WO2004106380A2

WO2004106380A2 - Human-anti-human cd3 binding molecules

Info

Publication number: WO2004106380A2
Application number: PCT/EP2004/005684
Authority: WO
Inventors: Peter Kufer; Tobias Raum; Meera Berry; Roman Kischel; Susanne Mangold; Eva Krinner; Birgit Kohleisen; Steven Zeman; Christian Itin; Patrick BÄUERLE
Original assignee: Micromet Ag
Priority date: 2003-05-31
Filing date: 2004-05-26
Publication date: 2004-12-09
Also published as: EP1629011B1; SI1629011T1; US8784821B1; WO2004106380A3; AU2004242845A1; DK1629011T3; EP1629011A2; AU2004242845B2; CA2523716C; CA2523716A1; DE602004025101D1; ATE455127T1

Abstract

The present invention provides a method for the preparation of a human binding molecule, fragment or derivative thereof which specifically binds to the human CD3 complex. Furthermore, the invention provides a human binding molecules specifically binding to the human CD3 complex and means comprising said human binding molecules.

Description

Human anti-human CD3 Binding Molecules

The present invention relates to a method for the preparation of a human binding molecule, fragment or derivative thereof which specifically binds to the human CD3 complex. Furthermore, the invention relates to human binding molecules specifically binding to the human CD3 complex and means comprising said human binding molecules.

A variety of documents is cited throughout this specification. The disclosure content of said documents is herewith incorporated by reference.

Human CD3 antigen denotes an antigen which is expressed on T cells as part of the multimolecular T cell receptor complex (TCR) and which consists of three different chains: CD3-ε, CD3-δ and CD3-γ. Clustering of CD3 on T cells, e.g. by immobilized antibodies specific for the CD3 molecule leads to T cell activation similar to the engagement of the T cell receptor but independent of its clone-typical specificity. The individual proteins of the CD3 complex are referred to as δ, γ (both glycosylated) and ε (non-glycosylated). In the TCR/CD3 complex, CD3-ε exists as a dimer with either the CD3-δ or the CD3-γ signaling subunit. Upon dimerization with either the CD3-δ or the CD3-γ subunit, solely expressed, i.e. monomeric, CD3- ε undergoes a conformational change into its natural conformation (Kastrup, Scand. J. Immunol. 56 (2002), 436-42).

Owing to its central role in the modulation of T cell activity, the TCR/CD3 complex has been the subject of much research aimed at developing molecules capable of binding TCR/CD3. Much of this work has focused on the development of anti- TCR/CD3 monoclonal antibodies. The prior art exemplifies antibodies with specificity for the human CD3 antigen. One such CD3 specific antibody is the murine monoclonal antibody OKT3 (proprietary name ORTHOCLONE^®). OKT3 was the first monoclonal antibody drug approved by the FDA (approved in 1986). OKT3 has been described in the literature as a potent T cell mitogen (Van Wauve, J. Immunol. 124 (1980), 2708-18) as well as a potent T cell killer (Wong Transplantation 50 (1990), 683-9). OKT3 exhibits both of these activities in a time-dependent fashion; following early activation of T cells leading to cytokine release, upon further administration OKT3 later blocks all known T cell functions. It is due to this later blocking of T cell function that OKT3 has found such wide application as an immunosuppressant in therapy regimens for reduction or even abolition of allograft tissue rejection.

OKT3 reverses allograft tissue rejection most probably by blocking the function of all T cells which play a major role in acute rejection. OKT3 reacts with and blocks the function of the CD3 complex in the membrane of human T cells which is associated with the antigen recognition structure of T cells (TCR) and is essential for signal transduction. Which subunit of the TCR/CD3 is bound by OKT3 has been the subject of multiple studies. Though some evidence has pointed to a specificity of OKT3 for the ε-subunit of the TCR/CD3 complex (Tunnacliffe, Int. Immunol. 1 (1989), 546-50). Further evidence has shown that OKT3 binding of the TCR/CD3 complex requires other subunits of this complex to be present (Salmeron, J. Immunol. 147 (1991), 3047-52). The evidence relating to the exact epitope bound by OKT3 remains, then, ultimately inconclusive.

Patients treated with OKT3 experience a rapid and concomitant decrease in the number of circulating CD2+, CD3+, CD4+ and CD8+ cells within minutes following administration. This decrease in the number of CD3+ T cells results from the specific interaction between OKT3 and the CD3 surface antigen, ubiquitous on all T cells.

Other well known antibodies specific for the CD3 molecule are listed in Tunnacliffe, Int. Immunol. 1 (1989), 546-50. As indicated above, such CD3 specific antibodies are able to induce various T cell responses such as lymphokine production (Von Wussow, J. Immunol. 127 (1981), 1197; Palacious, J. Immunol. 128 (1982), 337), proliferation (Van Wauve, J. Immunol. 124 (1980), 2708-18) and suppressor-T cell induction (Kunicka, in "Lymphocyte Typing II" 1 (1986), 223). That is, depending on the experimental conditions, CD3 specific monoclonal antibody can either inhibit or induce cytotoxicity (Leewenberg, J. Immunol. 134 (1985), 3770; Phillips, J. lmmunol. 136 (1986) 1579; Platsoucas, Proc. Nati. Acad. Sci. USA 78 (1981), 4500; Itoh, Cell. Immunol. 108 (1987), 283-96; Mentzer, J. Immunol. 135 (1985), 34; Landegren, J. Exp. Med. 155 (1982), 1579; Choi (2001), Eur. J. Immunol. 31, 94-106; Xu (2000), Cell Immunol. 200, 16-26; Kimball (1995), Transpl. Immunol. 3, 212-221).

Another serious problem hampering the therapeutic use of, especially, murine monoclonal antibodies in humans is the mounting of a humoral immune response against such antibodies, resulting in the production of human anti-mouse antibodies ("HAMAs"). HAMAs are typically generated during the second week of treatment with the murine antibody and neutralize the murine antibodies, thereby blocking their ability to bind to their intended target. The HAMA response can depend on a number of factors, including the nature of the murine constant ("Fc") antibody regions, the nature of the murine variable ("V") regions, human Ig allotypes, unusual glycosylation of the murine antibody, the patient's MHC haplotype, the specificity of the murine antibody, whether the murine antibody binds to a surface antigen or a soluble antigen, whether the murine antibody forms immune complexes with the antigen, complement activation by the murine antibody, the ability of the murine antibody to bind the Fc receptor as well as the state of inflammation and/or cytokine release.

The prior art contains various approaches to reducing or preventing the production of HAMAs by modifying monoclonal antibodies. One approach to reducing the immunogenicity of antibodies is by humanization, as for example described in WO 91/09968 and US 6,407,213. In general, humanization entails substitutions of non-human antibody sequences for corresponding human sequences, as for example is the case with CDR-grafting. In CDR-grafting, murine CDRs are inserted into human framework regions. However, being of murine origin, the grafted CDR regions can themselves lead to the production of HAMAs. Furthermore, CDR-grafting may affect the folding properties of the CDR regions, as the latter are at least partially dependent on amino acids in the original framework. Such alterations in the folding properties of the CDR regions can decrease the binding affinity and bioactivity of the CDR-grafted molecules. To ensure that the grafted CDR regions can fold into a conformation sufficient for the desired binding, certain murine amino acid residues considered important for the proper conformation of the amino acid residues within the CDR regions are reintroduced into the human framework region. However, such reintroduction can itself contribute to a production of HAMAs.

Another approach to reducing the immunogenicity of such antibodies is by deimmunization, as for example described in WO 92/10755, WO 00/34317, WO 98/52976, WO 02/079415, WO 02/012899 and WO 02/069232. In general, deimmunization entails carrying out substitutions of amino acids within potential T cell epitopes. In this way, the likelihood that a given sequence will give rise to T cell epitopes upon intracellular protein processing is reduced. However, deimmunization procedures such as those indicated above are purely predictive in nature, based as they are on theoretical approaches. For instance, predictions of potential T cell epitopes are made based on lists of known MHC haplotypes which are representative but incomplete. Therefore, it is impossible to ensure that removal of all predicted T cell epitopes will truly result in a fully deimmunized molecule.

Furthermore, both humanization and deimmunization approaches often lead to a significantly decreased binding affinity and therefore bioactivity with respect to the non-modified species.

Despite the numerous disadvantages indicated above, recent literature indicates - in the specific context of CD3 specific antibodies - that humanization still represents the most feasible and promising mode of decreasing immunogenicity (Chatenoud, Nature Reviews 3 (2003), 123-32).

Thus, the technical problem underlying the present invention was to provide means and methods for binding molecules with specificity for the human CD3 complex which avoid the disadvantages of immunogenicity of molecules known in the art.

The solution to said technical problem is achieved by providing the embodiments characterized in the claims.

Accordingly, the present invention relates to a method for the preparation of a human binding molecule, fragment or derivative thereof which specifically binds to the human CD3 complex, said method comprising the steps of

(a) selecting molecules specifically binding to/interacting with the extracellular domain of the recombinant ε-chain, expressed independent of the human CD3 complex in the absence of other members of said CD3 complex, from a population of candidate polypeptides encoded by a library;

(b) selecting molecules from a population identified in step (a) for binding to the human CD3 complex; and

(c) preparation of said selected binding molecule. The term "human binding molecule" defines a molecule of human source, i.e. of human origin. Said "human binding molecule" relates, for example, to (an) antibody molecule(s) or (a) fragment(s) thereof or to (a) specifically binding peptide(s) or protein(s) which is/are characterized by its/their ability to bind to the human CD3 complex, in particular to CD3 ε chain. As defined herein above, the CD3 complex is a part of the T-cell receptor (TCR). The term "binding to/interacting with" as used in the context of the present invention defines a binding/interaction of at least two "antigen-interaction-sites" with each other. The term "antigen-interaction-site" defines, in accordance with the present invention, a motif of a polypeptide which is able to specifically interact with a specific antigen or a specific group of antigens. Said binding/interaction is also understood to define a "specific recognition". The term "specifically recognizing" means in accordance with this invention that the antibody molecule is capable of specifically interacting with and/or binding to at least two, preferably at least three, more preferably at least four amino acids of the human CD3 antigen as defined herein. Said term relates to the specificity of the antibody molecule, i.e. to its ability to discriminate between the specific regions of the human CD3 molecule as defined herein. The specific interaction of the antigen-interaction-site with its specific antigen may result in the initiation of a signal, e.g. due to the induction of a change of the conformation of the antigen, an oligomerization of the antigen, etc. Further, said binding may be exemplified by the specificity of a "lock-and-key- principle". Thus, specific motifs in the amino acid sequence of the antigen- interaction-site and the antigen bind to each other as a result of their primary, secondary or tertiary structure as well as the result of secondary modifications of said structure. The specific interaction of the antigen-interaction-site with its specific antigen may result as well in a simple binding of said site to the antigen. The term "specific interaction" as used in accordance with the present invention means that the binding molecule does not or does not significantly cross-react with (poly)peptides which have similar structure as those bound by the binding molecule, and which are expressed by the same cells as the (poly)peptide of interest. Cross-reactivity of a panel of binding molecules under investigation may be tested, for example, by assessing binding of said panel of binding molecules under conventional conditions (see, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1988 and Using Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1999) .

Examples for the specific interaction of an antigen-interaction-site with a specific antigen comprise the specificity of a ligand for its receptor. Said definition particularly comprises the interaction of ligands which induce a signal upon binding to its specific receptor. Examples for corresponding ligands comprise cytokines which interact/bind with/to their specific cytokine-receptors. Also particularly comprised by said definition is the binding of an antigen-interaction-site to antigens such as antigens of the selectin family, integrins and of the family of growth factors like EGF. Another example for said interaction, which is also particularly comprised by said definition, is the interaction of an antigenic determinant (epitope) with the antigenic binding site of an antibody. The term "binding to/interacting with" may also relate to a conformational epitope, a structural epitope or a discontinuous epitope consisting of two regions of the human CD3 molecule or parts thereof. In the context of this invention, a conformational epitope is defined by two or more discrete amino acid sequences which are separated in the primary sequence, but which come together on the surface when the polypeptide folds to the native protein (Sela, (1969) Science 166, 1365 and Laver, (1990) Cell 61, 553-6).

The term "discontinuous epitope" means in context of the invention non-linear epitopes that are assembled from residues from distant portions of the polypeptide chain. These residues come together on the surface when the polypeptide chain folds into a three-dimensional structure to constitute a conformational/structural epitope.

The binding molecules of the present invention are also envisaged to specifically bind to/interact with a conformational/structural epitope(s) composed of and/or comprising at least two regions of the human CD3 complex, or composed of/comprising individual components, like CD3-ε, CD3-δ and CD3-γ and/or combinations of said components, such as CD3-ε/ CD3-δ or CD3-ε/ CD3- γ. Furthermore, it is envisaged that said conformational/structural epitope(s) described herein comprises individual parts/regions/stretches of at least two regions of a single component of the human CD3 complex, preferably at least two parts/regions/stretches of CD3-ε, even more preferably of the extracellular domain of CD3-ε. Specificity of the human binding molecules obtained by the method of this invention can be determined experimentally by methods known in the art and methods as disclosed and described herein. Such methods comprise, but are not limited to Western blots, ELISA-, EIA-1, R1A-, ECL-, IRMA-tests and peptide scans.

According to the present invention "human binding molecules" are (poly)peptides which specifically bind to the human CD3 complex and/or its individual components. The term "(poly)peptide" as used herein describes a group of molecules which comprise the group of peptides, as well as the group of polypeptides. The group of peptides is consisting of molecules with up to 30 amino acids, the group of polypeptides is consisting of molecules with consisting of more than 30 amino acids. Most preferably, said "human binding molecules" are selected from the group of antibodies, antibody fragments, antibody derivatives, specific binding peptides and specific binding proteins. Said antibody fragments are known in the art and comprise, but are not limited to, Fab-fragments, F(ab₂)' fragments, Fv fragments and the like. As will be detailed below, particular preferred fragments of antibodies in context of this invention are scFv fragments. Antibody derivatives comprise but are not limited to labeled antibodies/antibody fragments as well as chemically modified antibody molecules/antibody fragments. Therefore, fragments or derivatives of the recited human binding molecules also relate to (poly)peptides which are parts of the above defined (poly)peptides or which are modified posttranslationally or by chemical/biochemical or molecular biological methods. Corresponding methods are known in the art and are described, inter alia, in laboratory manuals (see Sambrook et al.; Molecular Cloning: A Laboratory Manual; Cold Spring Harbor Laboratory Press, 2nd edition 1989 and 3rd edition 2001 ; Gerhardt et al.; Methods for General and Molecular Bacteriology; ASM Press, 1994; Lefkovits; Immunology Methods Manual: The Comprehensive Sourcebook of Techniques; Academic Press, 1997; Golemis; Protein-Protein Interactions: A Molecular Cloning Manual; Cold Spring Harbor Laboratory Press, 2002). The recited extracellular domain of the recombinant ε-chain of the CD3 complex is known in the art and relates, in accordance with this invention, to the term "extracellular domain of recombinant ε-chain" and/or to the term "extracellular domain of human CD3-ε". Said extracellular domain comprises the amino acid positions 23 to 126 of the known human CD3-ε, as documented in NM_0O0733 / NP_000724 Homo sapiens CD3E [gi:4502670 / gi:450267]. In accordance with the present invention, a particular preferred extracellular domain of human CD3-ε is encoded by a nucleic acid molecule as shown in SEQ ID NO. 140. It is also envisaged that only parts of the extracellular domain of human CD3 ε-chain are employed in the method of the present invention. Yet, it is to be understood that the method of the present invention may also be carried out with recombinantly expressed extracellular domains of CD3 ε-chain which are homologous or mutated in relation to the extracellular domain shown in SEQ ID NO: 141. For example, the method of the present invention may be carried out with recombinantly expressed extracellular domains of CD3 ε-chains which are genetic variants, for example allelic variants, of the extracellular domain of the human CD3 ε chain. Such variants also comprise CD3 ε-chains from closely related primates. Preferably, said primate CD3 ε-chains, respectively their extracellular domains shown an homology to the human CD3 ε-chain of at least 80%, more preferably of at least 90%, most preferably of at least 95%.

For the step of selection of binding molecules of the present inventive method, said ε-chain is expressed independent of the human CD3 complex in the absence of other members of said CD3 complex. In the absence of other members of the complex the ε-chain is folded without any support in its folding by said other members. Consequently, the antigenicity of some domains of the ε-chain is different from the antigenicity of said other domains when the ε-chain is expressed in the context of the CD3 complex. The cloning and expression of the CD3 ε-chain is exemplified in the appended Example 1. The selection recited in steps (a) and (b) of the method of the invention particularly comprises the selection of binding molecules by affinity selection. Methods for affinity selection are known in the art (see Golemis, loc cit.; Rehm, Der Experimentator: Proteinbiochemie/Proteomics, Spektrum Akademischer Verlag, 2002; Lottspeich and Zorbas, Bioanalytik, Spektrum Akademischer Verlag, 1998). One embodiment of a corresponding method is described in appended Example 2. The term "population of candidate polypeptides" defines the population of polypeptides from which the binding molecules are selected from. In accordance with the present invention said polypeptides are encoded by a library. Thus, said population may be a peptide library as well as a population of peptides encoded by a library. Examples for said libraries comprise DNA-libraries such as cDNA- libraries and RNA-libraries, see, inter alia, Hoogenboom (2000) Immun Today 21 , 371-378. The preparation of a cDNA-library is exemplified in the appended examples. One population of candidate polypeptides is described in the appended examples as peptides encoded by a library derived from human cells, wherein the genes of said library encode human antibody molecules. Human antibody molecules encoded by said genes with specificity for the human CD3 complex are not expressed by mature B cells in the human body. This is because of the above discussed lack of T helper cell signals for self-reactive B cells (specific for autoantigens) since the necessary self-reactive T helper cells have been eliminated during the intrathymic clonal deletion of self-reactive pre-T cells. Identification of autoantigen-specific human antibodies from a library derived from such human B cells is therefore highly unlikely. When considering the human CD3 antigen, ubiquitously expressed throughout the entire T cell compartment, this likelihood is decreased even further. Human B cells which, by chance or accident, produce and surface-display an Ig with specificity for human CD3, and which by binding of the human CD3 antigen activate CD8⁺ T cells, will be killed by the very CD8⁺ cells they themselves activate (Itoh, Cellular Immunol. 108 (1987) 313-22; Hoffman, J. Immunol. 135 (1985), 5-8). The subpopulation of B cells bearing anti- human CD3 specific antibodies on their surface therefore becomes depleted below its already naturally low level within the entire B cell compartment. A random cross- section of B cells from the B cell compartment, such as is used in constructing a diverse antibody library, is thus all the less likely to comprise B cells producing antibody specific for human CD3. This explains the difficulty in identifying antibodies of human origin against the autoantigen human CD3 using antibody library techniques.

Said obstacle has been surprisingly overcome by the present invention which resulted in the preparation of binding molecules with specificity for the human CD3 complex, wherein said binding molecules themselves are human derived/of human origin. Due to the human source of the binding molecule, said molecules are most preferably non-immunogenic (or at least minimally immunogenic) for the human immune system under physiological conditions.

The term "preparation" as used in the present specification and in particular in the above described inventive method, defines method steps such as recovery of a peptide from a binding partner, i.e. from the ε-chain of the human CD3 complex, the purification of said peptide as well as their corresponding isolation, their further determination (like sequencing), the isolation/generation of corresponding encoding nucleic acid molecules as well as their expansion (general reproduction, recombinant reproduction, chemical synthesis, in-vitro translation etc). Corresponding techniques are detailed below and also shown in the appended examples.

A particularly surprising advantage of the present invention is the provision of human binders (in particular antibody binders) against the human CD3 antigen, which overcome several major limitations in the field of antibody technology.

In general, it is known that developing B cells which exhibit a binding specificity for autoantigens are naturally selected against before the mature B cells are released into the bloodstream. As such, human B cells in the blood which produce monoclonal antibody against human antigen make up an exceedingly small proportion of the peripheral B cell compartment. Identification of autoantigen- specific human antibodies from an antibody library derived from such human B cells is therefore highly unlikely. When considering the human CD3 antigen, ubiquitously expressed throughout the entire T cell compartment, this likelihood is decreased even further. Human B cells which, by chance or accident, produce and surface-display an Ig with specificity for human CD3, and which by binding of the human CD3 antigen activate CD8+ T cells, will be killed by the very CD8+ cells they themselves activate (i.e. redirected lysis) (Itoh, Cellular Immunol. 108 (1987) 313-22; Hoffman, J. lmmunol. 135 (1985), 5-8). The subpopulation of B cells bearing anti-human CD3 antibodies on their surface therefore becomes depleted below its already naturally low level within the entire B cell compartment. A random cross-section of B cells from the B cell compartment, such as is used in constructing a diverse antibody library, is thus all the less likely to comprise B cells producing antibody specific for human CDS. this explains the difficulty in identifying antibodies of human origin against the autoantigen human CD3 using antibody library techniques.

The above mentioned hurdles are surprisingly overcome by the method of the present invention, in particular by using an appropriate protein for selection of antibodies from a library, in particular from an antibody library. In accordance with this invention, solely expressed recombinant CD3-epsilon protein is used for selection of a CD3 binder, in particular an antibody binder from a diverse library, e.g. an antibody library derived from human B cells. Without being bound by theory, it is believed that the conformation adopted by solely expressed recombinant CD3-epsilon protein differs from that adopted in its natural form, that is, the form in which the CD3-epsilon subunit of the TCR/CD3 complex exists as part of a noncovalent complex with either the CD3-delta or the CD3-gamma subunit of the TCR/CD3 complex (Kastrup, Scand. J. Immunol. 56 (2002) 436-42). Were natural CD3-epsilon in its complexed form to be used as an antigen for selection of antibodies from an antibody library, the probability of identifying an antibody specifically binding to this protein would be very low. This is because the cells generating antibodies with binding specificity for natural CD3-epsilon. are preferentially depleted in vivo from the compartment used to construct the antibody library. However, when solely expressed recombinant CD3-epsilon protein is used as an antigen for selection of antibodies from an antibody library, antibodies specific for this antigen are identified from the library. This is due to the fact that solely expressed recombinant CD3-epsilon protein does not exist in vivo; it is not an autoantigen. Consequently, subpopulations of B cells expressing antibodies specific for this protein have not been depleted in vivo; an antibody library constructed from such B cells would contain genetic material for antibodies specific for solely expressed recombinant CD3-epsilon protein.

A major advantage according to the invention is that binders, like antibodies identified from (antibody) libraries as specific binders of solely expressed recombinant CD3-epsilon are also able to specifically bind CD3-epsilon in its natural, complexed form. This is especially surprising, given the failure of natural, complexed CD3-epsilon to identify specific antibodies when this protein is used as the selection antigen for human antibody libraries. According to the invention, the recombinant form of CD3-epsilon thus acts as a surrogate antigen which can be used to identify human antibodies to the human CD3 antigen. Such antibodies would normally remain unidentifiable using naturally-expressed human CD3 antigen in its complexed form.

In a further embodiment, the invention relates to the above described method, further comprising a step (d), relating to the identification of the nucleic acid sequence encoding the human CD3 binding molecule in the library. As mentioned above, said identification may comprise the sequence-analysis of the amino acid sequence of the selected polypeptide or the sequence-analysis of the nucleic acid molecule coding for the selected polypeptide. Methods for said analysis are known in the art. Furthermore, examples for said identification are described in the appended examples 2.8 and 3.2. In accordance with the present invention, the recited library which encodes the candidate polypeptides may be derived from a DNA-library or an RNA-library. Particularly comprised by said definition are cDNA-libraries. Further in accordance with the invention the library which encodes the candidate polypeptides is derived from primary or secondary lymphatic organs of humans. Said sources particularly comprise fetuses. Examples for said lymphatic organs are spleen, lymph nodes, MALT (mucosa associated lymphatic tissues), bone marrow, blood, proliferative disorder tissue, tonsil, umbilical cord blood and inflammatory tissue.

As pointed out above, in the method of the invention said selection of the human binding molecules may be effected by exposing the human binding molecules to immobilized recombinant, solely expressed ε- chain, expressed independent of the human CD3 complex in the absence of other members of said CD3 complex. The recombinant ε- chain may be immobilized or adsorbed on a solid support/surface. Examples for said solid support/surface are known in the art and comprise, inter alia, polymeric surfaces, such as polystyrene, polypropylene as well as specifically coated surfaces like PolySorp™, MaxiSorp™, MultiSorp™, etc.

According to a preferred embodiment of the method of the invention, the selection step of the method of the invention comprises a phage display method. Phage display technology has been described in the literature, for example in Hoogenboom, Methods Mol Biol 178 (2002), 1-37, Pini, Curr Protein Prep Sci 1 (2000), 155-69. A description of the selection of phage-displayed antibodies is described e.g. in Mutuberria, J. Immunol. Methods 231 (1999), 65-81. Phage display methology is also described in WO 99/25818 and is also exemplified in the appended examples.

As mentioned above and illustrated in the appended examples, the human binding molecule, fragment or derivative thereof, which is prepared/isolated by the method of the invention is preferably an antibody molecule, antibody fragment or derivative thereof or a construct comprising at least one antibody, antibody fragment or derivative thereof which specifically binds to the human CD3 complex. Said antibody is preferably a monoclonal antibody. The term "antibody fragment or derivative thereof" relates to single chain antibodies, or fragment thereof, synthetic antibodies, antibody fragments, such as Fab, a F(ab₂)', Fv or scFv fragments etc., or a chemically modified derivative of any of these. Antibodies to be employed in accordance with the invention or their corresponding immunoglobulin chain(s) can be further modified using conventional techniques known in the art, for example, by using amino acid deletion(s), insertion(s), substitution(s), addition(s), and/or recombination(s) and/or any other modification(s) known in the art either alone or in combination. Methods for introducing such modifications in the DNA sequence underlying the amino acid sequence of an immunoglobulin chain are well known to the person skilled in the art; see, e.g., Sambrook (1989), loc. cit.

According to a further preferred embodiment of the method of the invention, said method for the production of human anti-human CD3 binding molecules further comprises the steps of:

I: (a) taking the VH and/or VL region/s of at least one of the isolated human CD3 binders and (i) inserting mutations resulting in amino acid substitutions

(e.g. as described in Barbas III, TIBTECH 14 (1996) 230, Schier, J. Mol.

Biol. 263 (1996) 551, Hawkins, J. Mol. Biol. 226 (1992) 889) and/or (ii) shuffling a repertoire of human V-regions to the VH or VL of said human

CD3 binders (e.g. as described in Raum, Cancer Immunol Immunother 50

(2001) 141-150) and/or

(b) grafting at least one CDR of at least one of the isolated human CD3 binders into the corresponding position/s of the variable regions of a human antibody library (e.g. principle of inserting predetermined CDR/s into the context of human antibody libraries e.g. as described in Rader,

PNAS 95 (1998) 8910-5, Steinberger, J Biol Chem 17 (2000) 36073-8) and

II: subjecting the resulting library/ies to further selection on human CD3 antigen or parts thereof (e.g. for the purpose of affinity maturation). The CD3 antigen or parts thereof used for selection may be expressed (naturally or via transfection) on cells (e.g. T cells, see Tunnacliffe, International Immunology 1 (1989) 546) or isolated from a natural source (e.g. immunoprecipitated from human T cells following the method as described e.g. by Leo, PNAS 84 (1997) 1374-1378 adapted to human CD3) or produced as recombinant protein (as described e.g. in the present invention or by Tunnacliffe, Immunol. Lett. 21 (1989) 243,

Kastrup, Scand. J. Immunol. 56 (2002) 436-442), Kim, J. Mol. Biol. 302 (2000) 899-916 adapted to human CD3) or synthesized as peptide.

The term "antibody fragment or derivative thereof particularly relates to (poly)peptide constructs comprising at least one CDR

The complementary determining region (CDR) dictates the antigen specificity of the response and plays a central role in initiating activation. However, this interaction, by itself, is not sufficient to fully activate naϊve T cells. After the initial T cell stimulation there have to be further, antigen-independent co-stimulatory signals.

It is particularly envisaged by the invention that said derivative of an antibody is an scFv. The term "scFv fragment" (single-chain Fv fragment) is well understood in the art. ScFvs are preferred in context of this invention, due to their small size and the possibility of recombinantly producing these antibody fragments.

According to a preferred embodiment of the invention said human binding molecule specifically binding to the human CD3 complex is an antibody molecule, antibody fragment, derivative thereof or antibody construct comprising at least one further antigen-interaction-site and/or at least one further effector domain. Examples for the recited "further effector domain" comprise signal inducing domains of molecules, wherein the initiation of said signal results in the uptake of the molecule into the cell, cell death, cell proliferation or cell stimulation. Examples of such effector domains comprise, but are not limited to, B7.1 , Fas-ligand, cytokines (like IL2), NKG-2D, NKD-46, OX40L or 4.1 BBL. Corresponding binding molecules comprise bispecific constructs in molecular format as described e.g. in WO 99/54440 as well as molecular formats as described in WO 00/06605. Preferably said bispecific constructs are bispecific single chain antibody construct. The term "single-chain" as used in accordance with the present invention means that said first and second domain of the bispecific single chain construct are covalently linked, preferably in the form of a co-linear amino acid sequence encodable by a single nucleic acid molecule.

Preferably it is envisaged that said antibody molecule, antibody fragment, derivative thereof or construct is humanized and/or deimmunized in an additional step.

Since the domain specifically binding to/interacting with the human CD3 complex is a human (poly)peptide or human (poly)peptide fragment it is envisaged that only parts of said at least one further antigen-interaction-site and/or at least one further effector domain which are non-human derived are humanized. The non-human derived domains of said antibody molecule, antibody fragment, derivative thereof or construct may be also or alternatively be deimmunized. Furthermore, the fusion of human derived domains to non-human derived domains, preferably by the linker referred above, may result in immunogenic epitopes. Corresponding epitopes at said junctions between human derived domains and non-human derived domains may also be deleted by deimmunization. Methods for the humanization of antibodies and antibody constructs are known in the art and described e.g. in EP- A1 0 239400, WO 90/07861, Welt (2003) Clin Cancer Res 9, 1338-1346. Methods for the deimunization of (poly)peptides and (poly)peptide constructs are known in the art and described e.g. in WO 02/079415, WO02/069232 or WO00/34317.

Further in accordance with the invention said further antigen-interaction-site of the human binding molecule specific for human CD3 complex and as described herein is, in addition, specific for one or more cell surface molecule. The term "cell surface molecule" as used herein denotes molecules which are presented or/and attached on/to the surface of a cell. Examples for said cell surface molecules are membrane and transmembrane proteins (including modified variants, such as glycosylated variants), molecules attached to said proteins or the cell surface as well as glycosylated moieties such as for example lipids. Attachment is to be understood as being effected by way of an integral membrane protein, a GPI-linked (glycosyl phosphatidyl inositol-linked) protein, a proteinaceous or non-proteinaceous moiety bound covalently or non-covalently to another carrier molecule such as sugar moieties or ganglioside moieties. Preferably said cell surface molecule is a tumor-specific marker. A tumor-specific marker is a tumor-associated cell surface antigen which is either found exclusively on tumor cells or is overexpressed on tumor cells as compared to non-malignant cells. Tumor-associated cell surface antigens can be expressed not only on tumor cells but also on cells/tissue which are/is not essential for survival or which can be replenished by stem cells not expressing tumor-associated cell surface antigen. Furthermore, tumor-associated cell surface antigen can be expressed on malignant cells and non-malignant cells but is better accessible by a therapeutic agent of interest on malignant cells. Examples of over-expressed tumor-associated cell surface antigens are Her2/neu, EGF-Receptor, Her-3 and Her-4. An example of a tumor-associated cell surface antigen which is tumor specific is EGFRV-III. An example of a tumor-associated cell surface antigen which is presented on a cell which is non-essential for survival is PSMA. Examples of tumor-associated cell surface antigens which are presented on cells which are replenished are CD19, CD20 and CD33. An example of a tumor-associated cell surface antigen which is better accessible in a malignant state than in a non-malignant state is EpCAM.

It is envisaged and documented herein that said at least one further antigen- interaction-site is a domain which is derived from an antibody or antibody construct.

Preferably, said domain which is an antibody-derived region comprises a polypeptide sequence which corresponds to at least one variable region of an antibody. More preferably, said at least one further antigen-interaction-site is a further scFv. A particularly preferred molecular format of the invention provides a polypeptide construct wherein the antibody-derived region comprises one VH and one VL region.

The term "bispecific single chain antibody construct" relates to a construct comprising one domain consisting of (at least one) variable region(s) (or parts thereof) as defined above capable of specifically interacting with/binding to human CD3/human CD3 complex and comprising a second domain consisting of (at least one) variable region(s) (or parts thereof) as defined above capable of specifically interacting with/binding to a further antigen. Said binding/interaction is also understood to define a "specific recognition". The term "specifically recognizing" means in accordance with this invention that the antibody molecule is capable of specifically interacting with and/or binding to at least two amino acids of each of the human target molecule as defined herein. Said term relates to the specificity of the antibody molecule, i.e. to its ability to discriminate between the specific regions of the human target molecule as defined herein. The specific interaction of the antigen-interaction-site with its specific antigen may result in an initiation of a signal, e.g. due to the induction of a change of the conformation of the antigen, an oligomerization of the antigen, etc. Further, said binding may be exemplified by the specificity of a "key-lock-principle". Thus, specific motifs in the amino acid sequence of the antigen-interaction-site and the antigen bind to each other as a result of their primary, secondary or tertiary structure as well as the result of secondary modifications of said structure. The specific interaction of the antigen-interaction-site with its specific antigen may result as well in a simple binding of said site to the antigen. The term "specific interaction" as used in accordance with the present invention means that the bispecific single chain construct does not or essentially does not cross-react with (poly)peptides of similar structures. Cross-reactivity of a panel of bispecific single chain construct under investigation may be tested, for example, by assessing binding of said panel of bispecific single chain construct under conventional conditions (see, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1988 and Using Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1999) to the (poly)peptide of interest as well as to a number of more or less (structurally and/or functionally) closely related (poly)peptides. Only those antibodies that bind to the (poly)peptide/protein of interest but do not or do not essentially bind to any of the other (poly)peptides are considered specific for the (poly)peptide/protein of interest. Examples for the specific interaction of an antigen-interaction-site with a specific antigen comprise the specificity of a ligand for its receptor. Said definition particularly comprises the interaction of ligands which induce a signal upon binding to its specific receptor. Examples for corresponding ligands comprise cytokines which interact/bind with/to its specific cytokine-receptors. Also particularly comprised by said definition is the binding of an antigen-interaction-site to antigens like antigens of the selectin family, integrins and of the family of growth factors like EGF. An other example for said interaction, which is also particularly comprised by said definition, is the interaction of an antigenic determinant (epitope) with the antigenic binding site of an antibody. The term "binding to/interacting with" may also relate to a conformational epitope, a structural epitope or a discountinuous epitope consisting of two regions of the human target molecules or parts thereof. In context of this invention, a conformational epitope is defined by two or more discrete amino acid sequences separated in the primary sequence which come together on the surface of the molecule when the polypeptide folds to the native protein (Sela, (1969) Science 166, 1365 and Laver, (1990) Cell 61, 553-6).

The term "discontinuous epitope" means in context of the invention non-linear epitopes that are assembled from residues from distant portions of the polypeptide chain. These residues come together on the surface of the molecule when the polypeptide chain folds into a three-dimensional structure to constitute a conformational/structural epitope.

According to the present invention the term "variable region" used in the context with Ig-derived antigen-interaction comprises fragments and derivatives of (poly)peptides which at least comprise one CDR derived from an antibody, antibody fragment or derivative thereof. It is envisaged by the invention, that said at least one CDR is preferably a CDR3, more preferably the CDR3 of the heavy chain of an antibody (CDR-H3). However, other antibody derived CDRs are also particularly comprised by the term "variable region"

The "specific binding" of an antibody is characterized primarily by two parameters: a qualitative parameter (the binding epitope, or where the antibody binds) and a quantitative parameter (the binding affinity, or how strongly it binds where it does). Which epitope is bound by an antibody can advantageously be determined by e.g. known FACS methodology, peptide-spot epitope mapping, mass spectroscopy. The strength of antibody binding to a particular epitope may be advantageously be determined by e.g. known BIAcore and/or ELISA methodologies. A combination of such techniques allows the calculation of a signahnoise ratio as a representative measure of binding specificity. In such a signahnoise ratio, the signal represents the strength of antibody binding to the epitope of interest, whereas the noise represents the strength of antibody binding to other, non-related epitopes differing from the epitope of interest. In general, any time an antibody binds more frequently and/or strongly to one epitope than another epitope, such antibody may be said to bind the former epitope specifically. Preferably, a signal:noise ratio for an epitope of interest which is about 50-fold higher than for other epitopes different from the epitope of interest may be taken as an indication that the antibody evaluated binds the epitope of interest in a specific manner, i.e. is a "specific binder". A part of a variable region may be at least one CDR ("Complementary Determining Region"), most preferably at least the CDR3 region. Said two domains/regions in the single chain antibody construct are preferably covalently connected to one another as a single chain. This connection can be effected either directly (domain 1 interacting with CD3 - domain2 interacting with the further antigen or domainl interacting with the further antigen - domain2 interacting with CD3) or through an additional polypeptide linker sequence (domainl - linker sequence - domain2 or domain2 - linker sequence - domainl). In the event that a linker is used, this linker is preferably of a length and sequence sufficient to ensure that each of the first and second domains can, independently from one another, retain their differential binding specificities. Most preferably and as documented in the appended examples, the "bispecific single chain antibody construct" is a bispecific single chain Fv (bscFv). Bispecific single chain molecules are known in the art and are described in WO 99/54440, Mack, J. Immunol. (1997), 158, 3965-3970, Mack, PNAS, (1995), 92, 7021-7025; Kufer, Cancer Immunol. Immunother., (1997), 45, 193-197;Lδffler, Blood, (2000), 95, 6, 2098-2103; Brϋhl, lmmunol., (2001), 166, 2420-2426. Distinct examples for such bispecific single chain antibody construct are provided herein below and illustrated in the appended examples. In accordance with the invention, said at least one further antigen-interaction-site specifically binds to/interacts with an antigen selected from the group consisting of EpCAM, CCR5, CD19, EphA2, HER-2 neu, HER-3, HER-4, EGFR, PSMA, CEA, MUC-1 (mucin), MUC2, MUC3, MUC4, MUC5_AC, MUC5_B, MUC7, βhCG, Lewis-Y, CD20, CD22, CD52, CD33, CD30, ganglioside GD3, 9-0-Acetyl-GD3, GM2, Globo H, fucosyl GM1, Poly SA, GD2, Carboanhydrase IX (MN/CA IX), CD44v6, Sonic Hedgehog (Shh), Wue-1, Plasma Cell Antigen, (membrane-bound) IgE, Melanoma Chondroitin Sulfate Proteoglycan (MCSP), CCR8, TNF-alpha precursor, STEAP, STEAP II, mesothelin, A33 Antigen, Prostate Stem Cell Antigen (PSCA), Ly-6; desmoglein 4, E-cadherin neoepitope, Fetal Acetylcholine Receptor, CD25, CA19- 9 marker, CA-125 marker and Muellerian Inhibitory Substance (MIS) Receptor type II, sTn (sialylated Tn antigen; TAG-72), FAP (fibroblast activation antigen), endosialin, EGFRvIII, L6, SAS , CD63, Tu, TF, Le^a, Sialyl Le^a, Le^b, Le^x, Sialyl Le^x and polyfucosyl-Le^x.

Optionally the method of the invention may further comprise the step of recombinant expression of the binding molecule, fragment or derivative thereof encoded by a nucleic acid sequence selected from the group consisting of: (a) the identified nucleic acid sequence;

(b) a nucleic acid sequence hybridizing with the complementary strand of the identified nucleic acid sequence under stringent hybridization conditions;

(c) a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (a) and (b). The term "hybridizing" as used herein refers to polynucleotides which are capable of hybridizing to the recited nucleic acid sequence or parts thereof. Therefore, said nucleic acid sequence may be useful as probes in Northern or Southern Blot analysis of RNA or DNA preparations, respectively, or can be used as oligonucleotide primers in PCR analysis dependent on their respective size. Preferably, said hybridizing polynucleotides comprise at least 10, more preferably at least 15 nucleotides while a hybridizing polynucleotide of the present invention to be used as a probe preferably comprises at least 100, more preferably at least 200, or most preferably at least 500 nucleotides.

It is well known in the art how to perform hybridization experiments with nucleic acid molecules, i.e. the person skilled in the art knows what hybridization conditions s/he has to use in accordance with the present invention. Such hybridization conditions are referred to in standard text books such as Sambrook et al. (loc cit.) and other standard laboratory manuals known by the person skilled in the art or as recited above. Preferred in accordance with the present inventions are polynucleotides which are capable of hybridizing to the polynucleotides of the invention or parts thereof, under stringent hybridization conditions.

"Stringent hybridization conditions" refer, i.e. to an overnight incubation at 42°C in a solution comprising 50% formamide, 5x SSC (750 mM NaCl, 75 mM sodium citrate), 50 mM sodium phosphate (pH 7.6), 5x Denhardt's solution, 10% dextran sulfate, and 20 μg/ml denatured, sheared salmon sperm DNA, followed by washing the filters in 0.1 x SSC at about 65°C. Also contemplated are nucleic acid molecules that hybridize to the polynucleotides of the invention at lower stringency hybridization conditions. Changes in the stringency of hybridization and signal detection are primarily accomplished through the manipulation of formamide concentration (lower percentages of formamide result in lowered stringency); salt conditions, or temperature. For example, lower stringency conditions include an overnight incubation at 37°C in a solution comprising 6X SSPE (20X SSPE = 3M NaCl; 0.2M NaH₂P04; 0.02M EDTA, pH 7.4), 0.5% SDS, 30% formamide, 100 μg/ml salmon sperm blocking DNA; followed by washes at 50°C with 1 X SSPE, 0.1% SDS. In addition, to achieve even lower stringency, washes performed following stringent hybridization can be done at higher salt concentrations (e.g. 5X SSC). It is of note that variations in the above conditions may be accomplished through the inclusion and/or substitution of alternate blocking reagents used to suppress background in hybridization experiments. Typical blocking reagents include Denhardt's reagent, BLOTTO, heparin, denatured salmon sperm DNA, and commercially available proprietary formulations. The inclusion of specific blocking reagents may require modification of the hybridization conditions described above, due to problems with compatibility.

The recited nucleic acid molecules may be, e.g., DNA, cDNA, RNA or synthetically produced DNA or RNA or a recombinantly produced chimeric nucleic acid molecule comprising any of those polynucleotides either alone or in combination.

The invention further relates to a method, wherein said optional step of recombinant expression of the binding molecule, fragment or derivative thereof encoded by a nucleic acid sequence comprises the preparation of a vector comprising said nucleic acid sequence.

Many suitable vectors are known to those skilled in molecular biology, the choice of which would depend on the function desired and would include plasmids, cosmids, viruses, bacteriophages and other vectors used conventionally in genetic engineering. Methods which are well known to those skilled in the art can be used to construct various plasmids and vectors; see, for example, the techniques described in Sambrook et al. (loc cit.) and Ausubel, Current Protocols in Molecular Biology, Green Publishing Associates and Wiley Interscience, N.Y. (1989), (1994). Alternatively, the polynucleotides and vectors of the invention can be reconstituted into liposomes for delivery to target cells. As discussed in further details below, a cloning vector was used to isolate individual sequences of DNA. Relevant sequences can be transferred into expression vectors where expression of a particular polypeptide is required. Typical cloning vectors include pBluescript SK, pGEM, pUC9, pBR322 and pGBT9. Typical expression vectors include pTRE, pCAL-n-EK, pESP-1 , pOP13CAT.

Also in accordance with the invention said vector further comprises a nucleic acid sequence which is a regulatory sequence operably linked to said identified nucleic acid sequence.

The term " regulatory sequence" refers to DNA sequences which are necessary to effect the expression of coding sequences to which they are ligated. The nature of such control sequences differs depending upon the host organism. In prokaryotes, control sequences generally include promoter, ribosomal binding site, and terminators. In eukaryotes control sequences generally include promoters, terminators and, in some instances, enhancers, transactivators or transcription factors. The term "control sequence" is intended to include, at a minimum, all components the presence of which are necessary for expression, and may also include additional advantageous components.

The term "operably linked" refers to a arrangement/configuration wherein the components so described are in a relationship permitting them to function in their intended manner. A control sequence "operably linked" to a coding sequence is ligated in such a way that expression of the coding sequence is achieved under conditions compatible with the control sequences. In case the control sequence is a promoter, it is obvious for a skilled person that double-stranded nucleic acid is preferably used. Thus, the recited vector is preferably an expression vector. An "expression vector" is a construct that can be used to transform a selected host and provides for expression of a coding sequence in the selected host. Expression vectors can for instance be cloning vectors, binary vectors or integrating vectors. Expression comprises transcription of the nucleic acid molecule preferably into a translatable mRNA. Regulatory elements ensuring expression in prokaryotes and/or eukaryotic cells are well known to those skilled in the art. In the case of eukaryotic cells they comprise normally promoters ensuring initiation of transcription and optionally poly- A signals ensuring termination of transcription and stabilization of the transcript. Possible regulatory elements permitting expression in prokaryotic hosts comprise, e.g., the P|_, lac, trp or tae promoter in E. coli, and examples of regulatory elements permitting expression in eukaryotic host cells are the AOX1 or GAL1 promoter in yeast or the CMV-, SV40-, RSV-promoter (Rous sarcoma virus), CMV-enhancer, SV40-enhancer or a globin intron in mammalian and other animal cells. Besides elements which are responsible for the initiation of transcription such regulatory elements may also comprise transcription termination signals, such as the SV40-poly-A site or the tk-poly-A site, downstream of the polynucleotide. Furthermore, depending on the expression system used, leader sequences capable of directing the polypeptide to a cellular compartment or secreting it into the medium may be added to the coding sequence of the recited nucleic acid sequence and are well known in the art; see also, e.g., the appended examples. The leader sequence(s) is (are) assembled in appropriate phase with translation, initiation and termination sequences, and preferably, a leader sequence capable of directing secretion of translated protein, or a portion thereof, into the periplasmic space or extracellular medium. Optionally, the heterologous sequence can encode a fusion protein including an N-terminal identification peptide imparting desired characteristics, e.g., stabilization or simplified purification of expressed recombinant product; see supra. In this context, suitable expression vectors are known in the art such as Okayama-Berg cDNA expression vector pcDV1 (Pharmacia), pCDM8, pRc/CMV, pcDNAI, pcDNA3 (In-vitrogene), pEF-DHFR and pEF-ADA (Raum et al. Cancer Immunol Immunother (2001) 50(3), 141-150) or pSPORTI (GIBCO BRL). Preferably, the expression control sequences will be eukaryotic promoter systems in vectors capable of transforming or transfecting eukaryotic host cells, but control sequences for prokaryotic hosts may also be used. Once the vector has been incorporated into the appropriate host, the host is maintained under conditions suitable for high level expression of the nucleotide sequences, and as desired, the collection and purification of the polypeptide of the invention may follow; see, e.g., the appended examples.

An alternative expression system which could be used to express a cell cycle interacting protein is an insect system. In one such system, Autographa californica nuclear polyhedrosis virus (AcNPV) is used as a vector to express foreign genes in Spodoptera frugiperda cells or in Trichoplusia larvae. The coding sequence of a recited nucleic acid molecule may be cloned into a nonessential region of the virus, such as the polyhedrin gene, and placed under control of the polyhedrin promoter. Successful insertion of said coding sequence will render the polyhedrin gene inactive and produce recombinant virus lacking coat protein coat. The recombinant viruses are then used to infect S. frugiperda cells or Trichoplusia larvae in which the protein of the invention is expressed (Smith, J. Virol. 46 (1983), 584; Engelhard, Proc. Nat. Acad. Sci. USA 91 (1994), 3224-3227). Additional regulatory elements may include transcriptional as well as translational enhancers. Advantageously, the above-described vectors of the invention comprises a selectable and/or scorable marker. Selectable marker genes useful for the selection of transformed cells and, e.g., plant tissue and plants are well known to those skilled in the art and comprise, for example, antimetabolite resistance as the basis of selection for dhfr, which confers resistance to methotrexate (Reiss, Plant Physiol. (Life Sci. Adv.) 13 (1994), 143- 149); npt, which confers resistance to the aminoglycosides neomycin, kanamycin and paromycin (Herrera-Estrella, EMBO J. 2 (1983), 987-995) and hygro, which confers resistance to hygromycin (Marsh, Gene 32 (1984), 481-485). Additional selectable genes have been described, namely trpB, which allows cells to utilize indole in place of tryptophan; hisD, which allows cells to utilize histinol in place of histidine (Hartman, Proc. Nati. Acad. Sci. USA 85 (1988), 8047); mannose-6- phosphate isomerase which allows cells to utilize mannose (WO 94/20627) and ODC (ornithine decarboxylase) which confers resistance to the ornithine decarboxylase inhibitor, 2-(difluoromethyl)-DL-omithine, DFMO (McConlogue, 1987, In: Current Communications in Molecular Biology, Cold Spring Harbor Laboratory ed.) or deaminase from Aspergillus terreus which confers resistance to Blasticidin S (Tamura, Biosci. Biotechnol. Biochem. 59 (1995), 2336-2338).

Useful scorable marker are also known to those skilled in the art and are commercially available. Advantageously, said marker is a gene encoding luciferase (Giacomin, PI. Sci. 116 (1996), 59-72; Scikantha, J. Bact. 178 (1996), 121), green fluorescent protein (Gerdes, FEBS Lett. 389 (1996), 44-47) or β-glucuronidase (Jefferson, EMBO J. 6 (1987), 3901-3907). This embodiment is particularly useful for simple and rapid screening of cells, tissues and organisms containing a recited vector.

As described above, the recited nucleic acid molecule can be used alone or as part of a vector to express the encoded polypeptide in cells, for, e.g., gene therapy. The nucleic acid molecules or vectors containing the DNA sequence(s) encoding any one of the above described human binding molecules is introduced into the cells which in turn produce the polypeptide of interest. Gene therapy, which is based on introducing therapeutic genes into cells by ex-vivo or in-vivo techniques is one of the most important applications of gene transfer. Suitable vectors, methods or gene-delivery systems for in-vitro or in-vivo gene therapy are described in the literature and are known to the person skilled in the art; see, e.g., Giordano, Nature Medicine 2 (1996), 534-539; Schaper, Circ. Res. 79 (1996), 911-919; Anderson, Science 256 (1992), 808-813; Verma, Nature 389 (1994), 239; Isner, Lancet 348 (1996), 370-374; Muhlhauser, Circ. Res. 77 (1995), 1077-1086; Onodera, Blood 91 (1998), 30-36; Verma, Gene Ther. 5 (1998), 692-699; Nabel, Ann. N.Y. Acad. Sci. 811 (1997), 289-292; Verzeletti, Hum. Gene Ther. 9 (1998), 2243-51; Wang, Nature Medicine 2 (1996), 714-716; WO 94/29469; WO 97/00957, US 5,580,859; US 5,589,466; or Schaper, Current Opinion in Biotechnology 7 (1996), 635-640. The recited nucleic acid molecules and vectors may be designed for direct introduction or for introduction via liposomes, or viral vectors (e.g., adenoviral, retroviral) into the cell. Preferably, said cell is a germ line cell, embryonic cell, or egg cell or derived therefrom, most preferably said cell is a stem cell. An example for an embryonic stem cell can be, inter alia, a stem cell as described in, Nagy, Proc. Nati. Acad. Sci. USA 90 (1993), 8424-8428.

In accordance with the above, the present invention relates to method to derive vectors, particularly plasmids, cosmids, viruses and bacteriophages used conventionally in genetic engineering that comprise a nucleic acid molecule encoding the polypeptide sequence of a human binding molecule. Preferably, said vector is an expression vector and/or a gene transfer or targeting vector. Expression vectors derived from viruses such as retroviruses, vaccinia virus, adeno-associated virus, herpes viruses, or bovine papilloma virus, may be used for delivery of the recited polynucleotides or vector into targeted cell populations. Methods which are well known to those skilled in the art can be used to construct recombinant vectors; see, for example, the techniques described in Sambrook et al. (loc cit.), Ausubel (1989, loc cit.) or other standard text books. Alternatively, the recited nucleic acid molecules and vectors can be reconstituted into liposomes for delivery to target cells. The vectors containing the nucleic acid molecules of the invention can be transferred into the host cell by well-known methods, which vary depending on the type of cellular host. For example, calcium chloride transfection is commonly utilized for prokaryotes, whereas calcium phosphate treatment or electroporation may be used for other cellular hosts; see Sambrook, supra. The recited vector may be the pEF-Neo, pEF-DHFR or pEF-ADA. The vectors pEF- DHFR and pEF-ADA have been described in the art, e.g. in Mack, PNAS (1995) 92, 7021-7025 and Raum, Cancer lmmunol Immunother (2001) 50(3), 141-150. It is further envisaged that the method of the invention further comprises the step of transforming a host with the above described vector.

Said host may be produced by introducing said at least one of the above described vector or at least one of the above described nucleic acid molecules into the host. The presence of said at least one vector or at least one nucleic acid molecule in the host may mediate the expression of a gene encoding the above described human binding molecule. The described nucleic acid molecule or vector which is introduced in the host may either integrate into the genome of the host or it may be maintained extrachromosomally.

The host can be any prokaryotes or eukaryotic cell.

The term "prokaryote" is meant to include all bacteria which can be transformed or transfected with a DNA or RNA molecules for the expression of a protein of the invention. Prokaryotic hosts may include gram negative as well as gram positive bacteria such as, for example, E. coli, S. typhimurium, Serratia marcescens and Bacillus subtilis. The term "eukaryotic" is meant to include yeast, higher plant, insect and preferably mammalian cells. Depending upon the host employed in a recombinant production procedure, the protein encoded by the polynucleotide of the present invention may be glycosylated or may be non-glycosylated. Especially preferred is the use of a plasmid or a virus containing the coding sequence of the polypeptide of the invention and genetically fused thereto an N-terminal FLAG-tag and/or C-terminal His-tag. Preferably, the length of said FLAG-tag is about 4 to 8 amino acids, most preferably 8 amino acids. An above described polynucleotide can be used to transform or transfect the host using any of the techniques commonly known to those of ordinary skill in the art. Furthermore, methods for preparing fused, operably linked genes and expressing them in, e.g., mammalian cells and bacteria are well-known in the art (Sambrook, loc cit.).

Preferably, said host is a bacteria, an insect, fungal, plant or animal cell. It is particularly envisaged that the recited host may be a mammalian cell, more preferably a human cell or human cell line. Particularly preferred host cells comprise CHO cells, COS cells, myeloma cell lines like SP2/0 or NS/0.

It is further envisaged that the method of the invention may comprise the step of isolation and/or purification of the recombinantly expressed human binding molecule, fragment or derivative thereof. Said method consequently comprises the step of culturing a recited host under conditions allowing the expression of the recited human binding molecule and recovering said binding molecule from the culture. The transformed hosts can be grown in fermentors and cultured according to techniques known in the art to achieve optimal cell growth. The human binding molecule can then be isolated from the culture medium, cellular lysates, or cellular membrane fractions. The isolation and purification of the, say, microbially expressed human binding molecules may be effected by any conventional means such as, for example, preparative chromatographic separations and immunological separations such as those involving the use of monoclonal or polyclonal antibodies directed, for example against a tag of the human binding molecule or as described in the appended examples. The conditions for the culturing of a host which allow the expression are known in the art to depend on the host system and the expression system/vector used in such process. The parameters to be modified in order to achieve conditions allowing the expression of a recombinant polypeptide are known in the art. Thus, suitable conditions can be determined by the person skilled in the art in the absence of further inventive input.

Once expressed, the human binding molecule can be purified according to standard procedures of the art, including ammonium sulfate precipitation, affinity columns, column chromatography, gel electrophoresis and the like; see, Scopes, "Protein Purification", Springer-Verlag, N.Y. (1982). Substantially pure polypeptides of at least about 90 to 95% homogeneity are preferred, and 98 to 99% or more homogeneity are most preferred, for pharmaceutical uses. Once purified, partially or to homogeneity as desired, the human binding molecules may then be used therapeutically (including extracorporeally) or in developing and performing assay procedures. Furthermore, examples for methods for the recovery human binding molecules from a culture are described in detail in the appended examples.

In a preferred embodiment of the method of the invention, said method further comprises the step of formulating the human binding molecule as a pharmaceutical composition, which optionally further comprises a pharmaceutically acceptable carrier or diluent.

The term "pharmaceutical composition" as well as the terms "pharmaceutically acceptable carrier" and "pharmaceutically acceptable diluent" are defined in more detail herein below.

In an alternative embodiment the present invention relates to a human binding molecule specifically binding to/interacting with the human CD3 complex, whereby said binding molecule is an antibody molecule, antibody fragment or derivative thereof or an antibody construct. As described herein above, the method of the invention provides means for the preparation/isolation of a human binding molecule of the invention. Said particular human binding molecule of the invention is an antibody molecule, antibody fragment or derivative thereof or an antibody construct. The terms "antibody molecule", "antibody fragment or derivative thereof and "antibody construct" have been defined in the context of the above described method of the invention. In line with said definitions the antibody fragment or derivative thereof or an antibody construct of the invention comprises at least one CDR of a human antibody with specificity for the human CD3 complex, preferably at least one CDR3, which provides the capacity of the binding molecule to bind to/interact with the human CD3 complex.

The human binding molecule of the invention may comprise an additional domain which may be used for the isolation/preparation of the molecule. Examples for said additional domain comprise label and tags. Said tag may be selected from the group consisting of: His-tag, Flag-tag, Myc-tag, HA-tag, GST-tag, T100™, VSV-G, V5, S-tag™, HSV, CFP, RFP, YFP, GFP, BFP, Cellulose binding domain (CBD), Maltose binding protein (MBP), NusA-tag, thioredoxin (Trx), DsbA, DabC and a biotinylation sequence.

A human binding molecule wherein said derivative of an antibody is an scFv is particularly envisaged by the present invention.

As also discussed herein above, the terms "antibody fragment or derivative thereof and "antibody construct" relate, inter alia, to scFv constructs. The intramolecular orientation of the V_H-domain and the Vι_-domain, which are linked to each other by a linker-domain, in the scFv format is not decisive for binding molecules of the invention. Thus, scFvs with both possible arrangements (VH- domain - linker domain - V|_-domain; Vι_-donrιain - linker domain - V_H-domain) are particular embodiments of the human binding molecule of the invention. A corresponding format of the human binding molecule of the invention is described in the appended example 3.2. A human binding molecule of the invention is characterized as an antibody molecule, antibody fragment or derivative thereof or an antibody construct, which comprises a variable V_H-region as encoded by a nucleic acid molecule as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 1 ,17, 33, 49, 65, 81, 97 and 113 or a variable Vπ-region having an amino acid sequence as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 2, 18, 34, 50, 66, 82, 98 and 114.

Alternatively, the human binding molecule of the invention is characterized as an antibody molecule, antibody fragment or derivative thereof or an antibody construct, which comprises a variable Vι_-region as encoded by a nucleic acid molecule as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 9, 25, 41, 57, 73, 89, 105 and 121 or a variable V_L-region having an amino acid sequence as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 10, 26, 42, 58, 74, 90, 106 and 122.

The human binding molecule of the invention may also comprise at least one CDR3 of a V_H-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 7, 23, 39, 55, 71, 87, 103 or 119 or at least one CDR3 amino acid sequence of an V_H-region as shown in SEQ ID NOs: 8, 24, 40, 56, 72, 88, 104 or 120 and/or wherein said antibody molecule comprises at least one CDR3 of an VL-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 15, 31, 47, 63, 79, 95, 111 or 127 or at least one CDR3 amino acid sequence of a VL-region as shown in SEQ ID NOs: 16, 32, 48, 64, 80, 96, 112 or 128.

Alternatively the human binding molecule of the invention may also comprise at least one CDR2 of an Vπ-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 5, 21, 37, 53, 69, 85, 101 or 117 or at least one CDR2 amino acid sequence of an V_H-region as shown in SEQ ID NOs: 6, 22, 38, 54, 70, 86, 102 or 118 and/or wherein said antibody molecule comprises at least one CDR2 of an VL- region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 13, 29, 45, 61, 77, 93, 109 or 125 or at least one CDR2 amino acid sequence of an V_L- region as shown in SEQ ID NOs: 14, 30, 46, 62, 78, 94, 110 or 126.

A further alternative human binding molecule of the invention is characterized as an antibody molecule, antibody fragment or derivative thereof or an antibody construct, which comprises at least one CDR1 of an V_H-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 3, 19, 35, 51, 67, 83, 99 or 115 or at least one CDR1 amino acid sequence of an V_H-region as shown in SEQ ID NOs: 4, 20, 36, 52, 68, 84, 100 or 116 and/or wherein said antibody molecule comprises at least one CDR1 of an V_L-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 11, 27, 43, 59, 75, 91, 107 or 123 or at least one CDR1 amino acid sequence of an V_L-region as shown in SEQ ID NOs: 12, 28, 44, 60, 76, 92, 108 or 124.

It is further envisaged by the present invention that the human binding molecule additionally comprises at least one further antigen-interaction-site and/or at least one further effector domain.

The invention also relates to multispecific binding molecules. Bi-, tri-, tetra- as well as oligo-specific binding molecule are particularly comprised. The term "further effector domain" has been defined and exemplified herein above.

Human binding molecules of the invention, which comprise at least one further antigen-interaction-site and/or at least one further effector domain, may be humanized and/or deimmunized.

As noted herein above only non-human derived domains of the binding molecule may be humanized. Furthermore, immunogenic epitopes, at the junctions between human derived domains and non-human derived domains and in non-human derived domains may be deleted by deimmunization. Methods for the humanization and or deimmunization of corresponding domains are known by the person skilled in the art and some possible methods have been discussed herein above.

In one embodiment of the human binding molecule of the invention, said at least one further antigen-interaction-site is specific for one or more cell surface molecule.

The terms "cell surface molecule" and "tumor marker/tumor specific marker" have been defined herein above. Preferably said cell surface molecule is a tumor specific marker. Examples for said tumor specific markers are TAG72, PSMA, CD44v6, CEA, Her2-neu, Her-3, Her-4, Lewis Y. Further markers have been described above.

It is also envisaged that said at least one further antigen-interaction-site is a domain which is derived from an antibody or antibody construct.

The intramolecular orientation (N-terminal or C-terminal) of the different antigen interaction-sites (domains) in the human binding molecule is not decisive for the invention as long as said different antigen interaction-sites specifically bind to/interact with its specific antigens. Consequently, in the case of a bispecific binding molecule the domain specific for the human CD3 complex may be N- terminal (and the further antigen-interaction-site C-terminal) as well as C-terminal (and the further antigen-interaction-site N-terminal).

Preferably said at least one further antigen-interaction-site is a further scFv. In the particular format of an scFv the orientation of the V_H-domain and the VL-domain in the domain of the further aritigen-interaction-site is not decisive for the present invention. Thus, scFvs with both possible arrangements in the portion of the further antigen-interaction-site (V_H-domain - linker domain - V_L-domain; VL-domain - linker domain - Vπ-domain) are particular embodiments of the human binding molecule of the invention. Accordingly, for a corresponding bispecific human binding molecule said permutation of domains results in eight possible constructs for one specific human binding molecule.

In accordance with the invention said at least one further antigen-interaction-site specifically binds to/interacts with an antigen selected from the group consisting of EpCAM, CCR5, CD19, EphA2, HER-2 neu, HER-3, HER-4, EGFR, PSMA, CEA, TAG-72, MUC-1 (mucin), MUC2, MUC3, MUC4, MUC5_Ac, MUC5_B> MUC7, βhCG, Lewis-Y, CD20, CD33, CD30, ganglioside GD3, 9-0-Acetyl-GD3, GM2, Globo H, fucosyl GM1 , Poly SA, GD2, Carboanhydrase IX (MN/CA IX), CD44v6, Sonic Hedgehog (Shh), Wue-1 , Plasma Cell Antigen, (membrane-bound) IgE, Melanoma Chondroitin Sulfate Proteoglycan (MCSP), CCR8, TNF-alpha precursor, STEAP, STEAP II, mesothelin, A33 Antigen, Prostate Stem Cell Antigen (PSCA), Ly-6, desmoglein 4, E-cadherin neoepitope, Fetal Acetylcholine Receptor, CD25, CA19- 9 marker, CA-125 marker and Muellerian Inhibitory Substance (MIS) Receptor type II, sTn (sialylated Tn antigen; TAG-72), FAP (fibroblast activation antigen), endosialin, EGFRvlll, L6, SAS , CD63, Tu, TF, Le^a, Sialyl Le^a, Le^b, Le^x, Sialyl Le^x and polyfucosyl-Le^x.

In the following tables 1 to 8, specific bispecific constructs comprising as one specificity the human anti-human CD3 binder as described herein are provided. The following tables 1 and 2 relate to the above described embodiment of the present invention and describe specific human anti-human CD3xCD19 constructs. The following tables 3 and 4 relate to the above described embodiment of the present invention and describe specific human anti-human CD3xEpCAM constructs. The following tables 5 and 6 relate to the above described embodiment of the present invention and describe specific human anti-human CD3xCCR5 constructs. The following tables 7 and 8 relate to the above-described embodiment of the present invention and describe specific human anti-human CD3xCD20 constructs. In this context, it is of note that tables 1, 3, 5 and 7 relate to nucleic acid sequences encoding the corresponding bispecific constructs, whereas tables 2, 4, 6 and 8, respectively, show the corresponding proteinaceous sequences.

The following tables 1 ,3, 5 and 7 depict selected nucleic acid molecules encoding specific constructs of the inventions.

Table 1:

Table 3:

Table 5:

Table 7:

Nucleic acid constructs are as defined in Tables 1, 3, 5 and 7. Each nucleic acid construct in each of Tables 1 , 3, 5 and 7 comprises 7 distinct nucleic acid modules, denoted A-G. Nucleic acid modules A-G are directly and covalently linked to one another in a single contiguous nucleotide chain by phosphate glycoside bonds in the order A-B-C-D-E-F-G, with nucleic acid module A at the 5'-end and nucleic acid module G at the 3'-end of a respective nucleic acid construct. Nucleic acid modules A, C, E and G denote encoding regions for antibody variable domains which can be either VH or VL domains of antibodies having specificity for different antigens. Each construct comprises nucleic acid modules encoding a VH and VL region from a human antibody or fragment thereof having specificity for human CD3 as well as a VH and VL region from an antibody or fragment thereof having specificity for one of the human antigens CD19, EpCAM, CCR5 or CD20.

If nucleic acid module A encodes a VH antibody domain, then nucleic acid module C encodes a VL protein domain, and vice versa. If nucleic acid module E encodes a VH antibody domain, then nucleic acid module G encodes a VL protein domain, and vice versa.

Nucleic acid molecules encoding VH domains of human antibodies or fragments thereof having specificity for the human CD3 antigen can be selected from the sequences as set out in SEQ ID NOs: 1 , 17, 33, 49, 65, 81 , 97 or 113. Nucleic acid molecules encoding VL domains of human antibodies or fragments thereof having specificity for the human CD3 antigen can be selected from the sequences as set out in SEQ ID NOs: 9, 25, 41, 57, 73, 89, 105, 121. Nucleic acid molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the CD19 antigen have the nucleic acid sequences as set out in SEQ ID NOs: 129 and 131, respectively. Nucleic acid molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the EpCAM antigen have the nucleic acid sequences as set out in SEQ ID NOs: 133 and 135, respectively. Nucleic acid molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the CCR5 antigen have the nucleic acid sequences as set out in SEQ ID NOs: 196 and 198, respectively. Nucleic acid molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the CD20 antigen have the nucleic acid sequences as set out in SEQ ID NOs: 200 and 202, respectively.

Pairs of nucleic acids encoding antibody variable domains denoted by the nucleic acid module pairs A/C and E/G are joined by additional linking nucleic acid modules, wherein nucleic acid module B serves to directly link the module pair A/C and nucleic acid module F serves to directly link the module pair E/G. Nucleic acid modules B and F each have the nucleotide sequence as set out in SEQ ID NO: 174.

The combination of nucleic acid modules A-B-C and the combination of nucleic acid modules E-F-G each respectively constitute one scFv fragment of an antibody having specificity for either the human CD3 antigen or for any of the human antigens CD19, EpCAM, CCR5 or CD20. The respective groups of nucleic acid modules A-B-C and E-F-G are connected to one another through nucleic acid module D, having the nucleotide sequence as set out in SEQ ID NO: 176. Nucleic acid module D serves to connect the 3'-end of nucleic acid module C with the 5'- end of nucleic acid module E. Especially preferred nucleic acid constructs encoding bispecific single chain binding molecules comprising human anti-CD3 portions are (with corresponding SEQ ID NOs in parentheses) 20nuc (SEQ ID NO: 205), 21 nuc (SEQ ID NO: 215), 28nuc (SEQ ID NO: 207), 29nuc (SEQ ID NO: 217), 36nuc (SEQ ID NO: 209), 37nuc (SEQ ID NO: 219), 52nuc (SEQ ID NO: 211), 53nuc (SEQ ID NO: 221), 60nuc (SEQ ID NO: 213), 61nuc (SEQ ID NO: 223), 82nuc (SEQ ID NO: 225), 85nuc (SEQ ID NO: 235), 90nuc (SEQ ID NO: 227), 93nuc (SEQ ID NO: 237), 98nuc (SEQ ID NO: 229), 101nuc (SEQ ID NO: 239), 114nuc (SEQ ID NO: 231), 117nuc (SEQ ID NO: 241), 122nuc (SEQ ID NO: 233), 125nuc (SEQ ID NO: 243), 149nuc (SEQ ID NO: 251), 157nuc (SEQ ID NO: 249), 213nuc (SEQ ID NO: 247) and 221nuc (SEQ ID NO: 245).

Proteinaceous constructs as encoded, inter alia, by the nucleic acid molecules shown in Tables 1, 3, 5 and 7 (as detailed above) are shown and illustrated in the corresponding tables 2, 4, 6 and 8.

Table 2:

Table 4:

Table 6:

Table 8:

Protein constructs are as defined in Tables 2, 4, 6 and 8. Each protein construct in each of the Tables 2, 4, 6 and 8 comprises 7 distinct protein modules, denoted A- G. Protein modules A-G are directly and covalently linked to one another in a single contiguous polypeptide chain by peptide bonds in the order A-B-C-D-E-F-G, with protein module A at the N-terminus and protein module G at the C-terminus. Protein modules A, C, E and G denote antibody variable domains which can be either VH or VL domains of antibodies having specificity for the different antigens. Each construct protein modules encoding a VH and VL region from a human antibody or fragment thereof having specificity for human CD3 as well as a VH and VL region from an antibody or fragment thereof having specificity for one of the human antigens CD19, EpCAM, CCR5 or CD20.

If protein module A is a VH antibody domain, then protein module C is a VL protein domain, and vice versa. If protein module E is a VH antibody domain, then protein module G is a VL protein domain, and vice versa.

VH domains of human antibodies or fragments thereof having specificity for the human CD3 antigen can be selected from the amino acid sequences as set out in SEQ ID NOs: 2, 18, 34, 50, 66, 82, 98 or 114. VL domains of human antibodies or fragments thereof having specificity for the human CD3 antigen can be selected from the amino acid sequences as set out in SEQ ID NOs: 10, 26, 42, 58, 74, 90, 106 or 122. Protein molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the CD19 antigen have the amino acid sequences as set out in SEQ ID NOs: 130 and 132, respectively. Protein molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the EpCAM antigen have the amino acid sequences as set out in SEQ ID NOs: 134 and 136, respectively. Protein molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the CCR5 antigen have the amino acid sequences as set out in SEQ ID NOs: 197 and 199, respectively. Protein molecules encoding VH and VL domains of an antibody or fragment thereof having specificity for the CD20 antigen have the amino acid sequences as set out in SEQ ID NOs: 201 and 203, respectively. Pairs of antibody variable domains denoted by the protein module pairs A/C and E/G are joined by additional linking protein modules, wherein protein module B serves to directly link the module pair A/C and protein module F serves to directly link the module pair E/G. Protein modules B and F each have the amino acid sequence as set out in SEQ ID NO: 175.

The combination of protein modules A-B-C and the combination of protein modules E-F-G each respectively constitute one scFv fragment of an antibody having specificity for either the human CD3 antigen or for any of the human antigens CD19, EpCAM, CCR5 or CD20. The respective groups of protein modules A-B-C and E-F-G are connected to each other through protein module D, having the amino acid sequence as set out in SEQ ID NO: 177. Protein module D serves to connect the C-terminal end of protein module C with the N-terminal end of protein module E.

Especially preferred bispecific single chain binding molecules comprising human anti-CD3 portions are (with corresponding SEQ ID NOs in parentheses): 20prot (SEQ ID NO: 206), 21 prot (SEQ ID NO: 216), 28prot (SEQ ID NO: 208), 29prot (SEQ ID NO: 218), 36prot (SEQ ID NO: 210), 37prot (SEQ ID NO: 220), 52prot (SEQ ID NO: 212), 53prot (SEQ ID NO: 222), 60prot (SEQ ID NO: 214), 61 prot (SEQ ID NO: 224), 82prot (SEQ ID NO: 226), 85prot (SEQ ID NO: 236), 90prot (SEQ ID NO: 228), 93prot (SEQ ID NO: 238), 98prot (SEQ ID NO: 230), 101 prot (SEQ ID NO: 240), 114prot (SEQ ID NO: 232), 117prot (SEQ ID NO: 242), 122prot (SEQ ID NO: 234), 125prot (SEQ ID NO: 244), 149prot (SEQ ID NO: 252), 157prot (SEQ ID NO: 250), 213prot (SEQ ID NO: 248) and 221 prot (SEQ ID NO: 246).

Accordingly, in one embodiment of the inventive human binding molecule specifically binding to human CD3/human CD3 complex comprises a further antigen binding site, said further antigen binding site specifically binds to/interacts with the CD19 molecule. Preferably, the corresponding human binding molecule of the invention comprises an amino acid sequence selected from the group of: (a) an amino acid sequence corresponding to construct 1prot to 64prot of table 2 herein above;

(b) (an amino acid sequence encoded by a nucleic acid sequence corresponding to construct 1 nuc to 64nuc of table 1 herein above; (c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in (b) under stringent hybridization conditions; and

(d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of^"(b) and (c).

It is of note that the nucleic acid sequences referred to in (c) herein above specifically code for human anti-human CD3 bispecific constructs with a second specificity for CD 19, preferably human CD 19. Particular preferred human anti-human CD3xCD19 constructs (nucleic acid and protein) are depicted in SEQ ID NOs: 205, 206, 207, 208, 209, 210, 211, 212, 213 and 214. Also envisaged are constructs in the format CD19x human anti-human

CD3. Illustrative and preferred examples of said constructs (nucleic acid and protein) are shown in SEQ ID NOs.: 215, 216, 217, 218, 219, 220, 221, 222, 223 and 224.

In an alternative embodiment of the human binding molecule of the invention said further antigen binding site specifically binds to/interacts with the EpCAM molecule. The term "EpCAM" defines a cell surface molecule also known as 17-1 , GA733, C017-1a, EGP, KS1-4, KSA.ESA, Epithelial cell adhesion molecule, etc. (see, e.g. Helrich, Int. J. Cancer 76 (1998), 232-9; Staib, Int. J. Cancer 92 (2001), 79-87).

Accordingly, in one embodiment of the inventive human binding molecule specifically binding to human CD3/human CD3 complex comprises a further antigen binding site, said further antigen binding site specifically binds to/interacts with the EpCAM molecule. Preferably, the corresponding human binding molecule comprises an amino acid sequence selected from the group of: (a) an amino acid sequence corresponding to construct 65prot to 128prot of table 4 as shown above;

(b) an amino acid sequence encoded by a nucleic acid sequence corresponding to construct 65nuc to 128nuc of table 3 as shown above; (c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in (b) under stringent hybridization conditions; and

(d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (b) and (c).

It is of note that the nucleic acid sequences referred to in (c) herein above specifically code for human anti-human CD3 bispecific constructs with a second specificity for EpCAM, preferably human EpCAM.

Particular preferred human anti-human CD3xEpCAM constructs (nucleic acid and protein) are depicted in SEQ ID NOs: 225, 226, 227, 228, 229, 230, 231, 232, 233 and 234. Also envisaged are constructs in the format EpCAM x human anti-human CD3. Illustrative and preferred examples of said constructs (nucleic acid and protein) are shown in SEQ ID NOs.: 235, 236, 237, 238, 239, 240, 241, 242, 243 or 244.

In a further alternative embodiment of the human binding molecule of the invention, it comprises a further antigen binding site, said further antigen binding site being capable of specifically binding to/interacting with the CCR5 molecule. Therefore, it is envisaged that a human binding molecule of the invention comprises an amino acid sequence selected from the group of:

(a) an amino acid sequence corresponding to construct 129prot to 192prot of table 6 herein above;

(b) an amino acid sequence encoded by a nucleic acid sequence corresponding to construct 129nuc to 192nuc of table 5 herein above;

(c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in (b) under stringent hybridization conditions; and (d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (b) and (c).

It is of note that the nucleic acid sequences referred to in (c) herein above specifically code for human anti-human CD3 bispecific constructs with a second specificity for CCR5.

Particular preferred human anti-human CD3xCCR5 constructs (nucleic acid and protein) are depicted in SEQ ID NOs: 249, 250, 251 and 252.

Moreover, in an alternative embodiment of the human binding molecule of the invention, having at least two binding specificities, comprises a binding specificity for human CD3/CD3 complex and a further antigen binding site, further antigen binding site specifically binding to/interacting with the CD20 molecule, preferably the human CD20 molecule. Accordingly, it is also envisaged that a human binding molecule of the invention comprises an amino acid sequence selected from the group of: (a) an amino acid sequence corresponding to construct 193prot to 256prot of table 8 shown herein above;

(b) an amino acid sequence encoded by a nucleic acid sequence corresponding to construct 193nuc to 256nuc of table 7 shown herein above;

(c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in (b) under stringent hybridization conditions; and

(d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (b) and (c). It is of note that the nucleic acid sequences referred to in (c) herein above specifically code for human anti-human CD3 bispecific constructs with a second specificity for CD20, preferably human CD20.

Particular preferred constructs (nucleic acid and protein) in the format CD20x human anti-human CD3 are shown in SEQ ID NOs.: 245, 246, 247 and 248. The invention also relates to an above characterized human binding molecule, wherein said binding molecule is obtainable by a method of the invention.

Further, the invention relates to a nucleic acid sequence encoding a human binding molecule described herein. Said nucleic acid molecule may be a naturally nucleic acid molecule as well as a recombinant nucleic acid molecule. The nucleic acid molecule of the invention may, therefore, be of natural origin, synthetic or semi- synthetic. It may comprise DNA, RNA as well as PNA and it may be a hybrid thereof.

Thus, the present invention relates, in a preferred embodiment, to a nucleic acid molecule comprising a nucleotide sequence selected from the group consisting of:

(a) a nucleotide sequence encoding the mature form of a protein comprising the amino acid sequence of human binding molecule of the invention, preferably as given in SEQ ID Nos: 181, 183, 185, 187, 189, 191, 193, 195, 206, 208, 210, 212, 214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 236, 238,

240, 242, 244, 246, 248, 250 or 252;

(b) a nucleotide sequence comprising or consisting of the DNA sequence as given in SEQ ID NOs: 180, 182, 184, 186, 188, 190, 192, 194, 205, 207, 209, 211, 213, 215, 217, 219, 221, 223, 225, 227, 229, 231, 233, 235, 237, 239, 241 , 243, 245, 247, 249 or 251 ;

(c) a nucleotide sequence hybridizing with the complementary strand of a nucleotide sequence as defined in (b) under stringent hybridization conditions;

(d) a nucleotide sequence encoding a protein derived from the protein encoded by a nucleotide sequence of (a) or (b) by way of substitution, deletion and/or addition of one or several amino acids of the amino acid sequence encoded by the nucleotide sequence of (a) or (b);

(e) a nucleotide sequence encoding a protein having an amino acid sequence at least 60 %, preferably 70%, more preferably 80%, most preferably 90% identical to the amino acid sequence encoded by the nucleotide sequence of (a) or (b);

(f) a nucleotide sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (a) to (e);

The above mentioned nucleic acid SEQ ID NOs: 180, 182, 184, 186, 188, 190, 192 and 194 relate to specific human anti-human CD3-binders of the present invention in scFv format. The corresponding protein sequences are shown in SEQ ID NOs: 181 , 183, 185, 187, 189, 191, 193 and 195. As detailed above, the SEQ ID NOs: 206, 208, 210, 212, 214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 236, 238, 240, 242, 244, 246, 248, 250 and 252 relate to exemplified, bispecific protein constructs comprising, as one specificity, the human anti-human CD3 binding molecule of the invention. Corresponding encoding nucleic acid sequences are given in SEQ ID NOs: 205, 207, 209, 211, 213, 215, 217, 219, 221, 223, 225, 227, 229, 231 , 233, 235, 237, 239, 241, 243, 245, 247, 249 or 251, respectively. The term "mature form of the protein" defines in the context of the present invention a protein translated from its corresponding mRNA and optionally subsequently modified.

The term "hybridizing" has been defined in the context of the present invention herein above.

It is evident to the person skilled in the art that regulatory sequences may be added to the nucleic acid molecule of the invention. For example, promoters, transcriptional enhancers and/or sequences which allow for induced expression of the polynucleotide of the invention may be employed. A suitable inducible system is for example tetracycline-regulated gene expression as described, e.g., by Gossen and Bujard (Proc. Nati. Acad. Sci. USA 89 (1992), 5547-5551) and Gossen et al. (Trends Biotech. 12 (1994), 58-62), or a dexamethasone-inducible gene expression system as described, e.g. by Crook (1989) EMBO J. 8, 513-519 . Furthermore, it is envisaged for further purposes that nucleic acid molecule may contain, for example, thioester bonds and/or nucleotide analogues. Said modifications may be useful for the stabilization of the nucleic acid molecule against endo- and/or exonucleases in the cell. Said nucleic acid molecules may be transcribed by an appropriate vector containing a chimeric gene which allows for the transcription of said nucleic acid molecule in the cell. In this respect, it is also to be understood that the polynucleotide of the invention can be used for "gene targeting" or "gene therapeutic" approaches. In another embodiment said nucleic acid molecules are labeled. Methods for the detection of nucleic acids are well known in the art, e.g., Southern and Northern blotting, PCR or primer extension. This embodiment may be useful for screening methods for verifying successful introduction of the nucleic acid molecules described above during gene therapy approaches. Said nucleic acid molecule(s) may be a recombinantly produced chimeric nucleic acid molecule comprising any of the aforementioned nucleic acid molecules either alone or in combination. Preferably, the nucleic acid molecule is part of a vector. Examples for suitable vectors have been described herein above. Preferably said vector of the invention comprises a nucleic acid sequence which is a regulatory sequence operably linked to said nucleic acid sequence encoding a human binding molecule of the invention.

It is envisaged that the vector of the invention is an expression vector wherein the nucleic acid molecule encodes a human binding molecule of the invention. The terms "control sequence" and "operably linked", as well as examples for suitable vector systems have been described herein above.

The present invention furthermore relates to host containing at least one vector or at least one nucleic acid molecule of the invention.

Said host may be produced by introducing said at least one vector or at least one nucleic acid molecule into the host. The presence of said at least one vector or at least one nucleic acid molecule in the host may mediate the expression of a gene encoding a human binding molecule of the invention. The nucleic acid molecule or vector of the invention which is present in the host may either be integrated into the genome of the host or it may be maintained extrachromosomally.

Suitable hosts are discussed herein above. Yet, the host can be any prokaryote or eukaryotic cell. In a preferred embodiment the host is a bacteria, an insect, fungal, plant or animal cell. Preferably it is envisaged that the host of the invention may be a mammalian cell, more preferably a human cell or human cell line. Particularly preferred host cells comprise CHO cells, COS cells, myeloma cell lines like SP2/0 or NS/0. A method for the production of such host is exemplified in the appended examples. An alternative embodiment of the invention relates to a process for the production of a human binding molecule of the invention, said process comprising culturing a host of the invention under conditions allowing the expression of the polypeptide construct and recovering the produced polypeptide construct from the culture. The transformed hosts can be grown in fermentors and cultured according to techniques known in the art to achieve optimal cell growth. The polypeptide of the invention can then be isolated from the growth medium, cellular lysates, or cellular membrane fractions. The isolation and purification of the, e.g., microbially expressed polypeptides of the invention may be by any conventional means such as, for example, preparative chromatographic separations and immunological separations such as those involving the use of monoclonal or polyclonal antibodies directed, e.g., against a tag of the polypeptide of the invention or as described in the appended examples. The conditions for the culturing of a host which allow the expression are known in the art and discussed herein above. The same holds true for procedures for the purification/recovery of said polypeptide constructs.

The invention also provides for a composition comprising a human binding molecule(s) of the invention or as produced by the method of the invention. The compositions of the invention, which are pharmaceutical compositions may be administered simultaneously or in a non-simultaneous way with an above defined proteinaceous compound capable of mediating an activation signal for immune effector cells.

In the light of the present invention, said "proteinaceous compounds" providing an activation signal for immune effector cells" may be, e.g. an activation signal for T cells. Preferred formats of proteinaceous compounds comprise bispecifc antibodies and fragments or derivatives thereof, e.g. bispecific scFv. Preferably, said activation signal for T cells may be provided via the T cell receptor (TCR), more preferably via CD3 molecule of the TCR. Proteinaceous compounds can comprise, but are not limited to, scFv fragments specific for CD3, scFv fragments specific for the T cell receptor or superantigens. Superantigens directly bind to certain subfamilies of T cell receptor variable regions in an MHC-independent manner thus mediating the primary T cell activation signal. The proteinaceous compound may also provide an activation signal for an immune effector cell which is a non-T cell. Examples of immune effector cells which are non-T cells comprise, inter alia, B cells and NK cells.

The present invention also relates to compositions which are pharmaceutical compositions comprising these aforementioned human binding molecule(s), nucleic acid molecule(s), vector(s) or host(s) of the invention and, optionally, the described proteinaceous compound capable of an activation signal for immune effector cells.

The compositions of the invention, which are pharmaceutical compositions may be administered simultaneously or in a non-simultaneous way with an above defined proteinaceous compound capable of mediating an activation signal for immune effector cells.

In a further preferred embodiment of the invention the composition, which is a pharmaceutical composition, further comprises suitable formulations of carrier, stabilizers and/or excipients. In accordance with this invention, the term "pharmaceutical composition" relates to a composition for administration to a patient, preferably a human patient. In preferred embodiment, the pharmaceutical composition comprises a composition for parenteral, intraluminal, intra-arterial, intrathecal or transdermal administration. Also envisaged is direct injection into a tissue, for example into a tumor. It is in particular envisaged that said pharmaceutical composition is administered to a patient via infusion or injection. Administration of the suitable compositions may be effected by different ways, e.g., by intravenous, intraperitoneal, subcutaneous, intramuscular, topical or intradermal administration. The pharmaceutical composition of the present invention may further comprise a pharmaceutically acceptable carrier. Examples of suitable pharmaceutical carriers are well known in the art and include phosphate buffered saline solutions, water, emulsions, such as oil/water emulsions, various types of wetting agents, sterile solutions, etc. Compositions comprising such carriers can be formulated by well known conventional methods. These pharmaceutical compositions can be administered to the subject at a suitable dose. The dosage regimen will be determined by the attending physician and clinical factors. As is well known in the medical arts, dosages for any one patient depends upon many factors, including the patient's size, body surface area, age, the particular compound to be administered, sex, time and route of administration, general health, and other drugs being administered concurrently. A preferred dosage for administration might be in the range of 0.24 μg to 48 mg units per kilogram of body weight per day, preferably 0.24 μg to 24 mg, more preferably 0.24 μg to 2.4 mg even more preferably 0.24 μg to 0.24 μg and most preferably 0.24 μg to 240 μg units per kg body weight per day. Particularly preferred dosages are recited herein below. Progress can be monitored by periodic assessment. Dosages will vary but a preferred dosage for intravenous administration of DNA is from approximately 10⁶ to 10¹² copies of the DNA molecule. The compositions of the invention may be administered locally or systematically. Administration will generally be parenterally, e.g., intravenously; DNA may also be administered directed to the target site, e.g., by biolistic delivery to an internal or external target site or by catheter to a site in an artery. Preparations for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, and emulsions. Examples of non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oils such as olive oil, and injectable organic esters such as ethyl oleate. Aqueous carriers include water, alcoholic/aqueous solutions, emulsions or suspensions, including saline and buffered media. Parenteral vehicles include sodium chloride solution, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's, or fixed oils. Intravenous vehicles include fluid and nutrient replenishes, electrolyte replenishers (such as those based on Ringer's dextrose), and the like. Preservatives and other additives may also be present such as, for example, antimicrobials, anti-oxidants, chelating agents, and inert gases and the like. In addition, the pharmaceutical composition of the present invention might comprise proteinaceous carriers, like, e.g., serum albumine or immunoglobuline, preferably of human origin. It is envisaged that the pharmaceutical composition of the invention might comprise, in addition to the proteinaceous bispecific single chain antibody constructs or nucleic acid molecules or vectors encoding the same (as described in this invention), further biologically active agents, depending on the intended use of the pharmaceutical composition. Such agents might be drugs acting on the gastro-intestinal system, drugs acting as cytostatica, drugs preventing hyperurikemia, drugs inhibiting immunoreactions (e.g. corticosteroids), drugs acting on the circulatory system and/or agents such as T- cell co-stimulatory molecules or cytokines known in the art. Possible indications for administration of the human binding molecule(s) of the invention are tumorous diseases, especially epithelial cancers/carcinomas such as breast cancer, colon cancer, prostate cancer, ovarian cancer or lung cancer or other tumorous diseases like haematological tumors, gliomas, sarcomas, osteosarcomas, head and neck cancer, skin cancer, cancers of the genitor-urinary tract, endometrial cancer, cervix cancer, kidney cancer, gastric cancer, cancer of the small intestine, liver cancer, pancreas cancer, gall bladder cancer, cancers of the bile duct, esophageal cancer, cancer of the salivatory glands or cancer of the thyroid gland. The administration of the human binding molecule(s) of the invention of the invention is especially indicated for minimal residual disease, which is characterized by the local and non-local reoccurrance of the tumor caused by the survival of single cells. Further possible indications for administration of the constructs of the invention may comprise autoimmune diseases, especially T cell mediated autoimmune diseases, inflammatory diseases, infectious diseases, especially bacterial and fungal infections, viral diseases, allergic reactions, parasitic reactions, graft versus host disease, host versus graft disease, transplant rejection. The invention further envisages co-administration protocols with other compounds, e.g. bispecific antibody constructs, targeted toxins or other compounds, which act via T cells. The clinical regimen for co-administration of the inventive compound(s) may encompass co-administration at the same time, before or after the administration of the other component. The human binding molecule of the invention may also be modified or derivatized. Corresponding modifications may comprise the use of recombinant DNA technologies to improve the binding specificity, avidity, half life etc of the inventive human binding molecule.

A possible approach to demonstrate the efficacy/activity of the inventive constructs is an in vivo model. A suitable model may be a mouse model. Illustratively, such models may be chosen from mouse models expressing human CD3 and human EpCAM, chimeric mouse models expressing human CD3 and mouse models into which human tumors have been transplanted or tumor cells injected or chimeric mouse models into which human PBMCs have been injected. Preferred models for such assays are nude mice. As detailed herein, the pharmaceutical composition of the invention may be administered to a patient in need of medical intervention (preferably a human patient). The pharmaceutical composition may administered alone or in combination with other medicaments/pharmaceutical compositions. These further medicaments/pharmaceutical compositions may be administered simultaneously or non-simultaneously with the pharmaceutical composition of the invention. Alternatively the present invention relates in a preferred embodiment to a composition, which is a diagnostic composition further comprising, optionally, means and methods for detection.

A further alternative embodiment of the invention relates to the use of a human binding molecule of the invention or as produced by a process of the invention, a nucleic acid molecule of the invention, a vector of the invention or a host of the invention for the preparation of a pharmaceutical composition for the prevention, treatment or amelioration of a proliferative disease, a tumorous disease, an inflammatory disease, an immunological disorder, an autoimmune disease, an infectious disease, viral disease, allergic reactions, parasitic reactions, graft- versus-host diseases or host-versus-graft diseases.

In particular, the pharmaceutical composition of the present invention may be particularly useful in preventing, ameliorating and/or treating cancer, B-cell malignancies, acute myeloid leukaemia, chronic myeloid leukemia, leukemias, arthritis, asthma, allergies or other autoimmune disorders/diseases. The term "immunological disorders" relates to autoimmune diseases, skin diseases, allergic diseases, inflammatory diseases, diabetes, transplant rejections and graft versus host disease, wherein said autoimmune disease is selected from the group consisting of type l diabetes and rheumatoid arthritis. Said skin diseases, may comprise psoriatic lesions, psoriasis, atrophic dermatitis, atopic dermatitis, skin inflammation and the like. Inflammatory disease mentioned hereinabove is selected from the group consisting of inflammatory joint diseases, inflammatory renal diseases, inflammatory bowel diseases. In particular, said inflammatory bowel disease may comprise Morbus Crohn, sarcoidosis, systemic sclerosis, collagenosis, myositis, neuritis. Inflammatory renal diseases may comprise nephritis, glomerulonephritis, lupus nephritis, or IgA nephropathy and inflammatory joint disease may comprise (chronic) arthritis. Said autoimmune disease is selected from the group consisting of Pemphigus vulgaris, Bullous pemphigoid, Goodpasture's syndrome, autoimmune haemolytic anemia (AIHA), rheumatoid arthritis, Systemic Lupus erythematosus, Grave's disease (autoimmune hyperthyroidism), contact dermatitis, Myasthenia gravis, juvenile diabetes, Sjogren's syndrome, autoimmune thyroiditis, primary hypoadrenalism (Addison's disease), thrombocytopenic purpura, Morbus Wegener (granulomatosis), pemphigus foliaceous and celiac disease.

Autoimmune diseases are generally divided into three types: B-cell dominant, T- cell dominant or combinational types. Pathogenic phenotypes of B-cell dominant autoimmune diseases are caused by autoantibodies produced by autoreactive B- cells, while those of the T-cell dominant type are caused by tissue damage mediated by activated T-cells. These T-cells are activated by other cells presenting autoreactive peptide-MHC complexes on their surface. Yet, these distinctions are not perspicuous, since B-cells and T-cells cooperate with and depend on each other in each type of autoimmune disease. Autoimmune diseases are classified as combinatorial when both autoreactive B- and T-cells contribute directly to the pathogenesis observed ("Immunobiology", 4th edt. (1999), Chapter 13 pp 489-536, Janeway, C.A., Travers, P., Walport, M., Capra, J.D. eds and "Harrison's Principles in Internal Medicine" ,14th edt, Fauci, Braunwald, Isselbacher, Wilson, Martin, Kasper, Hauser, Longo, eds). The pathogenic effects of autoreactive B cells are caused by the secreted autoreactive antibodies. Antibody-mediated autoimmune diseases can be differentiated into two major groups based on their immunopathogenic mechanism. The first group comprises autoimmune responses against cell-surface or extracellular matrix antigens, while the second group consists of immune-complex diseases. Examples of the first group of antibody-mediated autoimmune diseases are autoimmune hemolytic anemia, autoimmune thrombocytopenic purpura, myasthenia gravis, Goodpasture's syndrome, immunologically mediated blistering diseases like Pemphigus vulgaris and pemphigus foliaceus, and acute rheumatic fever. Examples of the second group comprise mixed essential cryoglobulinemia, subacute bacterial endocarditis, and several rheumatic autoimmune diseases

Possible indications for administration of the human binding molecule of the invention are tumorous diseases especially epithelial cancers/carcinomas such as mamma carcinoma, colon carcinoma, prostate carcinoma, ovarial carcinoma or lung carcinoma or other tumorous diseases like haematological tumors, glioma, sarcoma or osteosarcoma. Preferably, the constructs of the invention may be administered in non-small cell lung cancer, prostate cancer, adenocarcinoma, squamous and adenocarcinomas of the cervix, breast cancer, squamous cell carcinoma of the head and neck, small cell lung cancer, colorectal and pancreatic carcinoma or colon carcinoma.

Preferably said tumorous disease is epithelial cancer or a minimal residual cancer.

Indications for administration of pharmaceutical compositions of the invention providing to a subject a human binding molecules with specificity for the human CD3 complex and at least one further second target domain are exemplified in table 9.

Table 9: Indications for preferred second target domains

Preferred second target domains Exemplified^disorders/mallgnancies

?Q^D««⁹ SS' n ^Mf ^rr°^W !αvf n ^nt Various B cell malignancies: Various B cell 1988, 3(1 ):31-41; Dorken, Lancet 1974 Dec maiiπnanri*_*,-

14;2(7894):1463) malⁱgnancⁱes.

CD30 (Wahl, Cancer Res 2002,

Hodgkin lymphoma 62(13):3736-42)

CD33 ( aslak, Expert Opin Investig Drugs 2000, 9(6): 1 97-205; Stadtmauer, Curr AML (acute myeloic leukemia) Oncol Rep 2002, 4(5):375-80)

CD33 (Lopez-Karpovitch, Rev Invest Clin

C L (chronic myeloic leukemia) 1997, 49(1):31-6)

CD25 (Dahmoush, Cancer 2002, 96(2): 110- 6; Savoie, Curr Treat Options Oncol 200 , Certain T-cell and B-cell leukemias 2(3):217-24)

CD19 (Issacs, Arthritis Rheum 2001, 44(9):1998-2008), CCR5 (Bruhl, J Immunol Rheumatoid arthritis 2001, 166(4):2420-6), TNF-alpha precursor (Wollheim, Expert Opin Investig Drugs 2002, 11 (7):947-53)

CD19 (Sato, J Immunol 2000, 165(11):6635-43, CCR5 (Zapico, Genes Immun 2000;1(4):288-9), CD30 (Okumura, Autoimmune diseases J Clin Endocrinol Metab 1997, 82(6): 1757- 60)

CCR8 (Owen, Pulm Pharmacol Ther

Asthma 2001 ;14(3):193-202)

IgE (membrane bound) (Lustgarten, Eur J

Allergy Immunol 1995, 25(10):2985-91)

EpCAM (Naundorf, Int J Cancer 2002, 100(1):101-10), EGFR (Liu, Br J Cancer 2000, 82(12):1991-9), CEA (Stewart, Cancer Immunol Immunother 1999, 47(6):299-306 ; Durbin, Proc Nati Acad Sci U S A 1994,91(10):4313-7), TAG-72 (tumor

Pan-carcinoma associated glycoprotein =>sTn antigen) (Kashmiri, Crit Rev Oncol Hematol 2001 , 38(1):3-16), Sonic Hedgehog (Shh) (Lacour, Br J Dermatol 2002, 146 Suppl 61:17-9 ; Tojo, Br J Dermatol 2002, 146(1):69-73)

Her-2 (Arteaga, Semin Oncol 2002, 29(3 Suppl 11):4-10; Wester, Acta Oncol Mamma carcinoma and other carcinomas 2002;41(3):282-8)

EGFR (Bonner, Semin Radiat Oncol 2002, 12 : 11-20 ; Kiyota, Oncology 2002; 63 (1) : 92-8) , CD44v6 related to stage of

Squamous cell carcinoma carcinoma (Rodrigo, Am J Clin Pathol 2002, 118(1):67-72; Fonseca, J Surg Oncol 2001 , 76(2):115-20)

PS A (Fracasso, Prostate 2002, 53(1 ):9- 23), STEAP (Hubert, Proc Nati Acad Sci U S A 1999, 96(25): 14523-8), PSCA (prostate Prostate cancer stem cell antigen) (Jalkut, Curr Opin Urol 2002, 12(5):401-6)

CEA (Stewart, Cancer Immunol Immunother 1999, 47(6) -.299-306 ; Durbin, Proc Nati Acad Sci U S A 1994,

Adenocarcinoma 91(10):4313-7), TAG-72 (tumor associated glycoprotein =>sTn antigen) (Kashmiri, Crit Rev Oncol Hematol 2001, 38(1):3-16),

MUC-1 (mucin) (Couto, Adv Exp Med Biol

Breast cancer 1994;353:55-9) ganglioside GD3 (Brezicka, Lung Cancer SCLC (small cell lung cancer) 2000, 28(1):29-36; Sheperd, Semin Oncol 2001, 28(2 Suppl 4):30-7) mesothelin (Scholler, Proc Nati Acad Sci U S A 1999, 96(20): 11531-6; Brinkmann, Int J Cancer 1997, 71(4):638-44), CA-125 (Hogdall, Anticancer Res 2002, 22(3): 1765- Ovarian cancer 8), Muellerian Inhibitory Substance (MIS) Receptor Type II (Stephen, Clin Cancer Res 2002, 8(8):2640-6)

Ly-6 (Eshel, Int J Cancer 2002, 98(6):803- 10), desmoglein 4 (Tomson, Clin Exp Head and Neck cancer Metastasis 1996, 14(6):501-11)

Lewis-Y (Power, Cancer Immunol

Epithelial cancers immunother 2001, 50(5):241-50)

E-cadherin neoepitope (Becker, Surg

Gastric cancers Oncol 2000, 9(1):5-11)

MUC-1 (mucin) (Hanski, Cancer Res 1993, 53(17):4082-8), Lewis-Y (Flieger, Clin Exp lmmunol 2001, 123(1):9-14; Power, Cancer

Colon carcinoma Immunol Immunother 2001, 50(5) :241-50), A33 antigen (Heath, Proc Nati Acad Sci U S A 1997, 94(2):469-74)

Carbonic anhydrase IX (MN/CA IX)

Renal cell carcinoma (Uemura, Br J Cancer 1999, 81(4)741-6

Carbonic anhydrase IX (MN/CA IX) (Longcaster, Cancer Res 2001, Cervix carcinoma 61(17):6394-9)

Carbonic anhydrase IX (MN/CA IX) (Chia,

Breast carcinoma J Clin Oncol 2001, 19(16):3660-8)

Carbonic anhydrase IX (MN/CA IX)

(Beasley, Cancer Res 2001 , 61 (13):5262-7) Head and neck squamous cell carcinoma

CA19-9 marker (Brockmann, Anticancer

Pancreas carcinoma Res 2000, 20(6D):4941-7)

Fetal AchR (acetylcholine receptor) (Gattenloehner, Am J Pathol 1998, Rhabdomyosarcoma 152(2):437-44)

EGFR (Kuan, Brain Tumor Pathol

Glioma 2000;17(2):71-8)

Wue-1 Plasma cell antigen (Greiner,

Multiple Myeloma Virchows Arch 2000, 437(4):372-9) ganglioside GD3 (Dippold, Cancer Res 1984, 44(2):806-10; Scott, J Clin Oncol Melanoma 2001 ,19(19):3976-87), MCSP (melanoma chondroitin sulfate proteoglycan) (Pluschke, Proc Nati Acad Sci U S A 1996, 93(18):9710-5; Geiser, Cancer Res 1999, 59(4):905-10)

CD44v6 (Rodrigo, Am J Clin Pathol 2002,

118(1):67-72; Fonseca, J Surg Oncol 2001 , Metastatic disease

76(2): 115-20)

CD20 (Chu, 2002, Leuk. Lymphoma 43, ,_, . . . , . _ . „

23335-23337₎ Non-Hodgkin's lymphoma

It is envisaged by the present invention that the human binding molecules, nucleic acid molecules and vectors of the invention are administered either alone or in any combination using standard vectors and/or gene delivery systems, and optionally together with a pharmaceutically acceptable carrier or excipient. Subsequent to administration, said nucleic acid molecules or vectors may be stably integrated into the genome of the subject.

On the other hand, viral vectors may be used which are specific for certain cells or tissues and persist in said cells. Suitable pharmaceutical carriers and excipients are well known in the art. The pharmaceutical compositions prepared according to the invention can be used for the prevention or treatment or delaying the above identified diseases.

Furthermore, it is possible to use a pharmaceutical composition of the invention which comprises nucleic acid molecules or vectors of the invention in gene therapy. Suitable gene delivery systems may include liposomes, receptor-mediated delivery systems, naked DNA, and viral vectors such as herpes viruses, retroviruses, adenoviruses, and adeno-associated viruses, among others. Delivery of nucleic acids to a specific site in the body for gene therapy may also be accomplished using a biolistic delivery system, such as that described by Williams (Proc. Nati. Acad. Sci. USA 88 (1991), 2726-2729). Further methods for the delivery of nucleic acids comprise particle-mediated gene transfer as, e.g., described in Verma, Gene Ther.15 (1998), 692-699.

Furthermore the invention relates to a method for the prevention, treatment or amelioration of a proliferative disease, a tumorous disease, an inflammatory disease, an immunological disorder, an autoimmune disease, an infectious disease, viral disease, allergic reactions, parasitic reactions, graft-versus-host diseases or host-versus-graft diseases in a subject in the need thereof, said method comprising the step of administration of an effective amount of a human binding molecule of the invention or as produced by a process of the invention, a nucleic acid molecule of the invention, a vector of the invention or a host of the invention.

Preferably said subject is a human.

The method for the prevention, treatment or amelioration of the invention may comprise the co-administration of an above defined proteinaceous compound capable of an activation signal for immune effector cells to the subject. The co- administration may be a simultaneous co-administration or a non-simultaneous co- administration.

Finally, the present invention relates to a kit comprising a human binding molecule of the invention or as produced by a process of the invention, a nucleic acid molecule of the invention, a vector of the invention or a host of the invention. It is also envisaged that the kit of this invention comprises a pharmaceutical composition as described herein above, either alone or in combination with further medicaments to be administered to a patient in need of medical treatment or intervention.

The Figures show:

Throughout the following figure legends as well as the appended examples, the abbreviation "Hu" shall denote "Human".

Fig. 1: DNA and protein sequences of the mouse C kappa domain with a C- terminally attached His6-tag. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The relevant restriction sites for cloning this DNA-fragment into a translational fusion protein with scFvs are shown (BsiWI, Notl). Fig. 2: CD3-specific ELISA-analysis of periplasmic preparations containing scFv protein fragments from the selection of huLIB-ST (phage pool 1). Periplasmic preparations of soluble scFv protein fragments were added to wells of an ELISA- plate, which had been coated with a soluble recombinant CD3-epsilon antigen. Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using a biotinylated anti-mouse kappa antibody (Southern Biotech, 1 μg/ml PBS) detected with horseradish peroxidase-conjugated avidine (Dako, 1 μg/ml PBS). The ELISA was developed by an ABTS (2,2'-Azino- di[3-ethylbenzthiazoline sulfonate (6)] diammonium salt )-substrate solution as described in Example 3. The OD-values (y axis) were measured at 405 nm by an ELISA reader. Clone numbers are presented on the x axis, where the first number of the clone number indicates the round of panning in which the respective clone was obtained, while the second number indicates the respective clone of this round.

Fig. 3: CD3-specific ELISA-analysis of periplasmic preparations containing scFv protein fragments from the selection of huLIB-ST (phage pool 2). Periplasmic preparations of soluble scFv protein fragments were added to wells of an ELISA- plate that had been coated with soluble recombinant CD3-epsilon antigen. Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using a biotinylated anti-mouse kappa antibody (Southern Biotech, 1 μg/ml PBS) detected with horseradish peroxidase-conjugated avidine (Dako, 1 μg/ml PBS). The ELISA was developed by an ABTS-substrate solution as described in example 3. The OD-values (Y-axis) were measured at 405 nm by an ELISA-reader. Clone numbers are presented on the X-axis, where the first number of the clone number indicates the round of panning in which the respective clone was obtained, while the second number indicates the respective clone of this round.

Fig. 4: CD3-specific ELISA-analysis of periplasmic preparations containing scFv protein fragments from the selection of huLIB-STE (phage pool 3). Periplasmic preparations of soluble scFv protein fragments were added to wells of an ELISA- plate that had been coated with soluble recombinant CD3-epsilon antigen. Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using a biotinylated anti-mouse kappa antibody (Southern Biotech, 1 μg/ml PBS) detected with horseradish peroxidase-conjugated avidine (Dako, 1 μg/ml PBS). The ELISA was developed by an ABTS-substrate solution as described in Example 3. The OD-values (Y-axis) were measured at 405 nm by an ELISA-reader. Clone numbers are presented on the X-axis, where the first number of the clone number indicates the round of panning in which the respective clone was obtained, while the second number indicates the respective clone of this round.

Fig. 5: CD3-specific ELISA-analysis of periplasmic preparations containing scFv protein fragments from the selection of huLIB-STE (phage pool 4). Periplasmic preparations of soluble scFv protein fragments were added to wells of an ELISA- plate that had been coated with soluble recombinant CD3-epsilon antigen.

Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using an anti-Flag-tag antibody (M2 Sigma 1 μg/ml PBS) detected with horseradish peroxidase-conjugated polyclonal anti-mouse antibody (Dako 1 μg/ml PBS). The ELISA was developed by an ABTS-substrate solution as described in Example 3. The OD-values (Y-axis) were measured at 405 nm by an ELISA-reader. Clone numbers are presented on the X-axis, where the first number of the clone number indicates the round of panning in which the respective clone was obtained, while the second number indicates the respective clone of this round.

Fig. 6: DNA and protein sequences of the human scFv fragment 3-106. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 375 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 421 and ends at nt 741. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 7: DNA and protein sequences of the human scFv fragment 3-114. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 366 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 412 and ends at nt 732. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 8: DNA and protein sequences of the human scFv fragment 3-148. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 360 followed by a (G₄Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 406 and ends at nt 726. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 9: DNA and protein sequences of the human scFv fragment 3-190. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 378 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 424 and ends at nt 744. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs). Fig. 10: DNA and protein sequences of the human scFv fragment 3-271. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 357 followed by a (G₄Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 403 and ends at nt 723. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 11: DNA and protein sequences of the human scFv fragment 3-550. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 381 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 427 and ends at nt 750. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 12: DNA and protein sequence of the human scFv fragment 4-10. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 363 followed by a (G4Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 409 and ends at nt 729. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 13: DNA and protein sequence of the human scFv fragment 4-48. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 369 followed by a (G₄Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 415 and ends at nt 753. Complementarity determining regions (CDRs) are indicated by boxes surrounding the relevant nt and aa positions (according to the Kabat definition for CDRs).

Fig. 14: CD3-specific ELISA-analysis of periplasmic preparations containing Flag- tagged scFv protein fragments from selected clones. Periplasmic preparations of soluble scFv protein fragments were added to wells of an ELISA-plate, which had been coated with soluble recombinant CD3-epsilon antigen and had been additionally blocked with PBS 3 % BSA. Detection was performed by a monoclonal anti-Flag antibody followed by a peroxidase-conjugated polyclonal goat anti-mouse antibody. The ELISA was developed by an ABTS-substrate solution as described in Example 3. The OD-values (Y-axis) were measured at 405 nm by an ELISA- reader. Clone numbers are presented on the X-axis, where the first number of the clone number indicates the round of panning in which the respective clone was obtained, while the second number indicates the respective clone of this round. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1, SP34 and OKT3 (concentration of each 1 μg/ml).

Fig. 15: ELISA-analysis of periplasmic preparations containing Flag-tagged scFv protein fragments from selected clones. The same periplasmic preparations of soluble scFv protein fragments as in Fig. 14 were added to wells of an ELISA-plate that had not been coated with soluble recombinant CD3-epsiIon antigen but rather only blocked with PBS 3 % BSA. Detection was performed by a monoclonal anti- Flag antibody followed by a peroxidase-conjugated polyclonal goat anti-mouse antibody. The ELISA was developed by an ABTS-substrate solution as described in example 3. The OD-values (Y-axis) were measured at 405 nm by an ELISA- reader. Clone numbers are presented on the X-axis, where the first number of the clone number indicates the round of panning in which the respective clone was obtained, while the second number indicates the respective clone of this round. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1, SP34 and OKT3 (concentration of each 1 μg/ml).

Fig. 16: Flow cytometric analysis of periplasmic preparations containing Flag- tagged scFv protein fragments from selected clones (4-10, 4-48, 3-550, 3-106, 3- 114, 3-148, 3-190, 3-271). Periplasmic preparations of soluble scFv protein fragments were added to CD3-positive Jurkat cells. Detection was performed by a monoclonal anti-Flag antibody followed by a PE-labeled polyclonal anti-mouse antibody. ScFvs binding to cells was measured by an increase in fluorescence intensity as compared to cells that were incubated with PBS alone. Fluorescence intensity is blotted on the X-axis, the number of events is blotted on the Y-axis. The negative control is shown in black, the respective scFvs are shown in gray. Shifting to the right indicates positive binding to the cells. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1, SP34 and OKT3 (concentration of each 5 μg/ml).

Fig. 17: Flow cytometric analysis of periplasmic preparations containing Flag- tagged scFv protein fragments from selected clones (3-106, 3-114, 3-148, 3-190,

3-271, 3-550, 4-10, 4-48). Periplasmic preparations of soluble scFv protein fragments were added to CD3-negative CHO cells. Detection was performed by a monoclonal anti-Flag antibody followed by a PE-labeled polyclonal anti-mouse antibody. Binding of scFv constructs to cells was measured by an increase in fluorescence intensity as compared to cells that were incubated with PBS alone.

Fluorescence intensity is blotted on the X-axis, the number of events is blotted on the Y-axis. The negative control is shown in black, the respective scFvs are shown in gray. Shifting to the right indicates positive binding to the cells. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1 , SP34 and OKT3 (concentration of each 5 μg/ml). Fig. 18: Flow cytometric analysis of periplasmic preparations containing Flag- tagged scFv protein fragments from selected clones (3-106, 3-114, 3-148, 3-190, 3-271, 3-550, 4-10, 4-48). Periplasmic preparations of soluble scFv protein fragments were added to CD3-negative Katolll cells. Detection was performed by a monoclonal anti-Flag antibody followed by a PE-labeled polyclonal anti-mouse antibody. Binding of scFv constructs to cells was measured by an increase in fluorescence intensity as compared to cells that were incubated with PBS alone. Fluorescence intensity is blotted on the X-axis, the number of events is blotted on the Y-axis. The negative control is shown in black, the respective scFvs are shown in gray. Shifting to the right indicates positive binding to the cells. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1, SP34 and OKT3 (concentration of each 5 μg/ml).

Fig. 19: Flow cytometric analysis of periplasmic preparations containing Flag- tagged 3-271 scFv protein fragments from selected clones. Periplasmic preparation of soluble 3-271 scFv protein fragments was added to CD3-positive Jurkat cells. Detection was performed by a monoclonal anti-Flag antibody followed by a PE-labeled polyclonal anti-mouse antibody. Binding of scFv constructs to cells was measured by an increase in fluorescence intensity as compared to cells that were incubated with PBS alone. Fluorescence intensity is blotted on the X-axis, the number of events is blotted on the Y-axis. The negative control is shown in black, the respective scFvs are shown in gray. Shifting to the right indicates positive binding to the cells. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1 , SP34 and OKT3 (concentrations of each 5 μg/ml).

Fig. 20: Flow cytometric analysis of periplasmic preparations containing Flag- tagged 3-271 scFv protein fragments from selected clones. Periplasmic preparations of soluble 3-271 scFv protein fragments was added to CD3-negative CHO cells. Detection was performed by a monoclonal anti-Flag antibody followed by a PE-labeled polyclonal anti-mouse antibody. ScFvs binding to cells was measured by an increase in fluorescence intensity as compared to cells that were incubated with PBS alone. Fluorescence intensity is blotted on the X-axis, the number of events is blotted on the Y-axis. The negative control is shown in black, the respective scFvs are shown in grey. Shifting to the right indicated positive binding to the cells. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1 , SP34 and OKT3 (concentration of each 5 μg/ml).

Fig. 21: Flow cytometric analysis of periplasmic preparations containing Flag- tagged 3-271 scFv protein fragments from selected clones. Periplasmic preparation of soluble 3-271 scFv protein fragments was added to CD3-epsilon and -gamma cotransfected CHO cells. Detection was performed by a monoclonal anti-Flag antibody followed by a PE-labeled polyclonal anti-mouse antibody. ScFvs binding to cells were measured by an increase in fluorescence intensity as compared to cells that were incubated with PBS alone. Fluorescence intensity is blotted on the X-axis, the number of events is blotted on the Y-axis. The negative control is shown in black, the respective scFvs are shown in grey. Shifting to the right indicates positive binding to the cells. Periplasmic preparation from cells producing the anti-CD3 scFv L2K was included, as well as the purified anti-CD3 antibodies UCHT1 , SP34 and OKT3 (concentration of each 5 μg/ml).

Fig. 22: DNA and protein sequences of the anti-EpCAM scFv fragment 5-10. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 360 followed by a (G₄Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 406 and ends at nt 744.

Fig. 23: DNA and protein sequences of the anti-CD19 scFv fragment. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 372 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 418 and ends at nt 750.

Fig. 24: DNA and protein sequences of the anti-CD20 scFv fragment. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 366 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 412 and ends at nt 729.

Fig. 25: DNA and protein sequences of the anti-CCR5 scFv fragment. Numbers indicate the nucleotide (nt) positions, amino acids (aa) are presented in single letter code. The coding region of the DNA sequence for the V-region of the heavy chain starts at nt 1 and ends at nt 354 followed by a (G Sι)₃-linker. The coding region of the DNA sequence for the V-region of the kappa (light) chain starts at nt 399 and ends at nt 732.

Fig. 26: Cytotoxic activity of the bispecific antibody biscFv anti-CD3 3-190 x anti- CD19 as measured by fluorochrome release. Purified bispecific scFv ("biscFv") 3- 190 x anti-CD19 P2 (protein fraction 2 from gel filtration) was evaluated using CD19 positive fluorochrome-labeled NALM6 cells as target cells and CD3-positive CB15 T cells as effector cells (E:T ratio of 1:10). biscFv 3-190 x anti-CD19 P2 was diluted in RPMI/10% FCS in a dilution series and 50 μl of the respective solution were added to the cell suspension. The same dilution series was performed using PBS as negative control, starting with the same volume as for biscFv 3-190 x anti- CD19 P2. After lysis of target cells, the dye released into the incubation medium was quantitated in a fluorescence reader and compared with the fluorescence signal from a control reaction (without bispecific antibody), and the fluorescence signal was obtained for totally lysed cells. Specific cytotoxicity was calculated according to the following formula: [Fluorescence (Sample) - Fluorescence (Control)] : [Fluorescence (Total Lysis)- Fluorescence (Control)] x 100, wherein ":" denotes mathematical division. Concentrations are plotted on the X-axis, % specific toxicity on the Y-axis.

Fig. 27: Cytotoxic activity of the bispecific antibodies anti-CD3 3-271 x 5-10 anti- EpCAM, 5-10 anti-EpCAM x anti-CD3 3-148 and 5-^0 anti-EpCAM x anti-CD3 3- 190 measured by fluorochrome release. For this experiment anti-CD3 3-271 x 5-10 anti-EpCAM P2 (protein fraction 2 from gel filtration), anti-CD3 3-271 x 5-10 anti- EpCAM P3 (protein fraction 3 from gelfiltration), 5-10 anti-EpCAM x anti-CD3 3-148 (main protein fraction from gelfiltration) and 5-10 anti-EpCAM x anti-CD3 3-190 P3 (protein fraction 3 from gelfiltration) were used with EpCAM-transfected CHO and non-transfected cells as target cells and CD3-positive CB15 T cells as effector cells (E:T ratio of 1:5). Anti-CD3 3-190 x anti-CD19 P2 (protein fraction 2 from gelfiltration) was included as an appropriate negative control for CD19-negative CHO-EpCAM cells. M79, an anti-EpCAM x anti-CD3 biscFv construct was used as a positive control. Untransfected CHO as well as CHO-EpCAM were labeled with PKH26. Antibody constructs were diluted in RPMI/10% FCS and added to the cell suspension. After 16 h propidium iodide (PI) was added and the cells were analyzed by flow cytometry. Cytotoxicity was measured as the ratio of PI positive cells over all target cells. The biscFv constructs are plotted on the X-axis according to the respective concentrations used for each construct, and the % specific cytotoxicity is plotted on the Y-axis.

The invention will now be described by reference to the following biological examples which are merely illustrative and are not to be construed as a limitation of scope of the present invention.

Example 1: Procurement of the extracellular domain of the human CD3- epsilon chain for use as selection antigen in phage display 1.1. Cloning of the extracellular domain of the human CD3 epsilon chain: cDNA was isolated from human peripheral blood mononuclear cells. Preparation of the cells was performed according to standard protocols (Current Protocols in Immunology (Coligan, Kruisbeek, Margulies, Shevach and Strober, John Wiley & Sons, Inc., USA, 2002)). The isolation of total RNA and cDNA synthesis by random-primed reverse transcription was performed according to standard protocols (Sambrock, Molecular Cloning; Laboratory Manual, 2nd edition, Cold Spring Harbor laboratory Press, Cold Spring Harbor, New York (1989)). PCR was used to amplify the coding sequence of the extracellular domain of the human CD3 epsilon chain. The primers used in the PCR were designed so as to introduce restriction sites at the beginning and the end of the cDNA coding for the extracellular portion of the human CD3 epsilon chain (SEQ ID NO: 137 and SEQ ID NO: 138). The introduced restriction sites, BsrGI and BspEI, were utilised in the following cloning procedures. The PCR product was then cloned via BsrGI and BspEI into a plasmid designated BS-Fss-Lsp derived from the Bluescript KS⁺ cloning vector (Stratagene Europe, Amsterdam-Zuiddoost, the Netherlands) following standard protocols. (The vector was generated by cloning a DNA fragment (SEQ ID NO: 139) via EcoRI and Sail into Bluescript KS⁺.) The sequence of different clones was determined by sequencing according to standard protocols. By cloning into BS-Fss-Lsp the coding sequence of a murine immunoglobulin heavy chain leader peptide was fused in-frame to the 5' end of the coding sequence for the extracellular portion of the human CD3 epsilon chain. The cDNA was then cloned via EcoRI and BspEI into another plasmid designated as BSCTI to attach a sequence to the C-terminus, coding for a polyhistidine tag of six consecutive histidine residues followed by a stop codon (BSCTI is described in Kufer, Cancer Immunity 1 (2001), 10). In this step the BspEI site of the cDNA was fused into an Xmal site of the plasmid thereby destroying both sites. All cloning steps were designed so as to generate an intact reading frame for the construct. The plasmid now contained a sequence coding for a protein comprising a murine immunoglobulin heavy chain leader peptide, to allow for secreted expression, followed by the extracellular domain of the human CD3 epsilon chain followed by a polyhistidine tag of six consecutive histidine residues, to allow for purification and detection via the polyhistidine tag (SEQ ID NO: 140 and SEQ ID NO: 141). This sequence was then cloned into the plasmid pFastBad™ (Invitrogen GmbH, Karlsruhe, FRG) via EcoRI and Sail.

1.2. Expression of the extracellular domain of the human CD3 epsilon chain in High Five™ cells, purification of the recombinant protein

Expression of the extracellular domain of the human CD3 epsilon chain in High Five™ cells was performed using the Bac-to-Bac^® Baculovirus Expression System (Invitrogen GmbH, Karlsruhe, FRG) according to the specifications of the manufacturer. 10 litres of supernatant in batches of 500 ml were produced. The construct was then purified out of the culture supernatant. Purification was performed as a two-step purification. First the diluted supernatants were loaded on ion exchange columns. The fractionated eluate was tested in an ELISA assay. To this end, an anti-human CD3 epsilon antibody (UCHT1 BD biosciences, Heidelberg, FRG) was coated (50 μl at 5 μg/ml in PBS) on a Maxisorp ELISA plate (Nunc GmbH, Wiesbaden, FRG) overnight Unspecific binding was blocked with 1.5 % BSA in PBS for 1 hour. All prior and subsequent washing steps were performed three times with 200 μl PBS. Afterwards, eluate fractions were incubated for 1 hour in the prepared cavities of the plate. Detection of the recombinant protein was performed with a horseradish peroxidase conjugated anti- His antibody (Roche Diagnostics GmbH, Mannheim, FRG; 50 μl of antibody diluted 1 :500 in 1.5 % BSA in PBS). Development of the ELISA was performed with ABTS (2,2'-Azino-bis(3-Ethylbenz-Thiazolin)-6-Sulfonic acid) Roche Diagnostics GmbH, Mannheim, FRG) according to the specifications of the manufacturer. Positive fractions were further purified over a cobalt-chelate column which preferentially binds histidine-tagged proteins. Eluate fractions were tested using the described ELISA assay. Positive fractions were pooled and concentrated. Example 2: Construction of the combinatorial antibody library and phage display

2.1. Isolation of RNA from selected IgD-positive B-cells

100 ml blood were taken from five healthy human donors. Peripheral blood mononuclear cells (PBMCs) were isolated by a ficoll-gradient according to standard methods. To select IgD-positive cells, 1 ml anti-mouse IgG-beads (CELLection™ Pan Mouse IgG Kit; DYNAL) were coated with 20 μg mouse anti- human IgD-antibody (PharMingen). Approximately 2.5 x 10 ⁷ PBMCs were added to the beads and incubated at 4°C for 15 minutes. After washing four times with 1 ml RPMI-medium (BioChrom) IgD-positive cells were released from the beads by adding 8 μl release buffer (DNase) and transferred to a fresh tube. By this method 0.9 x 10⁵to 3.7 x 10⁶ IgD-positive cells could be obtained. Total RNA was isolated from IgD-positive cells using the RNeasy® Midi Kit (QIAGEN) following the manufacturers instructions. cDNA was synthesized according to standard methods (Sambrook, Cold Spring Harbor Laboratory Press 1989, Second Edition).

2.2. Isolation of RNA from PBMCs

100 ml blood from five healthy donors were taken, PBMCs were separated using a ficoll-gradient and total RNA was isolated from approximately 2.5 x 10⁷ cells with the RNeasy® Midi Kit (QIAGEN) following the manufactures instructions. cDNA was synthesized according to standard methods (Sambrook, Cold Spring Harbor Laboratory Press 1989, Second Edition).

2.3. PCR-Amplification of variable regions (V-regions)

For the isolation of light chain V-region DNA, RT-PCR was carried out using V- kappa- (5'-huVK1-Sac-2001 (SEQ ID NO: 150), 5'-huVK2/4-Sac-2001 (SEQ ID NO: 152), 5'-huVK3-Sac-2001 (SEQ ID NO: 151), 5'-huVK5-Sac-2001 (SEQ ID NO: 153), 5'-huVK6-Sac-2001 (SEQ ID NO: 154), 3'-hu-Vk-J1-Spel-BsiWI (SEQ ID NO: 155), 3'-hu-Vk-J2/4-Spel-BsiWI (SEQ ID NO: 156), 3'-hu-Vk-J3-Spel-BsiWI (SEQ ID NO: 157), 3'-hu-Vk-J5-Spel-BsiWI (SEQ ID NO: 158) and V-lambda- specific (5'-huVL1a-Sacl-2001 (SEQ ID NO: 159), 5'-huVL1b-Sacl-2001 (SEQ ID NO: 160), 5'-huVL2-Sacl-2001 (SEQ ID NO: 161), 5'-huVL4-Sacl-2001 (SEQ ID NO: 162), 5'-huVL5-Sacl-2001 (SEQ ID NO: 163), 5'-huVL6-Sacl-2001 (SEQ ID NO: 164), 5'-huVL3/9-Sacl-2001 (SEQ ID NO: 165), 5'-huVL7/8-Sacl-2001 (SEQ ID NO: 166), 3'-hu-Vlam-Blnl-SpeI-2001 (SEQ ID NO: 167), 3'-hu-Vlam2-Blnl-Spel- 2002 (SEQ ID NO: 168) primer sets. RNA from IgD positive B-cells was transcribed into cDNA (as described before) and used as template DNA in PCR reactions. Per PCR reaction, one 5'-primer was combined with one 3'-primer, wherein the 5'- kappa primer was combined with the 3'-kappa primer and the 5'-lambda primer was combined with the 3'-lambda primer. The number of different PCR reactions was determined by the number of possible combinations of 5'- and 3'-primers. The following PCR-program was used for amplification: Denaturation at 94°C for 15 seconds, primer annealing at 52°C for 50 seconds and primer extension at 72°C for 90 seconds were performed over 40 cycles, followed by final extension at 72°C for 10 minutes. Light chain DNA V-fragments were then isolated according to standard protocols. For the isolation of VH-regions, RT-PCR was carried out in two steps. First, the heavy chain Fd-fragments of IgD were PCR-amplified using a 5'-VH-specific primer set (5'-huVH1 ,3,5-Xhol-2001 (SEQ ID NO: 142), 5'-huVH2-Xhol-2001 (SEQ ID NO: 143), 5'-huVH4-Xhol-2001 (SEQ ID NO: 144), 5'-huVH4B-Xhol-2001 (SEQ ID NO: 145), 5'-huVH6-Xhol-2001 (SEQ ID NO: 146)) and a 3'-specific IgD-primer (3'-CD1 (SEQ ID NO: 147)). cDNA transcribed from RNA isolated from unselected PBMCs (as described before) was used as template. Per PCR reaction, one 5'-primer was combined with the 3'-primer; the number of different PCR reactions was determined by the number of possible combinations of 5'- and the 3'-primer. The following PCR-programm was used for amplification: Denaturation at 94°C for 15 seconds, primer annealing at 52°C for 50 seconds and primer extension at 72°C for 90 seconds was performed over 40 cycles, followed by final extension at 72°C for 10 minutes.

These IgD-Fd DNA-fragments were then used as templates in a second PCR reaction using again the 5'VH-specific primer set and a set of two 3'-VH-specific primers (3'-hu-VH-BstEI 1-2001 (SEQ ID NO: 148), 3'-hu-VH-J3-BstEI 1-2001 (SEQ ID NO: 149)). Per PCR reaction, one 5'-primer was combined with one 3'-primer; the number of different PCR reactions was determined by the number of possible combinations of 5'- and 3'-primers.

The following PCR-program was used for the second step: Denaturation at 94°C for 15 seconds, primer annealing at 52°C for 50 seconds and primer extension at 72°C for 90 seconds was performed over 40 cycles, followed by final extension at 72°C for 10 minutes. Heavy chain DNA-fragments were then isolated according to standard protocols. 2.4. Library construction

A phage display library was generally constructed based on standard procedures, as for example disclosed in "Phage Display: A Laboratory Manual"; Ed. Barbas, Burton, Scott & Silverman; Cold Spring Harbor Laboratory Press, 2001.

The primers chosen for PCR amplification gave rise to a 5'- Xhol and a 3'-BstEII recognition site for the heavy chain V-fragments and to a 5'-Sacl and a 3'- Spel recognition site for light chain V-fragments. In two parallel reactions each 400 ng of the kappa light chain fragments (Sacl-Spel digested) were ligated with 1400 ng of the phagemid pComb3H5BHis (Sacl-Spel digested; large fragment, vector described in WO 99/25818). The two resulting antibody V-light chain libraries were then each transformed into 300 μl of electrocompetent Escherichia coli XL1 Blue by electroporation (2.5 kV, 0.2 cm gap cuvette, 25 FD, 200 Ohm, Biorad gene-pulser) resulting in a library size of 1.8 x 10⁸ independent clones in total.

Kappa (light chain) DNA-fragments from the different PCR amplifications were weighted for each ligation as follows: Each 5'-primer defines a specific group. Within these groups the 3'-primers define the subgroups. The subgroups were weighted 1 :2:1:1 corresponding to the primers 3'-hu-Vk-J1-Spel-BsiWI : 3'-hu-Vk- J2/4-Spel-BsiWI : 3'-hu-Vk-J3-Spel-BsiWI : 3'-hu-Vk-J5-Spel-BsiWI . The groups were weighted according to their germline distribution 1:1:1:0.2:0.2 corresponding to the primers 5'-huVK1-Sac-2001 : 5'-huVK3-Sac-2001 : 5'-huVK2/4-Sac- 2001 : 5'-huVK5-Sac-2001 : 5'-huVK6-Sac-2001.

As described for the kappa DNA fragments, two parallel ligation reactions were carried out, each containing 400 ng of the lambda light chain fragments (Sacl-Spel digested) and 1400 ng of the phagemid pComb3H5BHis (Sacl-Spel digested). The two resulting antibody V-light chain libraries were then each transformed into 300 μl of electrocompetent Escherichia coli XL1 Blue by electroporation (2.5 kV, 0.2 cm gap cuvette, 25 FD, 200 Ohm, Biorad gene-pulser) resulting in a library size of 2.3 x 10⁸ independent clones in total.

Lambda DNA-fragments from the different PCR amplifications were weighted for each ligation as follows: Each 5'-primer defines a specific group. Within these groups the 3'-primers define the subgroups. The subgroups were weighted 3:1 corresponding to the primers 3'-hu-Vlam-Blnl-Spel-2001 : 3'-hu-Vlam2-Blnl-Spel- 2002. The groups were weighted according to their germline distribution 1:1:2:3:1:1:1:1 corresponding to the primers 5'-huVL1a-Sacl-2001 : 5'-huVL1b- Sacl-2001 : 5'-huVL2-Sacl-2001 : 5'-huVL3/9-Sacl-2001 : 5'-huVL4-Sacl-2001 : 5'- huVL5-Sacl-2001 : 5'-huVL6-Sacl-2001 : 5'-huVL7/8-Sacl-2001. Heavy chain DNA fragments were first subcloned into pBluescript KS vector (Stratagene). To this end, eight times 400 ng of VH fragments (Xhol-BstEII digested) were each ligated with 1200 ng pBluescript KS (Xhol-BstEII digested) and transformed into electrocompetent E. coli XL1 Blue by electroporation as described for the light chains resulting in a library of 1.4 x 10⁹ independent clones in total. Heavy chain DNA-fragments from the different PCR amplifications were weighted for each ligation as follows: Each δ'-primer defines a specific group. Within these groups the 3'-primers define the subgroups. The subgroups were weighted 3:1 corresponding to the primers 3'-hu-VH-BstEI 1-2001 : 3'-hu-VH-J3-BstEII. The groups were weighted according to their germline distribution 7:1:1:1:0.3 corresponding to the primers 5'-huVH1 ,3,5-Xhol-2001 : 5'-huVH2-Xhol-2001 : 5'- huVH4-Xhol-2001 : 5'-huVH4B-Xhol-2001 : 5'-huVH6-Xhol-2001. After electroporation each assay was incubated in SOC for phenotype expression. The different cultures were then separately incubated in 500 ml of SB selection medium containing 50 μg/ml Carbeniciliin and 2 % v/v Glucose overnight. The next day, cells of each culture were harvested by centrifugation and plasmid preparation of each culture was carried out using a commercially available plasmid preparation kit (Qiagen).

2.5. Construction of the combinatorial antibody library huLIB-ST

3600 ng of this plasmid-DNA containing the VK-library (Sall-BstEII digested; large fragment) were ligated with 1200 ng of the heavy chain V-fragments (Xhol-BstEII digested, pooled in equal amounts from restriction of the eight different pBluescript/VH-plasmid preparations) and again transformed into three 300 μl aliquots of electrocompetent E. coli XL1 Blue by electroporation (2.5 kV, 0.2 cm gap cuvette, 25 FD, 200 Ohm) resulting in a total VH-VK scFv (single chain variable fragment) library size of 5.4 x 10⁸ independent clones. 3600 ng of this plasmid-DNA containing the Vlambda-library (Sall-BstEII digested; large fragment) were ligated with 1200 ng of the heavy chain V-fragments (Xhol- BstEII digested, pooled in equal amounts from restriction of the eight different pBluescript/VH-plasmid preparations) and again transformed into three 300 μl aliquots of electrocompetent E. coli XL1 Blue by electroporation (2.5 kV, 0.2 cm gap cuvette, 25 FD, 200 Ohm) resulting in a total VH-Vlambda scFv library size of 4.1 x 10⁸ independent clones.

After phenotype expression and slow adaption to Carbeniciilin one third of the overall kappa library and one third of the overall lambda library were each transferred into SB-Carbenicillin (50 μg/ml) selection medium; the rest was used for expansion and long term storage of the library. The Vkappa/VH-library and the Vlambda/VH-library were then infected with an infectious dose of 1 x 10¹² particles of helper phage VCSM13 resulting in the production and secretion of filamentous M13 phage, wherein each phage particle contained single stranded pComb3H5BHis-DNA encoding a human scFv-fragment and displayed the corresponding scFv-protein as a translational fusion to phage coat protein III.

2.6. Construction of the combinatorial antibody library huLIB-STE

6 μg of this plasmid-DNA containing the VK-library (Xhol-BstEII digested; large fragment) were ligated with 2000 ng of the heavy chain V-fragments (Xhol-BstEII digested, pooled in equal amounts from restriction of the eight different pBluescript/VH-plasmid preparations) and again transformed into five 300 μl aliquots of electrocompetent E. coli XL1 Blue by electroporation (2.5 kV, 0.2 cm gap cuvette, 25 FD, 200 Ohm) resulting in a total VH-VK scFv (single chain variable fragment) library size of 4.3 x 10⁹ independent clones. 6 μg of the plasmid-DNA containing the Vlambda-library (Xhol-BstEII digested; large fragment) were ligated with 2 μg of the heavy chain V-fragments (Xhol-BstEII digested, pooled in equal amounts from restriction of the eight different pBluescriptA/H-plasmid preparations) and again transformed into five 300 μl aliquots of electrocompetent E. coli XL1 Blue by electroporation (2.5 kV, 0.2 cm gap cuvette, 25 FD, 200 Ohm) resulting in a total VH-Vlambda scFv (single chain variable fragment) library size of 4.6 x 10⁹ independent clones. After phenotype expression and slow adaption to Carbenicillin one third of the overall kappa library and one third of the overall lambda library were each transferred into SB-Carbenicillin (50 μg/ml) selection medium; the rest was used for expansion and long term storage of the library. The Vkappa/VH-library and the Vlambda/VH-library were then infected with an infectious dose of 1 x 10¹² particles of helper phage VCSM13 resulting in the production and secretion of filamentous M13 phage, wherein each phage particle contained single stranded pComb3H5BHis-DNA encoding a human scFv-fragment and displayed the corresponding scFv-protein with the N2 domain on the phage surface as a translational fusion to phage coat protein III. 2.7. Selections

Phage libraries huLIB-ST (kappa and lambda) and huLIB-STE (kappa and lambda) carrying the cloned scFv-repertoire were each harvested from the culture supernatant by PEG8000/NaCI precipitation and centrifugation. 2.7.1. Selections with huLIB-ST For huLIB-ST approximately 1 x 10¹¹ to 1 x 10¹² kappa phages and roughly the same amount of lambda phages were each resuspended in 150 μl of TBS/1 % BSA and then pooled (= phage pool 1). For phage pool 2, approximately 1 x 10¹⁰ to 1 x 10¹¹ kappa phages and roughly the same amount of lambda phages were each resuspended in 150 μl of PBS/10% FCS and then pooled. Selection on recombinant antigen (huLIB-ST phage pool 1) huLIB-ST phage pool 1 was incubated with recombinant soluble human CD3 epsilon immobilized on 96 well ELISA plates. Recombinant soluble human CD3 epsilon was prepared as described in Example 1. Human CD3-epsilon normally exists in the TCR/CD3 complex as a dimer together with either the gamma or the delta subunit of the same complex. Upon dimerization with either CD3-gamma or CD3-delta, CD3-epsilon undergoes a conformational change.

The conformation of recombinant, soluble CD3-epsilon differs significantly from its native conformation in the CD3 complex (Kastrup, Scand. J. Immunol. 56 (2002), 436-42) and therefore is not significantly bound by most existing anti-CD3 antibodies (note the low ELISA signals of OKT3, SP34 and UCHT1 in binding to soluble, recombinant CD3-epsilon in Figure 14). scFv phage that did not specifically bind to the target antigen were eliminated by up to ten washing steps with TBS/Tween. Binding entities were eluted by using HCI-Glycine pH 2.2 and after neutralization with 2 M Tris pH 12, the eluate was used for infection of a fresh uninfected E. coli XL1 Blue culture. Cells successfully transduced with a phagemid copy, encoding a human scFv-fragment, were again selected for Carbenicillin resistance and subsequently infected with VCMS13 helper phage to start the second round of antibody display and in vitro selection. After five rounds of production and selection for antigen-binding scFv-displaying phage, plasmid DNA from E. coli cultures was isolated that corresponds to 3, 4 and 5 rounds of panning as well as to the unselected repertoire prior to the first round of panning. For the production of soluble scFv-proteins two strategies were pursued:

I) ScFv-DNA fragments were excised from the plasmids (EcoRI-BsiWI), and cloned via the same restriction sites in a similar plasmid pComb3H5BFIag differing in that it adds to the expression construct (e.g. scFv) a Flag-tag

(TGDYKDDDDK) instead of a His6-tag and having the phage gene III deleted.

Instead of excising the fragments from the plasmids, standard PCR amplifications of the scFv-DNA were carried out by using the previously mentioned 3'-Vkappa primers (3'-hu-Vk-J1-Spel-BsiWI, 3'-hu-Vk-J2/4-

Spel-BsiWI, 3'-hu-Vk-J3-Spel-BsiWI, 3'-hu-Vk-J5-Spel-BsiWI) and the 5'- VH-primers (5'-huVH1 ,3,5-XhoI-2001, 5^*-huVH2-Xhol-2001, 5'-huVH4- Xhol-2001, 5'-huVH4B-Xhol-2001, 5'-huVH6-Xhol-2001). The scFv- fragments were isolated and cloned via Xhol-BsiWI- (fragments) and Sall- BsiWI-restriction (expression plasmid) into the above mentioned 5 expression vector including the Flag-tag.

II) The isolated plasmids from the phage selection rounds were cut with BsiWI and Not I and ligated with a DNA fragment (BsiWI /Not I restricted) which added, in-frame, a murine ckappa domain, a myc tag (EEQKLISEEDL) and a His6-tag to the scFv. This ckappa/myc/His6 0 domain was derived by a first standard PCR using δ'-primer (5'-Mouse ckappa BsiWI (SEQ ID NO: 169)), 3'-primer (3'-Mouse-ck-myc (SEQ ID NO: 170) and murine PBMC cDNA as template. In a second standard PCR reaction the isolated product (approximately 350 bp) from the first PCR was used as template using δ'-primer (5'-Mouse ckappa BsiWI), 3'- δ primer (3'-myc-His6-Not (SEQ ID NO: 171). The resulting PCR-fragment was isolated (approximately 370 bp), cut with BsiWI/Notl and subcloned into a pComb3HδBHis-derivative. From this vector the ckappa/myc/His6 fragment was excised via BsiWI/Notl and used for cloning (the respective sequence is shown in Figure 1 (SEQ ID NO: 178 and SEQ ID NO: 179)). 0 After ligation each pool (different rounds of panning) of plasmid DNA was transformed into 100 μl heat shock competent E. co//XL1 Blue and plated on Carbenicillin LB- Agar. Single colonies were grown in δ ml LB-Carb-cultures/20 mM MgCI₂ and expression of scFv was induced after six hours by adding Isopropyl-β- D-thiogalactosid (IPTG) to a final concentration of 1 mM and then incubated at 30 δ °C.

These cells were harvested after 20 hours by centrifugation and typically resuspended in 500 μl PBS. Through four rounds of freezing at -70°C and thawing at 37°C the outer membrane of the bacteria was destroyed by temperature shock so that the soluble periplasmic proteins including the scFv fusion-proteins were 0 released into the liquid. After elimination of intact cells and cell-debris by centrifugation, the supernatant was tested by ELISA for CD3 epsilon-binding scFv- fusion-proteins.

Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using a biotinylated anti-mouse kappa antibody (Southern Biotech, 1 μg/ml PBS) detected with horseradish peroxidase-conjugated avidine (Dako, 1 μg/ml PBS). The signal was developed by adding ABTS substrate solution and detected at a wavelength of 405 nm. In contrast to PBS as negative control and most of the clones after three rounds of panning, many clones after four rounds of panning already showed significant ELISA signals. Figure 2 is illustrative of typical ELISA results. In the selection of scFvs shown, construct 4-10 showed especially strong binding to recombinant CD3 epsilon antigen.

Sequence analysis showed that most of the positive clones from round 4 and 5 were closely related. Further investigations of different CD3 positive clones was therefore focused on clones of round three, since the sequence diversity of these was expected to be higher than for clones of rounds 4 and δ (see Example 2.8). Selection on Jurkat cells and by specific elution with recombinant antigen (huLIB- ST phage pool 2) huLIB-ST phage pool 2 was incubated with 2 x 10⁵ Jurkat cells (a CD3-positive human T-cell line) for 1 hour on ice under slow agitation. These Jurkat cells had been grown in RPMI medium enriched with fetal calf serum (10 %), glutamin and penicillin/streptomycin, harvested by centrifugation, washed in PBS and resuspended in PBS 10 % FCS. scFv phage which did not specifically bind to the Jurkat cells were eliminated by up to five washing steps with PBS/10 % FCS. Jurkat cells with bound scFv phages were then incubated with 10 μg soluble recombinant CD3 epsilon antigen for 2 hours on ice under gentle agitation. Cells were pelleted by centrifugation and the supernatant used for infection of fresh uninfected E. coli XL1 blue cells.

Cells successfully transduced with a phagemid copy encoding a human scFv- fragment were again selected for Carbenicillin resistance and subsequently infected with VCMS13 helper phage to start the second round of antibody display and in vitro selection.

After five rounds of production and selection for antigen-binding scFv-displaying phage, plasmid DNA from E. coli cultures was isolated corresponding to 3, 4 and δ rounds of panning as well as to the unselected repertoire prior to the first round of panning.

The cloning and expression of soluble scFvs in E. coli and the processing of the 5 periplasmic preparations were carried out as described earlier for selection of huLIB-ST on recombinant antigen. These periplasmic preparations of single clones were then tested by ELISA for CD3epsilon-binding scFv-fusion-proteins. Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using a biotinylated anti-mouse kappa antibody (Southern Biotech, 0 1 μg/ml PBS) detected with horseradish peroxidase-conjugated avidine (Dako, . 1 μg/ml PBS). The signal was developed by adding ABTS substrate solution and detected at a wavelength of 405 nm. Compared to PBS as negative control, Figure 3 shows that most of the clones after panning round 3 give significantly higher ELISA signals. Only one of the clones tested after panning round 4 and 5 showed δ significant binding.

2.7.2. Selections with huLIB-STE

For huLIB-STE approximately 5 x 10¹¹ to 5 x 10¹² kappa phages and roughly the same amount of lambda phage were each resuspended in 1δ0 μl of TBS/1% BSA and then pooled (= phage pool 3). For phage pool 4, approximately 2 x 10¹¹ to 2 x 0 10¹² kappa phages and roughly the same amount of lambda phage were each resuspended in 160 μl of PBS/10% FCS and then pooled. Selection on recombinant antigen (huLIB-STE phage pool 3) huLIB-STE phage pool 3 was incubated with recombinant soluble human CD3 epsilon immobilized on 96 well ELISA plates. Recombinant soluble human CD3 δ epsilon was prepared as described in example 1. scFv phage which did not specifically bind to the target antigen were eliminated by up to ten washing steps with TBS/Tween. Binding entities were eluted by using HCI-Glycine pH 2.2 and after neutralization with 2 M Tris pH 12, the eluate was used for infection of a fresh uninfected E. coli XL1 Blue culture. Cells successfully transduced with a phagemid 0 copy encoding a human scFv-fragment were again selected for Carbenicillin resistance and subsequently infected with VCMS13 helper phage to start the second round of antibody display and in vitro selection. After five rounds of production and selection for antigen-binding scFv-dispIaying phage, plasmid DNA from E. coli cultures were isolated corresponding to 3, 4 and δ rounds of panning as well as to the unselected repertoire prior to the first round of panning. The cloning and expression of soluble scFvs in E. coli and the processing of the periplasmic preparations were carried out as described earlier for selection of huLIB-ST on recombinant antigen.

These periplasmic preparations of single clones were then tested by ELISA for CD3epsilon-binding scFv-fusion-proteins. Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using a biotinylated anti-mouse kappa antibody (Southern Biotech, 1 μg/ml PBS) detected with horseradish peroxidase-conjugated avidine (Dako, 1 μg/ml PBS). The signal was developed by adding ABTS substrate solution and detected at a wavelength of 405 nm. PBS as negative control and the clones after three and four rounds of panning did not show significant ELISA signals (Figure 4). Only one clone (δ-13), obtained after the fifth panning round, showed a strong signal. In further experiments positive clones could be obtained after panning round 3 and 4. Flow cytometric analysis showed that clone δ-13 from Fig. 4 was not able to significantly bind to CD3-positive Jurkat cells. From restriction analysis of the plasmid preparations after three, four and five rounds of panning, it is probable that clones identical or at least similar to 5-13 were overgrowing other clones in rounds 4 and 5. Further investigations for different CD3-positive clones were therefore focused on clones of round three, which seems to have a higher diversity than rounds 4 and 5 (see Example 2.8). Selection on Jurkat cells and by specific elution with recombinant ahtigen (huLIB- STE phage pool 4) huLIB-STE phage pool 4 was incubated with 2 x 10⁵ Jurkat cells (a CD3-positive human T-cell line) for 1 hour on ice under slow agitation. These Jurkat cells had been grown in RPMI medium enriched with fetal calf serum (10 %), glutamine and penicillin/streptomycin, harvested by centrifugation, washed in PBS and resuspended in PBS 10 % FCS. scFv phage which did not specifically bind to the Jurkat cells were eliminated by up to five washing steps with PBS/10 % FCS. Jurkat cells with bound scFv phages were then incubated with 10 μg (100 μl) soluble recombinant CD3-epsilon antigen for 2 hours on ice under gentle agitation. Cells were pelleted by centrifugation and the supernatant was used for infection of 5 fresh uninfected E. coli XL1 blue cells.

Cells successfully transduced with a phagemid copy encoding a human scFv- fragment were again selected for carbenicillin resistance and subsequently infected with VCMS13 helper phage to start the second round of antibody display and in vitro selection. After five rounds of production and selection for antigen-binding 0 scFv-displaying phages, plasmid DNA from E. coli cultures was isolated corresponding to 3, 4 and 5 rounds of panning as well as to the unselected repertoire prior to the first round of panning.

The cloning and expression of soluble scFvs in E. coli and the processing of the periplasmic preparations were carried out as described earlier for 5 selection of huLIB-ST on recombinant antigen. These periplasmic preparations of single clones were then tested by ELISA for CD3epsilon- binding scFv-fusion-proteins. Detection of scFv-fragments bound to immobilized recombinant human CD3 epsilon antigen was carried out using an anti-Flag-tag antibody (M2 Sigma 1 μg/ml PBS) detected with horseradish 0 peroxidase-conjugated polyclonal anti-mouse antibody (Dako) 1 μg/ml PBS). The signal was developed by adding ABTS substrate solution and detected at a wavelength of 405 nm. Compared to the negative control, some of the clones after panning round 3 and 4 show strong ELISA signals, as seen in Figure 5. Figure δ is illustrative of typical ELISA results. Of particular interest in Figure δ is δ the identification of clone 4-48. This clone later showed positive binding to Jurkat CD3+ cells.

2.8. Screening of scFvs on CD3-positive Jurkat cells

From huLIB-ST and huLIB-STE (selections on immobilized antigen or specific elution from Jurkat cells), more than 1000 scFv-producing E. coli clones were 0 isolated and used for periplasmic preparations as described in the next example. These scFv-containing periplasmic preparations were then screened for positive binding signals on Jurkat cells in flow cytometric assays as described in the next example. Binding signals of positive clones were reproduced at least twice and respective scFv DNA-sequences were determined by plasmid preparation and sequencing. The ratio of CD3-positive clones versus high sequence diversity likely reached its highest level after round 3 of panning on immobilized, solely expressed recombinant CD3 using huLIB-ST and huLIB-STE. For this reason, most of the clones that were screened originated from round 3.

From huLIB-ST and huLIB-STE pannings on Jurkat cells with selection by elution using recombinant CD3 antigen, periplasmic preparations ("PPPs") from scFv- producing E. coli clones obtained after round 3, 4 and 5 were used for screening.

Example 3: Prokaryotic expression as scFv: Binding to recombinant antigen and to human CD3-positive and negative cells 3.1. Bacterial expression in E. coli XL1 Blue

As previously mentioned, E. coli XL1 Blue transformed with pComb3H5BHis containing a VL- and VH-segment produce soluble scFv in sufficient amounts after excision of the gene III fragment and induction with 1 mM IPTG. The scFv-chain is exported into the periplasm where it folds into a functional conformation. For periplasmic preparations the cells were grown in SB-medium supplemented with 20 mM MgCI₂ and carbenicillin δO μg/ml and redissolved in PBS after harvesting. By four rounds of freezing at -70°C and thawing at 37°C, the outer membrane of the bacteria was destroyed by temperature shock and the soluble periplasmic proteins including the scFvs were released into the supernatant. After elimination of intact cells and cell-debris by centrifugation, the supernatant containing the human anti-human CD3-scFvs was collected and used for further examination. These crude supernatants containing scFv will be further termed PPP.

3.2. Binding to recombinant human CD3 epsilon antigen in ELISA

After screening experiments (see Example 2.8) the following human scFv clones (all FLAG-tagged) were chosen for further investigation (sequences are shown in Figures 6-13, corresponding to SEQ ID NOs: 180-195):

From huLIB-ST: 4-10 (SEQ ID NO: 192, 193); 3-106 (SEQ ID NO: 180, 181); 3- 114 (SEQ ID NO: 182, 183); 3-148 (SEQ ID NO: 184, 185). From huLIB-STE: 4-48 (SEQ ID NO: 194, 195); 3-190 (SEQ ID NO: 186, 187); 3-

271 (SEQ ID NO: 188, 189), 5-550 (SEQ ID NO: 190, 191). ELISA experiments were carried out by coating the recombinant CD3 epsilon on wells of 96 well plastic plates (Nunc, maxisorb) typically at 4° C over night. The antigen was then removed, wells washed once with PBS/0.05 % Tween 20 and subsequently blocked with PBS/3 % BSA for at least one hour. After removal of the blocking solution, PPPs and control solutions were added to the wells and incubated for typically one hour at room temperature. The wells were then washed three times with PBS/O.Oδ % Tween 20. Detection of scFvs and control antibodies bound to immobilized antigen was carried out using a monoclonal murine anti-His6 or anti FLAG-tag antibody (Qiagen anti-PentaHis and M2 anti Flag Sigma, typically each at a final concentration of 1 μg/ml PBS) detected with a peroxidase-labeled polyclonal goat anti-(mouse Fab-fragment) antibody (Dianova, 1 μg/ml PBS). The signal was developed by adding ABTS substrate solution and measured at a wavelength of 40δ nm. Unspecific binding of the test-samples to the blocking agent was examined by carrying out the identical assays with the identical reagents and identical timing on ELISA plates which were not coated but blocked with BSA, only. As a negative control, LK2 (a human CD3-specific svFv; described in WO 98/64440), which does not bind to the recombinant CD3 epsilon antigen, was cloned into the same phage display/expression vector pComb3HδBHis. Periplasmic preparations of L2K scFv were carried out as described for the selected scFvs.

Human CD3-specific antibodies OKT3 (Janssen Cilag GmbH), SP34 (Pharmingen) and UCHT1 (Pharmingen) were also tested for binding to the recombinant ("r") CD3-epsilon antigen (final concentrations 1 μg/ml). Figure 14 shows the binding, measured by ELISA, of human anti-CD3 scFvs to rCD3-epsilon. It should be remembered that, prior to this ELISA experiment, these scFv constructs have first been selected in phage display using rCD3-epsilon and then have yielded positive signals upon screening on CD3+ Jurkat cells. As shown in Figure 14, all of the human scFvs show significantly higher binding signals than PBS, L2K-scFv (anti-CD3) control or the anti-CD3 antibodies UCHT1, SP34 and OKT3. It can be seen that the human scFvs show different intensities of ELISA signals when binding to recombinant CD3-epsilon. For example, human scFv constructs 4-10, 3-190, 4-48 and 3-650 show significantly higher ELISA signals than do human scFv constructs 3-271 and 3-106. To exclude the possibility that the positive binding shown in Figure 14 might be due to binding to BSA (used as a blocking agent in the first ELISA experiment shown in Figure 14), a second ELISA experiment was performed in parallel. In this second ELISA experiment, all parameters were identical to those in the first ELISA experiment, except that in the second ELISA experiment no coating with antigen, but only blocking with BSA took place. The results of the second ELISA experiment are shown in Figure 15. It can clearly be seen in Figure 1δ that none of the human scFvs showing binding in Figure 14 showed any significant binding to BSA. Taken together with the positive binding on CD3+ Jurkat cells, the results shown in Figures 14 and 1δ allow the conclusion that the scFvs 4-10, 3-271, 3-148, 3-190, 4-48, 3-106, 3-114, and 3-δδO specifically bind to the human CD3 antigen. 3.3. Binding to CD3-positive and -negative cell lines in flow cytometric analysis

The test for binding to CD3-positive and -negative cell lines was also carried out with the periplasmic preparations: From huLIB-ST: 4-10 (SEQ ID NO: 192, 193); 3-106 (SEQ ID NO: 180, 181);

3-114 (SEQ ID NO: 182, 183); 3-148 (SEQ ID NO: 184, 185). From huLIB-STE: 4-48 (SEQ ID NO: 194, 195); 3-190 (SEQ ID NO: 186, 187); 3-271 (SEQ ID NO: 188, 189),

3-560 (SEQ ID NO: 190, 191). Positive controls: L2K scFv was again included in the experiments as well as the commercially available murine anti-human CD3 antibodies OKT3, UCHT1 and SP34. PBS was used as an appropriate negative control.

The human T-cell line Jurkat and CHO cells cotransfected with both human CD3- δ epsilon and human CD3-gamma (CHOe/g) were used as CD3-positive cell lines. The human gastric cancer cell line Katolll and untransfected CHO cells were included as CD3-negative cell lines.

Cell binding assays were carried out by initially incubating between 100,000 and 200,000 cells with periplasmic preparation (PPP) containing human scFv or 0 relevant controls. After incubation the cells were washed in PBS/1 % FCS (fetal calf serum) and further incubated with δ-10 μg/ml of anti-FLAG M2 antibody. After the cells had again been washed, they were incubated with polyclonal, PE-labeled anti-mouse antibodies (Dianova) and subsequently analyzed by flow cytometry. Figures 16-21 depict binding of human scFv constructs to various cell lines as δ measured by flow cytometric analysis. Each of figures 16-21 contains multiple diagrams, one for each construct tested. In any given diagram, the black distribution shows fluorescence intensity for cells incubated only with PBS alone in the absence of any construct but with all appropriate detection agents as used for detection of scFvs. In this way, any fluorescence shift observed can be definitely 0 attributed to scFv construct rather than detection agents or buffer. Shifts in fluorescence which are indicative of construct binding to the respective cell line are depicted by a gray line in each diagram. Generally, a shift of higher magnitude away from, i.e. further to the (black) control indicates stronger binding, whereas a shift of lower magnitude away from, i.e. closer to the (black) control indicates δ weaker binding.

Figure 16 depicts the results of experiments measuring the binding of human scFv constructs to CD3(+) human Jurkat cells as measured by flow cytometric analysis. It can be seen that the constructs 3-148, 3-190, 3-271, 4-10 and 4-48 show clearly discernable shifts in fluorescence intensity as compared to the respective control. 0 Constructs 3-106, 3-114 and 3-550 show only minimal, although reproducible shifts in fluorescence. The positive controls L2K scFv (anti-CD3), UCHT1, SP34 and OKT3 all show, as expected, clearly discemable shifts in fluorescence intensity as compared to the respective control. All constructs tested therefore show binding to CD3+ cells, with 3-148, 3-190, 3-271, 4-10 and 4-48 being stronger than 3-106, 3- 114 and 3-δδ0. δ Figures 17 and 18 each show the results of the test constructs' binding to CD3(-) cells. In one case (Figure 17), the CD3(-) cells are of non-human origin. In the other case (Figure 18), the CD3(-) cells are of human origin. Figure 17 depicts the results of experiments measuring the binding of human scFv constructs to CD3(-) CHO cells as measured by flow cytometric analysis. It can be seen that none of the 0 constructs show clearly discemable shifts in fluorescence intensity as compared to the respective control, regardless of whether these constructs are scFv test constructs or the positive control constructs L2K scFv (anti-CD3), UCHT1 , SP34 and OKT3. Figure 18 depicts the results of experiments measuring the binding of human scFv constructs to CD3(-) Katolll cells as measured by flow cytometric δ analysis. It can be seen that none of the constructs show clearly discemable shifts in fluorescence intensity as compared to the respective control, regardless of whether these constructs are scFv constructs to be tested or the positive control constructs L2K scFv (anti-CD3 scFv), UCHT1, SP34 and OKT3. Comparing the results from Figure 16 with those from either Figure 17 or Figure 18 0 indicates that the magnitudes of fluorescence shift for the constructs 3-148, 3-190, 3-271, 4-10 and 4-48 are significantly less when binding to CD3(-) cells than when binding to CD3(+) cells. Taken together with the ELISA results described above, it can therefore be concluded that at least the human scFv constructs 3-148, 3-190, 3-271, 4-10 and 4-48 bind to the native human CD3 on human CD3+ cells. 5 To further confirm the specificity of the scFv constructs, binding studies were also performed using CHO cells which had been cotransfected with both CD3-epsilon ("CD3-e") and CD3-gamma ("CD3-g"). Non-transfected CHO cells express neither CD3-e nor CD3-g. CHO cells transfected with both CD3-e and CD3-g express these two proteins much more weakly than do Jurkat cells. For this reason, using 0 . CHO cells tranfected with CD3-e and CD3-g confers a higher degree of stringency on the binding experiments than would be possible using Jurkat cells. Figures 19-21 depict the results of such binding studies as measured by flow cytometric analysis. Figure 19 depicts the results of binding by the scFv construct 3-271 to CD3(+) Jurkat cells. Figure 20 depicts the results of binding by the scFv construct 3-271 to CHO cells lacking CD3 antigen. Figure 21 depicts the results of 5 binding by the scFv construct 3-271 to CHO cells transfected with both CD3- epsilon and CD3-gamma. Therefore, the only difference between non-transfected CHO cells and CHO cells doubly transfected with CD3-epsilon and CD3-garnma is the presence of CD3-e and CD3-g on the doubly transfected cells. Considering Figures 19 and 21 , it is clear that interaction of scFv construct 3-271 with Jurkat 0 cells (Figure 19) and with CHO cells doubly transfected with CD3-epsilon and CD3- gamma (Figure 21) in each case gives rise to a strong fluorescence shift away from the control. In contrast, the interaction of scFv 3-271 with non-transfected CHO cells (Figure 20) gives rise to no significant fluorescence shift as compared to those observed in Figures 19 and 21. This emphasizes the specificity for CD3 δ previously shown for the scFv construct 3-271.

It should not be forgotten that the human scFv construct 3-271 showed a weak signal in the ELISA experiment using recombinant CD3-epsilon as antigen (Figure 14). Taken together with the strong binding manifested by 3-271 on CD3(+) Jurkat cells, it becomes clear that CD3 epsilon likely makes up only part of the epitope 0 recognized by 3-271. Without being bound by theory, it is therefore believed that the epitope specifically recognized by human scFv construct 3-271 comprises CD3-epsilon as well as at least another subunit of the CD3 complex. Similar experiments were performed for the remaining human scFv constructs, but these constructs were unable to significantly bind to CHO cells transfected with δ CD3-epsilon and CD3-gamma. This finding is most likely due to the lower activity of these constructs as compared to the construct 3-271 as well as to the fact that the level of expression of CD3 on the transfected CHO cells is much lower than that on Jurkat CD3+ cells. This assumption is supported by the weaker binding, in Figure 21, of positive controls UCHT1, OKT3, SP34 and scFv L2K (anti-CD3) to 0 . the transfected CHO cells. Example 4: Eukaryotic expression of human anti-human CD3 binding specificity as part of bispecific single chain constructs: Testing the biological activity as T-cell engagers against various target cells

In order to test whether the human anti-CD3 molecules as disclosed herein above δ retain their biological activity in a more complicated molecular context, various bispecific single chain antibody molecules comprising anti-CD3 specificity were prepared. Each bispecific single chain antibody comprised a human scFv specifically binding to the human CD3 antigen as well as another molecular domain which specifically binds to an antigen other than the human CD3 antigen. 0 Expression in bacteria might lead to functionally less active bispecific single chain antibodies.

Mammalian cells were used for the production of functional bispecific antibodies. To this end, the chosen human anti-human CD3 scFvs were cloned into the eukaryotic expression vector pEFDHFR (Mack, Proc. Nati. Acad. Sci. U.S.A. 92 δ (1995) 7021-δ) already containing a target specificity, for example anti-CD19 (e.g. VH-VL as in Figure 23), anti-EpCAM (e.g. 5-1 θ^' from WO 99/25818, e.g. VH-VL as in Figure 22), anti-CD20 (e.g. as in Figure 24) or anti-CCR5 (e.g. as in Figure 26). 4.1. Cloning of bispecific single chain constructs against human CD3 and human CD19 0 In order to create a model to test the chosen human anti-human CD3 scFvs as part of a bispecific antibody, nucleic acid sequences encoding these human anti-human CD3 scFvs were cloned into a eukaryotic expression vector in translational fusion to an scFv antibody fragment directed against human CD19. 4.1.1. Construction of antiCD3-antiCD19 bispecific single chain antibodies δ The pEFDHFR vector containing the DNA sequence coding for mouse anti-human CD3 x anti-human CD 19 was used to generate corresponding human anti-CD3 constructs wherein the human anti-CD3 portion was expressed co-linearly with and N-terminal to the anti-CD19 portion in the resulting bispecific single chain antibody construct (biscFv). 0 To replace the mouse anti-human CD3 specificity in VH-VL configuration with the selected human anti-human CD3 specificity, the appropriate restriction sites had to be introduced into the human anti-human CD3-constructs by PCR. The primers 5'- 5BVH-BsrGI (SEQ ID NO: 172) and 3'-5BVL-BspEI (SEQ ID NO: 173) added a BsrGI-site to the δ-prime VH-domain and a BspEI-site to the 3' VL-domain, respectively, δ The PCR amplified DNA-fragments were then purified. These fragments and the vector anti-human CD19 pEFDHFR were restricted with BrsGI and BspEI (NEB enzymes) and ligated after purification in an appropriate ratio. The ligation was transformed into E. coli XLI blue by heatshock transformation and clones were screened with the vector-specific primer leader seq and the insert-specific primer 0 3'-δBVL-BspEI. Positive clones were inoculated in δO ml of SB-medium containing carbenicillin as a selection marker and were grown overnight at 37°C in a shaker. Plasmid preparation was carried out using a commercial kit (QIAGEN plasmid midi kit) before the constructs were finally checked by sequencing. In this way, the following biscFv-constructs were prepared: 5 • Human anti-CD3 3-148 VH-VL x anti-CD19 VL-VH (nucleic acid: Table 1 ,

Construct 20nuc; amino acid: Table 2, Construct 20prot; SEQ ID NOS: 205, 206)

• Human anti-CD3 3-190 VH-VL x anti-CD19 VL-VH (nucleic acid: Table 1, Construct 28nuc; amino acid: Table 2, Construct 28prot; SEQ ID NOS: 207, 0 208)

• Human anti-CD3 3-271 VH-VL x anti-GD19 VL-VH (nucleic acid: Table 1, Construct 36nuc; amino acid: Table 2, Construct 36prot; SEQ ID NOS: 209, 210)

• Human anti-CD3 4-10 VH-VL x anti-CD19 VL-VH (nucleic acid: Table 1, 5 Construct 52nuc; amino acid: Table 2, Construct 62prot; SEQ ID NOS: 211 ,

212)

• Human anti-CD3 4-48 VH-VL x anti-CD19 VL-VH (nucleic acid: Table 1, Construct 60nuc; amino acid: Table 2, Construct 60prot; SEQ ID NOS: 213, 214) 0 4.1.2. Construction of antiCD19-antiCD3 bispecific single chain antibodies The pEFDHFR vector containing the DNA sequence coding for anti-human CD19 x mouse - anti-human CD3 was used as a vector backbone for subcloning. To replace the VHVL mouse anti-human CD3-epsilon specificities with the selected human anti-human CD3-specificities the appropriate restriction sites had to be introduced into the human anti-human CD3-constructs by PCR and cloning into 5 intermediate vectors. First, to introduce an Xhol-site to clones derived from selection within the library huLIB-ST, PCR was carried out on the anti-human CD3- pComb3H5BFIag-constructs using the specific 5'-VH and 3'-VK-J-primers corresponding to their individual sequence. The amplified DNA-fragments were cloned by restriction with Xhol and BsiWI enzymes (both from Roche) into 0 pComb3HδBFIag. Anti-human CD3-pComb3HδBFIag constructs were then digested with BspEI (NEB) and BsiWI and the approximately 7δ0 - 800 bp scFv DNA-fragments were isolated. The scFv fragment 4-10 was then ligated into an intermediate cloning vector 3B10 pEFDHFRHis which had been restricted with the same enzymes. This step introduced a His-Tag followed by a Sail restriction site, δ the latter being necessary for the next cloning step.

Both 3B10 (anti-EpCAM) x anti-human CD3 4-10 pEFDHFR-His and the anti- CD19-bearing vector mentioned above were restricted with Sail (Roche) and BspEI(NEB). The scFv DNA fragment 4-10 His and the vector fragment of anti- CD19 pEFDHFR were isolated and then ligated in an appropriate ratio. The ligation 0 was transformed into E. coli XLI blue by heatshock transformation, and clones were screened with the vector-specific primer leader seq and the insert-specific primer 3'-δBVL-BspEI. Positive clones were inoculated in δO ml of SB-medium containing carbenicillin as a selection marker and grown overnight at 37°C in a shaker. δ Plasmid preparation was carried out using a commercial kit (QIAGEN plasmid midi kit) before, the constructs were finally checked by sequencing. The isolated BspEI- BsiWI fragments of the other human CD3-specific clones (3-148, 3-190, 3-271, 4- 48) were then cloned into the anti-CD 19 x anti-CD3 4-10 pEFDHFR via the same cloning sites in place of 4-10. Finally, the following biscFv-constructs were 0 generated:

• anti-CD19 VL-VH x human anti-CD3 3-148 VH-VL (nucleic acid: Table 1, Construct 21nuc; amino acid: Table 2, Construct 21prot; SEQ ID NOS: 216, 216)

• anti-CD19 VL-VH x human anti-CD3 3-190 VH-VL (nucleic acid: Table 1 , Construct 29nuc; amino acid: Table 2, Construct 29prot; SEQ ID NOS: 217, δ 218)

• anti-CD19 VL-VH x human anti-CD3 3-271 VH-VL (nucleic acid: Table 1 , Construct 37nuc; amino acid: Table 2, Construct 37prot; SEQ ID NOS: 219, 220)

• anti-CD19 VL-VH x human anti-CD3 4-10 VH-VL (nucleic acid: Table 1, 0 Construct δ3nuc; amino acid: Table 2, Construct δ3prot; SEQ ID NOS: 221 ,

222)

• anti-CD19 VL-VH x human anti-CD3 4-48 VH-VL (nucleic acid: Table 1, Construct 61 nuc; amino acid: Table 2, Construct 61 prot; SEQ ID NOS: 223, 224) 6 4.2. Cloning of bispecific sc-constructs against huCD3 and hu EpCAM

4.2.1. Construction of antiCD3-antiEpCAM bispecific single chain antibodies The pEFDHFR vector containing the sequence coding for mouse anti-human CD3 x 5-10 (anti human-EpCAM) was used as a vector backbone for subcloning. To replace the mouse anti-human CD3-epitope in VH/VL configuration with the 0 selected human anti-human CD3 specificities, the appropriate restriction sites had to be introduced into the human anti-human CD3-constructs by standard PCR and DNA from the human CD3-binders as template. The primers 5'-5BVH-BsrGl (SEQ ID NO: 172) and 3'-5BVL-BspEI (SEQ ID NO: 173) added a BsrGI-site to the δ' VH-domain and a BspEI-site to the 3'-VL-domain, respectively. δ The PCR-amplified DNA fragments were then purified. These fragments and the pEFDHFR vector containing the DNA-fragment coding for mouse anti-CD3 x 5-10 were restricted with BrsGI and BspEI (NEB enzymes) and were ligated after purification in an appropriate ratio. The ligation was transformed into E. coli XLI blue by heatshock transformation and clones were screened with the vector- 0 specific primer leader sequence and the insert-specific primer 3'-5BVL-BspEI (SEQ ID NO: 173). Positive clones were inoculated into δO ml of SB-medium containing carbenicillin as a selection-marker and grown overnight at 37°C in a shaker. Plasmid preparation was carried out using a commercial kit (QIAGEN plasmid midi kit) before the constructs were finally checked by sequencing. In this way, the following 5 biscFv-constructs were generated:

• Human anti-CD3 3-148 VH-VL x anti-EpCAM 5-10 VH-VL (nucleic acid: Table 3, Construct 82nuc;. amino acid: Table 4, Construct 82prot; SEQ ID NOS: 225, 226)

• Human anti-CD3 3-190 VH-VL x anti- EpCAM 5-10 VH-VL (nucleic acid: 0 Table 3, Construct 90nuc; amino acid: Table 4, Construct 90prot; SEQ ID

NOS: 227, 228)

• Human anti-CD3 3-271 VH-VL x anti- EpCAM 5-10 VH-VL (nucleic acid: Table 3, Construct 98nuc; amino acid: Table 4, Construct 98prot; SEQ ID NOS: 229, 230) 5 . • Human anti-CD3 4-10 VH-VL x anti- EpCAM 5-10 VH-VL (nucleic acid: Table 3, Construct 114nuc; amino acid: Table 4, Construct 114prot; SEQ ID NO: 231, 232)

• Human anti-CD3 4-48 VH-VL x anti- EpCAM 5-10 VH-VL (nucleic acid: Table 3, Construct 122nuc; amino acid: Table 4, Construct 122prot; SEQ ID 0 NOS: 233, 234)

4.2.2. Construction of anti-EpCAM x anti-CD3 bispecific single chain antibodies

The pEFDHFR vector containing the sequence coding for mouse anti-human CD3 x 6-10 (anti human-EpCAM) was used as a vector backbone for subcloning. δ To create the desired constructs, an intermediate cloning was necessary to insert the required restriction site Sail. First, the δ' mouse anti-human CD3 scFv-domain was exchanged with another δ-10 domain to create a suitable intermediate cloning vector 5-10 x 5-10 pEFDHFR.

For the insert, the vector 5-10 x mouse (anti-human CD3) pEFDHFR was restricted 0 with the restriction enzymes BsrGI and BspEI. The excised and purified fragment was then ligated into the vector mentioned above, which had been restricted with the same enzymes. The resulting construct 5-10 x 5-10 pEFDHFR could than be used for further cloning of human anti-human CD3-epitopes at the C-terminus of 5- 10 by restricting the latter with BspEI and Sail.

The chosen human anti-human CD3-specificities were taken from the pEFDHFR constructs containing the sequence mouse anti-human CD 19 x human anti-human CD3 which were created as described in Example 4.1.2 . The 3' anti-CD3-domains were restricted from the vector with BspEI and Sail and were ligated into 5'- 5-10 pEFDHFR (x BspEI-Sall) in an appropriate ratio. The ligation was transformed into E. coli XLI blue by heatshock transformation, clones were screened with the vector-specific primers leader seq and EF pol. Positive clones were inoculated in 50 ml of SB-medium containing carbenicillin as a selection marker and grown overnight at 37°C in a shaker. Plasmid preparation was carried out using a commercial kit (QIAGEN plasmid midi kit) before the constructs were finally checked by sequencing. In this way, the following biscFv-constructs were generated:

• anti-EpCAM 5-10 VL-VH x human anti-CD3 3-148 VH-VL (nucleic acid: Table 3, Construct 85nuc; amino acid: Table 4, Construct δδprot; SEQ ID NOS: 23δ, 236)

• anti- EpCAM 5-10 VL-VH x human anti-CD3 3-190 VH-VL (nucleic acid: Table 3, Construct 93nuc; amino acid: Table 4, Construct 93prot; SEQ ID

NOS: 237, 238)

• anti- EpCAM 5-10 VL-VH x human anti-CD3 3-271 VH-VL (nucleic acid: Table 3, Construct 101 nuc; amino acid: Table 4, Construct 101 prot; SEQ ID NOS: 239, 240) • anti- EpCAM 5-10 VL-VH x human anti-CD3 4-10 VH-VL (nucleic acid:

Table 3, Construct 117nuc; amino acid: Table 4, Construct 117prot; SEQ ID NOS: 241, 242)

• anti- EpCAM 5-10 VL-VH x human anti-CD3 4-48 VH-VL (nucleic acid: Table 3, Construct 125nuc; amino acid: Table 4, Construct 12δprot; SEQ ID NOS: 243, 244)

Primers used for cloning of anti-target/anti-CD3 bispecific antibodies were 5'- 5BVH-BsrGI (SEQ ID NO: 172) and 3'-δBVL-BspEI (SEQ ID NO: 173). The leader seq is shown in SEQ ID NO: 204.

4.3. Cloning of bispecific single chain constructs against human CD3 and human CD20

5 Human CD3-specificities were combined with a single chain directed against the human CD20 antigen in an analogous manner as described herein above for the cloning of anti-CD19 (or anti-EpCAM) x human anti-human CD3 and human anti- human CD3 x anti-CD19 (or anti-EpCAM). The following examples of such constructs were generated: 0 • anti-CD20 VL-VH x human anti-CD3 3-190 VH-VL (nucleic acid: Table 7,

Construct 221 nuc; amino acid: Table 8, Construct 221 prot; SEQ ID NOs: 245, 246)

• anti-CD20 VL-VH x human anti-CD3 3-148 VH-VL (nucleic acid: Table 7, Construct 213nuc; amino acid: Table 8, Construct 213prot; SEQ ID NOs: 5 247, 248)

4.4. Cloning of bispecific single chain constructs against human CD3 and human CCR5

Human CD3-specificities were combined with a single chain directed against the human CCR5 antigen in an analogous manner as described herein above for the 0 cloning of anti-CD19 (or anti-EpCAM) x human anti-human CD3 and human anti- human CD3 x anti-CD19 (or anti-EpCAM). The following examples are generated:

• anti-CCR5 VL-VH x human anti-CD3 3-190 VH-VL (nucleic acid: Table 5, Construct 1δ7nuc; amino acid: Table 7, Construct 1δ7prot; SEQ ID NOs: 249, 2δ0) δ • anti-CCRδ VL-VH x human anti-CD3 3-148 VH-VL (nucleic acid: Table δ,

Construct 149nuc; amino acid: Table 7, Construct 149prot; SEQ ID NOs: 251, 252)

4.5. Expression and purification of the respective bispecific single chain 0 constructs in CHO cells

Before transfection, DHFR-negative CHO cells were grown in alpha MEM-medium ((Bio Whittaker) +10 % FCS +glutamine + Penicillin/Streptomycin) containing a mix of nucleosides. The day before transfection, 4x10⁵ cells/3 ml were seeded in a sterile 6-well cell culture plastic plate and grown overnight in supplemented medium, δ Transient transfection was carried out using the PolyFect® Transfection Reagent (QIAGEN) following the manufacturer's instructions. The cells were incubated for four days, followed by harvesting of the supernatants. After sedimentation of cells by centrifugation and transfer into fresh tubes, the supernatants could be tested for binding in an ELISA- and/or FACS-assay. 0 For stable transfection after collecting the transiently produced supernatants, CHO cells were transferred into a small cell-culture bottle (26 cm²) and grown in selection medium (alpha-MEM without nucleosides). Cells were expanded (75 cm² culture flask) in this medium and finally grown in a 150 cm² cell culture flask to confluence. Cells from one 150 cm² culture flask were then transferred to plastic 5 roller bottles with 600 ml HyQ®-medium (HyClone; serumfree, containing Penicilin/Streptomycin) and grown for 7 days before harvest of the cell culture supernatant. The cells were removed by centrifugation and the supernatant containing the expressed protein was stored at -20°C. 4.6. Purification of the bispecific single chain constructs 0 The single chain bispecific antibodies were isolated in a two step purification process of immobilized metal affinity chromatography (IMAC) and gel filtration. All constructs were purified according to this method. Akta® FPLC System (Pharmacia) and Unicorn® Software were used for chromatography. All chemicals were of research grade and purchased from Sigma (Deisenhofen) or Merck 5 (Darmstadt).

IMAC was performed using a Fractogel® column (Merck) which was loaded with ZnCI₂ according to the protocol provided by the manufacturer. The column was equilibrated with buffer A2 (20 mM sodium phosphate pH 7.6, 0.4 M NaCl) and the cell culture supernatant (δOO ml) was applied to the column (10 ml) at a flow rate of 0 3 ml/min. The column was washed with buffer A2 to remove unbound sample. Bound protein was eluted using a 2 step gradient of buffer B2 (20 mM sodium phosphate pH 7.5, 0.4 M NaCl, 0.5 M Imidazol) according to the following: Step 1: 20% buffer B2 in 6 column volumes; Step 2: 100% buffer B2 in 6 column volumes.

Eluted protein fractions from step 2 were pooled for further purification. Gel filtration chromatography was performed on a Sephadex S200 HiPrep column (Pharmacia) equilibrated with PBS (Gibco). Eluted protein samples (flow rate 1 ml/min) were subjected to standard SDS-PAGE and Western Blot for detection. Prior to purification, the column was calibrated for molecular weight determination (molecular weight marker kit, Sigma MW GF-200). Protein concentrations were determined using protein assay dye (MicroBCA, Pierce) and IgG (Biorad) as standard protein.

Purified bispecific protein was analyzed by SDS PAGE under reducing conditions performed with pre-cast 4-12% Bis Tris gels (Invitrogen). Sample preparation and application were performed according to the protocol provided by the manufacturer. The molecular weight was determined with MultiMark protein standard (Invitrogen). The gel was stained with colloidal Coomassie (Invitrogen protocol). Western Blot was performed using an Optitran® BA-S83 membrane and the Invitrogen Blot Module according to the protocol provided by the manufacturer. The antibodies used were directed against the His Tag (Penta His, Qiagen) and goat-anti-mouse Ig labeled with alkaline phosphatase (AP) (Sigma), and BCIP/NBT (Sigma) as substrate. The single chain bispecific antibody could be specifically detected by Western Blot.

4.7. Bioactivity of bispecific antibodies specific for CD19 and CD3 Cytotoxic activity of the bispecific antibodies was determined in a fluorochrome release based cytotoxicity assay. For this experiment purified biscFv 3-190 x anti- CD19 P2 (protein fraction 2 from gel filtration) was used.

CD19 positive NALM6 cells were used as target cells (1.5x10⁷) labeled with 10 μM calcein AM (Molecular Probes, Leiden, Netherland, no. C-1430) for 30 min at 37°C in cell culture medium. After two washes in cell culture medium, cells were counted and mixed with cells from the CD4-positive T cell clone CB1δ (kindly provided by Dr. Fickenscher, University of Erlangen/Nuernberg, Germany). 2 x 10⁶ CB15 cells and 2 x 10⁵ Nalmδ cells were mixed per ml (E:T ratio of 1:10) and δO μl of this suspension were used per well in a 96 well round bottom plate. biscFv 3-190 x anti-CD19 P2 was diluted in RPMI/10% FCS in a dilution series and δO μl of the δ respective solution were added to the cell suspension. The same dilution series was performed using PBS as negative control, starting with the same volume as for biscFv 3-190 x anti-CD19 P2. A standard reaction was incubated at 37°C/δ% C02 for 2 hours. After the cytotoxic reaction, the released dye in the incubation medium was quantitated in a fluorescence reader (Tecan, Crailsheim, Germany) and 0 compared with the fluorescence signal from a control reaction (without bispecific antibody), and the fluorescence signal obtained for totally lysed cells (for 10 min in 1% saponin). On the basis of these readings, the specific cytotoxicity was calculated according to the following formula: [Fluorescence (Sample) - Fluorescence (Control)] : [Fluorescence (Total Lysis)- Fluorescence (Control)] x 5 100.

Sigmoidal dose response curves typically had R2 values >0.97 as determined by Prism Software (GraphPad Software Inc., San Diego, USA; EC50 values calculated by the analysis program were used for comparison of bioactivity). As shown in Figure 26 the anti-human CD3 x anti-CD19 biscFv mediated cytotoxic 0 activity against the CD19-positive NALM6-cells using CB1δ cells as effector cells. In this experiment half maximal toxicity could be obtained in the low ng/ml concentrations of the biscFv 3-190 x anti-CD19. Control dilutions with PBS instead of biscFv did not show significant cytotoxicity. Based on the results shown in Figure 26, it can therefore be concluded that the anti-human CD3 x anti-CD19 biscFv δ binds to the CD 19 antigen on target cells and to the CD3 antigen on the effector inducing lysis of target.

4.8. Bioactivity of bispecific antibodies specific for EpCAM and CD3 For this experiment anti-CD3 3-271 x δ-10 anti-EpCAM P2 (protein fraction 2 from gel filtration), anti-CD3 3-271 x 5-10 anti-EpCAM P3 (protein fraction 3 from 0 gelfiltration), 5-10 anti-EpCAM x anti-CD3 3-148 (main protein fraction from gelfiltration) and 5-10 anti-EpCAM x anti-CD3 3-190 P3 (protein fraction 3 from gelfiltration) were evaluated with respect to their ability to mediate specific toxicity. Anti-CD3 3-190 x anti-CD19 P2 (protein fraction 2 from gelfiltration) which proved to mediate specific cytotoxicity to CD19-positive NALMδ-cells (see Figure 26) was included as an appropriate negative control for CD19-negative CHO-EpCAM cells, δ M79, an anti-EpCAM x anti-CD3 biscFv construct (Mack, PNAS 92 (1996), 7021- 5), was used as a positive control.

CHO cells from the American Type Cell Culture Collection (ATCC, Manassas, USA) were transfected with epithelial cell adhesion molecule (EpCAM). A cell clone derived from this transfection, referred to as CHO-EpCAM cells, was used for the 0 experiments. Untransfected CHO cells were also included in this experiment to demonstrate the EpCAM specificity of the cytotoxicity to the EpCAM-transfected cells. The CD4-positive T cell clone CB15 was kindly provided by Dr. Fickenscher, University of Erlangen/Nuernberg, Germany. Cells were cultured as recommended by the suppliers. δ 4.9. Flow cytometry-based cytotoxicity assay

Untransfected CHO as well as CHO-EpCAM (1.5x10⁷) cells were respectively washed free of serum two times with PBS and incubated with PKH26 dye (Sigma- Aldrich Co.) according to the manufacturer's instructions. After staining, cells were washed two times with RPMI/10% FCS. Cells were counted and mixed with CB15 0 effector cells. The resulting cell suspension contained 400,000 target and 2 x 10⁶ effector cells per ml. 50 μl of the mixture was used per well in a 96 well round bottom plate. Antibody constructs were diluted in RPMI/10% FCS to the required concentration and 50 μl of this solution were added to the cell suspension. A standard reaction was incubated for 16 h at 37°C / 5% C0₂. Propidium iodide was δ added to a final concentration of 1 μg/ml. After 10 min of incubation at room temperature, cells were analyzed by flow cytometry. PKH26 fluorescence was used for positive identification of target cells. Cytotoxicity was measured as ratio of PI positive over all target cells. Specific cytotoxicity mediated by the purified biscFv-constructs was plotted in 0 Figure 27. This figure shows the mediation of a significant specific cytotoxicity by the anti-human CD3 x anti-human EpCAM biscFvs as well as by the positive control M79 x CD3 (Mack Proc Nati Acad Sci USA 92 (1995), 7021-5) on EpCAM- transfected CHO-cells. No relevant specific lysis could be obtained on non- transfected CHO cells as well as in case of the CHO-EpCAM cells irrelevant biscFv 3-190 x anti CD19. In the cytotoxicity experiments shown in Figure 26 and 27 it is clearly demonstrated that the respective human anti-CD3 binders, combined with a target specificity in the context of a bispecific single chain construct, are able to mediate specific toxicity to target cells by recruiting CD3-positive effector cells. This not only corroborates the CD3 specificity of the respective human anti-CD3 constructs themselves, but also clearly demonstrates the retention of this specificity as well as T cell triggering potential within a bispecific single chain antibody format.

Claims

1. A method for the preparation of a human binding molecule, fragment or 5 derivative thereof which specifically binds to the human CD3 complex, said method comprising the steps of:

(a) selecting molecules specifically binding to/interacting with the extracellular domain of the recombinant ε-chain, expressed independent of the human CD3 complex in the absence of other 0 members of said CD3 complex, from a population of candidate polypeptides encoded by a library;

(c) preparation of said selected binding molecule. 6

2. The method of claim 1 , further comprising the step (d) identifying the nucleic acid sequence encoding said binding molecule in the library.

3. The method of claim 1 or 2, wherein the library which encodes the candidate 0 polypeptides is derived from a DNA-library or an RNA-library.

4. The method of any of claims 1 to 3, wherein the library which encodes the candidate polypeptides is derived from primary of secondary lymphatic organs of humans. δ

5. The method of any of claims 1 to 4, wherein the selection of the human binding molecules is effected by exposing the human binding molecules to immobilized recombinant, solely expressed ε- chain, expressed independent of the human CD3 complex in the absence of other members of said CD3 0 complex.

6. The method of any of claims 1 to 5, wherein said selection comprises a phage display method.

7. The method of any of claims 1 to 6, wherein said human binding molecule, δ fragment or derivative thereof is an antibody molecule, antibody fragment or derivative thereof or a construct comprising at least one antibody, antibody fragment or derivative thereof which specifically binds to the human CD3 complex.

0 8. The method of claim 7, wherein said derivative of an antibody is an scFv.

9. The method of claim 7 or 8, wherein said antibody molecule, antibody fragment, derivative thereof or construct comprises at least one further antigen-interaction-site and/or at least one further effector domain. 5

10. The method of claim 9, wherein said antibody molecule, antibody fragment, derivative thereof or construct is humanized and/or deimmunized in an additional step.

0 11. The method of claims 9 or 10, wherein said further antigen-interaction-site is specific for one or more cell surface molecule.

12. The method of claim 11 , wherein said cell surface molecule is a tumor specific marker. 5

13. The method of claims 9 to 12, wherein said at least one further antigen- interaction-site is a further scFv.

14. The method of claims 9 to 13, wherein said at least one further antigen- 0 interaction-site specifically binds to/interacts with an antigen selected from the group consisting of EpCAM, CCRδ, CD19, EphA2, HER-2 neu, HER-3,

HER-4, EGFR, PSMA, CEA, , MUC-1 (mucin), MUC2, MUC3, MUC4, MUCδ_AC, MUCδ_B, MUC7, βhCG, Lewis-Y, CD20, CD33, CD30, ganglioside GD3, 9-0-Acetyl-GD3, GM2, Globo H, fucosyl GM1, Poly SA, GD2, Carboanhydrase IX (MN/CA IX), CD44v6, Sonic Hedgehog (Shh), Wue-1 , Plasma Cell Antigen, (membrane-bound) IgE, Melanoma Chondroitin Sulfate Proteoglycan (MCSP), CCR8, TNF-alpha precursor, STEAP, mesothelin, A33 Antigen, Prostate Stem Cell Antigen (PSCA), Ly-6; desmoglein 4, E-cadherin neoepitope, Fetal Acetylcholine Receptor, CD25, CA19-9 marker, CA-125 marker and Muellerian Inhibitory Substance (MIS) Receptor type II, sTn (sialylated Tn antigen; TAG-72), FAP (fibroblast activation antigen), endosialin, EGFRvlll, LG, SAS and CD63.

15. The method of any of claims 2 to 14, further comprising the step of recombinant expression of the binding molecule, fragment or derivative thereof encoded by a nucleic acid sequence selected from the group consisting of:

(a) the identified nucleic acid sequence;

(b) a nucleic acid sequence hybridizing with the complementary strand of the nucleic identified nucleic acid sequence under stringent hybridization conditions; (c) a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (a) and (b).

16. The method of claim 1δ, wherein said step of recombinant expression of the binding molecule, fragment or derivative thereof encoded by a nucleic acid sequence comprises the preparation of a vector comprising said nucleic acid sequence.

17. The method of claim 16, wherein said vector further comprises a nucleic acid sequence which is a regulatory sequence operably linked to said identified nucleic acid sequence.

18. The method of claim 16 or 17, wherein the vector is an expression vector.

19. The method of any of claims 16 to 18, further comprising the step of transforming a host with said vector.

5 20. The method of any of claims 15 to 19, further comprising the step of isolation and/or purification of the recombinantly expressed human binding molecule, fragment or derivative thereof.

21. The method of any of claims 1 to 20, further comprising the step of 0 formulating the human binding molecule as a pharmaceutical composition, which optionally further comprises a pharmaceutically acceptable carrier or diluent.

22. A human binding molecule specifically binding to/interacting with the human 5 CD3 complex, whereby said binding molecule is an antibody molecule, antibody fragment or derivative thereof or an antibody construct.

23. The human binding molecule of claim 22, wherein said derivative of an antibody is an scFv. 0

24. The human binding molecule according to claim 22 or 23, wherein said antibody molecule, antibody fragment or derivative thereof or an antibody construct, comprises a variable V_H-region as encoded by a nucleic acid molecule as shown in a SEQ ID NO selected from the group consisting of δ SEQ ID NOs: 1 ,17, 33, 49, 66, 81 , 97 and 113 or a variable V_H-region having an amino acid sequence as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 2, 18, 34, 60, 66, 82, 98 and 114.

25. The human binding molecule according to claim 22 or 23, wherein said 0 antibody molecule, antibody fragment or derivative thereof or an antibody construct, comprises a variable V_L-region as encoded by a nucleic acid molecule as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 9, 26, 41, 57, 73, 89, 105 and 121 or a variable V -region having an amino acid sequence as shown in a SEQ ID NO selected from the group consisting of SEQ ID NOs: 10, 26, 42, 68, 74, 90, 106 and 122.

δ 26. The human binding molecule according to any of claims 22 to 2δ, wherein said antibody molecule, antibody fragment or derivative thereof or an antibody construct, comprises at least one CDR3 of an Vn-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 7, 23, 39, 65, 71 , 87, 103 or 119 or at least one CDR3 amino acid sequence of an VH- 0 region as shown in SEQ ID NOs: 8, 24, 40, 56, 72, 88, 104 or 120 and/or wherein said antibody molecule comprises at least one CDR3 of an VL- region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 15, 31, 47, 63, 79, 95, 111 or 127 or at least one CDR3 amino acid sequence of an V_L-region as shown in SEQ ID NOs: 16, 32, 48, 64, 80, 96, 112 or 128. 5

27. The human binding molecule according to any of claims 22 to 25, wherein said antibody molecule, antibody fragment or derivative thereof or an antibody construct, comprises at least one CDR2 of an V_H-region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 5, 21 , 37, 63, 0 69, 86, 101 or 117 or at least one CDR2 amino acid sequence of an VH- region as shown in SEQ ID NOs: 6, 22, 38, 54, 70, 86, 102 or 118 and/or wherein said antibody molecule comprises at least one CDR2 of an VL- region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 13, 29, 46, 61, 77, 93, 109 or 125 or at least one CDR2 amino acid sequence of 5 an V_L-region as shown in SEQ ID NOs: 14, 30, 46, 62, 78, 94, 110 or 126.

28. The human binding molecule according to any of claims 22 to 25, wherein said antibody molecule, antibody fragment or derivative thereof or an antibody construct, comprises at least one CDR1 of an Vπ-region as 0 encoded by a nucleic acid molecule as shown in SEQ ID NOs: 3, 19, 3δ, 61 ,

67, 83, 99 or 115 or at least one CDR1 amino acid sequence of an V_H- region as shown in SEQ ID NOs: 4, 20, 36, 52, 68, 84, 100 or 116 and/or wherein said antibody molecule comprises at least one CDR1 of an VL- region as encoded by a nucleic acid molecule as shown in SEQ ID NOs: 11 , 27, 43, 59, 75, 91, 107 or 123 or at least one CDR1 amino acid sequence of an V_L-region as shown in SEQ ID NOs: 12, 28, 44, 60, 76, 92, 108 or 124.

29. The human binding molecule according to any of claims 22 to 28, additionally comprising at least one further antigen-interaction-site and/or at least one further effector domain.

30. The human binding molecule according to claim 29, which is humanized and/or deimmunized.

31. The human binding molecule according to claim 29 or 30, wherein said at least one further antigen-interaction-site is specific for one or more cell surface molecule.

32. The human binding molecule according to claim 31 , wherein said cell surface molecule is a tumor specific marker.

33. The human binding molecule according to any of claims 29 to 32, wherein said at least one further antigen-interaction-site is a further scFv.

34. The human binding molecule according to any of claims 29 to 33, wherein said at least one further antigen-interaction-site specifically binds to/interacts with an antigen selected from the group consisting of EpCAM, CCRδ, CD19,

EphA2, HER-2 neu, HER-3, HER-4, EGFR, PSMA, CEA, , MUC-1 (mucin), MUC2, MUC3, MUC4, MUCδ_Ac, MUC6_B, MUC7, βhCG, Lewis-Y, CD20, CD33, CD30, ganglioside GD3, 9-0-Acetyl-GD3, GM2, Globo H, fucosyl GM1, Poly SA, GD2, Carboanhydrase IX (MN/CA IX), CD44v6, Sonic Hedgehog (Shh), Wue-1, Plasma Cell Antigen, (membrane-bound) IgE,

Melanoma Chondroitin Sulfate Proteoglycan (MCSP), CCR8, TNF-alpha precursor, STEAP, mesothelin, A33 Antigen, Prostate Stem Cell Antigen (PSCA), Ly-6; desmoglein 4, E-cadherin neoepitope, Fetal Acetylcholine Receptor, CD2δ, CA19-9 marker, CA-125 marker and Muellerian Inhibitory Substance (MIS) Receptor type II, sTn (sialylated Tn antigen; TAG-72), FAP (fibroblast activation antigen), endosialin, EGFRvlll, LG, SAS and CD63. 5

3δ. The human binding molecule according to claim 34, wherein said further antigen binding site specifically binds to/interacts with the CD19 molecule.

36. The human binding molecule according to claim 36, comprising an amino 0 acid sequence selected from the group of

(a) an amino acid sequence corresponding to construct 1prot to 64prot of table 2;

(b) (b) an amino acid sequence encoded by a nucleic acid sequence corresponding to construct 1nuc to 64nuc of table 1 ; 6 (c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in (b) under stringent hybridization conditions; and

(d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide 0 sequence of any one of (b) and (c).

37. The human binding molecule according to claim 34, wherein said further antigen binding site specifically binds to/interacts with the EpCAM molecule.

δ 38. The human binding molecule according to claim 37, comprising an amino acid sequence selected from the group of

(a) an amino acid sequence corresponding to construct 65prot to 128prot of table 4;

(b) an amino acid sequence encoded by a nucleic acid sequence 0 corresponding to construct 65nuc to 128nuc of in table 3;

(c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in (b) under stringent hybridization conditions;and (d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (b) and (c). 5

39. The human binding molecule according to claim 34, wherein said further antigen binding site specifically binds to/interacts with the CCRδ molecule.

40. The human binding molecule according to claim 39, comprising an amino 0 acid sequence selected from the group of

(a) an amino acid sequence corresponding to construct 129prot to 192prot of table 6;

(b) an amino acid sequence encoded by a nucleic acid sequence corresponding to construct 129nuc to 192nuc of table 5; δ (c) an amino acid sequence encoded by a nucleic acid sequence hybridizing with the complementary strand of a nucleic acid sequence as defined in

(b) under stringent hybridization conditions; and

(d) an amino acid sequence encoded by a nucleic acid sequence which is degenerate as a result of the genetic code to a nucleotide sequence of 0 any one of (b) and (c).

41. The human binding molecule according to claim 34, wherein said further antigen binding site specifically binds to/interacts with the CD20 molecule.

6 42. The human binding molecule according to claim 41, comprising an amino acid sequence selected from the group of

(a) an amino acid sequence corresponding to construct 193prot to 2δ6prot of table 8;

(b) an amino acid sequence encoded by a nucleic acid sequence 0 corresponding to construct 193nuc to 2δ6nuc of table 7;

43. The human binding molecule according to any of claim 22 to 42, wherein said binding molecule is obtainable by a method according to any of claims 1 to 21.

44. A nucleic acid sequence encoding a human binding molecule according to any of claims 22 to 42.

46. The nucleic acid molecule of claim 44 comprising a nucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding the mature form of a protein comprising the amino acid sequence of human binding molecule of the invention, preferably as given in SEQ ID Nos: 181, 183, 186, 187, 189, 191 , 193, 196, 206, 208, 210, 212, 214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 236, 238, 240, 242, 244, 246, 248, 260 or 262;

(b) a nucleotide sequence comprising or consisting of the DNA sequence as given in SEQ ID NOs: 180, 182, 184, 186, 188, 190, 192, 194, 20δ, 207, 209, 211, 213, 216, 217, 219, 221, 223, 226, 227, 229, 231, 233, 236, 237, 239, 241, 243, 245, 247, 249 or 251; (c) a nucleotide sequence hybridizing with the complementary strand of a nucleotide sequence as defined in (b) under stringent hybridization conditions;

(e) a nucleotide sequence encoding a protein having an amino acid sequence at least 60 % identical to the amino acid sequence encoded by the nucleotide sequence of (a) or (b); (f) a nucleotide sequence which is degenerate as a result of the genetic code to a nucleotide sequence of any one of (a) to (e);

46. A vector comprising a nucleic acid sequence according to claim 44 or 45.

47. The vector of claim 46, which further comprises a nucleic acid sequence which is a regulatory sequence operably linked to said nucleic acid sequence according to claim 44 or 45.

48. The vector of claim 46 or 47, wherein the vector is an expression vector.

49. A host transformed or transfected with a vector according to any of claims 46 to 48.

50. A process for the production of a human binding molecule according to any of claims 22 to 42 said process comprising culturing a host of claim 49 under conditions allowing the expression of the polypeptide construct and recovering the produced polypeptide construct from the culture.

51. A composition comprising a human binding molecule according to any of claims 22 to 42 or as produced by the process of claim 50, a nucleic acid molecule of claim 44 or 45, a vector of any one of claims 46 to 48 or a host of claim 49 and, optionally, a proteinaceous compound capable of providing an activation signal for immune effector cells.

52. The composition of claim 51 which is a pharmaceutical composition further comprising, optionally, suitable formulations of carrier, stabilizers and/or excipients.

53. The composition of claim 51 which is a diagnostic composition further comprising, optionally, means and methods for detection.

54. Use of a human binding molecule according to any of claims 22 to 42 or as produced by the process of claim 50, a nucleic acid molecule of claim 44 or

45, a vector of any one of claims .46 to 48 or a host of claim 49 for the preparation of a pharmaceutical composition for the prevention, treatment or amelioration of a proliferative disease, a tumorous disease, an inflammatory disease, an immunological disorder, an autoimmune disease, an infectious disease, viral disease, allergic reactions, parasitic reactions, graft-versus- host diseases or host-versus-graft diseases.

55. A method for the prevention, treatment or amelioration a proliferative disease, a tumorous disease, an inflammatory disease, an immunological disorder, an autoimmune disease, an infectious disease, viral disease, allergic reactions, parasitic reactions, graft-versus-host diseases or host- versus-graft diseases in a subject in the need thereof, said method comprising the step of administration of an effective amount a human binding molecule according to any of claims 22 to 42 or as produced by the process of claim 50, a nucleic acid molecule of claim 44 or 45, a vector of any one of claims 46 to 48 or a host of claim 49.

56. The method of claim 55, wherein said subject is a human.

57. The method of claim 55 or 56 further comprising, the administration of a proteinaceous compound capable of providing an activation signal for immune effector cells.

58. The method of claim 57, wherein said proteinaceous compound is administered simultaneously or non-simultaneously with a human binding molecule according to any of claims 22 to 42 or as produced by the process of claim 50, a nucleic acid molecule of claim 44 or 45, a vector of any one of claims 46 to 48 or a host of claim 49.

59. A kit comprising a human binding molecule according to any of claims 22 to 42 or as produced by the process of claim 50, a nucleic acid molecule of claim 44 or 45, a vector of any one of claims 46 to 48 or a host of claim 49.

BsiWI ^•

R D A A P T V S I F P P S S E Q L T S ^• 1 CGTACGGATG GTGCACCAAC. TGTATCCATC TTCCCACCAT CCAGTGAGCA GTTAACATCT GCATGCCTAC GACGTGGTTG ACATAGGTAG AAGGGTGGTA GGTCACTCGT CAATTGTAGA

G G A S V V C F L N N F Y P. D I N V 61. GGAGGTGCCT CAGTCGTGTG CTTCTTGAAC AACTTCTACC CCAAAGACAT CAATGTCAAG CCTCCACGGA GTCAGCACAC GAAGAACTTG TTGAAGATGG GGTTTCTGTA GTTACAGTTC I D G S Ξ R Q . N G V N S W T D Q D _.. .121 TGGAAGATTG ATGGCAGTGA ACGACAAAAT GGCGTCCTGA ACAGTTGGAC TGATCAGGAC σ> •' ACCTTCTAAC TACCGTCACT TGCTGTTTTA CCGCAGGACT TGTCAACCTG ACTAGTCCTG

S K- D* -S ^• .T. Y^' S M S St T L T L . T K D E Y E 181 AGCAAAGACA GCACCTACAG CATGAGCAGC ACCCTCACGT TGACCAAGGA CGAGTATGAA TCGTTTCTGT CGTGGATGTC GTACTCGTCG TGGGAGTGCA ACTGGTTCCT GCTCATACTT

Fig.1