (Va) and the other polypeptide comprises the antibody variable heavy chain domain (VH) and the TCR beta variable domain (VP).

17. The antigen-binding protein of any one of claims 1 to 16, wherein the first polypeptide further comprises a CH2 domain and / orthe second polypeptide further comprises a CH2 domain.

18. The antigen-binding protein of claim 17, wherein in one polypeptide the CH2 domain and the CH3 domain form a Fc domain FC1 and / or in the other polypeptide the CH2 domain and the CH3 domain form a Fc domain FC2.

19. The antigen-binding protein of any one of claims 1 to 18, wherein the first polypeptide and the second polypeptide are on separate polypeptide chains or are connected by a linker.

20. The antigen-binding protein of any one of claims 13 to 19, wherein the first polypeptide comprises a structure represented by the formula:V1-V2         [I];and the second polypeptide comprises a structure represented by the formula:V3-V4         [II];wherein VI is Va, V2 is VH, V3 is VL, V4 is VP;VI is VL, V2 is Va, V3 is VP, V4 is VH;VI is VP, V2 is VL, V3 is VH, V4 is Va;VI is VH, V2 is Va, V3 is VP, V4 is VL;VI is Va, V2 is VL, V3 is VH, V4 is VP;VI is VL, V2 is VP, V3 is Va, V4 is VH;VI is VP, V2 is VH, V3 is VL, V4 is Va; orVI is VH, V2 is VP, V3 is Va, V4 is VL.

21. The antigen-binding protein of any one of claims 13 to 20, wherein the variable domains are connected by linkers.

22. The antigen-binding protein of any one of claims 13 to 21, wherein the first polypeptide comprises a structure represented by the formula:V1-L1-V2              [III];and the second polypeptide comprises a structure represented by the formula:V3-L2-V4             [IV];wherein LI and L2 are linkers and may be the same or different,wherein VI is Va, V2 is VH, V3 is VL, V4 is VP;VI is VL, V2 is Va, V3 is VP, V4 is VH;VI is VP, V2 is VL, V3 is VH, V4 is Va;VI is VH, V2 is Va, V3 is VP, V4 is VL;VI is Va, V2 is VL, V3 is VH, V4 is VP;VI is VL, V2 is VP, V3 is Va, V4 is VH;VI is VP, V2 is VH, V3 is VL, V4 is Va; orVI is VH, V2 is VP, V3 is Va, V4 is VL.

23. The antigen-binding protein of any one of claims 13 to 22, wherein the first polypeptide comprises a structure represented by the formula:V1-L1-V2-FC1        [V];and the second polypeptide comprises a structure represented by the formula:V3-L2-V4-FC2        [VI];wherein LI and L2 are linkers and may be the same or different,wherein VI is Va, V2 is VH, V3 is VL, V4 is VP;VI is VL, V2 is Va, V3 is VP, V4 is VH;VI is VP, V2 is VL, V3 is VH, V4 is Va;VI is VH, V2 is Va, V3 is VP, V4 is VL;VI is Va, V2 is VL, V3 is VH, V4 is VP;VI is VL, V2 is VP, V3 is Va, V4 is VH;VI is VP, V2 is VH, V3 is VL, V4 is Va; orVI is VH, V2 is VP, V3 is Va, V4 is VL.

24. The antigen-binding protein of any one of claims 13 to 23, wherein the first polypeptide comprises a structure represented by the formula:V1-L1-V2-L3-FC1            [VII];and the second polypeptide comprises a structure represented by the formula:V3-L2-V4-L4-FC2             [VIII];wherein LI, L2, L3 and L4 are linkers and may be the same or different, andwherein VI is Va, V2 is VH, V3 is VL, V4 is VP;VI is VL, V2 is Va, V3 is VP, V4 is VH;VI is VP, V2 is VL, V3 is VH, V4 is Va;VI is VH, V2 is Va, V3 is VP, V4 is VL;VI is Va, V2 is VL, V3 is VH, V4 is VP;VI is VL, V2 is VP, V3 is Va, V4 is VH;VI is VP, V2 is VH, V3 is VL, V4 is Va; orVI is VH, V2 is VP, V3 is Va, V4 is VL.

25. The antigen-binding protein of any one of claims 21 to 24, wherein the linkers LI, L2, L3 and / or L4 comprise or consist of SEQ ID NO: 16 (GGGSGGGG).

26. The antigen-binding protein of any one of claims 18 to 25, wherein FC1 and / or FC2 further comprise a hinge region, preferably wherein the hinge region comprises or consists of SEQ ID NO: 15 (EPKSS) or SEQ ID NO: 92 (EPKSC).

27. The antigen-binding protein of any one of claim 18 to 26, wherein the FC1 and / or FC2 comprises at least one effector function silencing mutation at a residue selected from positions 233, 234, 235, 236, 297 and 331, preferably wherein said effector function silencing mutation is generated by replacing at least one residue in position 233, 234, 235, 236, and 331 with the corresponding residue derived from lgG2 or lgG4.

28. The antigen-binding protein of any one of claims 18 to 27, wherein FC1 comprises or consists of the amino acid sequence according to SEQ ID NO: 1, 39, 88 or 90 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 39, 88 or 90; and / orFC2 comprises or consists of the amino acid sequence according to SEQ ID NO: 2, 40, 89 or 91 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2, 40, 89 or 91.

29. The antigen-binding protein of any one of claims 13 to 28, wherein the antibody variable light chain domain (VL) and the antibody variable heavy chain domain (VH) associate to form a functional antibody antigen binding site (VD).

30. The antigen-binding protein of any one of claims 14 to 29, wherein the TCR alpha variable domain (Va) and the TCR beta variable domain (VP) associate to form a functional TCR antigen binding site (VR).

31. The antigen-binding protein of any one of claim 8 to 30, wherein the cell surface molecule is known to induce the activation of the immune cell, or is at least one selected from the group consisting of immune response-related molecules, CD3, such as the CD3y, CD36, and CD3e chains, CD4, CD7, CD8, CD10, CDllb, CDllc, CD14, CD16, CD18,CD22, CD25, CD28, CD32a, CD32b, CD33, CD41, CD41b, CD42a, CD42b, CD44, CD45RA, CD49, CD55, CD56, CD61, CD64, CD68, CD94, CD90, CD117, CD123, CD125, CD134, CD137, CD152, CD163, CD193, CD203c, CD235a, CD278, CD279, CD287, Nkp46, NKG2D, GITR, FceRI, TCRa / P, TCRy / 6, and HLA-DR.

32. The antigen-binding protein of any one of claim 8 to 31, wherein the cell surface molecule is a TCR / CD3 complex, preferably an alpha / beta TCR / CD3 complex.

33. The antigen-binding protein of claim 32, wherein the antigen-binding protein comprises: an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises(i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6,(ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and(iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises(i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10, (ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and (iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12;wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution.

34. The antigen-binding protein of claim 32 or 33, wherein the antigen-binding protein comprises:a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; anda VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 11, and 12, respectively.

35. The antigen-binding protein of claim 32, wherein the antigen-binding protein comprises: an antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises(i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6,(ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and(iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises(i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10,(ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and(iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12;wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution.

36. The antigen-binding protein of claim 32 or 35, wherein the antigen-binding protein comprises:a VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; anda VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10,14, and 12, respectively.

37. The antigen-binding protein of any one of claims 12 to 36, wherein the TCR antigen binding site (VR) specifically binds to a bacterial peptide, a viral peptide or a tumor associated antigen peptide, preferably bound to a major histocompatibility complex (MHC) protein.

38. A nucleic acid or separate nucleic acids encoding an antigen-binding protein according to any one of the preceding claims.

39. A vector comprising the nucleic acid or the separate nucleic acids or separate vectors comprising the separate nucleic acids according to claim 38.

40. A host cell comprising the antigen-binding protein, the nucleic acid or separate nucleic acids, or the vector or the separate vectors according to any one of the preceding claims.

41. A method for producing an antigen-binding protein, wherein the method comprises(i) cultivating the host cell of claim 40,(ii) producing the antigen-binding protein, and optionally(iii) harvesting the host cell, and preferably(iv) isolating the antigen-binding protein.

42. The protein as obtained or obtainable by claim 41.

43. A pharmaceutical composition comprising the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell according to any one of the preceding claims or the antigen binding protein as obtained by claim 42.

44. The pharmaceutical composition, the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell according to any one of the preceding claims or the antigen binding protein as obtained by claim 42 for use in medicine.

45. The pharmaceutical composition, the antigen-binding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, or the host cell according to any one of the preceding claims or the antigen binding protein as obtained by claim 42 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders.

46. A method of treatment of a disease or disorder comprising administering a therapeutically effective amount of the pharmaceutical composition, the antigenbinding protein, the nucleic acid or separate nucleic acids, the vector or the separate vectors, the host cell according to any one of the preceding claims or the antigen binding protein as obtained by claim 42 to a patient in need thereof.

47. A method of mutating an antigen-binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises:(i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cystein, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cystein; or(ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cystein, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; andoptionally isolating the antigen binding protein.

48. A method of increasing the heterodimerisation of an antigen binding protein, wherein the antigen-binding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises:(i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or(ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; andoptionally isolating the antigen binding protein.

49. A method of increasing the stability of an antigen binding protein, wherein the antigenbinding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises:(i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or(ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; andoptionally isolating the antigen binding protein.

50. A method of increasing the yield of an antigen binding protein, wherein the antigenbinding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises:(i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or(ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; andoptionally isolating the antigen binding protein.

51. A method of increasing the purity of an antigen binding protein, wherein the antigenbinding protein comprises two (human) IgG CH3-containing polypeptides, wherein the method comprises:(i) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 349 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 354 by cysteine; or(ii) substituting in the first polypeptide the amino acids at position 351 and at position 368 by a negatively charged amino acid and substituting the amino acid at position 354 by cysteine, andsubstituting in the second polypeptide the amino acids at position 351 and at position 366 by a positively charged amino acid and substituting the amino acid at position 349 by cysteine; andoptionally isolating the antigen binding protein.

52. A method for producing at least two different heteromeric antigen-binding proteins in a single host cell, comprising(i) cultivating the host cell,(ii) producing the antigen-binding proteins, and optionally(iii) harvesting the host cell, and preferably(iv) isolating the antigen-binding proteins,wherein the host cell comprises a nucleic acid encoding a first antigen-binding protein comprising at least one heteromerization improving amino acid substitution and a nucleic acid encoding a second antigen-binding protein comprising at least one heteromerization improving substitution.

53. The method of claim 52, wherein the heteromeric antigen-binding proteins are heterodimers and the heteromerization improving amino acid substitutions are heterodimerization improving amino acid substitutions.

54. The method of claim 53, wherein the first antigen-binding protein is an antigen-binding protein according to any one of the preceding claims.

55. The method of claim 54, wherein the heteromerization improving amino acid substitutions of the second antigen-binding protein are knob-into-hole amino acid substitutions or wherein the second antigen-binding protein is an antigen-binding protein according to any one of the preceding claims.

56. The method of claim 55, wherein the second antigen-binding protein comprises two IgG CH3-containing polypeptides, wherein one polypeptide comprises the amino acidvariant T366W and the other polypeptide comprises the amino acid variant T366S, L368A and Y407V.

57. The method of claim 56, wherein of the second antigen-binding protein one polypeptide further comprises the amino acid variant S354C and the other polypeptide further comprises the amino acid variant Y349C.

58. The method of claim 57, wherein the second antigen-binding protein comprises one polypeptide comprising the amino acid sequence according to SEQ ID NO: 17 and another polypeptide comprising the amino acid sequence according to SEQ ID NO: 18.

59. The method of any one of claims 52 to 54, wherein the second antigen-binding protein comprises one polypeptide comprising the sequence according to SEQ ID NO: 19 and another polypeptide comprising the amino acid sequence according to SEQ ID NO: 20.

60. The method of any one of claims 52 to 54, wherein the second antigen-binding protein comprises one polypeptide comprising the sequence according to SEQ ID NO: 21 and another polypeptide comprising the amino acid sequence according to SEQ ID NO: 22.

61. The antigen-binding proteins as obtained or obtainable by the method of any one of claims 52 to 60.

62. A pharmaceutical composition comprising at least two of the antigen-binding proteins as defined in any one of the preceding claims.

63. A pharmaceutical composition comprising a nucleic acid or separate nucleic acids encoding at least two of the antigen-binding proteins as defined in any one of the preceding claims.

64. The pharmaceutical composition of claim 62 or 63 for use in medicine.

65. The pharmaceutical composition of claim 64 for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders.

66. A method of treatment of a disease or disorder comprising administering a therapeutically effective amount of the pharmaceutical composition of claim 62 or 63 to a patient in need thereof.

67. An antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex(MHC) protein for use as medicine.

68. An antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders.

69. A combination comprising an antigen-binding protein binding to MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigenbinding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

70. A pharmaceutical composition comprising an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

71. A pharmaceutical composition for use in a method of treating a condition or disease by producing at least two antigen-binding proteins in vivo, wherein the pharmaceutical composition comprises a nucleic acid or nucleic acids encoding at least two antigenbinding proteins, wherein the method comprises contacting a cell, tissue or organismwith the pharmaceutical composition and wherein one of the at least two antigenbinding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and another of the at least two antigenbinding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

72. An antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

73. An antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein for use in the treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders, wherein said antigen-binding protein is administered in combination with an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein.

74. A method of protein production in a cell population, wherein the method comprises contacting a cell population with a nucleic acid or nucleic acids encoding at least two antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid or nucleic acids under conditions such that an effective amount of the protein is produced in the cell population, wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

75. A method for inducing in vivo translation of at least two antigen-binding proteins in a subject in need thereof, comprising administering to the subject an effective amount of a nucleic acid or nucleic acids encoding the at least two antigen-binding proteins or a pharmaceutical composition comprising said nucleic acid or nucleic acids underconditions such that the nucleic acid(s) is / are localized into a cell of the subject and the antigen-binding proteins are capable of being translated in the cell from the nucleic acid(s), wherein one of the at least two antigen-binding proteins binds to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and another of the at least two antigen-binding proteins binds to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

76. A method of treatment of cancer, a tumor or tumorous disease or disorder, infectious diseases, or immunological disorders comprising administering to a subject in need thereof an antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and an antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) protein.

77. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 67 to 76, comprising one or more further antigenbinding proteins.

78. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 67 to 77, wherein the antigen-binding protein binding to a MAGEA4 / 8 derived peptide bound to a major histocompatibility complex (MHC) protein and the antigen-binding protein binding to a PRAME derived peptide bound to a major histocompatibility complex (MHC) and optionally one or more further antigen-binding proteins act together to provide a desired therapeutic effect.

79. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 67 to 78, wherein the MAGEA4 / 8 derived peptide is a peptide according to SEQ ID NO: 57.

80. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 67 to 79, wherein the PRAME derived peptide is a peptide according to SEQ ID NO: 58.

81. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 79 to 80, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises a T cell receptor (TCR) alpha variable domain (Va) and a TCR beta variable domain (VP), wherein the Va domain comprises(i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 62,(ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 63, and (iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 64; and wherein the VP domain comprises(i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 59, (ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 60, and (iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 61, wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution.

82. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 79 to 81, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprisesa Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 54 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 54 and comprising the CDRal, CDRa2, and CDRa3 according to SEQ ID NOs: 62, 63, and 64, respectively; anda VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 53 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 53 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQ ID NOs: 59, 60, and 61, respectively.

83. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 79 to 82, wherein the antigen-binding proteinbinding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprisesan antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises(i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6,(ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and(iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises(i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10,(ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 11, and(iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12;wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution.

84. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 79 to 83, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprisesa VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; anda VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 9 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 9 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10, 11, and 12, respectively.

85. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 79 to 84, wherein the antigen-binding proteinbinding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises or consists ofa first polypeptide chain comprising a structure represented by the formula:VL-L1-VP-FC1;and a second polypeptide chain comprising a structure represented by the formula: Va-L2-VH-FC2;wherein LI and L2 are linkers and may be the same or different and FC1 and FC2 are Fc-domains and may be the same or different.

86. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of claim 85, wherein LI and / or L2 comprise or consist of an amino acid sequence according to SEQ ID NO: 16.

87. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of claim 85 or 86, whereinFC1 comprises or consists of an amino acid sequence according to SEQ ID NOs: 1,17,19, 21 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 17, 19, 21 or 39 and / orFC2 comprises or consists of an amino acid sequence according to SEQ ID NOs: 2,18, 20, 22 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2, 18, 20, 22 or 40.

88. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 79 to 87, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 57 bound to a major histocompatibility complex (MHC) protein comprises a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 75, 79, 80 or 82 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 76, 81 or 83.

89. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 80 to 88, wherein the antigen-binding proteinbinding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises a T cell receptor (TCR) alpha variable domain (Va) and a TCR beta variable domain (VP), wherein the Va domain comprises(i) a CDRal comprising the amino acid sequence according to SEQ ID NO: 68,(ii) a CDRa2 comprising the amino acid sequence according to SEQ ID NO: 69, and(iii) a CDRa3 comprising the amino acid sequence according to SEQ ID NO: 70; and wherein the VP domain comprises(i) a CDRpi comprising the amino acid sequence according to SEQ ID NO: 65,(ii) a CDRP2 comprising the amino acid sequence according to SEQ ID NO: 66, and(iii) a CDRP3 comprising the amino acid sequence according to SEQ ID NO: 67,wherein one or more of CDRal, CDRa2, CDRa3, CDRpi, CDRP2 and CDRP3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution.

90. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 80 to 89, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprisesa Va comprising or consisting of the amino acid sequence according to SEQ ID NO: 56 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 56 and comprising the CDRal, CDRa2, and CDRa3 according to SEQ ID NOs: 68, 69, and 70, respectively; anda VP comprising or consisting of the amino acid sequence according to SEQ ID NO: 55 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 55 and comprising the CDRpi, CDRP2, and CDRP3 according to SEQ ID NOs: 65, 66, and 67, respectively.

91. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 80 to 90, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprisesan antibody variable light chain domain (VL), and an antibody variable heavy chain domain (VH), wherein the VL comprises(i) a CDRL1 comprising the amino acid sequence according to SEQ ID NO: 6,(ii) a CDRL2 comprising the amino acid sequence according to SEQ ID NO: 7, and(iii) a CDRL3 comprising the amino acid sequence according to SEQ ID NO: 8; and wherein the VH comprises(i) a CDRH1 comprising the amino acid sequence according to SEQ ID NO: 10,(ii) a CDRH2 comprising the amino acid sequence according to SEQ ID NO: 14, and(iii) a CDRH3 comprising the amino acid sequence according to SEQ ID NO: 12;wherein one or more of CDRL1, CDRL2, CDRL3, CDRH1, CDRH2, and CDRH3 may comprise one, two or three amino acid mutations, wherein the mutation may be a deletion, an insertion, or a substitution, preferably a conservative substitution.

92. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 80 to 91, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprisesa VL comprising or consisting of the amino acid sequence according to SEQ ID NO: 5 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 5 and comprising the CDRL1, CDRL2, and CDRL3 according to SEQ ID NOs: 6, 7, and 8, respectively; anda VH comprising or consisting of the amino acid sequence according to SEQ ID NO: 13 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 13 and comprising the CDRH1, CDRH2, and CDRH3 according to SEQ ID NOs: 10,14, and 12, respectively.

93. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 80 to 92, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises or consists ofa first polypeptide chain comprising a structure represented by the formula:VL-L1-VP-FC1;and a second polypeptide chain comprising a structure represented by the formula:Va-L2-VH-FC2;wherein LI and L2 are linkers and may be the same or different and FC1 and FC2 are Fc-domains and may be the same or different.

94. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of claim 93, wherein LI and / or L2 comprise or consist of an amino acid sequence according to SEQ ID NO: 16.

95. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of claim 93 or 94, whereinFC1 comprises or consists of an amino acid sequence according to SEQ ID NOs: 1,17,19, 21 or 39 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 1, 17, 19, 21 or 39 and / orFC2 comprises or consists of an amino acid sequence according to SEQ ID NOs: 2,18, 20, 22 or 40 or an amino acid sequence having at least 85%, 90%, 95%, 98% or 99% identity to SEQ ID NO: 2, 18, 20, 22 or 40.

96. The antigen binding proteins for use, the combination, the pharmaceutical compositions or the methods of any one of claims 80 to 95, wherein the antigen-binding protein binding to the peptide according to SEQ ID NO: 58 bound to a major histocompatibility complex (MHC) protein comprises a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 71, 74, 84 or 86 and a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NOs: 72, 85 or 87.

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