Patent Publication Number: US-2009226466-A1

Title: Therapeutic anti-her2 antibody fusion polypeptides

Description:
This is a non-provisional application claiming priority under 35 USC §119 to provisional application No. 60/733, 441 filed 3 Nov. 2005, the entire disclosure of which is hereby incorporated by reference. 
    
    
     FIELD OF INVENTION 
     The invention relates to fusion polypeptides comprising an anti-HER2 antibody and the NKG2D ligand MicB, which are effective for killing of targeted tumor cells. 
     BACKGROUND OF INVENTION 
     Conventional cancer chemotherapy lacks specificity resulting in general toxicity and target cell drug resistance. In contrast, targeted, tumor-specific immunotherapy, such as passive antibody-mediated immunotherapy, provides targeted killing of tumor cells via delivery of antibodies directed against tumor-specific antigens. 
     An example of targeted immunotherapy is treatment with anti-HER2 monoclonal antibodies directed against the ErbB2 (HER2) tumor antigen. HER2 amplification/overexpression is an early event in breast cancer that is associated with aggressive disease and poor prognosis. HER2 gene amplification is found in 20-25% of primary breast tumors (Slamon et al. Science 244:707-12 (1989); Owens et al. Breast Cancer Res Treat 76:S68 abstract 236 (2002)). HER2 positive disease correlates with decreased relapse-free and overall survival (Slamon et al. Science 235:177-82 (1987); Pauletti et al. J Clin Oncol 18:3651-64 (2000)). Amplification of the HER2 gene is associated with significantly reduced time to relapse and poor survival in node-positive disease (Slamon et al. (1987); Pauletti et al. (2000)) and poor outcome in node-negative disease (Press et al. J Clin Oncol 1997; 15:2894-904 (1997); Pauletti et al. (2000)). A recombinant humanized version of the murine HER2 antibody 4D5 (huMAb4D5-8, rhuMAb HER2, trastuzumab or HERCEPTIN®; U.S. Pat. No. 5,821,337) is clinically active in patients with HER2-overexpressing metastatic breast cancers that have received extensive prior anti-cancer therapy (Baselga et al., J. Clin. Oncol. 14:737-744 (1996)). 
     Novel and more effective therapies are needed to enhance the effectiveness of anti-HER2 antibodies for cancer treatment. 
     SUMMARY OF THE INVENTION 
     The invention relates to fusion polypeptides comprising an anti-HER2 antibody and the NK cell activator MicB as well as methods for their production and therapeutic use. The invention is based, in part, on the discovery that fusion polypeptides of anti-HER2 antibody and MicB exhibit enhanced cell killing of HER2-expressing cells. Thus, these molecules may be used to enhance the effectiveness of anti-HER2 antibodies for cancer treatment. 
     In one aspect, the invention provides a fusion polypeptide comprising an anti-HER2 antibody or an antigen-binding fragment and MICB or a fragment that binds the NKG2D receptor. In some embodiments, the fusion polypeptide further comprises a linker between the antibody or antigen-binding fragment and MICB or fragment. In some embodiments, the linker comprises the amino acid sequence GGGGS (SEQ ID NO: 5). 
     In some embodiments, the fusion polypeptide comprises the extracellular domain of MICB. In some embodiments, the fusion polypeptide comprises at least two copies of MICB or a fragment. In some embodiments, the fusion polypeptide comprises one copy of MICB or a fragment on each heavy chain of the antibody or antigen-binding fragment. In some embodiments, the activating polypeptide is fused to the carboxy terminus of the antibody. 
     In some embodiments, the antibody is a monoclonal antibody. In some embodiments, the antibody is humanized. In some embodiments, the monoclonal antibody is selected from the group consisting of: huMAb4D5-1, huMAb4D5-2, huMAb4D5-3, huMAb4D5-4, huMAb4D5-5, huMAb4D5-6, huMAb4D5-7, huMAb4D5-8 and trastuzumab. In some embodiments, the monoclonal antibody blocks binding of trastuzumab to HER2. 
     In some embodiments, the invention provides a pharmaceutical composition comprising a fusion polypeptide of the invention. 
     In some embodiments, the invention provides nucleic acid molecule encoding a fusion polypeptide of the invention. In some embodiments, the invention provides a vector comprising such a nucleic acid molecule. In some embodiments, the invention provides a host cell comprising such a nucleic acid molecule or vector. In some embodiments, the invention provides a method for producing a fusion polypeptide of the invention comprising culturing a host cell comprising such a nucleic acid molecule or vector. 
     In some embodiments, the invention provides a method of killing a cell expressing HER2 comprising exposing the cell to a fusion polypeptide of the invention in the presence of a natural killer cell. In some embodiments, the invention provides a method of treating a patient with a tumor comprising cells expressing HER2 comprising administering to the patient an effective amount of the fusion polypeptide or pharmaceutical composition of the invention. In some embodiments, these methods further comprise administering to the patient a growth inhibitory agent, a chemotherapeutic agent, an EGFR inhibitor, a tyrosine kinase inhibitor, or an anti-angiogenic agent. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the amino acid sequence of trastuzumab light chain (SEQ ID NO: 1). 
         FIG. 2  illustrates the amino acid sequence of trastuzumab heavy chain (SEQ ID NO: 2). 
         FIG. 3  illustrates the amino acid sequence of pertuzumab light chain (SEQ ID NO: 3). 
         FIG. 4  illustrates the amino acid sequence of pertuzumab heavy chain (SEQ ID NO: 4). 
         FIG. 5  illustrates Anti HER2-H60 fusion antibody binding to Her2 positive cells. 
         FIGS. 6   a  and  6   b  illustrate the cytotoxic activity of an anti-HER2-H60 fusion antibody against BT474 cells. 
         FIG. 7  illustrates the activity of the anti-HER2 fusion proteins in a BT474 xenograft model. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     I. Definitions 
     “Breast cancer” herein refers to cancer involving breast cells or tissue. 
     “Metastatic” breast cancer refers to cancer which has spread to parts of the body other than the breast and the regional lymph nodes. 
     “Nonmetastatic” breast cancer is cancer which is confined to the breast and/or regional lymph nodes. 
     The term “effective amount” refers to an amount of a drug or drug combination effective to treat cancer in the patient. The effective amount of the drug may reduce the number of cancer cells; reduce the tumor size; inhibit (i.e., slow to some extent and preferably stop) cancer cell infiltration into peripheral organs; inhibit (i.e., slow to some extent and preferably stop) tumor metastasis; inhibit, to some extent, tumor growth; and/or relieve to some extent one or more of the symptoms associated with the cancer. To the extent the drug may prevent growth and/or kill existing cancer cells, it may be cytostatic and/or cytotoxic. The effective amount may improve disease free survival (DFS), improve overall survival (OS), decrease likelihood of recurrence, extend time to recurrence, extend time to distant recurrence (i.e. recurrence outside of the breast), cure cancer, improve symptoms of breast cancer (e.g. as gauged using a breast cancer specific survey), reduce contralateral breast cancer, reduce appearance of second primary cancer, etc. 
     A “subject” or “patient” herein is a human subject or patient. 
     An antibody which “binds to HER2 Domain IV bound by trastuzumab (HERCEPTIN®)” binds to an epitope comprising or including residues from about 489-630 (SEQ ID NO:4) of HER2 ECD. The preferred such antibody is trastuzumab, or an affinity matured variant thereof, and/or comprising a variant Fc region (for instance with improved effector function). 
     An antibody which “blocks binding of trastuzumab (HERCEPTIN®) to HER2” is one which can be demonstrated to block trastuzumab&#39;s binding to HER2, or compete with trastuzumab for binding to HER2. Such antibodies may be identified using cross-blocking assays such as those described in  Antibodies, A Laboratory Manual , Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988); or Fendly et al.  Cancer Research  50: 1550-1558 (1990), for example. 
     The “trastuzumab (HERCEPTIN®) epitope” herein is the region in the extracellular domain of HER2 to which the antibody 4D5 (ATCC CRL 10463) or trastuzumab bind. This epitope is close to the transmembrane domain of HER2, and within Domain IV of HER2. To screen for antibodies which bind to this epitope, a cross-blocking assay such as that described in  Antibodies, A Laboratory Manual , Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988) or Fendly et al.  Cancer Research  50: 1550-1558 (1990), can be performed. Alternatively, epitope mapping can be performed to assess whether the antibody binds to the Trastuzumab epitope of HER2 (e.g. any one or more residues in the region from about residue 529 to about residue 625, inclusive of the HER2 ECD, residue numbering including signal peptide). One can also study the antibody-HER2 structure (Franklin et al.  Cancer Cell  5:317-328 (2004)) to see what epitope of HER2 is bound by the antibody. 
     For the purposes herein, “trastuzumab,” “HERCEPTIN®” and “huMAb4D5-8” refer to an antibody comprising the light and heavy chain amino acid sequences shown in  FIGS. 1 and 2 , respectively. 
     For the purposes herein, a “HER2 positive” cancer or tumor is one which expresses HER2 at a level which exceeds the level found on normal breast cells or tissue. Such HER2 positivity may be caused by HER2 gene amplification, and/or increased transcription and/or translation. HER2 positive tumors can be identified in various ways, for instance, by evaluating protein expression/overexpression (e.g. using the DAKO HERCEPTEST®) immunohistochemistry assay, by evaluating HER2 nucleic acid in the cell (for example via fluorescent in situ hybridization (FISH), see WO98/45479 published October, 1998, including as the Vysis PATHVISION® FISH assay; southern blotting; or polymerase chain reaction (PCR) techniques, including quantitative real time PCR (qRT-PCR)), by measuring shed antigen (e.g., HER extracellular domain) in a biological fluid such as serum (see, e.g., U.S. Pat. No. 4,933,294 issued Jun. 12, 1990; WO91/05264 published Apr. 18, 1991; U.S. Pat. No. 5,401,638 issued Mar. 28, 1995; and Sias et al.  J. Immunol. Methods  132: 73-80 (1990)), or by exposing cells within the body of the patient to an antibody which is optionally labeled with a detectable label, e.g. a radioactive isotope, and binding of the antibody to cells in the patient can be evaluated, e.g. by external scanning for radioactivity or by analyzing a biopsy taken from a patient previously exposed to the antibody. Moreover, HER2 positive cancer or tumor samples can be identified indirectly, for instance by evaluating downstream signaling mediated through HER2 receptor, gene expression profiling etc. 
     A HER2 antibody that “binds to a heterodimeric binding site” of HER2, binds to residues in domain II (and optionally also binds to residues in other of the domains of the HER2 extracellular domain, such as domains I and III), and can sterically hinder, at least to some extent, formation of a HER2-EGFR, HER2-HER3, or HER2-HER4 heterodimer. Franklin et al.  Cancer Cell  5:317-328 (2004) characterize the HER2-pertuzumab crystal structure, deposited with the RCSB Protein Data Bank (ID Code IS78), illustrating an exemplary antibody that binds to the heterodimeric binding site of HER2. 
     Protein “expression” refers to conversion of the information encoded in a gene into messenger RNA (mRNA) and then to the protein. 
     Herein, a sample or cell that “expresses” a protein of interest (such as HER2) is one in which mRNA encoding the protein, or the protein, including fragments thereof, is determined to be present in the sample or cell. 
     A “native sequence” polypeptide is one which has the same amino acid sequence as a polypeptide (e.g., HER receptor or HER ligand) derived from nature, including naturally occurring or allelic variants. Such native sequence polypeptides can be isolated from nature or can be produced by recombinant or synthetic means. Thus, a native sequence polypeptide can have the amino acid sequence of naturally occurring human polypeptide, murine polypeptide, or polypeptide from any other mammalian species. 
     The term “antibody” herein is used in the broadest sense and specifically covers monoclonal antibodies, polyclonal antibodies, multispecific antibodies (e.g. bispecific antibodies), and antibody fragments, so long as they exhibit the desired biological activity. 
     The term “monoclonal antibody” as used herein refers to an antibody from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical and/or bind the same epitope(s), except for possible variants that may arise during production of the monoclonal antibody, such variants generally being present in minor amounts. Such monoclonal antibody typically includes an antibody comprising a polypeptide sequence that binds a target, wherein the target-binding polypeptide sequence was obtained by a process that includes the selection of a single target binding polypeptide sequence from a plurality of polypeptide sequences. For example, the selection process can be the selection of a unique clone from a plurality of clones, such as a pool of hybridoma clones, phage clones or recombinant DNA clones. It should be understood that the selected target binding sequence can be further altered, for example, to improve affinity for the target, to humanize the target binding sequence, to improve its production in cell culture, to reduce its immunogenicity in vivo, to create a multispecific antibody, etc., and that an antibody comprising the altered target binding sequence is also a monoclonal antibody of this invention. In contrast to polyclonal antibody preparations which typically include different antibodies directed against different determinants (epitopes), each monoclonal antibody of a monoclonal antibody preparation is directed against a single determinant on an antigen. In addition to their specificity, the monoclonal antibody preparations are advantageous in that they are typically uncontaminated by other immunoglobulins. The modifier “monoclonal” indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method. For example, the monoclonal antibodies to be used in accordance with the present invention may be made by a variety of techniques, including, for example, the hybridoma method (e.g., Kohler et al.,  Nature,  256:495 (1975); Harlow et al.,  Antibodies: A Laboratory Manual , (Cold Spring Harbor Laboratory Press, 2nd ed. 1988); Hammerling et al., in: Monoclonal Antibodies and T-Cell Hybridomas 563-681, (Elsevier, N.Y., 1981)), recombinant DNA methods (see, e.g., U.S. Pat. No. 4,816,567), phage display technologies (see, e.g., Clackson et al.,  Nature,  352:624-628 (1991); Marks et al.,  J. Mol. Biol.,  222:581-597 (1991); Sidhu et al.,  J. Mol. Biol.  338(2):299-310 (2004); Lee et al.,  J. Mol. Biol.,  340(5):1073-1093 (2004); Fellouse,  Proc. Nat. Acad. Sci. USA  101(34):12467-12472 (2004); and Lee et al.  J. Immunol. Methods  284(1-2):119-132 (2004), and technologies for producing human or human-like antibodies in animals that have parts or all of the human immunoglobulin loci or genes encoding human immunoglobulin sequences (see, e.g., WO 1998/24893; WO 1996/34096; WO 1996/33735; WO 1991/10741; Jakobovits et al.,  Proc. Natl. Acad. Sci. USA,  90:2551 (1993); Jakobovits et al.,  Nature,  362:255-258 (1993); Bruggemann et al.,  Year in Immuno.,  7:33 (1993); U.S. Pat. Nos. 5,545,806; 5,569,825; 5,591,669 (all of GenPharm); U.S. Pat. No. 5,545,807; WO 1997/17852; U.S. Pat. Nos. 5,545,807; 5,545,806; 5,569,825; 5,625,126; 5,633,425; and 5,661,016; Marks et al.,  Bio/Technology,  10: 779-783 (1992); Lonberg et al.,  Nature,  368: 856-859 (1994); Morrison,  Nature,  368: 812-813 (1994); Fishwild et al.,  Nature Biotechnology,  14: 845-851 (1996); Neuberger,  Nature Biotechnology,  14: 826 (1996); and Lonberg and Huszar,  Intern. Rev. Immunol.,  13: 65-93 (1995)). 
     The monoclonal antibodies herein specifically include “chimeric” antibodies in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity (U.S. Pat. No. 4,816,567; and Morrison et al.,  Proc. Natl. Acad. Sci. USA,  81:6851-6855 (1984)). Chimeric antibodies of interest herein include “primatized” antibodies comprising variable domain antigen-binding sequences derived from a non-human primate (e.g. Old World Monkey, Ape etc) and human constant region sequences, as well as “humanized” antibodies. 
     “Humanized” forms of non-human (e.g., rodent) antibodies are chimeric antibodies that contain minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a hypervariable region of the recipient are replaced by residues from a hypervariable region of a non-human species (donor antibody) such as mouse, rat, rabbit or nonhuman primate having the desired specificity, affinity, and capacity. In some instances, framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies may comprise residues that are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see Jones et al.,  Nature  321:522-525 (1986); Riechmann et al.,  Nature  332:323-329 (1988); and Presta,  Curr. Op. Struct. Biol.  2:593-596 (1992). 
     Humanized HER2 antibodies include huMAb4D5-1, huMAb4D5-2, huMAb4D5-3, huMAb4D5-4, huMAb4D5-5, huMAb4D5-6, huMAb4D5-7 and huMAb4D5-8 or trastuzumab (HERCEPTIN®) as described in Table 3 of U.S. Pat. No. 5,821,337 expressly incorporated herein by reference; humanized 520C9 (WO93/21319); and humanized 2C4 antibodies such as pertuzumab as described herein. 
     Herein, “pertuzumab” and “OMNITARG™” refer to an antibody comprising the light and heavy chain amino acid sequences shown in  FIGS. 3 and 4 , respectively. 
     An “intact antibody” herein is one which comprises two antigen binding regions, and an Fc region. Preferably, the intact antibody has a functional Fc region. 
     “Antibody fragments” comprise a portion of an intact antibody, preferably comprising the antigen binding region thereof. Examples of antibody fragments include Fab, Fab′, F(ab′) 2 , and Fv fragments; diabodies; linear antibodies; single-chain antibody molecules; and multispecific antibodies formed from antibody fragment(s). 
     “Native antibodies” are usually heterotetrameric glycoproteins of about 150,000 daltons, composed of two identical light (L) chains and two identical heavy (H) chains. Each light chain is linked to a heavy chain by one covalent disulfide bond, while the number of disulfide linkages varies among the heavy chains of different immunoglobulin isotypes. Each heavy and light chain also has regularly spaced intrachain disulfide bridges. Each heavy chain has at one end a variable domain (V H ) followed by a number of constant domains. Each light chain has a variable domain at one end (V L ) and a constant domain at its other end. The constant domain of the light chain is aligned with the first constant domain of the heavy chain, and the light-chain variable domain is aligned with the variable domain of the heavy chain. Particular amino acid residues are believed to form an interface between the light chain and heavy chain variable domains. 
     The term “variable” refers to the fact that certain portions of the variable domains differ extensively in sequence among antibodies and are used in the binding and specificity of each particular antibody for its particular antigen. However, the variability is not evenly distributed throughout the variable domains of antibodies. It is concentrated in three segments called hypervariable regions both in the light chain and the heavy chain variable domains. The more highly conserved portions of variable domains are called the framework regions (FRs). The variable domains of native heavy and light chains each comprise four FRs, largely adopting a β-sheet configuration, connected by three hypervariable regions, which form loops connecting, and in some cases forming part of, the β-sheet structure. The hypervariable regions in each chain are held together in close proximity by the FRs and, with the hypervariable regions from the other chain, contribute to the formation of the antigen-binding site of antibodies (see Kabat et al.,  Sequences of Proteins of Immunological Interest,  5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)). The constant domains are not involved directly in binding an antibody to an antigen, but exhibit various effector functions, such as participation of the antibody in antibody dependent cellular cytotoxicity (ADCC). 
     The term “hypervariable region” when used herein refers to the amino acid residues of an antibody which are responsible for antigen-binding. The hypervariable region generally comprises amino acid residues from a “complementarity determining region” or “CDR” (e.g. residues 24-34 (L1), 50-56 (L2) and 89-97 (L3) in the light chain variable domain and 31-35 (H1), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain; Kabat et al.,  Sequences of Proteins of Immunological Interest,  5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)) and/or those residues from a “hypervariable loop” (e.g. residues 26-32 (L1), 50-52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (H1), 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain; Chothia and Lesk  J. Mol. Biol.  196:901-917 (1987)). “Framework Region” or “FR” residues are those variable domain residues other than the hypervariable region residues as herein defined. 
     Papain digestion of antibodies produces two identical antigen-binding fragments, called “Fab” fragments, each with a single antigen-binding site, and a residual “Fc” fragment, whose name reflects its ability to crystallize readily. Pepsin treatment yields an F(ab′) 2  fragment that has two antigen-binding sites and is still capable of cross-linking antigen. 
     “Fv” is the minimum antibody fragment which contains a complete antigen-recognition and antigen-binding site. This region consists of a dimer of one heavy chain and one light chain variable domain in tight, non-covalent association. It is in this configuration that the three hypervariable regions of each variable domain interact to define an antigen-binding site on the surface of the V H -V L  dimer. Collectively, the six hypervariable regions confer antigen-binding specificity to the antibody. However, even a single variable domain (or half of an Fv comprising only three hypervariable regions specific for an antigen) has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site. 
     The Fab fragment also contains the constant domain of the light chain and the first constant domain (CH1) of the heavy chain. Fab′ fragments differ from Fab fragments by the addition of a few residues at the carboxy terminus of the heavy chain CH1 domain including one or more cysteines from the antibody hinge region. Fab′-SH is the designation herein for Fab′ in which the cysteine residue(s) of the constant domains bear at least one free thiol group. F(ab′) 2  antibody fragments originally were produced as pairs of Fab′ fragments which have hinge cysteines between them. Other chemical couplings of antibody fragments are also known. 
     The “light chains” of antibodies from any vertebrate species can be assigned to one of two clearly distinct types, called kappa (κ) and lambda (λ), based on the amino acid sequences of their constant domains. 
     The term “Fc region” herein is used to define a C-terminal region of an immunoglobulin heavy chain, including native sequence Fc regions and variant Fc regions. Although the boundaries of the Fc region of an immunoglobulin heavy chain might vary, the human IgG heavy chain Fc region is usually defined to stretch from an amino acid residue at position Cys226, or from Pro230, to the carboxyl-terminus thereof. The C-terminal lysine (residue 447 according to the EU numbering system) of the Fc region may be removed, for example, during production or purification of the antibody, or by recombinantly engineering the nucleic acid encoding a heavy chain of the antibody. Accordingly, a composition of intact antibodies may comprise antibody populations with all K447 residues removed, antibody populations with no K447 residues removed, and antibody populations having a mixture of antibodies with and without the K447 residue. 
     Unless indicated otherwise, herein the numbering of the residues in an immunoglobulin heavy chain is that of the EU index as in Kabat et al.,  Sequences of Proteins of Immunological Interest,  5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991), expressly incorporated herein by reference. The “EU index as in Kabat” refers to the residue numbering of the human IgG1 EU antibody. 
     A “functional Fc region” possesses an “effector function” of a native sequence Fc region. Exemplary “effector functions” include Clq binding; complement dependent cytotoxicity; Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; down regulation of cell surface receptors (e.g. B cell receptor; BCR), etc. Such effector functions generally require the Fc region to be combined with a binding domain (e.g. an antibody variable domain) and can be assessed using various assays as herein disclosed, for example. 
     A “native sequence Fc region” comprises an amino acid sequence identical to the amino acid sequence of an Fc region found in nature. Native sequence human Fc regions include a native sequence human IgG1 Fc region (non-A and A allotypes); native sequence human IgG2 Fc region; native sequence human IgG3 Fc region; and native sequence human IgG4 Fc region as well as naturally occurring variants thereof. 
     A “variant Fc region” comprises an amino acid sequence which differs from that of a native sequence Fc region by virtue of at least one amino acid modification, preferably one or more amino acid substitution(s). Preferably, the variant Fc region has at least one amino acid substitution compared to a native sequence Fc region or to the Fc region of a parent polypeptide, e.g. from about one to about ten amino acid substitutions, and preferably from about one to about five amino acid substitutions in a native sequence Fc region or in the Fc region of the parent polypeptide. The variant Fc region herein will preferably possess at least about 80% homology with a native sequence Fc region and/or with an Fc region of a parent polypeptide, and most preferably at least about 90% homology therewith, more preferably at least about 95% homology therewith. 
     Depending on the amino acid sequence of the constant domain of their heavy chains, intact antibodies can be assigned to different “classes”. There are five major classes of intact antibodies: IgA, IgD, IgE, IgG, and IgM, and several of these may be further divided into “subclasses” (isotypes), e.g., IgG1, IgG2, IgG3, IgG4, IgA, and IgA2. The heavy-chain constant domains that correspond to the different classes of antibodies are called α, δ, ε, γ, and μ, respectively. The subunit structures and three-dimensional configurations of different classes of immunoglobulins are well known. 
     “Antibody-dependent cell-mediated cytotoxicity” and “ADCC” refer to a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) (e.g. Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and subsequently cause lysis of the target cell. The primary cells for mediating ADCC, NK cells, express FcγRIII only, whereas monocytes express FcγRI, FcγRII and FcγRIII. FcR expression on hematopoietic cells in summarized is Table 3 on page 464 of Ravetch and Kinet,  Annu. Rev. Immunol  9:457-92 (1991). To assess ADCC activity of a molecule of interest, an in vitro ADCC assay, such as that described in U.S. Pat. No. 5,500,362 or 5,821,337 may be performed. Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e.g., in a animal model such as that disclosed in Clynes et al.  PNAS  ( USA ) 95:652-656 (1998). 
     “Human effector cells” are leukocytes which express one or more FcRs and perform effector functions. Preferably, the cells express at least FcγRIII and perform ADCC effector function. Examples of human leukocytes which mediate ADCC include peripheral blood mononuclear cells (PBMC), natural killer (NK) cells, monocytes, cytotoxic T cells and neutrophils; with PBMCs and NK cells being preferred. The effector cells may be isolated from a native source thereof, e.g. from blood or PBMCs as described herein. 
     The terms “Fc receptor” or “FcR” are used to describe a receptor that binds to the Fc region of an antibody. The preferred FcR is a native sequence human FcR. Moreover, a preferred FcR is one which binds an IgG antibody (a gamma receptor) and includes receptors of the FcγRI, FcγRII, and Fcγ RIII subclasses, including allelic variants and alternatively spliced forms of these receptors. FcγRII receptors include FcγRIIA (an “activating receptor”) and FcγRIIB (an “inhibiting receptor”), which have similar amino acid sequences that differ primarily in the cytoplasmic domains thereof. Activating receptor FcγRIIA contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain. Inhibiting receptor FcγRIIB contains an immunoreceptor tyrosine-based inhibition motif (ITIM) in its cytoplasmic domain (see review M. in Daëron,  Annu. Rev. Immunol.  15:203-234 (1997)). FcRs are reviewed in Ravetch and Kinet,  Annu. Rev. Immunol  9:457-92 (1991); Capel et al.,  Immunomethods  4:25-34 (1994); and de Haas et al.,  J. Lab. Clin. Med.  126:330-41 (1995). Other FcRs, including those to be identified in the future, are encompassed by the term “FcR” herein. The term also includes the neonatal receptor, FcRn, which is responsible for the transfer of maternal IgGs to the fetus (Guyer et al.,  J. Immunol.  117:587 (1976) and Kim et al.,  J. Immunol.  24:249 (1994)), and regulates homeostasis of immunoglobulins. 
     “Complement dependent cytotoxicity” or “CDC” refers to the ability of a molecule to lyse a target in the presence of complement. The complement activation pathway is initiated by the binding of the first component of the complement system (Clq) to a molecule (e.g. an antibody) complexed with a cognate antigen. To assess complement activation, a CDC assay, e.g. as described in Gazzano-Santoro et al.,  J. Immunol. Methods  202:163 (1996), may be performed. 
     An “affinity matured” antibody is one with one or more alterations in one or more hypervariable regions thereof which result an improvement in the affinity of the antibody for antigen, compared to a parent antibody which does not possess those alteration(s). Preferred affinity matured antibodies will have nanomolar or even picomolar affinities for the target antigen. Affinity matured antibodies are produced by procedures known in the art. Marks et al.  Bio/Technology  10:779-783 (1992) describes affinity maturation by VH and VL domain shuffling. Random mutagenesis of CDR and/or framework residues is described by: Barbas et al.  Proc Nat. Acad. Sci, USA  91:3809-3813 (1994); Schier et al.  Gene  169:147-155 (1995); Yelton et al.  J. Immunol.  155:1994-2004 (1995); Jackson et al.,  J. Immunol.  154(7):3310-9 (1995); and Hawkins et al,  J. Mol. Biol.  226:889-896 (1992). 
     The term “main species antibody” herein refers to the antibody structure in a composition which is the quantitatively predominant antibody molecule in the composition. In one embodiment, the main species antibody is a HER2 antibody, such as an antibody that binds Domain IV of HER2 ECD bound by trastuzumab (HERCEPTIN®). The preferred embodiment herein of the main species antibody is one comprising the light chain and heavy chain amino acid sequences in SEQ ID Nos. 5 and 6 (trastuzumab). 
     A “glycosylation variant” antibody herein is an antibody with one or more carbohydrate moeities attached thereto which differ from one or more carbohydate moieties attached to a main species antibody. Examples of glycosylation variants herein include antibody with a G1 or G2 oligosaccharide structure, instead a G0 oligosaccharide structure, attached to an Fc region thereof, antibody with one or two carbohydrate moieties attached to one or two light chains thereof, antibody with no carbohydrate attached to one or two heavy chains of the antibody, etc, and combinations of glycosylation alterations. 
     Where the antibody has an Fc region, an oligosaccharide structure may be attached to one or two heavy chains of the antibody, e.g. at residue 299 (298, Eu numbering of residues). 
     A “deamidated” antibody is one in which one or more asparagine residues thereof has been derivitized, e.g. to an aspartic acid, a succinimide, or an iso-aspartic acid. 
     A “tumor sample” herein is a sample derived from, or comprising tumor cells from, a patient&#39;s tumor. Examples of tumor samples herein include, but are not limited to, tumor biopsies, circulating tumor cells, circulating plasma proteins, ascitic fluid, primary cell cultures or cell lines derived from tumors or exhibiting tumor-like properties, as well as preserved tumor samples, such as formalin-fixed, paraffin-embedded tumor samples or frozen tumor samples. 
     A “fixed” tumor sample is one which has been histologically preserved using a fixative. 
     A “formalin-fixed” tumor sample is one which has been preserved using formaldehyde as the fixative. 
     An “embedded” tumor sample is one surrounded by a firm and generally hard medium such as paraffin, wax, celloidin, or a resin. Embedding makes possible the cutting of thin sections for microscopic examination or for generation of tissue microarrays (TMAs). 
     A “paraffin-embedded” tumor sample is one surrounded by a purified mixture of solid hydrocarbons derived from petroleum. 
     Herein, a “frozen” tumor sample refers to a tumor sample which is, or has been, frozen. 
     Herein, “gene expression profiling” refers to an evaluation of expression of one or more genes as a surrogate for determining HER2 receptor expression directly. 
     A “phospho-ELISA assay” herein is an assay in which phosphorylation of one or more HER receptors, especially HER2, is evaluated in an enzyme-linked immunosorbent assay (ELISA) using a reagent, usually an antibody, to detect phosphorylated HER receptor, substrate, or downstream signaling molecule. Preferably, an antibody which detects phosphorylated HER2 is used. The assay may be performed on cell lysates, preferably from fresh or frozen biological samples. 
     A “growth inhibitory agent” when used herein refers to a compound or composition which inhibits growth of a cell, especially a HER expressing cancer cell either in vitro or in vivo. Thus, the growth inhibitory agent may be one which significantly reduces the percentage of HER expressing cells in S phase. Examples of growth inhibitory agents include agents that block cell cycle progression (at a place other than S phase), such as agents that induce G1 arrest and M-phase arrest. Classical M-phase blockers include the vincas (vincristine and vinblastine), taxoids, and topo II inhibitors such as doxorubicin, epirubicin, daunorubicin, etoposide, and bleomycin. Those agents that arrest G1 also spill over into S-phase arrest, for example, DNA alkylating agents such as tamoxifen, prednisone, dacarbazine, mechlorethamine, cisplatin, methotrexate, 5-fluorouracil, and ara-C. Further information can be found in  The Molecular Basis of Cancer , Mendelsohn and Israel, eds., Chapter 1, entitled “Cell cycle regulation, oncogenes, and antineoplastic drugs” by Murakami et al. (WB Saunders: Philadelphia, 1995), especially p. 13. 
     Examples of “growth inhibitory” antibodies are those which bind to HER2 and inhibit the growth of cancer cells overexpressing HER2. Preferred growth inhibitory HER2 antibodies inhibit growth of SK-BR-3 breast tumor cells in cell culture by greater than 20%, and preferably greater than 50% (e.g. from about 50% to about 100%) at an antibody concentration of about 0.5 to 30 μg/ml, where the growth inhibition is determined six days after exposure of the SK-BR-3 cells to the antibody (see U.S. Pat. No. 5,677,171 issued Oct. 14, 1997). The SK-BR-3 cell growth inhibition assay is described in more detail in that patent and hereinbelow. The preferred growth inhibitory antibody is a humanized variant of murine monoclonal antibody 4D5, e.g., trastuzumab. 
     An antibody which “induces apoptosis” is one which induces programmed cell death as determined by binding of annexin V, fragmentation of DNA, cell shrinkage, dilation of endoplasmic reticulum, cell fragmentation, and/or formation of membrane vesicles (called apoptotic bodies). The cell is usually one which overexpresses the HER2 receptor. Preferably the cell is a tumor cell, e.g. a breast, ovarian, stomach, endometrial, salivary gland, lung, kidney, colon, thyroid, pancreatic or bladder cell. In vitro, the cell may be a SK-BR-3, BT474, Calu 3 cell, MDA-MB-453, MDA-MB-361 or SKOV3 cell. Various methods are available for evaluating the cellular events associated with apoptosis. For example, phosphatidyl serine (PS) translocation can be measured by annexin binding; DNA fragmentation can be evaluated through DNA laddering; and nuclear/chromatin condensation along with DNA fragmentation can be evaluated by any increase in hypodiploid cells. Preferably, the antibody which induces apoptosis is one which results in about 2 to 50 fold, preferably about 5 to 50 fold, and most preferably about 10 to 50 fold, induction of annexin binding relative to untreated cell in an annexin binding assay using BT474 cells. Examples of HER2 antibodies that induce apoptosis are 7C2 and 7F3. See, in particular, WO98/17797. 
     “Treatment” refers to both therapeutic treatment and prophylactic or preventative measures. Those in need of treatment include those already with cancer as well as those in which cancer is to be prevented. Hence, the patient to be treated herein may have been diagnosed as having cancer or may be predisposed or susceptible to cancer. 
     The term “cytotoxic agent” as used herein refers to a substance that inhibits or prevents the function of cells and/or causes destruction of cells. The term is intended to include radioactive isotopes (e.g. At 211 , I 131 , I 125 , Y 90 , Re 186 , Re 188 , Sm 153 , Bi 212 , P 32  and radioactive isotopes of Lu), chemotherapeutic agents, and toxins such as small molecule toxins or enzymatically active toxins of bacterial, fungal, plant or animal origin, including fragments and/or variants thereof. 
     A “chemotherapeutic agent” is a chemical compound useful in the treatment of cancer. Examples of chemotherapeutic agents include alkylating agents such as thiotepa and cyclosphosphamide (CYTOXAN®); alkyl sulfonates such as busulfan, improsulfan and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines including altretamine, triethylenemelamine, trietylenephosphoramide, triethiylenethiophosphoramide and trimethylolomelamine; acetogenins (especially bullatacin and bullatacinone); delta-9-tetrahydrocannabinol (dronabinol, MARINOL®); beta-lapachone; lapachol; colchicines; betulinic acid; a camptothecin (including the synthetic analogue topotecan (HYCAMTIN®), CPT-11 (irinotecan, CAMPTOSAR®), acetylcamptothecin, scopolectin, and 9-aminocamptothecin); bryostatin; callystatin; CC-1065 (including its adozelesin, carzelesin and bizelesin synthetic analogues); podophyllotoxin; podophyllinic acid; teniposide; cryptophycins (particularly cryptophycin 1 and cryptophycin 8); dolastatin; duocarmycin (including the synthetic analogues, KW-2189 and CB1-TM1); eleutherobin; pancratistatin; a sarcodictyin; spongistatin; nitrogen mustards such as chlorambucil, chlornaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide, uracil mustard; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine; antibiotics such as the enediyne antibiotics (e.g., calicheamicin, especially calicheamicin gamma1I and calicheamicin omegaI1 (see, e.g., Agnew,  Chem Intl. Ed. Engl.,  33: 183-186 (1994)); dynemicin, including dynemicin A; an esperamicin; as well as neocarzinostatin chromophore and related chromoprotein enediyne antiobiotic chromophores), aclacinomysins, actinomycin, authramycin, azaserine, bleomycins, cactinomycin, carabicin, caminomycin, carzinophilin, chromomycinis, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin (including ADRIAMYCIN®, morpholino-doxorubicin, cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin, doxorubicin HCl liposome injection (DOXIL®), liposomal doxorubicin TLC D-99 (MYOCET®), peglylated liposomal doxorubicin (CAELYX®), and deoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins such as mitomycin C, mycophenolic acid, nogalamycin, olivomycins, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; anti-metabolites such as methotrexate, gemcitabine (GEMZAR®), tegafur (UFTORAL®), capecitabine (XELODA®), an epothilone, and 5-fluorouracil (5-FU); folic acid analogues such as denopterin, methotrexate, pteropterin, trimetrexate; purine analogs such as fludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine; anti-adrenals such as aminoglutethimide, mitotane, trilostane; folic acid replenisher such as frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil; amsacrine; bestrabucil; bisantrene; edatraxate; defofamine; demecolcine; diaziquone; elformithine; elliptinium acetate; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoids such as maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol; nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone; 2-ethylhydrazide; procarbazine; PSK® polysaccharide complex (JHS Natural Products, Eugene, Oreg.); razoxane; rhizoxin; sizofiran; spirogermanium; tenuazonic acid; triaziquone; 2,2′,2″-trichlorotriethylamine; trichothecenes (especially T-2 toxin, verracurin A, roridin A and anguidine); urethan; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside (“Ara-C”); thiotepa; taxoid, e.g., paclitaxel (TAXOL®), albumin-engineered nanoparticle formulation of paclitaxel (ABRAXANE™), and docetaxel (TAXOTERE®); chloranbucil; 6-thioguanine; mercaptopurine; methotrexate; platinum agents such as cisplatin, oxaliplatin, and carboplatin; vincas, which prevent tubulin polymerization from forming microtubules, including vinblastine (VELBAN®), vincristine (ONCOVIN®), vindesine (ELDISINE®, FILDESIN®), and vinorelbine (NAVELBINE®); etoposide (VP-16); ifosfamide; mitoxantrone; leucovovin; novantrone; edatrexate; daunomycin; aminopterin; ibandronate; topoisomerase inhibitor RFS 2000; difluoromethylornithine (DMFO); retinoids such as retinoic acid, including bexarotene (TARGRETIN®); bisphosphonates such as clodronate (for example, BONEFOS® or OSTAC®), etidronate (DIDROCAL®), NE-58095, zoledronic acid/zoledronate (ZOMETA®), alendronate (FOSAMAX®), pamidronate (AREDIA®), tiludronate (SKELID®), or risedronate (ACTONEL®); troxacitabine (a 1,3-dioxolane nucleoside cytosine analog); antisense oligonucleotides, particularly those that inhibit expression of genes in signaling pathways implicated in aberrant cell proliferation, such as, for example, PKC-alpha, Raf, H-Ras, and epidermal growth factor receptor (EGF-R); vaccines such as THERATOPE® vaccine and gene therapy vaccines, for example, ALLOVECTIN® vaccine, LEUVECTIN® vaccine, and VAXID® vaccine; topoisomerase 1 inhibitor (e.g., LURTOTECAN®); rmRH (e.g., ABARELIX®); BAY439006 (sorafenib; Bayer); SU-11248 (Pfizer); perifosine, COX-2 inhibitor (e.g. celecoxib or etoricoxib), proteosome inhibitor (e.g. PS341); bortezomib (VELCADE®); CCI-779; tipifarnib (R11577); orafenib, ABT510; Bcl-2 inhibitor such as oblimersen sodium (GENASENSE®); pixantrone; EGFR inhibitors (see definition below); tyrosine kinase inhibitors (see definition below); and pharmaceutically acceptable salts, acids or derivatives of any of the above; as well as combinations of two or more of the above such as CHOP, an abbreviation for a combined therapy of cyclophosphamide, doxorubicin, vincristine, and prednisolone, and FOLFOX, an abbreviation for a treatment regimen with oxaliplatin (ELOXATIN™) combined with 5-FU and leucovovin. 
     Herein, chemotherapeutic agents include “anti-hormonal agents” or “endocrine therapeutics” which act to regulate, reduce, block, or inhibit the effects of hormones that can promote the growth of cancer. They may be hormones themselves, including, but not limited to: anti-estrogens with mixed agonist/antagonist profile, including, tamoxifen (NOLVADEX®), 4-hydroxytamoxifen, toremifene (FARESTON®), idoxifene, droloxifene, raloxifene (EVISTA®), trioxifene, keoxifene, and selective estrogen receptor modulators (SERMs) such as SERM3; pure anti-estrogens without agonist properties, such as fulvestrant (FASLODEX®), and EM800 (such agents may block estrogen receptor (ER) dimerization, inhibit DNA binding, increase ER turnover, and/or suppress ER levels); aromatase inhibitors, including steroidal aromatase inhibitors such as formestane and exemestane (AROMASIN®), and nonsteroidal aromatase inhibitors such as anastrazole (ARIMIDEX®), letrozole (FEMARA®) and aminoglutethimide, and other aromatase inhibitors include vorozole (RIVISOR®), megestrol acetate (MEGASE®), fadrozole, and 4(5)-imidazoles; lutenizing hormone-releasing hormone agonists, including leuprolide (LUPRON® and ELIGARD®), goserelin, buserelin, and tripterelin; sex steroids, including progestines such as megestrol acetate and medroxyprogesterone acetate, estrogens such as diethylstilbestrol and premarin, and androgens/retinoids such as fluoxymesterone, all transretionic acid and fenretinide; onapristone; anti-progesterones; estrogen receptor down-regulators (ERDs); anti-androgens such as flutamide, nilutamide and bicalutamide; and pharmaceutically acceptable salts, acids or derivatives of any of the above; as well as combinations of two or more of the above. 
     Herein, a “taxoid” is a chemotherapeutic agent that functions to inhibit microtubule depolymerization. Examples include paclitaxel (TAXOL®), albumin-engineered nanoparticle formulation of paclitaxel (ABRAXANE™), and docetaxel (TAXOTERE®). The preferred taxoid is paclitaxel. 
     As used herein, the term “EGFR inhibitor” refers to compounds that bind to or otherwise interact directly with EGFR and prevent or reduce its signaling activity, and is alternatively referred to as an “EGFR antagonist.” Examples of such agents include antibodies and small molecules that bind to EGFR. Examples of antibodies which bind to EGFR include MAb 579 (ATCC CRL HB 8506), MAb 455 (ATCC CRL HB8507), MAb 225 (ATCC CRL 8508), MAb 528 (ATCC CRL 8509) (see, U.S. Pat. No. 4,943,533, Mendelsohn et al.) and variants thereof, such as chimerized 225 (C225 or Cetuximab; ERBUTIX®) and reshaped human 225 (H225) (see, WO 96/40210, Imclone Systems Inc.); IMC-11F8, a fully human, EGFR-targeted antibody (Imclone); antibodies that bind type II mutant EGFR (U.S. Pat. No. 5,212,290); humanized and chimeric antibodies that bind EGFR as described in U.S. Pat. No. 5,891,996; and human antibodies that bind EGFR, such as ABX-EGF or Panitumumab (see WO98/50433, Abgenix/Amgen); EMD 55900 (Stragliotto et al.  Eur. J. Cancer  32A:636-640 (1996)); EMD7200 (matuzumab) a humanized EGFR antibody directed against EGFR that competes with both EGF and TGF-alpha for EGFR binding (EMD/Merck); human EGFR antibody, HuMax-EGFR (GenMab); fully human antibodies known as E1.1, E2.4, E2.5, E6.2, E6.4, E2.11, E6.3 and E7.6.3 and described in U.S. Pat. No. 6,235,883; MDX-447 (Medarex Inc); and mAb 806 or humanized mAb 806 (Johns et al.,  J. Biol. Chem.  279(29):30375-30384 (2004)). The anti-EGFR antibody may be conjugated with a cytotoxic agent, thus generating an immunoconjugate (see, e.g., EP659,439A2, Merck Patent GmbH). EGFR antagonists include small molecules such as compounds described in U.S. Pat. Nos. 5,616,582, 5,457,105, 5,475,001, 5,654,307, 5,679,683, 6,084,095, 6,265,410, 6,455,534, 6,521,620, 6,596,726, 6,713,484, 5,770,599, 6,140,332, 5,866,572, 6,399,602, 6,344,459, 6,602,863, 6,391,874, 6,344,455, 5,760,041, 6,002,008, and 5,747,498, as well as the following PCT publications: WO98/14451, WO98/50038, WO99/09016, and WO99/24037. Particular small molecule EGFR antagonists include OSI-774 (CP-358774, erlotinib, TARCEVA® Genentech/OSI Pharmaceuticals); PD 183805 (CI 1033, 2-propenamide, N-[4-[(3-chloro-4-fluorophenyl)amino]-7-[3-(4-morpholinyl)propoxy]-6-quinazolinyl]-, dihydrochloride, Pfizer Inc.); ZD1839, gefitinib (IRESSA™) 4-(3′-Chloro-4′-fluoroanilino)-7-methoxy-6-(3-morpholinopropoxy)quinazoline, AstraZeneca); ZM 105180 ((6-amino-4-(3-methylphenyl-amino)-quinazoline, Zeneca); BIBX-1382 (N8-(3-chloro-4-fluoro-phenyl)-N2-(1-methyl-piperidin-4-yl)-pyrimido[5,4-d]pyrimidine-2,8-diamine, Boehringer Ingelheim); PKI-166 ((R)-4-[4-[(1-phenylethyl)amino]-1H-pyrrolo[2,3-d]pyrimidin-6-yl]-phenol); (R)-6-(4-hydroxyphenyl)-4-[(1-phenylethyl)amino]-7H-pyrrolo[2,3-d]pyrimidine); CL-387785 (N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide); EKB-569 (N-[4-[(3-chloro-4-fluorophenyl)amino]-3-cyano-7-ethoxy-6-quinolinyl]-4-(dimethylamino)-2-butenamide) (Wyeth); AG1478 (Sugen); AG1571 (SU 5271; Sugen); dual EGFR/HER2 tyrosine kinase inhibitors such as lapatinib (GW 572016 or N-[3-chloro-4-[(3 fluorophenyl)methoxy]phenyl]6[5[[[2methylsulfonyl)ethyl]amino]methyl]-2-furanyl]-4-quinazolinamine; Glaxo-SmithKline). 
     A “tyrosine kinase inhibitor” is a molecule which inhibits tyrosine kinase activity of a tyrosine kinase such as a HER receptor. Examples of such inhibitors include the EGFR-targeted drugs noted in the preceding paragraph; small molecule HER2 tyrosine kinase inhibitor such as TAK165 available from Takeda; CP-724,714, an oral selective inhibitor of the ErbB2 receptor tyrosine kinase (Pfizer and OSI); dual-HER inhibitors such as EKB-569 (available from Wyeth) which preferentially binds EGFR but inhibits both HER2 and EGFR-overexpressing cells; lapatinib (GW572016; available from Glaxo-SmithKline) an oral HER2 and EGFR tyrosine kinase inhibitor; PKI-166 (available from Novartis); pan-HER inhibitors such as canertinib (CI-1033; Pharmacia); Raf-1 inhibitors such as antisense agent ISIS-5132 available from ISIS Pharmaceuticals which inhibits Raf-1 signaling; non-HER targeted TK inhibitors such as Imatinib mesylate (GLEEVEC®) available from Glaxo; MAPK extracellular regulated kinase I inhibitor CI-1040 (available from Pharmacia); quinazolines, such as PD 153035,4-(3-chloroanilino) quinazoline; pyridopyrimidines; pyrimidopyrimidines; pyrrolopyrimidines, such as CGP 59326, CGP 60261 and CGP 62706; pyrazolopyrimidines, 4-(phenylamino)-7H-pyrrolo[2,3-d]pyrimidines; curcumin (diferuloyl methane, 4,5-bis(4-fluoroanilino)phthalimide); tyrphostines containing nitrothiophene moieties; PD-0183805 (Warner-Lamber); antisense molecules (e.g. those that bind to HER-encoding nucleic acid); quinoxalines (U.S. Pat. No. 5,804,396); tryphostins (U.S. Pat. No. 5,804,396); ZD6474 (Astra Zeneca); PTK-787 (Novartis/Schering AG); pan-HER inhibitors such as CI-1033 (Pfizer); Affinitac (ISIS 3521; Isis/Lilly); Imatinib mesylate (Gleevac; Novartis); PKI 166 (Novartis); GW2016 (Glaxo SmithKline); CI-1033 (Pfizer); EKB-569 (Wyeth); Semaxinib (Sugen); ZD6474 (AstraZeneca); PTK-787 (Novartis/Schering AG); INC-1C11 (Imclone); or as described in any of the following patent publications: U.S. Pat. No. 5,804,396; WO99/09016 (American Cyanamid); WO98/43960 (American Cyanamid); WO97/38983 (Warner Lambert); WO99/06378 (Warner Lambert); WO99/06396 (Warner Lambert); WO96/30347 (Pfizer, Inc); WO96/33978 (Zeneca); WO96/3397 (Zeneca); and WO96/33980 (Zeneca). 
     Herein, “standard of care” chemotherapy refers to the chemotherapeutic agents routinely used to treat a particular cancer. For example, for operable breast cancer, including node positive breast cancer, the standard of care adjuvant therapy can be anthracycline/cyclophosphamide (AC) chemotherapy, cyclophosphamide, methotrexate, fluorouracil (CMF) chemotherapy, fluorouracil, anthracycline and cyclophosphamide (FAC) chemotherapy, or AC followed by paclitaxel (T) (AC→T). For the patients described in the examples herein, “standard of care” has been AC→T treatment. 
     Where an anti-cancer agent, such as HERCEPTIN®, is administered as a “single agent” it is the only agent administered to the subject, during a treatment regimen, to treat the cancer, i.e. the agent is not provided in combination with other anti-cancer agents. However, such treatment includes the administration of other anti-cancer agents substantially prior to, or following, administration of the anti-cancer agent. 
     An “anti-angiogenic agent” refers to a compound which blocks, or interferes with to some degree, the development of blood vessels. The anti-angiogenic factor may, for instance, be a small molecule or antibody that binds to a growth factor or growth factor receptor involved in promoting angiogenesis. The preferred anti-angiogenic factor herein is an antibody that binds to vascular endothelial growth factor (VEGF), such as bevacizumab (AVASTIN®). 
     The term “cytokine” is a generic term for proteins released by one cell population which act on another cell as intercellular mediators. Examples of such cytokines are lymphokines, monokines, and traditional polypeptide hormones. Included among the cytokines are growth hormone such as human growth hormone, N-methionyl human growth hormone, and bovine growth hormone; parathyroid hormone; thyroxine; insulin; proinsulin; relaxin; prorelaxin; glycoprotein hormones such as follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), and luteinizing hormone (LH); hepatic growth factor; fibroblast growth factor; prolactin; placental lactogen; tumor necrosis factor-α and -β; mullerian-inhibiting substance; mouse gonadotropin-associated peptide; inhibin; activin; vascular endothelial growth factor; integrin; thrombopoietin (TPO); nerve growth factors such as NGF-β; platelet-growth factor; transforming growth factors (TGFs) such as TGF-α and TGF-β; insulin-like growth factor-I and -II; erythropoietin (EPO); osteoinductive factors; interferons such as interferon-α, -β, and -γ; colony stimulating factors (CSFs) such as macrophage-CSF (M-CSF); granulocyte-macrophage-CSF (GM-CSF); and granulocyte-CSF (G-CSF); interleukins (ILs) such as IL-1, IL-1α, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12; a tumor necrosis factor such as TNF-α or TNF-β; and other polypeptide factors including LIF and kit ligand (KL). As used herein, the term cytokine includes proteins from natural sources or from recombinant cell culture and biologically active equivalents of the native sequence cytokines. 
     “Cytotoxic hematopoietic cell” refers herein to a cell from the hematopoietic system that is toxic to, for example, prevents the function of, or causes destruction of other cells. Examples of hematopoietic cytotoxic cells include natural killer (NK) cells, cytotoxic T-cells (a subset of CD8 +  lymphocytes), and activated macrophages. 
     The term “fusion protein” refers to a first protein coupled to a second, heterologous protein. The first and second proteins may be fused via genetic engineering techniques, such that the first and second proteins are expressed in frame. A polypeptide linker can be genetically engineered between the first and second proteins. For example, a polypeptide linker, such as GGGGS, can be is placed between the Fc of the heavy chain of the antibody and the N-terminus of MICB. 
     The term “heterologous” refers to molecules such as polynucleotide and polypeptide molecules, that differ in origin, for example, cell or tissue origin, species origin, and the like. Heterologous also refers to molecules that differ in structure and/or function, for example, ligand-binding molecules that each recognize a different ligand. 
     The term “host cell”, as used herein, refers to a cell expressing a heterologous polynucleotide molecule. Examples of host cells useful in the invention include, but are not limited to, bacterial, insect, and mammalian cells. Specific examples of such cells include SF9 insect cells (ATCC CRL-1711), NIH 3T3 cells (ATCC CRL-1658), human embyonic kidney cells (293 cells), Chinese hamster ovary (CHO) cells (Puck et al., 1958 , Proc. Natl. Acad. Sci. USA  60:1275-81), human breast cancer cells (MCF-7) (ATCC HTB22), Daudi cells (ATCC CRL-213), HEK293 and the like. 
     As used herein, “isolated”, refers to a polynucleotide or polypeptide that has been separated from at least one contaminant (polynucleotide or polypeptide) with which it is normally associated, e.g., in a form different from that found in nature. 
     The terms “nucleic acid,” “nucleotide,” “polynucleotide,” and “oligonucleotide” are used interchangeably and refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides, or analogs thereof. Polynucleotides may have any three-dimensional structure, and may perform one or more functions, known or unknown. The following are non-limiting examples of polynucleotides: coding or non-coding regions of a gene or gene fragment, loci (locus) defined from linkage analysis, exons, introns, messenger RNA (mRNA), transfer RNA, ribosomal RNA, ribozymes, cDNA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, isolated DNA of any sequence, isolated RNA of any sequence, nucleic acid probes, and primers. A polynucleotide may comprise modified nucleotides, such as methylated nucleotides and nucleotide analogs. If present, modifications to the nucleotide structure may be imparted before or after assembly of the polymer. The sequence of nucleotides may be interrupted by non-nucleotide components. A polynucleotide may be further modified after polymerization, such as by conjugation with a labeling component. 
     A nucleic acid is “operably linked” when it is placed into a functional relationship with another nucleic acid sequence. For example, DNA for a presequence or secretory leader is operably linked to DNA for a polypeptide if it is expressed as a preprotein that participates in the secretion of the polypeptide; a promoter or enhancer is operably linked to a coding sequence if it affects the transcription of the sequence; or a ribosome binding site is operably linked to a coding sequence if it is positioned so as to facilitate translation. Generally, “operably linked” means that the DNA sequences being linked are contiguous, and, in the case of a secretory leader, contiguous and in reading phase. However, enhancers do not have to be contiguous. Linking is accomplished by ligation at convenient restriction sites. If such sites do not exist, the synthetic oligonucleotide adaptors or linkers are used in accordance with conventional practice. See, for example, Lowman, U.S. Pat. No. 5,994,511; U.S. Pat. No. 6,172,213. 
     The terms “protein,” “polypeptide,” and “peptide” are used interchangeably herein to refer to polymers of amino acids of any length. The polymer may be linear or branched, it may comprise modified amino acids, and it may be interrupted by non-amino acids. The terms also encompass an amino acid polymer that has been modified; for example, disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation, such as conjugation with a labeling component. 
     The terms, “purify” or “purified”, as used herein, refers to a target protein that is free from at least 5-10% of contaminating protein. The purification of a protein from contaminating protein can be accomplished using known techniques, such as ammonium sulfate or ethanol precipitation, anion or cation exchange chromatography, phosphocellulose chromatography, hydrophobic interaction chromatography, affinity chromatography, hydroxylapatite chromatography, and lectin chromatography. For example, see Mage et al., in  Monoclonal Antibody Production Techniques and Applications , pp. 79-97 (Marcel Dekker, Inc.: New York, 1987) and  Current Protocols in Molecular Biology , Ausubel et al., eds. (Wiley &amp; Sons, New York, 1988, and quarterly updates). 
     A polypeptide “variant” (e.g. “MICB variant”), as used herein, means a biologically active polypeptide having at least 80%, preferably at least 85%, most preferably at least 90%, still more preferably at least 95% amino acid sequence identity with a parent sequence polypeptide, for example, with a full-length MICB reference sequence or with a soluble form sMICB reference sequence. Such variants include polypeptides having one or more amino acid residue added or deleted at the N- or C-terminus of the polypeptide. 
     A “loading” dose herein generally comprises an initial dose of a therapeutic agent administered to a patient, and is followed by one or more maintenance dose(s) thereof. Generally, a single loading dose is administered, but multiple loading doses are contemplated herein. Usually, the amount of loading dose(s) administered exceeds the amount of the maintenance dose(s) administered and/or the loading dose(s) are administered more frequently than the maintenance dose(s), so as to achieve the desired steady-state concentration of the therapeutic agent earlier than can be achieved with the maintenance dose(s). 
     A “maintenance” dose herein refers to one or more doses of a therapeutic agent administered to the patient over a treatment period. Usually, the maintenance doses are administered at spaced treatment intervals, such as approximately every week, approximately every 2 weeks, approximately every 3 weeks, or approximately every 4 weeks. 
     II. Production of Anti-HER2-MicB Fusion Proteins 
     Techniques for producing fusion proteins between Anti-HER antibodies and MicB are well known to one of skill in the art. Exemplary anti-HER2 antibodies and Mic B sequences and fragments that may be used in the invention are described below. 
     HER Receptors and Antibodies Thereagainst 
     The HER family of receptor tyrosine kinases are important mediators of cell growth, differentiation and survival. The receptor family includes four distinct members including epidermal growth factor receptor (EGFR, ErbB1, or HER1), HER2 (ErbB2 or p185 neu ), HER3 (ErbB3) and HER4 (ErbB4 or tyro2). 
     EGFR, encoded by the erbB1 gene, has been causally implicated in human malignancy. In particular, increased expression of EGFR has been observed in breast, bladder, lung, head, neck and stomach cancer as well as glioblastomas. Increased EGFR receptor expression is often associated with increased production of the EGFR ligand, transforming growth factor alpha (TGF-α), by the same tumor cells resulting in receptor activation by an autocrine stimulatory pathway. Baselga and Mendelsohn  Pharmac. Ther.  64:127-154 (1994). Monoclonal antibodies directed against the EGFR or its ligands, TGF-α and EGF, have been evaluated as therapeutic agents in the treatment of such malignancies. See, e.g., Baselga and Mendelsohn., supra; Masui et al.  Cancer Research  44:1002-1007 (1984); and Wu et al.  J. Clin. Invest.  95:1897-1905 (1995). 
     The second member of the HER family, p185 neu , was originally identified as the product of the transforming gene from neuroblastomas of chemically treated rats. The activated form of the neu proto-oncogene results from a point mutation (valine to glutamic acid) in the transmembrane region of the encoded protein. Amplification of the human homolog of neu is observed in breast and ovarian cancers and correlates with a poor prognosis (Slamon et al.,  Science,  235:177-182 (1987); Slamon et al.,  Science,  244:707-712 (1989); and U.S. Pat. No. 4,968,603). To date, no point mutation analogous to that in the neu proto-oncogene has been reported for human tumors. Overexpression of HER2 (frequently but not uniformly due to gene amplification) has also been observed in other carcinomas including carcinomas of the stomach, endometrium, salivary gland, lung, kidney, colon, thyroid, pancreas and bladder. See, among others, King et al.,  Science,  229:974 (1985); Yokota et al.,  Lancet:  1:765-767 (1986); Fukushige et al.,  Mol Cell Biol.,  6:955-958 (1986); Guerin et al.,  Oncogene Res.,  3:21-31 (1988); Cohen et al.,  Oncogene,  4:81-88 (1989); Yonemura et al.,  Cancer Res.,  51:1034 (1991); Borst et al.,  Gynecol. Oncol.,  38:364 (1990); Weiner et al.,  Cancer Res.,  50:421-425 (1990); Kern et al.,  Cancer Res.,  50:5184 (1990); Park et al.,  Cancer Res.,  49:6605 (1989); Zhau et al.,  Mol. Carcinog.,  3:254-257 (1990); Aasland et al.  Br. J. Cancer  57:358-363 (1988); Williams et al.  Pathobiology  59:46-52 (1991); and McCann et al.,  Cancer,  65:88-92 (1990). HER2 may be overexpressed in prostate cancer (Gu et al.  Cancer Lett.  99:185-9 (1996); Ross et al.  Hum. Pathol.  28:827-33 (1997); Ross et al.  Cancer  79:2162-70 (1997); and Sadasivan et al.  J. Urol.  150:126-31 (1993)). 
     HER2 amplification/overexpression is an early event in breast cancer that is associated with aggressive disease and poor prognosis. HER2 gene amplification is found in 20-25% of primary breast tumors (Slamon et al.  Science  244:707-12 (1989); Owens et al.  Breast Cancer Res Treat  76:S68 abstract 236 (2002)). HER2 positive disease correlates with decreased relapse-free and overall survival (Slamon et al.  Science  235:177-82 (1987); Pauletti et al.  J Clin Oncol  18:3651-64 (2000)). Amplification of the HER2 gene is associated with significantly reduced time to relapse and poor survival in node-positive disease (Slamon et al. (1987); Pauletti et al. (2000)) and poor outcome in node-negative disease (Press et al.  J Clin Oncol  1997; 15:2894-904 (1997); Pauletti et al. (2000)). 
     Antibodies directed against the rat p185 neu  and human HER2 protein products have been described. 
     Drebin and colleagues have raised antibodies against the rat neu gene product, p185 neu  See, for example, Drebin et al.,  Cell  41:695-706 (1985); Myers et al.,  Meth. Enzym.  198:277-290 (1991); and WO94/22478. Drebin et al.  Oncogene  2:273-277 (1988) report that mixtures of antibodies reactive with two distinct regions of p185 neu  result in synergistic anti-tumor effects on neu-transformed NIH-3T3 cells implanted into nude mice. See also U.S. Pat. No. 5,824,311 issued Oct. 20, 1998. 
     Hudziak et al.,  Mol. Cell. Biol.  9(3):1165-1172 (1989) describe the generation of a panel of HER2 antibodies which were characterized using the human breast tumor cell line SK-BR-3. Relative cell proliferation of the SK-BR-3 cells following exposure to the antibodies was determined by crystal violet staining of the monolayers after 72 hours. Using this assay, maximum inhibition was obtained with the antibody called 4D5 which inhibited cellular proliferation by 56%. Other antibodies in the panel reduced cellular proliferation to a lesser extent in this assay. The antibody 4D5 was further found to sensitize HER2-overexpressing breast tumor cell lines to the cytotoxic effects of TNF-α. See also U.S. Pat. No. 5,677,171 issued Oct. 14, 1997. The HER2 antibodies discussed in Hudziak et al. are further characterized in Fendly et al.  Cancer Research  50:1550-1558 (1990); Kotts et al. In Vitro 26(3):59A (1990); Sarup et al.  Growth Regulation  1:72-82 (1991); Shepard et al.  J. Clin. Immunol.  11(3):117-127 (1991); Kumar et al.  Mol. Cell. Biol.  11(2):979-986 (1991); Lewis et al.  Cancer Immunol. Immunother.  37:255-263 (1993); Pietras et al.  Oncogene  9:1829-1838 (1994); Vitetta et al.  Cancer Research  54:5301-5309 (1994); Sliwkowski et al.  J. Biol. Chem.  269(20):14661-14665 (1994); Scott et al.  J. Biol. Chem.  266:14300-5 (1991); D&#39;souza et al.  Proc. Natl. Acad. Sci.  91:7202-7206 (1994); Lewis et al.  Cancer Research  56:1457-1465 (1996); and Schaefer et al.  Oncogene  15:1385-1394 (1997). 
     A recombinant humanized version of the murine HER2 antibody 4D5 (huMAb4D5-8, rhuMAb HER2, trastuzumab or HERCEPTIN®; U.S. Pat. No. 5,821,337) is clinically active in patients with HER2-overexpressing metastatic breast cancers that have received extensive prior anti-cancer therapy (Baselga et al.,  J. Clin. Oncol.  14:737-744 (1996)). 
     Other HER2 antibodies with various properties have been described in Tagliabue et al.  Int. J. Cancer  47:933-937 (1991); McKenzie et al.  Oncogene  4:543-548 (1989); Maier et al.  Cancer Res.  51:5361-5369 (1991); Bacus et al.  Molecular Carcinogenesis  3:350-362 (1990); Stancovski et al.  PNAS  ( USA ) 88:8691-8695 (1991); Bacus et al.  Cancer Research  52:2580-2589 (1992); Xu et al.  Int. J. Cancer  53:401-408 (1993); WO94/00136; Kasprzyk et al.  Cancer Research  52:2771-2776 (1992); Hancock et al.  Cancer Res.  51:4575-4580 (1991); Shawver et al.  Cancer Res.  54:1367-1373 (1994); Arteaga et al.  Cancer Res.  54:3758-3765 (1994); Harwerth et al.  J. Biol. Chem.  267:15160-15167 (1992); U.S. Pat. No. 5,783,186; and Klapper et al.  Oncogene  14:2099-2109 (1997). 
     Homology screening has resulted in the identification of two other HER receptor family members; HER3 (U.S. Pat. Nos. 5,183,884 and 5,480,968 as well as Kraus et al.  PNAS  ( USA ) 86:9193-9197 (1989)) and HER4 (EP Pat Appln No 599,274; Plowman et al.,  Proc. Natl. Acad. Sci. USA,  90:1746-1750 (1993); and Plowman et al.,  Nature,  366:473-475 (1993)). Both of these receptors display increased expression on at least some breast cancer cell lines. 
     The HER receptors are generally found in various combinations in cells and heterodimerization is thought to increase the diversity of cellular responses to a variety of HER ligands (Earp et al.  Breast Cancer Research and Treatment  35: 115-132 (1995)). EGFR is bound by six different ligands; epidermal growth factor (EGF), transforming growth factor alpha (TGF-α), amphiregulin, heparin binding epidermal growth factor (HB-EGF), betacellulin and epiregulin (Groenen et al.  Growth Factors  11:235-257 (1994)). A family of heregulin proteins resulting from alternative splicing of a single gene are ligands for HER3 and HER4. The heregulin family includes alpha, beta and gamma heregulins (Holmes et al.,  Science,  256:1205-1210 (1992); U.S. Pat. No. 5,641,869; and Schaefer et al.  Oncogene  15:1385-1394 (1997)); neu differentiation factors (NDFs), glial growth factors (GGFs); acetylcholine receptor inducing activity (ARIA); and sensory and motor neuron derived factor (SMDF). For a review, see Groenen et al.  Growth Factors  11:235-257 (1994); Lemke, G.  Molec . &amp;  Cell. Neurosci.  7:247-262 (1996) and Lee et al.  Pharm. Rev.  47:51-85 (1995). Recently three additional HER ligands were identified; neuregulin-2 (NRG-2) which is reported to bind either HER3 or HER4 (Chang et al.  Nature  387 509-512 (1997); and Carraway et al  Nature  387:512-516 (1997)); neuregulin-3 which binds HER4 (Zhang et al.  PNAS  ( USA ) 94(18):9562-7 (1997)); and neuregulin-4 which binds HER4 (Harari et al.  Oncogene  18:2681-89 (1999)) HB-EGF, betacellulin and epiregulin also bind to HER4. 
     While EGF and TGFα do not bind HER2, EGF stimulates EGFR and HER2 to form a heterodimer, which activates EGFR and results in transphosphorylation of HER2 in the heterodimer. Dimerization and/or transphosphorylation appears to activate the HER2 tyrosine kinase. See Earp et al., supra. Likewise, when HER3 is co-expressed with HER2, an active signaling complex is formed and antibodies directed against HER2 are capable of disrupting this complex (Sliwkowski et al.,  J. Biol. Chem.,  269(20):14661-14665 (1994)). Additionally, the affinity of HER3 for heregulin (HRG) is increased to a higher affinity state when co-expressed with HER2. See also, Levi et al.,  Journal of Neuroscience  15: 1329-1340 (1995); Morrissey et al.,  Proc. Natl. Acad. Sci. USA  92: 1431-1435 (1995); and Lewis et al.,  Cancer Res.,  56:1457-1465 (1996) with respect to the HER2-HER3 protein complex. HER4, like HER3, forms an active signaling complex with HER2 (Carraway and Cantley,  Cell  78:5-8 (1994)). 
     Patent publications related to HER antibodies include: U.S. Pat. No. 5,677,171, U.S. Pat. No. 5,720,937, U.S. Pat. No. 5,720,954, U.S. Pat. No. 5,725,856, U.S. Pat. No. 5,770,195, U.S. Pat. No. 5,772,997, U.S. Pat. No. 6,165,464, U.S. Pat. No. 6,387,371, U.S. Pat. No. 6,399,063, US2002/0192211A1, U.S. Pat. No. 6,015,567, U.S. Pat. No. 6,333,169, U.S. Pat. No. 4,968,603, U.S. Pat. No. 5,821,337, U.S. Pat. No. 6,054,297, U.S. Pat. No. 6,407,213, U.S. Pat. No. 6,719,971, U.S. Pat. No. 6,800,738, US2004/0236078A1, U.S. Pat. No. 5,648,237, U.S. Pat. No. 6,267,958, U.S. Pat. No. 6,685,940, U.S. Pat. No. 6,821,515, WO98/17797, U.S. Pat. No. 6,127,526, U.S. Pat. No. 6,333,398, U.S. Pat. No. 6,797,814, U.S. Pat. No. 6,339,142, U.S. Pat. No. 6,417,335, U.S. Pat. No. 6,489,447, WO99/31140, US2003/0147884A1, US2003/0170234A1, US2005/0002928A1, U.S. Pat. No. 6,573,043, US2003/0152987A1, WO99/48527, US2002/0141993A1, WO01/00245, US2003/0086924, US2004/0013667A1, WO00/69460, WO01/00238, WO01/15730, U.S. Pat. No. 6,627,196B1, U.S. Pat. No. 6,632,979B1, WO01/00244, US2002/0090662A1, WO01/89566, US2002/0064785, US2003/0134344, WO 04/24866, US2004/0082047, US2003/0175845A1, WO03/087131, US2003/0228663, WO2004/008099A2, US2004/0106161, WO2004/048525, US2004/0258685A1, U.S. Pat. No. 5,985,553, U.S. Pat. No. 5,747,261, U.S. Pat. No. 4,935,341, U.S. Pat. No. 5,401,638, U.S. Pat. No. 5,604,107, WO 87/07646, WO 89/10412, WO 91/05264, EP 412,116 B1, EP 494,135 B1, U.S. Pat. No. 5,824,311, EP 444,181 B1, EP 1,006,194 A2, US 2002/0155527A1, WO 91/02062, U.S. Pat. No. 5,571,894, U.S. Pat. No. 5,939,531, EP 502,812 B1, WO 93/03741, EP 554,441 B1, EP 656,367 A1, U.S. Pat. No. 5,288,477, U.S. Pat. No. 5,514,554, U.S. Pat. No. 5,587,458, WO 93/12220, WO 93/16185, U.S. Pat. No. 5,877,305, WO 93/21319, WO 93/21232, U.S. Pat. No. 5,856,089, WO 94/22478, U.S. Pat. No. 5,910,486, U.S. Pat. No. 6,028,059, WO 96/07321, U.S. Pat. No. 5,804,396, U.S. Pat. No. 5,846,749, EP 711,565, WO 96/16673, U.S. Pat. No. 5,783,404, U.S. Pat. No. 5,977,322, U.S. Pat. No. 6,512,097, WO 97/00271, U.S. Pat. No. 6,270,765, U.S. Pat. No. 6,395,272, U.S. Pat. No. 5,837,243, WO 96/40789, U.S. Pat. No. 5,783,186, U.S. Pat. No. 6,458,356, WO 97/20858, WO 97/38731, U.S. Pat. No. 6,214,388, U.S. Pat. No. 5,925,519, WO 98/02463, U.S. Pat. No. 5,922,845, WO 98/18489, WO 98/33914, U.S. Pat. No. 5,994,071, WO 98/45479, U.S. Pat. No. 6,358,682 B1, US 2003/0059790, WO 99/55367, WO 01/20033, US 2002/0076695 A1, WO 00/78347, WO 01/09187, WO 01/21192, WO 01/32155, WO 01/53354, WO 01/56604, WO 01/76630, WO02/05791, WO 02/11677, U.S. Pat. No. 6,582,919, US2002/0192652A1, US 2003/0211530A1, WO 02/44413, US 2002/0142328, U.S. Pat. No. 6,602,670 B2, WO 02/45653, WO 02/055106, US 2003/0152572, US 2003/0165840, WO 02/087619, WO 03/006509, WO03/012072, WO 03/028638, US 2003/0068318, WO 03/041736, EP 1,357,132, US 2003/0202973, US 2004/0138160, U.S. Pat. No. 5,705,157, U.S. Pat. No. 6,123,939, EP 616,812 B1, US 2003/0103973, US 2003/0108545, U.S. Pat. No. 6,403,630 B1, WO 00/61145, WO 00/61185, U.S. Pat. No. 6,333,348 B1, WO 01/05425, WO 01/64246, US 2003/0022918, US 2002/0051785 A1, U.S. Pat. No. 6,767,541, WO 01/76586, US 2003/0144252, WO 01/87336, US 2002/0031515 A1, WO 01/87334, WO 02/05791, WO 02/09754, US 2003/0157097, US 2002/0076408, WO 02/055106, WO 02/070008, WO 02/089842 and WO 03/86467. 
     Patients treated with the fusion polypeptides of the invention may be selected for therapy based on HER2 overexpression/amplification. See, for example, WO99/31140 (Paton et al.), US2003/0170234A1 (Hellmann, S.), and US2003/0147884 (Paton et al.); as well as WO01/89566, US2002/0064785, and US2003/0134344 (Mass et al.). See, also, US2003/0152987, Cohen et al., concerning immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for detecting HER2 overexpression and amplification. 
     WO2004/053497 and US2004/024815A1 (Bacus et al.), as well as US 2003/0190689 (Crosby and Smith), refer to determining or predicting response to trastuzumab therapy. US2004/013297A1 (Bacus et al.) concerns determining or predicting response to ABX0303 EGFR antibody therapy. WO2004/000094 (Bacus et al.) is directed to determining response to GW572016, a small molecule, EGFR-HER2 tyrosine kinase inhibitor. WO2004/063709, Amler et al., refers to biomarkers and methods for determining sensitivity to EGFR inhibitor, erlotinib HCl. US2004/0209290, Cobleigh et al., concerns gene expression markers for breast cancer prognosis. 
     Patients treated with pertuzumab can be selected for therapy based on HER activation or dimerization. Patent publications concerning pertuzumab and selection of patients for therapy therewith include: WO01/00245 (Adams et al.); US2003/0086924 (Sliwkowski, M.); US2004/0013667A1 (Sliwkowski, M.); as well as WO2004/008099A2, and US2004/0106161 (Bossenmaier et al.). 
     Cronin et al.  Am. J. Path.  164(1): 35-42 (2004) describes measurement of gene expression in archival paraffin-embedded tissues. Ma et al.  Cancer Cell  5:607-616 (2004) describes gene profiling by gene oliogonucleotide microarray using isolated RNA from tumor-tissue sections taken from archived primary biopsies. 
     A description follows as to exemplary techniques for the production of additional HER2 antibodies used in accordance with the present invention. The HER2 antigen to be used for production of antibodies may be, e.g., a soluble form of the extracellular domain of a HER2 receptor or a portion thereof, containing the desired epitope. Alternatively, cells expressing HER2 at their cell surface (e.g. NIH-3T3 cells transformed to overexpress HER2; or a carcinoma cell line such as SK-BR-3 cells, see Stancovski et al.  PNAS  ( USA ) 88:8691-8695 (1991)) can be used to generate antibodies. Other forms of HER2 useful for generating antibodies will be apparent to those skilled in the art. 
     (i) Polyclonal Antibodies 
     Polyclonal antibodies are preferably raised in animals by multiple subcutaneous (sc) or intraperitoneal (ip) injections of the relevant antigen and an adjuvant. It may be useful to conjugate the relevant antigen to a protein that is immunogenic in the species to be immunized, e.g., keyhole limpet hemocyanin, serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor using a bifunctional or derivatizing agent, for example, maleimidobenzoyl sulfosuccinimide ester (conjugation through cysteine residues), N-hydroxysuccinimide (through lysine residues), glutaraldehyde, succinic anhydride, SOCl 2 , or R 1 N═C═NR, where R and R 1  are different alkyl groups. 
     Animals are immunized against the antigen, immunogenic conjugates, or derivatives by combining, e.g., 100 μg or 5 μg of the protein or conjugate (for rabbits or mice, respectively) with 3 volumes of Freund&#39;s complete adjuvant and injecting the solution intradermally at multiple sites. One month later the animals are boosted with ⅕ to 1/10 the original amount of peptide or conjugate in Freund&#39;s complete adjuvant by subcutaneous injection at multiple sites. Seven to 14 days later the animals are bled and the serum is assayed for antibody titer. Animals are boosted until the titer plateaus. Preferably, the animal is boosted with the conjugate of the same antigen, but conjugated to a different protein and/or through a different cross-linking reagent. Conjugates also can be made in recombinant cell culture as protein fusions. Also, aggregating agents such as alum are suitably used to enhance the immune response. 
     (ii) Monoclonal Antibodies 
     Various methods for making monoclonal antibodies herein are available in the art. For example, the monoclonal antibodies may be made using the hybridoma method first described by Kohler et al.,  Nature,  256:495 (1975), by recombinant DNA methods (U.S. Pat. No. 4,816,567). 
     In the hybridoma method, a mouse or other appropriate host animal, such as a hamster, is immunized as hereinabove described to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the protein used for immunization. Alternatively, lymphocytes may be immunized in vitro. Lymphocytes then are fused with myeloma cells using a suitable fusing agent, such as polyethylene glycol, to form a hybridoma cell (Goding,  Monoclonal Antibodies: Principles and Practice , pp. 59-103 (Academic Press, 1986)). 
     The hybridoma cells thus prepared are seeded and grown in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, parental myeloma cells. For example, if the parental myeloma cells lack the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT or HPRT), the culture medium for the hybridomas typically will include hypoxanthine, aminopterin, and thymidine (HAT medium), which substances prevent the growth of HGPRT-deficient cells. 
     Preferred myeloma cells are those that fuse efficiently, support stable high-level production of antibody by the selected antibody-producing cells, and are sensitive to a medium such as HAT medium. Among these, preferred myeloma cell lines are murine myeloma lines, such as those derived from MOPC-21 and MPC-11 mouse tumors available from the Salk Institute Cell Distribution Center, San Diego, Calif. USA, and SP-2 or X63-Ag8-653 cells available from the American Type Culture Collection, Rockville, Md. USA. Human myeloma and mouse-human heteromyeloma cell lines also have been described for the production of human monoclonal antibodies (Kozbor,  J. Immunol.,  133:3001 (1984); and Brodeur et al.,  Monoclonal Antibody Production Techniques and Applications , pp. 51-63 (Marcel Dekker, Inc., New York, 1987)). 
     Culture medium in which hybridoma cells are growing is assayed for production of monoclonal antibodies directed against the antigen. Preferably, the binding specificity of monoclonal antibodies produced by hybridoma cells is determined by immunoprecipitation or by an in vitro binding assay, such as radioimmunoassay (RIA) or enzyme-linked immunoabsorbent assay (ELISA). 
     The binding affinity of the monoclonal antibody can, for example, be determined by the Scatchard analysis of Munson et al.,  Anal. Biochem.,  107:220 (1980). 
     After hybridoma cells are identified that produce antibodies of the desired specificity, affinity, and/or activity, the clones may be subcloned by limiting dilution procedures and grown by standard methods (Goding,  Monoclonal Antibodies: Principles and Practice , pp. 59-103 (Academic Press, 1986)). Suitable culture media for this purpose include, for example, D-MEM or RPMI-1640 medium. In addition, the hybridoma cells may be grown in vivo as ascites tumors in an animal. 
     The monoclonal antibodies secreted by the subclones are suitably separated from the culture medium, ascites fluid, or serum by conventional antibody purification procedures such as, for example, protein A-Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography. 
     DNA encoding the monoclonal antibodies is readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of murine antibodies). The hybridoma cells serve as a preferred source of such DNA. Once isolated, the DNA may be placed into expression vectors, which are then transfected into host cells such as  E. coli  cells, simian COS cells, Chinese Hamster Ovary (CHO) cells, or myeloma cells that do not otherwise produce antibody protein, to obtain the synthesis of monoclonal antibodies in the recombinant host cells. Review articles on recombinant expression in bacteria of DNA encoding the antibody include Skerra et al.,  Curr. Opinion in Immunol.,  5:256-262 (1993) and Plückthun,  Immunol. Revs.,  130:151-188 (1992). 
     In a further embodiment, monoclonal antibodies or antibody fragments can be isolated from antibody phage libraries generated using the techniques described in McCafferty et al.,  Nature,  348:552-554 (1990). Clackson et al.,  Nature,  352:624-628 (1991) and Marks et al.,  J. Mol. Biol.,  222:581-597 (1991) describe the isolation of murine and human antibodies, respectively, using phage libraries. Subsequent publications describe the production of high affinity (nM range) human antibodies by chain shuffling (Marks et al.,  Bio/Technology,  10:779-783 (1992)), as well as combinatorial infection and in vivo recombination as a strategy for constructing very large phage libraries (Waterhouse et al.,  Nuc. Acids. Res.,  21:2265-2266 (1993)). Thus, these techniques are viable alternatives to traditional monoclonal antibody hybridoma techniques for isolation of monoclonal antibodies. 
     The DNA also may be modified, for example, by substituting the coding sequence for human heavy chain and light chain constant domains in place of the homologous murine sequences (U.S. Pat. No. 4,816,567; and Morrison, et al.,  Proc. Natl. Acad. Sci. USA,  81:6851 (1984)), or by covalently joining to the immunoglobulin coding sequence all or part of the coding sequence for a non-immunoglobulin polypeptide. 
     Typically such non-immunoglobulin polypeptides are substituted for the constant domains of an antibody, or they are substituted for the variable domains of one antigen-combining site of an antibody to create a chimeric bivalent antibody comprising one antigen-combining site having specificity for an antigen and another antigen-combining site having specificity for a different antigen. 
     (iii) Humanized Antibodies 
     Methods for humanizing non-human antibodies have been described in the art. Preferably, a humanized antibody has one or more amino acid residues introduced into it from a source which is non-human. These non-human amino acid residues are often referred to as “import” residues, which are typically taken from an “import” variable domain. Humanization can be essentially performed following the method of Winter and co-workers (Jones et al.,  Nature,  321:522-525 (1986); Riechmann et al.,  Nature,  332:323-327 (1988); Verhoeyen et al.,  Science,  239:1534-1536 (1988)), by substituting hypervariable region sequences for the corresponding sequences of a human antibody. Accordingly, such “humanized” antibodies are chimeric antibodies (U.S. Pat. No. 4,816,567) wherein substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species. In practice, humanized antibodies are typically human antibodies in which some hypervariable region residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies. 
     The choice of human variable domains, both light and heavy, to be used in making the humanized antibodies is very important to reduce antigenicity. According to the so-called “best-fit” method, the sequence of the variable domain of a rodent antibody is screened against the entire library of known human variable-domain sequences. The human sequence which is closest to that of the rodent is then accepted as the human framework region (FR) for the humanized antibody (Sims et al.,  J. Immunol.,  151:2296 (1993); Chothia et al.,  J. Mol. Biol.,  196:901 (1987)). Another method uses a particular framework region derived from the consensus sequence of all human antibodies of a particular subgroup of light or heavy chains. The same framework may be used for several different humanized antibodies (Carter et al.,  Proc. Natl. Acad. Sci. USA,  89:4285 (1992); Presta et al.,  J. Immunol.,  151:2623 (1993)). 
     It is further important that antibodies be humanized with retention of high affinity for the antigen and other favorable biological properties. To achieve this goal, according to a preferred method, humanized antibodies are prepared by a process of analysis of the parental sequences and various conceptual humanized products using three-dimensional models of the parental and humanized sequences. Three-dimensional immunoglobulin models are commonly available and are familiar to those skilled in the art. Computer programs are available which illustrate and display probable three-dimensional conformational structures of selected candidate immunoglobulin sequences. Inspection of these displays permits analysis of the likely role of the residues in the functioning of the candidate immunoglobulin sequence, i.e., the analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen. In this way, FR residues can be selected and combined from the recipient and import sequences so that the desired antibody characteristic, such as increased affinity for the target antigen(s), is achieved. In general, the hypervariable region residues are directly and most substantially involved in influencing antigen binding. 
     Various forms of the humanized antibody or affinity matured antibody are contemplated. For example, the humanized antibody or affinity matured antibody may be an antibody fragment, such as a Fab, which is optionally conjugated with one or more cytotoxic agent(s) in order to generate an immunoconjugate. Alternatively, the humanized antibody or affinity matured antibody may be an intact antibody, such as an intact IgG1 antibody. 
     Humanization of murine 4D5 antibody to generate humanized variants thereof, including Trastuzumab, is described in U.S. Pat. Nos. 5,821,337, 6,054,297, 6,407,213, 6,639,055, 6,719,971, and 6,800,738, as well as Carter et al.  PNAS  ( USA ) 89: 4285-4289 (1992). HuMAb4D5-8 (trastuzumab) bound HER2 antigen 3-fold more tightly than the mouse 4D5 antibody, and had secondary immune function (ADCC) which allowed for directed cytotoxic activity of the humanized antibody in the presence of human effector cells. HuMAb4D5-8 comprised variable light (VL) CDR residues incorporated in a VL kappa subgroup I consensuse framework, and variable heavy (VH) CDR residues incorporated into a VH subgroup III consensus framework. The antibody further comprised framework region (FR) substitutions as positions: 71, 73, 78, and 93 of the VH (Kabat numbering of FR residues; and a FR substitution at position 66 of the VL (Kabat numbering of FR residues). Trastuzumab comprises non-A allotype human gamma 1 Fc region. 
     (iv) Human Antibodies 
     As an alternative to humanization, human antibodies can be generated. For example, it is now possible to produce transgenic animals (e.g., mice) that are capable, upon immunization, of producing a full repertoire of human antibodies in the absence of endogenous immunoglobulin production. For example, it has been described that the homozygous deletion of the antibody heavy-chain joining region (J H ) gene in chimeric and germ-line mutant mice results in complete inhibition of endogenous antibody production. Transfer of the human germ-line immunoglobulin gene array in such germ-line mutant mice will result in the production of human antibodies upon antigen challenge. See, e.g., Jakobovits et al.,  Proc. Natl. Acad. Sci. USA,  90:2551 (1993); Jakobovits et al.,  Nature,  362:255-258 (1993); Bruggermann et al.,  Year in Immuno.,  7:33 (1993); and U.S. Pat. Nos. 5,591,669, 5,589,369 and 5,545,807. Alternatively, phage display technology (McCafferty et al.,  Nature  348:552-553 (1990)) can be used to produce human antibodies and antibody fragments in vitro, from immunoglobulin variable (V) domain gene repertoires from unimmunized donors. According to this technique, antibody V domain genes are cloned in-frame into either a major or minor coat protein gene of a filamentous bacteriophage, such as M13 or fd, and displayed as functional antibody fragments on the surface of the phage particle. Because the filamentous particle contains a single-stranded DNA copy of the phage genome, selections based on the functional properties of the antibody also result in selection of the gene encoding the antibody exhibiting those properties. Thus, the phage mimics some of the properties of the B-cell. Phage display can be performed in a variety of formats; for their review see, e.g., Johnson, Kevin S. and Chiswell, David J.,  Current Opinion in Structural Biology  3:564-571 (1993). Several sources of V-gene segments can be used for phage display. Clackson et al.,  Nature,  352:624-628 (1991) isolated a diverse array of anti-oxazolone antibodies from a small random combinatorial library of V genes derived from the spleens of immunized mice. A repertoire of V genes from unimmunized human donors can be constructed and antibodies to a diverse array of antigens (including self-antigens) can be isolated essentially following the techniques described by Marks et al.,  J. Mol. Biol.  222:581-597 (1991), or Griffith et al.,  EMBO J.  12:725-734 (1993). See, also, U.S. Pat. Nos. 5,565,332 and 5,573,905. 
     As discussed above, human antibodies may also be generated by in vitro activated B cells (see U.S. Pat. Nos. 5,567,610 and 5,229,275). 
     Human HER2 antibodies are described in U.S. Pat. No. 5,772,997 issued Jun. 30, 1998 and WO 97/00271 published Jan. 3, 1997. 
     (v) Antibody Fragments 
     Various techniques have been developed for the production of antibody fragments comprising one or more antigen binding regions. Traditionally, these fragments were derived via proteolytic digestion of intact antibodies (see, e.g., Morimoto et al.,  Journal of Biochemical and Biophysical Methods  24:107-117 (1992); and Brennan et al.,  Science,  229:81 (1985)). However, these fragments can now be produced directly by recombinant host cells. For example, the antibody fragments can be isolated from the antibody phage libraries discussed above. Alternatively, Fab′-SH fragments can be directly recovered from  E. coli  and chemically coupled to form F(ab′) 2  fragments (Carter et al., Bio/Technology 10: 163-167 (1992)). According to another approach, F(ab′) 2  fragments can be isolated directly from recombinant host cell culture. Other techniques for the production of antibody fragments will be apparent to the skilled practitioner. The antibody fragment may also be a “linear antibody”, e.g., as described in U.S. Pat. No. 5,641,870 for example. Such linear antibody fragments may be monospecific or bispecific. Generally, they are bispecific when used in a fusion polypeptide of the invention. 
     (vi) Bispecific Antibodies 
     Bispecific antibodies are antibodies that have binding specificities for at least two different epitopes. Exemplary bispecific antibodies may bind to two different epitopes of the HER2 protein. Other such antibodies may combine a HER2 binding site with binding site(s) for EGFR, HER3 and/or HER4. Alternatively, a HER2 arm may be combined with an arm which binds to a triggering molecule on a leukocyte such as a T-cell receptor molecule (e.g. CD2 or CD3), or Fc receptors for IgG (FcγR), such as FcγRI (CD64), FcγRII (CD32) and FcγRIII (CD16) so as to focus cellular defense mechanisms to the HER2-expressing cell. Bispecific antibodies may also be used to localize cytotoxic agents to cells which express HER2. These antibodies possess a HER2-binding arm and an arm which binds the cytotoxic agent (e.g. saporin, anti-interferon-α, vinca alkaloid, ricin A chain, methotrexate or radioactive isotope hapten). Bispecific antibodies can be prepared as full length antibodies or antibody fragments (e.g. F(ab′) 2  bispecific antibodies). 
     WO 96/16673 describes a bispecific HER2/FcγRIII antibody and U.S. Pat. No. 5,837,234 discloses a bispecific HER2/FcγRI antibody IDM1 (Osidem). A bispecific HER2/Fcα antibody is shown in WO98/02463. U.S. Pat. No. 5,821,337 teaches a bispecific HER2/CD3 antibody. MDX-210 is a bispecific HER2-FcγRIII Ab. 
     Methods for making bispecific antibodies are known in the art. Traditional production of full length bispecific antibodies is based on the coexpression of two immunoglobulin heavy chain-light chain pairs, where the two chains have different specificities (Millstein et al.,  Nature,  305:537-539 (1983)). Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of 10 different antibody molecules, of which only one has the correct bispecific structure. Purification of the correct molecule, which is usually done by affinity chromatography steps, is rather cumbersome, and the product yields are low. Similar procedures are disclosed in WO 93/08829, and in Traunecker et al.,  EMBO J.,  10:3655-3659 (1991). 
     According to a different approach, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences. The fusion preferably is with an immunoglobulin heavy chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions. It is preferred to have the first heavy-chain constant region (CH1) containing the site necessary for light chain binding, present in at least one of the fusions. DNAs encoding the immunoglobulin heavy chain fusions and, if desired, the immunoglobulin light chain, are inserted into separate expression vectors, and are co-transfected into a suitable host organism. This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields. It is, however, possible to insert the coding sequences for two or all three polypeptide chains in one expression vector when the expression of at least two polypeptide chains in equal ratios results in high yields or when the ratios are of no particular significance. 
     In a preferred embodiment of this approach, the bispecific antibodies are composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain-light chain pair (providing a second binding specificity) in the other arm. It was found that this asymmetric structure facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations, as the presence of an immunoglobulin light chain in only one half of the bispecific molecule provides for a facile way of separation. This approach is disclosed in WO 94/04690. For further details of generating bispecific antibodies see, for example, Suresh et al.,  Methods in Enzymology,  121:210 (1986). 
     According to another approach described in U.S. Pat. No. 5,731,168, the interface between a pair of antibody molecules can be engineered to maximize the percentage of heterodimers which are recovered from recombinant cell culture. The preferred interface comprises at least a part of the C H 3 domain of an antibody constant domain. In this method, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with larger side chains (e.g. tyrosine or tryptophan). Compensatory “cavities” of identical or similar size to the large side chain(s) are created on the interface of the second antibody molecule by replacing large amino acid side chains with smaller ones (e.g. alanine or threonine). This provides a mechanism for increasing the yield of the heterodimer over other unwanted end-products such as homodimers. 
     Bispecific antibodies include cross-linked or “heteroconjugate” antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U.S. Pat. No. 4,676,980), and for treatment of HIV infection (WO 91/00360, WO 92/200373, and EP 03089). Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. Pat. No. 4,676,980, along with a number of cross-linking techniques. 
     Techniques for generating bispecific antibodies from antibody fragments have also been described in the literature. For example, bispecific antibodies can be prepared using chemical linkage. Brennan et al.,  Science,  229: 81 (1985) describe a procedure wherein intact antibodies are proteolytically cleaved to generate F(ab′) 2  fragments. These fragments are reduced in the presence of the dithiol complexing agent sodium arsenite to stabilize vicinal dithiols and prevent intermolecular disulfide formation. The Fab′ fragments generated are then converted to thionitrobenzoate (TNB) derivatives. One of the Fab′-TNB derivatives is then reconverted to the Fab′-thiol by reduction with mercaptoethylamine and is mixed with an equimolar amount of the other Fab′-TNB derivative to form the bispecific antibody. The bispecific antibodies produced can be used as agents for the selective immobilization of enzymes. 
     Recent progress has facilitated the direct recovery of Fab′-SH fragments from  E. coli , which can be chemically coupled to form bispecific antibodies. Shalaby et al.,  J. Exp. Med.,  175: 217-225 (1992) describe the production of a fully humanized bispecific antibody F(ab′) 2  molecule. Each Fab′ fragment was separately secreted from  E. coli  and subjected to directed chemical coupling in vitro to form the bispecific antibody. The bispecific antibody thus formed was able to bind to cells overexpressing the HER2 receptor and normal human T cells, as well as trigger the lytic activity of human cytotoxic lymphocytes against human breast tumor targets. 
     Various techniques for making and isolating bispecific antibody fragments directly from recombinant cell culture have also been described. For example, bispecific antibodies have been produced using leucine zippers. Kostelny et al.,  J. Immunol.,  148(5):1547-1553 (1992). The leucine zipper peptides from the Fos and Jun proteins were linked to the Fab′ portions of two different antibodies by gene fusion. The antibody homodimers were reduced at the hinge region to form monomers and then re-oxidized to form the antibody heterodimers. This method can also be utilized for the production of antibody homodimers. The “diabody” technology described by Hollinger et al.,  Proc. Natl. Acad. Sci. USA,  90:6444-6448 (1993) has provided an alternative mechanism for making bispecific antibody fragments. The fragments comprise a heavy-chain variable domain (V H ) connected to a light-chain variable domain (V L ) by a linker which is too short to allow pairing between the two domains on the same chain. Accordingly, the V H  and V L  domains of one fragment are forced to pair with the complementary V L  and V H  domains of another fragment, thereby forming two antigen-binding sites. Another strategy for making bispecific antibody fragments by the use of single-chain Fv (sFv) dimers has also been reported. See Gruber et al.,  J. Immunol.,  152:5368 (1994). 
     Antibodies with more than two valencies are contemplated. For example, trispecific antibodies can be prepared. Tutt et al.  J. Immunol.  147: 60 (1991). 
     (vii) Other Amino Acid Sequence Modifications 
     Amino acid sequence modification(s) of the antibodies described herein are contemplated. For example, it may be desirable to improve the binding affinity and/or other biological properties of the antibody. Amino acid sequence variants of the antibody are prepared by introducing appropriate nucleotide changes into the antibody nucleic acid, or by peptide synthesis. Such modifications include, for example, deletions from, and/or insertions into and/or substitutions of, residues within the amino acid sequences of the antibody. Any combination of deletion, insertion, and substitution is made to arrive at the final construct, provided that the final construct possesses the desired characteristics. The amino acid changes also may alter post-translational processes of the antibody, such as changing the number or position of glycosylation sites. 
     A useful method for identification of certain residues or regions of the antibody that are preferred locations for mutagenesis is called “alanine scanning mutagenesis” as described by Cunningham and Wells  Science,  244:108′-1085 (1989). Here, a residue or group of target residues are identified (e.g., charged residues such as arg, asp, his, lys, and glu) and replaced by a neutral or negatively charged amino acid (most preferably alanine or polyalanine) to affect the interaction of the amino acids with antigen. Those amino acid locations demonstrating functional sensitivity to the substitutions then are refined by introducing further or other variants at, or for, the sites of substitution. Thus, while the site for introducing an amino acid sequence variation is predetermined, the nature of the mutation per se need not be predetermined. For example, to analyze the performance of a mutation at a given site, ala scanning or random mutagenesis is conducted at the target codon or region and the expressed antibody variants are screened for the desired activity. 
     Amino acid sequence insertions include amino- and/or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing a hundred or more residues, as well as intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include antibody with an N-terminal methionyl residue or the antibody fused to a cytotoxic polypeptide. Other insertional variants of the antibody molecule include the fusion to the N- or C-terminus of the antibody to an enzyme (e.g. for ADEPT) or a polypeptide which increases the serum half-life of the antibody. 
     Another type of variant is an amino acid substitution variant. These variants have at least one amino acid residue in the antibody molecule replaced by a different residue. The sites of greatest interest for substitutional mutagenesis include the hypervariable regions, but FR alterations are also contemplated. Conservative substitutions are shown in Table 1 under the heading of “preferred substitutions”. If such substitutions result in a change in biological activity, then more substantial changes, denominated “exemplary substitutions” in Table 1, or as further described below in reference to amino acid classes, may be introduced and the products screened. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Original 
                 Exemplary 
                 Preferred 
               
               
                   
                 Residue 
                 Substitutions 
                 Substitutions 
               
               
                   
                   
               
             
            
               
                   
                 Ala (A) 
                 Val; Leu; Ile 
                 Val 
               
               
                   
                 Arg (R) 
                 Lys; Gln; Asn 
                 Lys 
               
               
                   
                 Asn (N) 
                 Gln; His; Asp, Lys; Arg 
                 Gln 
               
               
                   
                 Asp (D) 
                 Glu; Asn 
                 Glu 
               
               
                   
                 Cys (C) 
                 Ser; Ala 
                 Ser 
               
               
                   
                 Gln (Q) 
                 Asn; Glu 
                 Asn 
               
               
                   
                 Glu (E) 
                 Asp; Gln 
                 Asp 
               
               
                   
                 Gly (G) 
                 Ala 
                 Ala 
               
               
                   
                 His (H) 
                 Asn; Gln; Lys; Arg 
                 Arg 
               
               
                   
                 Ile (I) 
                 Leu; Val; Met; Ala; 
                 Leu 
               
               
                   
                   
                 Phe; Norleucine 
               
               
                   
                 Leu (L) 
                 Norleucine; Ile; Val; 
                 Ile 
               
               
                   
                   
                 Met; Ala; Phe 
               
               
                   
                 Lys (K) 
                 Arg; Gln; Asn 
                 Arg 
               
               
                   
                 Met (M) 
                 Leu; Phe; Ile 
                 Leu 
               
               
                   
                 Phe (F) 
                 Trp; Leu; Val; Ile; Ala; Tyr 
                 Tyr 
               
               
                   
                 Pro (P) 
                 Ala 
                 Ala 
               
               
                   
                 Ser (S) 
                 Thr 
                 Thr 
               
               
                   
                 Thr (T) 
                 Val; Ser 
                 Ser 
               
               
                   
                 Trp (W) 
                 Tyr; Phe 
                 Tyr 
               
               
                   
                 Tyr (Y) 
                 Trp; Phe; Thr; Ser 
                 Phe 
               
               
                   
                 Val (V) 
                 Ile; Leu; Met; Phe; 
                 Leu 
               
               
                   
                   
                 Ala; Norleucine 
               
               
                   
                   
               
            
           
         
       
     
     Substantial modifications in the biological properties of the antibody are accomplished by selecting substitutions that differ significantly in their effect on maintaining (a) the structure of the polypeptide backbone in the area of the substitution, for example, as a sheet or helical conformation, (b) the charge or hydrophobicity of the molecule at the target site, or (c) the bulk of the side chain. Amino acids may be grouped according to similarities in the properties of their side chains (in A. L. Lehninger, in  Biochemistry , second ed., pp. 73-75, Worth Publishers, New York (1975)): 
     (1) non-polar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M) 
     (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q) 
     (3) acidic: Asp (D), Glu (E) 
     (4) basic: Lys (K), Arg (R), His(H) 
     Alternatively, naturally occurring residues may be divided into groups based on common side-chain properties: 
     (1) hydrophobic: Norleucine, Met, Ala, Val, Leu, Ile; 
     (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; 
     (3) acidic: Asp, Glu; 
     (4) basic: His, Lys, Arg; 
     (5) residues that influence chain orientation: Gly, Pro; 
     (6) aromatic: Trp, Tyr, Phe. 
     Non-conservative substitutions will entail exchanging a member of one of these classes for another class. 
     Any cysteine residue not involved in maintaining the proper conformation of the antibody also may be substituted, generally with serine, to improve the oxidative stability of the molecule and prevent aberrant crosslinking. Conversely, cysteine bond(s) may be added to the antibody to improve its stability (particularly where the antibody is an antibody fragment such as an Fv fragment). 
     A particularly preferred type of substitutional variant involves substituting one or more hypervariable region residues of a parent antibody (e.g. a humanized or human antibody). Generally, the resulting variant(s) selected for further development will have improved biological properties relative to the parent antibody from which they are generated. A convenient way for generating such substitutional variants involves affinity maturation using phage display. Briefly, several hypervariable region sites (e.g. 6-7 sites) are mutated to generate all possible amino substitutions at each site. The antibody variants thus generated are displayed in a monovalent fashion from filamentous phage particles as fusions to the gene III product of M13 packaged within each particle. The phage-displayed variants are then screened for their biological activity (e.g. binding affinity) as herein disclosed. In order to identify candidate hypervariable region sites for modification, alanine scanning mutagenesis can be performed to identify hypervariable region residues contributing significantly to antigen binding. Alternatively, or additionally, it may be beneficial to analyze a crystal structure of the antigen-antibody complex to identify contact points between the antibody and human HER2. Such contact residues and neighboring residues are candidates for substitution according to the techniques elaborated herein. Once such variants are generated, the panel of variants is subjected to screening as described herein and antibodies with superior properties in one or more relevant assays may be selected for further development. 
     Exemplary trastuzumab variants herein include those described in US2003/0228663A1 (Lowman et al.), including substitutions of one or more of the following VL positions: Q27, D28, N30, T31, A32, Y49, F53, Y55, R66, H91, Y92, and/or T94; and/or substitutions of one or more of VH positions: W95, D98, F100, Y100a, and/or Y102. 
     Another type of amino acid variant of the antibody alters the original glycosylation pattern of the antibody. By altering is meant deleting one or more carbohydrate moieties found in the antibody, and/or adding one or more glycosylation sites that are not present in the antibody. 
     Glycosylation of antibodies is typically either N-linked or O-linked. N-linked refers to the attachment of the carbohydrate moiety to the side chain of an asparagine residue. The tripeptide sequences asparagine-X-serine and asparagine-X-threonine, where X is any amino acid except proline, are the recognition sequences for enzymatic attachment of the carbohydrate moiety to the asparagine side chain. Thus, the presence of either of these tripeptide sequences in a polypeptide creates a potential glycosylation site. O-linked glycosylation refers to the attachment of one of the sugars N-aceylgalactosamine, galactose, or xylose to a hydroxyamino acid, most commonly serine or threonine, although 5-hydroxyproline or 5-hydroxylysine may also be used. 
     Addition of glycosylation sites to the antibody is conveniently accomplished by altering the amino acid sequence such that it contains one or more of the above-described tripeptide sequences (for N-linked glycosylation sites). The alteration may also be made by the addition of, or substitution by, one or more serine or threonine residues to the sequence of the original antibody (for O-linked glycosylation sites). 
     Where the antibody comprises an Fc region, the carbohydrate attached thereto may be altered. For example, antibodies with a mature carbohydrate structure that lacks fucose attached to an Fc region of the antibody are described in US Pat Appl No US 2003/0157108 A1, Presta, L. See also US 2004/0093621 A1 (Kyowa Hakko Kogyo Co., Ltd). Antibodies with a bisecting N-acetylglucosamine (GlcNAc) in the carbohydrate attached to an Fc region of the antibody are referenced in WO03/011878, Jean-Mairet et al. and U.S. Pat. No. 6,602,684, Umana et al. Antibodies with at least one galactose residue in the oligosaccharide attached to an Fc region of the antibody are reported in WO97/30087, Patel et al. See, also, WO98/58964 (Raju, S.) and WO99/22764 (Raju, S.) concerning antibodies with altered carbohydrate attached to the Fc region thereof. 
     It may be desirable to modify the antibody of the invention with respect to effector function, e.g. so as to enhance antigen-dependent cell-mediated cyotoxicity (ADCC) and/or complement dependent cytotoxicity (CDC) of the antibody. This may be achieved by introducing one or more amino acid substitutions in an Fc region of the antibody. Alternatively or additionally, cysteine residue(s) may be introduced in the Fc region, thereby allowing interchain disulfide bond formation in this region. The homodimeric antibody thus generated may have improved internalization capability and/or increased complement-mediated cell killing and antibody-dependent cellular cytotoxicity (ADCC). See Caron et al.,  J. Exp Med.  176:1191-1195 (1992) and Shopes, B.  J. Immunol.  148:2918-2922 (1992). Homodimeric antibodies with enhanced anti-tumor activity may also be prepared using heterobifunctional cross-linkers as described in Wolff et al.  Cancer Research  53:2560-2565 (1993). Alternatively, an antibody can be engineered which has dual Fc regions and may thereby have enhanced complement lysis and ADCC capabilities. See Stevenson et al.  Anti - Cancer Drug Design  3:219-230 (1989). 
     WO00/42072 (Presta, L.) describes antibodies with improved ADCC function in the presence of human effector cells, where the antibodies comprise amino acid substitutions in the Fc region thereof. Preferably, the antibody with improved ADCC comprises substitutions at positions 298, 333, and/or 334 of the Fc region (Eu numbering of residues). Preferably the altered Fc region is a human IgG1 Fc region comprising or consisting of substitutions at one, two or three of these positions. Such substitutions are optionally combined with substitution(s) which increase Clq binding and/or CDC. 
     Antibodies with altered Clq binding and/or complement dependent cytotoxicity (CDC) are described in WO99/51642, U.S. Pat. No. 6,194,551B1, U.S. Pat. No. 6,242,195B1, U.S. Pat. No. 6,528,624B1 and U.S. Pat. No. 6,538,124 (Idusogie et al.). The antibodies comprise an amino acid substitution at one or more of amino acid positions 270, 322, 326, 327, 329, 313, 333 and/or 334 of the Fc region thereof (Eu numbering of residues). 
     To increase the serum half life of the antibody, one may incorporate a salvage receptor binding epitope into the antibody (especially an antibody fragment) as described in U.S. Pat. No. 5,739,277, for example. As used herein, the term “salvage receptor binding epitope” refers to an epitope of the Fc region of an IgG molecule (e.g., IgG 1 , IgG 2 , IgG 3 , or IgG 4 ) that is responsible for increasing the in vivo serum half-life of the IgG molecule. 
     Antibodies with improved binding to the neonatal Fc receptor (FcRn), and increased half-lives, are described in WO00/42072 (Presta, L.) and US2005/0014934A1 (Hinton et al.). These antibodies comprise an Fc region with one or more substitutions therein which improve binding of the Fc region to FcRn. For example, the Fc region may have substitutions at one or more of positions 238, 250, 256, 265, 272, 286, 303, 305, 307, 311, 312, 314, 317, 340, 356, 360, 362, 376, 378, 380, 382, 413, 424, 428 or 434 (Eu numbering of residues). The preferred Fc region-comprising antibody variant with improved FcRn binding comprises amino acid substitutions at one, two or three of positions 307, 380 and 434 of the Fc region thereof (Eu numbering of residues). 
     Engineered antibodies with three or more (preferably four) functional antigen binding sites are also contemplated (US Appln No. US2002/0004587 A1, Miller et al.). 
     Nucleic acid molecules encoding amino acid sequence variants of the antibody are prepared by a variety of methods known in the art. These methods include, but are not limited to, isolation from a natural source (in the case of naturally occurring amino acid sequence variants) or preparation by oligonucleotide-mediated (or site-directed) mutagenesis, PCR mutagenesis, and cassette mutagenesis of an earlier prepared variant or a non-variant version of the antibody. 
     (viii) Screening for Antibodies with the Desired Properties 
     Techniques for generating antibodies have been described above. One may further select antibodies with certain biological characteristics, as desired. 
     To identify a HER2 antibody which binds to HER2 Domain IV bound by trastuzumab (HERCEPTIN®), one can evaluate the ability to bind to the isolated Domain IV peptide, Domain IV as present in HER2 ECD; or as it exists in the intact HER2 receptor (where the ECD or receptor can be isolated or present on the surface of a cell), etc. Optionally, one may evaluate whether the HER2 antibody of interest binds to the Trastuzumab or 4D5 epitope, or blocks or competes with binding of Trastuzumab or 4D5 to HER2; such antibodies would necessarily be considered to bind to HER2 Domain IV bound by trastuzumab (HERCEPTIN®). To screen for antibodies which bind to an epitope on HER2 bound by an antibody of interest, a routine cross-blocking assay such as that described in  Antibodies, A Laboratory Manual , Cold Spring Harbor Laboratory, Ed Harlow and David Lane (1988), can be performed to assess whether the antibody blocks binding of an antibody, such as trastuzumab or 4D5 to HER2. See, also, Fendly et al.  Cancer Research  50:1550-1558 (1990), where cross-blocking studies were done on HER2 antibodies by direct fluorescence on intact HER2 positive cells. HER2 monoclonal antibodies were considered to share an epitope if each blocked binding of the other by 50% or greater in comparison to an irrelevant monoclonal antibody control. In the studies in Fendly et al. 3H4 and 4D5 bound to the same epitope. Alternatively, or additionally, epitope mapping can be performed by methods known in the art and/or one can study the antibody-HER2 structure (Franklin et al.  Cancer Cell  5:317-328 (2004)) to see what domain or epitope of HER2 is/are bound by the antibody. 
     Trastuzumab has been shown in both in vitro assays and in animals, to inhibit the proliferation of human tumor cells that overexpress HER2. Hudziak et al.  Mol. Cell. Biol.  9:1165-1172 (1989); U.S. Pat. No. 5,677,171; Lewis et al.  Cancer Immunol. Immunother  37: 255-263 (1993); Pietras et al.  Oncogene  1998; 17:2235-49 (1998); and Baselga et al.  Cancer Res.  58: 2825-2831 (1998). HERCEPTIN® has both cytostatic and cytotoxic effects on HER2-positive tumor cell lines (Lewis et al., (1993)). 
     In order to select another growth inhibitory HER2 antibody with this property, those in vitro or in vivo assays can be used to screen HER2 antibodies for growth inhibition biological activity. In particular, to identify growth inhibitory HER2 antibodies, one may screen for antibodies which inhibit the growth of cancer cells which overexpress HER2 in vitro. In one embodiment, the growth inhibitory antibody of choice is able to inhibit growth of SK-BR-3 cells in cell culture by about 20-100% and preferably by about 50-100% at an antibody concentration of about 0.5 to 30 μg/ml. To identify such antibodies, the SK-BR-3 assay described in U.S. Pat. No. 5,677,171 can be performed. According to this assay, SK-BR-3 cells are grown in a 1:1 mixture of F12 and DMEM medium supplemented with 10% fetal bovine serum, glutamine and penicillin streptomycin. The SK-BR-3 cells are plated at 20,000 cells in a 35 mm cell culture dish (2 mls/35 mm dish). 0.5 to 30 μg/ml of the HER2 antibody is added per dish. After six days, the number of cells, compared to untreated cells are counted using an electronic COULTER™ cell counter. Those antibodies which inhibit growth of the SK-BR-3 cells by about 20-100% or about 50-100% may be selected as growth inhibitory antibodies. See U.S. Pat. No. 5,677,171 for assays for screening for growth inhibitory antibodies, such as 4D5 and 3E8. 
     In order to select HER2 antibodies that inhibit growth of HER2 positive tumors in vivo, xenograft studies, such as those in Pietras et al. (1998) and Baselga et al. (1998), can be used to screen HER2 antibodies for this property. 
     Trastuzumab is a mediator of antibody-dependent cellular cytotoxicity (ADCC). Hotaling et al.  Proc. Am. Assoc. Cancer Res.  37: 471 (1996), Abstract 3215; Pegram et al.  Proc. Am. Assoc Cancer Res  38:602 (1997), Abstract 4044; U.S. Pat. Nos. 5,821,337, 6,054,297, 6,407,213, 6,639,055, 6,719,971, and 6,800,738; and Carter et al.  PNAS  ( USA ) 89: 4285-4289 (1992); Clynes et al.  Nature Medicine  6:443-6 (2000)). Other HER2 antibodies which mediate ADCC can be identified using various assays, including those described in these references. 
     Trastuzumab has also been reported to inhibit HER2 ectodomain cleavage (Molina et al.  Cancer Res.  61:4744-4749 (2001)), and other HER2 antibodies with this function can be identified using the methodology used by Molina et al., for example. 
     HERCEPTIN® has also been reported to induce normalization and regression of tumor vasculature in HER2 positive human breast tumors by modulating the effects of angiogenic factors (Izumi et al.  Nature  416:279-80 (2002)). Other HER2 antibodies with this property can be identified using the experiments described in Izumi et al. 
     (ix) HERCEPTIN® Compositions 
     The HERCEPTIN®-derived compositions of the invention may comprises a mixture of a main species antibody, and variant forms thereof, in particular acidic variants (including deamidated variants). Preferably, the amount of such acidic variants in the composition is less than about 25%. See, U.S. Pat. No. 6,339,142. See, also, Harris et al.  J. Chromatography B  752:233-245 (2001) concerning forms of trastuzumab resolvable by cation-exchange chromatography, including Peak A (Asn30 deamidated to Asp in both light chains): Peak B (Asn55 deamidated to isoAsp in one heavy chain); Peak 1 (Asn30 deamidated to Asp in one light chain); Peak 2 (Asn30 deamidated to Asp in one light chain, and Asp102 isomerized to isoAsp in one heavy chain); Peak 3 (main peak form, or main species antibody); Peak 4 (Asp102 isomerized to isoAsp in one heavy chain); and Peak C (Asp102 succinimide (Asu) in one heavy chain). Such variant forms and compositions are included in the invention herein. 
     NK Cells, the MicB Ligand and Receptors 
     Classical natural killer (NK) cells are large granular lymphocytes, phenotypically defined as CD3-, sig-, CD16+ and CD56+, that have been found to play a critical role in the innate immune response to an initial immunologic challenge. They are called natural killer cells because they exhibit rapid spontaneous killing against a variety of target cell types without the need for antigen-specific activation. The peak of NK cell cytotoxicity and IFN-γ production occur within the first several hours to days after a primary infection. Whereas the adaptive immune responses from T and B cells take more than a week to develop (Biron, C. A., et. al.  Annu. Rev. Immunol.  17:189-220 (1999)). NK cells are considered innate, because they do not express clonally distributed receptors for antigens which is characteristic of the slower adaptive immune response. Because of these innate mechanisms, they can rapidly detect and effectively eliminate highly dangerous cells. These mechanisms represent recently evolved human immunologic adaptations as demonstrated by the substantial differences in expression between chimpanzees and humans. (De Maria, A. et. al.,  Eur. J. Immunol.  31:3546-3556 (2001)). 
     NK cells are confined mainly to the peripheral blood, spleen and bone marrow but can migrate to inflamed tissues in response to chemoattractants. Upon activation, they not only lyse target cells but also express cytokines and chemokines that induce inflammatory responses, modulate hematopoiesis, control monocyte and granulocyte cell growth and function which, in turn, influence subsequent immune responses. Specifically, NK secrete cytokines such as interferon γ (IFN-γ), granulocyte-macrophage colony-stimulating factors (GM-CSFs), tumor necrosis factor α (TNF-α), macrophage colony-stimulating factor (M-CSF), interleukin-3 (IL-3), and IL-8 (Scott, F., et. al., Current Opinion in Immunology, 7:34-40, (1995)). In addition, cytokines such as IL-2, IL-12, TNF-α, and Il-1 can induce NK cells to produce cytokines. 
     NK cells direct interaction with other cells by way of their surface molecules also plays a role in their cytotoxic activities. These include F γ RIII (CD16) the low-affinity receptor for human IgG which is the molecule responsible for mediating Ab-dependent cellular cytotoxicity (ADCC) by NK cells (Lanier, L L. et. al., J. Immunol. 141:3478-85 (1988)), CD69 (Moretta, A., et. al., J. Exp. Med., 174:1393-98 (1991)), CD44 (Galandrini, R., et. al., J. Immunol. 153:4399-4407 (1994)), CD 56 (Geitenbeek, T B et. al., Placenta 22 (Suppl. A):S19-23 (2001)), the family of killer-activating receptors (KIRs) capably of recognizing the MHC molecules and delivering inhibitory or stimulatory signals when engaged and the adhesion molecules such as CD2 or CD18 (Colonna, M., Immunol. Rev., 155:127-133 (1997)). 
     NK cells lyse cells through the action of cytoplasmic granules containing proteases, nucleases and perforin (See, D., et. al., Scand. J. Immunol. 46:217-224, 1997). In addition, NK cells can also lyse cells through antibody-dependent cellular cytotoxicity (See, D, et. al., 1997). 
     Despite their lack of antigen-specific activation, NK cells demonstrate surprising specificity in their ability to recognize targets. NK cells were originally identified because of their discriminating ability to kill certain tumor and virally infected cells while sparing normal cells. NK cells achieve this specificity through a complex combination of activating and inhibitory receptors on the NK cell surface. NK cell activation and the degree of activation is determined by the balance of both activation and inhibition signals. 
     The molecular mechanism whereby NK cells spare normal cells is due to specialized inhibitory receptors that recognize major histocompatability complex (MHC) class I molecules which are expressed on almost all normal nucleated cells. Karre et. al. proposed the “missing self” hypothesis wherein NK cells detect and eliminate target cells that do not adequately express normal self-MHC molecules. (Ljunggren H-G, J. Exp. Med. 162:1745-59 (1985), Pionteck G E, et. al., J. Immunol. 135:4281-88 (1985), Karre K., et al., Nature 319:675-78 (1986)). An inverse correlation was established between the expression of surface MHC class I molecules on target cells and their susceptibility to NK cell-mediated lysis. Virus-infected or tumor cells typically downregulate certain class I alleles or express an altered peptide pattern presented by MHC class I molecules. (Chadwick B S, et al., J. Immunol. 149:3150-56 (1992)). Thus, NK cells complement cytolytic T cells that are triggered by class I proteins presenting foreign peptides. Infected or tumor cells which downregulate their MHC class I molecules to escape detection by cytolytic T cells are detected and targeted for killing instead by NK cells. 
     However, this “missing self” hypothesis did not explain the targeted killing of cells that expressed adequate amounts of MHC Class I molecules. Further the sensitivity of the NK cell activation did not always correlate with the MHC Class I expression. (Correa I, et. al., Eur J Immunol 24:1323-1331, (1994)). Subsequently, related MHC class I molecules were discovered, such as MICA (Major Histocompatibility I Chain-related antigen A), which were found to function as activating ligands to NK cell activating receptors. (Diefenbach, A. at. al., Current Biology, 9:R851-R853. (1999)). Subsequent research has identified a host of NK cell activating and inhibiting receptors. It is now known that NK cell activation requires the interaction and balancing of a number of receptors that have opposite functions, some activating and some inhibiting. The activation and degree of NK cell activation are determined by a balancing of the competing signals. (Moretta, A. et. al., Nature Immunol. 3:1 (2002)). 
     NK cells have long been known as involved in the prevention and control of cancer. NK cells were originally identified because of their selective recognition and lyses of tumor cells. (Trinchieri, G., Adv. Immunol. 47:187 (1989)) NK cells have been shown involved in both the resistance to and control of metastasis (Whiteside, T., et. al., Current Opinion in Immunology 7:704-710, (1995)) 
     NK cell activity has been studied in the context of a wide range of viral infections. Elevated NK cell activity has been observed during infections of the following viruses: arenaviruses e.g. lyphocytic choriomentigitis (LCMV) (Biron, C A, et. al., J. Immunol. 139:1704-1710, (1987), Welsh, R M., J. Exp. Med., 148:163-181, (1978)), the herpesviruses, e.g. murine cytomegalovirus (MCMV) (Welsh, R M, (1978), Orange, J S, et. al., J. Immunol. 156:4746-4756 (1996)) herpes simplex virus (HSV) (Ching, C., et. al., Infect. Immun. 26:49-56 (1979)), the orthomyxoviruses e.g. influenza virus (Santoli, D., et. al., J. Immunol. 121:532-38 (1978)), picornaviruses e.g. Coxsackie virus (Godeny, E K, et. al., J. Immunol. 137:1695-702 (1986)). 
     Further evidence of NK cell involvement in the defense against viral infections comes from clinical data involving human infections. Low NK cell activity has been correlated with increased sensitivity to severe disseminating herpesgroup virus infections, (Ching, C., (1979), Biron, C., et. al., N. Eng. J. Med. 320:1731-35 (1989)), Epstein-Barr virus (EBV) (Merino, R., et. al., J. Clin. Immunol. 6:299-305 (1986), Joncas, J. et. al., J. Med. Virol. 28:110-17 (1989)), human cytomegalovirus (HCMV) (Biron, C A, (1989), Quinnan, G V., et. al., N. Engl. J. Med. 307:7-13, (1982)) and in late stages of human immunodeficiency virus (HIV) infections (Bonavida, B., et. al., J. Immunol. 137:1157-63 (1986), Katz, J D., et. al., J. Immunol. 139:55-60 (1987)). 
     A population of T cells sharing characteristics with classical NK cells has been identified based on expression of NK cell markers (“NKT cells”; Benedelac, A., et. al., Annu. Rev. Immunol. 15:535-62 (1997), Ohteki, T., et. al., J. Exp. Med. 180:699-704 (1994)). These cells express a limited range of T cell receptor (TCR) and predominantly express TCR α/β in mice (Lanz, O., et. al., J. Exp. Med., 180:1097-106 (1994), Taniguchi, M., et. al., Proc. Natl. Acad. Sci., 93:11025-28 (1996)). Some activated NKT cells can lyse cells sensitive to classical NK cell-mediated cytotoxicity (Koyasu, S., J. Exp. Med., 179:1957-72, (1994), NKT cells proliferate in response to IL-2 and they release IL-4 upon stimulation via the CD3 complex. (Arase, H., et. al., J. Exp. Med. 183:2391-96 (1996). Yoshimoto, T., et. al., J. Exp. Med. 179:1286-95 (1994), Chen, H., et. al., J. Immunol. 159:2240-44 (1997)). NKT cells participate in the innate immune response in that they secrete IL-4 during a primary challenge (Yoshimoto, T., (1994), Chen, H., (1997)). As such, NKT cells participate closely with but are distinct from and not to be confused with classical NK cells. 
     In light of the critical role NK cells play in vivo, in immune surveillance, host defenses in cancer, viral infections and autoimmune disease, NK cell cytotoxic activity stands as a powerful yet unused immunologic therapeutic potential. The present invention utilizes the cytotoxic mechanisms of the NK cell in a targeted fusion polypeptide molecule to enhance therapy. 
     MICB is a cell surface protein and an activating ligand to the NK cell receptor. MICB is recognized by receptors present on cytotoxic hematopoietic cells, such as the NKG2D receptor on the surface of NK cells, cytotoxic T-cells, and activated macrophages. MICs are expressed on stress-induced intestinal epithelium tumor cells, including epithelial cell tumors from lung, breast, kidney, ovary, prostate, and intestine (Groh et al., 1999, Proc. Natl. Acad. Sci. USA 96:6879-84; Groh et al., 1996, Proc. Natl. Acad. Sci. USA 93:12445-50). 
     Protein domains for MICB have been defined and include signal peptide, alpha-1 domain, alpha-2 domain, alpha-3 domain, transmembrane domain, and cytoplasmic tail shown in Table 2, and having the approximate amino acid residues shown below. The exact amino acid borders for each domain can vary, for example, by about 5 to 10 amino acids (Barham, 1994, supra; Steinle, 1998, supra). 
     
       
         
           
               
            
               
                   
               
               
                 MICB DOMAINS 
               
            
           
           
               
               
               
            
               
                   
                 MICB Domain 
                 Approximate Amino Acid Position* 
               
               
                   
                   
               
               
                   
                 Signal peptide 
                  1-23 
               
               
                   
                 Alpha-1 domain 
                  24-108 
               
               
                   
                 Alpha-2 domain 
                 109-204 
               
               
                   
                 Alpha-3 domain 
                 205-297 
               
               
                   
                 Transmembrane domain 
                 298-331/341 
               
               
                   
                 Cytoplasmic tail 
                 332/342-383 
               
               
                   
                   
               
            
           
         
       
     
     GenBank lists several reference sequences for MICB. These include Accession Numbers: X91625 for MICB cDNA and CAA62823 for MICB protein. These reference sequences represent a “reference MICB”, but it is understood that many variant sequence are known as discussed below, for example. 
     Nucleic acid sequences encoding MICB are highly polymorphic, and correspondingly display an unusual distribution of a number of variant amino acids in their extracellular alpha-1, alpha-2, and alpha-3 domains (exons 2-4). Numerous allelic variants encoding MICB genes are described. (Stephens, 2001, supra; Zhang et al., 2001, supra; Fischer et al., 2000, supra; and Petersdorf et al., 1999, supra). To date, at least 13 MICB sequence depositions have been made (http://www.ncbi.nlm.nih.gov). Fischer et al. (2000, supra) described several MICB alleles (i.e. three novel alleles) confirming previous findings that most of the polymorphisms in the MICB gene occur in coding regions and suggesting that the extent of polymorphism in the two genes may be comparable. 
     As used herein, MICB further includes variants that are truncated, for example, by deletion of all, or a portion of one or more of the signal peptide/leader sequence, transmembrane domain, and cytoplasmic tail. Such MIC variants, comprising at least the α1, α2, and α3 domains, are useful as soluble MICB. 
     In some embodiments of the invention, the MicB portion of the fusion protein is linked to the anti-HER2 antibody via a linker. The linker component of the hybrid molecule of the invention does not necessarily participate in the binding of the molecule. Therefore, according to the present invention, the linker domain, is any group of molecules that provides a spatial bridge between the active domain and the peptide ligand domain of the molecule. 
     The linker domain can be of variable length and makeup, however, according to the present invention, it is the length of the linker domain and not its structure that is important. The linker domain preferably allows for the MicB portion to bind to the NK cell and the anti-HER2 antibody portion to bind, substantially free of steric and/or conformational restrictions, to the target cell. Therefore, the length of the linker domain is dependent upon the character of the two “functional” domains of the hybrid molecule. 
     One skilled in the art will recognize that various combinations of atoms provide for variable length molecules based upon known distances between various bonds (Morrison, and Boyd,  Organic Chemistry,  3rd Ed, Allyn and Bacon, Inc., Boston, Mass. (1977)). For example, the linker domain may be a polypeptide of variable length. The amino acid composition of the polypeptide determines the character and length of the linker. In a preferred embodiment, the linker molecule comprises a flexible, hydrophilic polypeptide chain. Exemplary linker domains comprises one or more [(Gly) 4 -Ser] units (SEQ ID NO: 5), such as those described in the Example sections herein. 
     In another embodiment, the fusion polypeptides may be conjugated to a “receptor” (such as streptavidin) for utilization in tumor pretargeting wherein the fusion polypeptide is administered to a patient, followed by removal of unbound conjugate from the circulation using a clearing agent and then administration of a “ligand” (e.g. biotin or avidin) which is conjugated to a cytotoxic agent (e.g. a radionucleotide). 
     The invention also provides isolated nucleic acid encoding a fusion polypeptide comprising an antibody and MicB as disclosed herein, vectors and host cells comprising the nucleic acid, and recombinant techniques for the production of the fusion polypeptide. 
     For recombinant production of the fusion polypeptide, the nucleic acid encoding it is isolated and inserted into a replicable vector for further cloning (amplification of the DNA) or for expression. DNA encoding the fusion polypeptide is readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the polypeptide variant). Many vectors are available. The vector components generally include, but are not limited to, one or more of the following: a signal sequence, an origin of replication, one or more marker genes, an enhancer element, a promoter, and a transcription termination sequence. 
     (i) Signal Sequence Component 
     The fusion polypeptide of this invention may be produced recombinantly not only directly, but also as a fusion polypeptide with a heterologous polypeptide, which is preferably a signal sequence or other polypeptide having a specific cleavage site at the N-terminus of the mature protein or polypeptide. The heterologous signal sequence selected preferably is one that is recognized and processed (i.e., cleaved by a signal peptidase) by the host cell. For prokaryotic host cells that do not recognize and process the native polypeptide variant signal sequence, the signal sequence is substituted by a prokaryotic signal sequence selected, for example, from the group of the alkaline phosphatase, penicillinase, lpp, or heat-stable enterotoxin II leaders. For yeast secretion the native signal sequence may be substituted by, e.g., the yeast invertase leader, α factor leader (including  Saccharomyces  and  Kluyveromyces  α-factor leaders), or acid phosphatase leader, the  C. albicans  glucoamylase leader, or the signal described in WO 90/13646. In mammalian cell expression, mammalian signal sequences as well as viral secretory leaders, for example, the herpes simplex gD signal, are available. 
     The DNA for such precursor region is ligated in reading frame to DNA encoding the fusion polypeptide. 
     (ii) Origin of Replication Component 
     Both expression and cloning vectors contain a nucleic acid sequence that enables the vector to replicate in one or more selected host cells. Generally, in cloning vectors this sequence is one that enables the vector to replicate independently of the host chromosomal DNA, and includes origins of replication or autonomously replicating sequences. Such sequences are well known for a variety of bacteria, yeast, and viruses. The origin of replication from the plasmid pBR322 is suitable for most Gram-negative bacteria, the 2μ plasmid origin is suitable for yeast, and various viral origins (SV40, polyoma, adenovirus, VSV or BPV) are useful for cloning vectors in mammalian cells. Generally, the origin of replication component is not needed for mammalian expression vectors (the SV40 origin may typically be used only because it contains the early promoter). 
     (iii) Selection Gene Component 
     Expression and cloning vectors may contain a selection gene, also termed a selectable marker. Typical selection genes encode proteins that (a) confer resistance to antibiotics or other toxins, e.g., ampicillin, neomycin, methotrexate, or tetracycline, (b) complement auxotrophic deficiencies, or (c) supply critical nutrients not available from complex media, e.g., the gene encoding D-alanine racemase for  Bacilli.    
     One example of a selection scheme utilizes a drug to arrest growth of a host cell. Those cells that are successfully transformed with a heterologous gene produce a protein conferring drug resistance and thus survive the selection regimen. Examples of such dominant selection use the drugs neomycin, mycophenolic acid and hygromycin. 
     Another example of suitable selectable markers for mammalian cells are those that enable the identification of cells competent to take up the polypeptide variant nucleic acid, such as DHFR, thymidine kinase, metallothionein-I and -II, preferably primate metallothionein genes, adenosine deaminase, ornithine decarboxylase, etc. 
     For example, cells transformed with the DHFR selection gene are first identified by culturing all of the transformants in a culture medium that contains methotrexate (Mtx), a competitive antagonist of DHFR. An appropriate host cell when wild-type DHFR is employed is the Chinese hamster ovary (CHO) cell line deficient in DHFR activity. 
     Alternatively, host cells (particularly wild-type hosts that contain endogenous DHFR) transformed or co-transformed with DNA sequences encoding polypeptide variant, wild-type DHFR protein, and another selectable marker such as aminoglycoside 3′-phosphotransferase (APH) can be selected by cell growth in medium containing a selection agent for the selectable marker such as an aminoglycosidic antibiotic, e.g., kanamycin, neomycin, or G418. See U.S. Pat. No. 4,965,199. 
     A suitable selection gene for use in yeast is the trp1 gene present in the yeast plasmid YRp7 (Stinchcomb et al.,  Nature,  282:39 (1979)). The trp1 gene provides a selection marker for a mutant strain of yeast lacking the ability to grow in tryptophan, for example, ATCC No. 44076 or PEP4-1. Jones,  Genetics,  85:12 (1977). The presence of the trp1 lesion in the yeast host cell genome then provides an effective environment for detecting transformation by growth in the absence of tryptophan. Similarly, Leu2-deficient yeast strains (ATCC 20,622 or 38,626) are complemented by known plasmids bearing the Leu2 gene. 
     In addition, vectors derived from the 1.6 μm circular plasmid pKD1 can be used for transformation of  Kluyveromyces  yeasts. Alternatively, an expression system for large-scale production of recombinant calf chymosin was reported for  K. lactis . Van den Berg,  Bio/Technology,  8:135 (1990). Stable multi-copy expression vectors for secretion of mature recombinant human serum albumin by industrial strains of  Kluyveromyces  have also been disclosed. Fleer et al.,  Bio/technology,  9:968-975 (1991). 
     (iv) Promoter Component 
     Expression and cloning vectors usually contain a promoter that is recognized by the host organism and is operably linked to the nucleic acid encoding a fusion polypeptide of the invention. Promoters suitable for use with prokaryotic hosts include the phoA promoter, β-lactamase and lactose promoter systems, alkaline phosphatase, a tryptophan (trp) promoter system, and hybrid promoters such as the tac promoter. However, other known bacterial promoters are suitable. Promoters for use in bacterial systems also will contain a Shine-Dalgarno (S.D.) sequence operably linked to the DNA encoding the polypeptide variant. 
     Promoter sequences are known for eukaryotes. Virtually all eukaryotic genes have an AT-rich region located approximately 25 to 30 bases upstream from the site where transcription is initiated. Another sequence found 70 to 80 bases upstream from the start of transcription of many genes is a CNCAAT region where N may be any nucleotide (SEQ ID NO: 6). At the 3′ end of most eukaryotic genes is an AATAAA sequence (SEQ ID NO: 7) that may be the signal for addition of the poly A tail to the 3′ end of the coding sequence. All of these sequences are suitably inserted into eukaryotic expression vectors. 
     Examples of suitable promoting sequences for use with yeast hosts include the promoters for 3-phosphoglycerate kinase or other glycolytic enzymes, such as enolase, glyceraldehyde-3-phosphate dehydrogenase, hexokinase, pyruvate decarboxylase, phosphofructokinase, glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase, phosphoglucose isomerase, and glucokinase. 
     Other yeast promoters, which are inducible promoters having the additional advantage of transcription controlled by growth conditions, are the promoter regions for alcohol dehydrogenase 2, isocytochrome C, acid phosphatase, degradative enzymes associated with nitrogen metabolism, metallothionein, glyceraldehyde-3-phosphate dehydrogenase, and enzymes responsible for maltose and galactose utilization. Suitable vectors and promoters for use in yeast expression are further described in EP 73,657. Yeast enhancers also are advantageously used with yeast promoters. 
     The fusion polypeptide transcription from vectors in mammalian host cells is controlled, for example, by promoters obtained from the genomes of viruses such as polyoma virus, fowlpox virus, adenovirus (such as Adenovirus 2), bovine papilloma virus, avian sarcoma virus, cytomegalovirus, a retrovirus, hepatitis-B virus and most preferably Simian Virus 40 (SV40), from heterologous mammalian promoters, e.g., the actin promoter or an immunoglobulin promoter, from heat-shock promoters, provided such promoters are compatible with the host cell systems. 
     The early and late promoters of the SV40 virus are conveniently obtained as an SV40 restriction fragment that also contains the SV40 viral origin of replication. The immediate early promoter of the human cytomegalovirus is conveniently obtained as a HindIII E restriction fragment. A system for expressing DNA in mammalian hosts using the bovine papilloma virus as a vector is disclosed in U.S. Pat. No. 4,419,446. A modification of this system is described in U.S. Pat. No. 4,601,978. See also Reyes et al.,  Nature  297:598-601 (1982) on expression of human β-interferon cDNA in mouse cells under the control of a thymidine kinase promoter from herpes simplex virus. Alternatively, the rous sarcoma virus long terminal repeat can be used as the promoter. 
     (v) Enhancer Element Component 
     Transcription of a DNA encoding the fusion polypeptide of this invention by higher eukaryotes is often increased by inserting an enhancer sequence into the vector. Many enhancer sequences are now known from mammalian genes (globin, elastase, albumin, α-fetoprotein, and insulin). Typically, however, one will use an enhancer from a eukaryotic cell virus. Examples include the SV40 enhancer on the late side of the replication origin (bp 100-270), the cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers. See also Yaniv,  Nature  297:17-18 (1982) on enhancing elements for activation of eukaryotic promoters. The enhancer may be spliced into the vector at a position 5′ or 3′ to the fusion polypeptide-encoding sequence, but is preferably located at a site 5′ from the promoter. 
     (vi) Transcription Termination Component 
     Expression vectors used in eukaryotic host cells (yeast, fungi, insect, plant, animal, human, or nucleated cells from other multicellular organisms) will also contain sequences necessary for the termination of transcription and for stabilizing the mRNA. Such sequences are commonly available from the 5′ and, occasionally 3′, untranslated regions of eukaryotic or viral DNAs or cDNAs. These regions contain nucleotide segments transcribed as polyadenylated fragments in the untranslated portion of the mRNA encoding the polypeptide variant. One useful transcription termination component is the bovine growth hormone polyadenylation region. See WO94/11026 and the expression vector disclosed therein. 
     (vii) Selection and Transformation of Host Cells 
     Suitable host cells for cloning or expressing the DNA in the vectors herein are the prokaryote, yeast, or higher eukaryote cells described above. Suitable prokaryotes for this purpose include eubacteria, such as Gram-negative or Gram-positive organisms, for example, Enterobacteriaceae such as  Escherichia , e.g.,  E. coli, Enterobacter, Erwinia, Klebsiella, Proteus, Salmonella , e.g.,  Salmonella typhimurium, Serratia , e.g.,  Serratia marcescans , and  Shigella , as well as Bacilli such as  B. subtilis  and  B. licheniformis  (e.g.,  B. licheniformis  41P disclosed in DD 266,710 published 12 Apr. 1989),  Pseudomonas  such as  P. aeruginosa , and  Streptomyces . One preferred  E. coli  cloning host is  E. coli  294 (ATCC 31,446), although other strains such as  E. coli  B,  E. coli  X1776 (ATCC 31,537), and  E. coli  W3110 (ATCC 27,325) are suitable. These examples are illustrative rather than limiting. 
     In addition to prokaryotes, eukaryotic microbes such as filamentous fungi or yeast are suitable cloning or expression hosts for polypeptide variant-encoding vectors.  Saccharomyces cerevisiae , or common baker&#39;s yeast, is the most commonly used among lower eukaryotic host microorganisms. However, a number of other genera, species, and strains are commonly available and useful herein, such as  Schizosaccharomyces pombe; Kluyveromyces  hosts such as, e.g.,  K. lactis, K. fragilis  (ATCC 12,424),  K. bulgaricus  (ATCC 16,045),  K. wickeramii  (ATCC 24,178),  K. waltii  (ATCC 56,500),  K. drosophilarum  (ATCC 36,906),  K. thermotolerans , and  K. marxianus; yarrowia  (EP 402,226);  Pichia pastoris  (EP 183,070);  Candida; Trichoderma reesia  (EP 244,234);  Neurospora crassa; Schwanniomyces  such as  Schwanniomyces occidentalis ; and filamentous fungi such as, e.g.,  Neurospora, Penicillium, Tolypocladium , and  Aspergillus  hosts such as  A. nidulans  and  A. niger.    
     Suitable host cells for the expression of glycosylated polypeptide variant are derived from multicellular organisms. Examples of invertebrate cells include plant and insect cells. Numerous baculoviral strains and variants and corresponding permissive insect host cells from hosts such as  Spodoptera frugiperda  (caterpillar),  Aedes aegypti  (mosquito),  Aedes albopictus  (mosquito),  Drosophila melanogaster  (fruitfly), and  Bombyx mori  have been identified. A variety of viral strains for transfection are publicly available, e.g., the L-1 variant of  Autographa californica  NPV and the Bm-5 strain of  Bombyx mori  NPV, and such viruses may be used as the virus herein according to the present invention, particularly for transfection of  Spodoptera frugiperda  cells. 
     Plant cell cultures of cotton, corn, potato, soybean, petunia, tomato, and tobacco can also be utilized as hosts. 
     However, interest has been greatest in vertebrate cells, and propagation of vertebrate cells in culture (tissue culture) has become a routine procedure. Examples of useful mammalian host cell lines are monkey kidney CV1 line transformed by SV40 (COS-7, ATCC CRL 1651); human embryonic kidney line (293 or 293 cells subcloned for growth in suspension culture, Graham et al.,  J. Gen Virol.  36:59 (1977)); baby hamster kidney cells (BHK, ATCC CCL 10); Chinese hamster ovary cells/-DHFR (CHO, Urlaub et al.,  Proc. Natl. Acad. Sci. USA  77:4216 (1980)); mouse sertoli cells (TM4, Mather,  Biol. Reprod.  23:243-251 (1980)); monkey kidney cells (CV1 ATCC CCL 70); African green monkey kidney cells (VERO-76, ATCC CRL-1587); human cervical carcinoma cells (HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL 34); buffalo rat liver cells (BRL 3A, ATCC CRL 1442); human lung cells (W138, ATCC CCL 75); human liver cells (Hep G2, HB 8065); human mammary cells (HEK293), mouse mammary tumor (MMT 060562, ATCC CCL51); TRI cells (Mather et al.,  Annals N.Y. Acad. Sci.  383:44-68 (1982)); MRC 5 cells; FS4 cells; and a human hepatoma line (Hep G2). 
     Host cells are transformed with the above-described expression or cloning vectors for the fusion polypeptide production and cultured in conventional nutrient media modified as appropriate for inducing promoters, selecting transformants, or amplifying the genes encoding the desired sequences. (viii) 
     Culturing the Host Cells 
     The host cells used to produce a fusion polypeptide of this invention may be cultured in a variety of media. Commercially available media such as Ham&#39;s F10 (Sigma), Minimal Essential Medium ((MEM), (Sigma), RPMI-1640 (Sigma), and Dulbecco&#39;s Modified Eagle&#39;s Medium ((DMEM), Sigma) are suitable for culturing the host cells. In addition, any of the media described in Ham et al.,  Meth. Enz.  58:44 (1979), Barnes et al.,  Anal. Biochem.  102:255 (1980), U.S. Pat. Nos. 4,767,704; 4,657,866; 4,927,762; 4,560,655; or 5,122,469; WO 90/03430; WO 87/00195; or U.S. Pat. No. Re. 30,985 may be used as culture media for the host cells. Any of these media may be supplemented as necessary with hormones and/or other growth factors (such as insulin, transferrin, or epidermal growth factor), salts (such as sodium chloride, calcium, magnesium, and phosphate), buffers (such as HEPES), nucleotides (such as adenosine and thymidine), antibiotics (such as GENTAMYCIN™ drug), trace elements (defined as inorganic compounds usually present at final concentrations in the micromolar range), and glucose or an equivalent energy source. Any other necessary supplements may also be included at appropriate concentrations that would be known to those skilled in the art. The culture conditions, such as temperature, pH, and the like, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan. 
     (ix) Fusion Polypeptide Purification 
     When using recombinant techniques, the fusion polypeptide can be produced intracellularly, in the periplasmic space, or directly secreted into the medium. If the fusion polypeptide is produced intracellularly, as a first step, the particulate debris, either host cells or lysed fragments, is removed, for example, by centrifugation or ultrafiltration. Carter et al.,  Bio/Technology  10:163-167 (1992) describe a procedure for isolating antibodies which are secreted to the periplasmic space of  E. coli . Briefly, cell paste is thawed in the presence of sodium acetate (pH 3.5), EDTA, and phenylmethylsulfonylfluoride (PMSF) over about 30 min. Cell debris can be removed by centrifugation. Where the fusion polypeptide is secreted into the medium, supernatants from such expression systems are generally first concentrated using a commercially available protein concentration filter, for example, an Amicon or Millipore Pellicon ultrafiltration unit. A protease inhibitor such as PMSF may be included in any of the foregoing steps to inhibit proteolysis and antibiotics may be included to prevent the growth of adventitious contaminants. 
     The fusion polypeptide composition prepared from the cells can be purified using, for example, hydroxylapatite chromatography, gel electrophoresis, dialysis, and affinity chromatography, with affinity chromatography being the preferred purification technique. The suitability of protein A as an affinity ligand depends on the species and isotype of any immunoglobulin Fc region that is present in the polypeptide variant. Protein A can be used to purify polypeptide variants that are based on human γ1, γ2, or γ4 heavy chains (Lindmark et al.,  J. Immunol. Meth.  62:1-13 (1983)). Protein G is recommended for all mouse isotypes and for human γ3 (Guss et al.,  EMBO J.  5:15671575 (1986)). The matrix to which the affinity ligand is attached is most often agarose, but other matrices are available. Mechanically stable matrices such as controlled pore glass or poly(styrenedivinyl)benzene allow for faster flow rates and shorter processing times than can be achieved with agarose. Where the polypeptide variant comprises a C H 3 domain, the Bakerbond ABX™ resin (J. T. Baker, Phillipsburg, N.J.) is useful for purification. Other techniques for protein purification such as fractionation on an ion-exchange column, ethanol precipitation, Reverse Phase HPLC, chromatography on silica, chromatography on heparin SEPHAROSE™ chromatography on an anion or cation exchange resin (such as a polyaspartic acid column), chromatofocusing, SDS-PAGE, and ammonium sulfate precipitation are also available depending on the polypeptide variant to be recovered. 
     Following any preliminary purification step(s), the mixture comprising the polypeptide variant of interest and contaminants may be subjected to low pH hydrophobic interaction chromatography using an elution buffer at a pH between about 2.5-4.5, preferably performed at low salt concentrations (e.g., from about 0-0.25M salt). 
     III. Pharmaceutical Formulations 
     Therapeutic formulations of the fusion polypeptide are prepared for storage by mixing the fusion polypeptide having the desired degree of purity with optional physiologically acceptable carriers, excipients or stabilizers ( Remington&#39;s Pharmaceutical Sciences  16th edition, Osol, A. Ed. (1980)), in the form of aqueous solutions, lyophilized or other dried formulations. Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g., Zn-protein complexes); and/or non-ionic surfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG). 
     The formulation herein may also contain more than one active compound as necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other. Such molecules are suitably present in combination in amounts that are effective for the purpose intended. 
     The active ingredients may also be entrapped in microcapsule prepared, for example, by coacervation techniques or by interfacial polymerization, for example, hydroxymethylcellulose or gelatin-microcapsule and poly-(methylmethacylate) microcapsule, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in  Remington&#39;s Pharmaceutical Sciences  16th edition, Osol, A. Ed. (1980). 
     The formulations to be used for in vivo administration must be sterile. This is readily accomplished by filtration through sterile filtration membranes. 
     Sustained-release preparations may be prepared. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing the fusion polypeptide, which matrices are in the form of shaped articles, e.g., films, or microcapsule. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides (U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and γ ethyl-L-glutamate, non-degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the LUPRON DEPOT™ (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), and poly-D-(−)-3-hydroxybutyric acid. While polymers such as ethylene-vinyl acetate and lactic acid-glycolic acid enable release of molecules for over 100 days, certain hydrogels release proteins for shorter time periods. When encapsulated antibodies remain in the body for a long time, they may denature or aggregate as a result of exposure to moisture at 37° C., resulting in a loss of biological activity and possible changes in immunogenicity. Rational strategies can be devised for stabilization depending on the mechanism involved. For example, if the aggregation mechanism is discovered to be intermolecular S—S bond formation through thio-disulfide interchange, stabilization may be achieved by modifying sulfhydryl residues, lyophilizing from acidic solutions, controlling moisture content, using appropriate additives, and developing specific polymer matrix compositions. 
     IV. Articles of Manufacture 
     In another embodiment of the invention, an article of manufacture containing materials useful for the treatment of the disorders described above is provided. The article of manufacture comprises a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, etc. The containers may be formed from a variety of materials such as glass or plastic. The container holds a composition which is effective for treating the condition and may have a sterile access port (for example the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). At least one active agent in the composition is the fusion polypeptide described herein. The label or package insert indicates that the composition is used for treating the condition of choice, such as cancer. The article of manufacture in this embodiment of the invention may further comprise a package insert indicating that the first and second compositions can be used to treat cancer. Alternatively, or additionally, the article of manufacture may further comprise a second (or third) container comprising a pharmaceutically-acceptable buffer, such as bacteriostatic water for injection (BWFI), phosphate-buffered saline, Ringer&#39;s solution and dextrose solution. It may further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syringes. 
     V. In Vivo Uses for the Fusion Polypeptide 
     It is contemplated that the fusion polypeptide of the present invention may be used to treat a mammal e.g. a patient suffering from, or predisposed to, a disease or disorder who could benefit from administration of the fusion polypeptide. The conditions which can be treated with the fusion polypeptide include, e.g., HER2-expressing cancer, e.g. a benign or malignant tumor characterized by overexpression of the HER2 receptor. Such cancers include, but are not limited to, breast cancer, squamous cell cancer, small-cell lung cancer, non-small cell lung cancer, gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, bladder cancer, hepatoma, colon cancer, colorectal cancer, endometrial carcinoma, salivary gland carcinoma, kidney cancer, liver cancer, prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma and various types of head and neck cancer. According to the teachings herein, one may prepare a polypeptide with a variant Fc region which has improved ADCC activity. Such molecules will find applications in the treatment of different disorders. 
     The fusion polypeptide is administered by any suitable means, including parenteral, subcutaneous, intraperitoneal, intrapulmonary, and intranasal, and, if desired for local immunosuppressive treatment, intralesional administration. Parenteral infusions include intramuscular, intravenous, intraarterial, intraperitoneal, or subcutaneous administration. Preferably the dosing is given by injections, most preferably intravenous or subcutaneous injections, depending in part on whether the administration is brief or chronic. 
     For the prevention or treatment of disease, the appropriate dosage of the fusion polypeptide will depend on the type of disease to be treated, the severity and course of the disease, whether the fusion polypeptide is administered for preventive or therapeutic purposes, previous therapy, the patient&#39;s clinical history and response to the fusion polypeptide, and the discretion of the attending physician. The fusion polypeptide is suitably administered to the patient at one time, or over a series of treatments. 
     Depending on the type and severity of the disease, about 1 μg/kg to 15 mg/kg (e.g., 0.1-20 mg/kg) of fusion polypeptide is an initial candidate dosage for administration to the patient, whether, for example, by one or more separate administrations, or by continuous infusion. A typical daily dosage might range from about 1 μg/kg to 100 mg/kg or more, depending on the factors mentioned above. For repeated administrations over several days or longer, depending on the condition, the treatment is sustained until a desired suppression of disease symptoms occurs. However, other dosage regimens may be useful. The progress of this therapy is easily monitored by conventional techniques and assays. 
     The fusion polypeptide composition will be formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disorder being treated, the particular mammal being treated, the clinical condition of the individual patient, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. The “therapeutically effective amount” of the polypeptide variant to be administered will be governed by such considerations, and is the minimum amount necessary to prevent, ameliorate, or treat a disease or disorder. The polypeptide variant need not be, but is optionally formulated with one or more agents currently used to prevent or treat the disorder in question. The effective amount of such other agents depends on the amount of polypeptide variant present in the formulation, the type of disorder or treatment, and other factors discussed above. These are generally used in the same dosages and with administration routes as used hereinbefore or about from 1 to 99% of the heretofore employed dosages. 
     VI. Selecting Patients for Therapy 
     The patient herein is generally subjected to a diagnostic test prior to therapy so as to identify HER2 positive subjects. For example, the diagnostic test may evaluate HER2 expression (including overexpression), amplification, and/or activation (including phosphorylation or dimerization). 
     Generally, if a diagnostic test is performed, a sample may be obtained from a patient in need of therapy. Where the subject has cancer, the sample is generally a tumor sample. In the preferred embodiment, the tumor sample is from a breast cancer biopsy. The biological sample herein may be a fixed sample, e.g. a formalin fixed, paraffin-embedded (FFPE) sample, or a frozen sample. 
     To determine HER2 expression or amplification in the cancer, various diagnostic/prognostic assays are available. In one embodiment, HER2 overexpression may be analyzed by IHC, e.g. using the HERCEPTEST® (Dako). Parrafin embedded tissue sections from a tumor biopsy may be subjected to the IHC assay and accorded a HER2 protein staining intensity criteria as follows: 
     Score 0 no staining is observed or membrane staining is observed in less than 10% of tumor cells.
 
Score 1+ a faint/barely perceptible membrane staining is detected in more than 10% of the tumor cells. The cells are only stained in part of their membrane.
 
Score 2+ a weak to moderate complete membrane staining is observed in more than 10% of the tumor cells.
 
Score 3+ a moderate to strong complete membrane staining is observed in more than 10% of the tumor cells.
 
     Those tumors with 0 or 1+ scores for HER2 overexpression assessment may be characterized as not overexpressing HER2, whereas those tumors with 2+ or 3+ scores may be characterized as overexpressing HER2. 
     Tumors overexpressing HER2 may be rated by immunohistochemical scores corresponding to the number of copies of HER2 molecules expressed per cell, and can been determined biochemically: 
     0=0-10,000 copies/cell,
 
1+=at least about 200,000 copies/cell,
 
2+=at least about 500,000 copies/cell,
 
3+=at least about 2,000,000 copies/cell.
 
     Overexpression of HER2 at the 3+ level, which leads to ligand-independent activation of the tyrosine kinase (Hudziak et al.,  Proc. Natl. Acad. Sci. USA,  84:7159-7163 (1987)), occurs in approximately 30% of breast cancers, and in these patients, relapse-free survival and overall survival are diminished (Slamon et al.,  Science,  244:707-712 (1989); Slamon et al.,  Science,  235:177-182 (1987)). 
     Alternatively, or additionally, FISH assays such as the INFORM™ (sold by Ventana, Arizona) or PATHVISION™ (Vysis, Illinois) may be carried out on formalin-fixed, paraffin-embedded tumor tissue to determine the extent (if any) of HER2 amplification in the tumor. 
     HER2 positivity may also be evaluated using an in vivo diagnostic assay, e.g. by administering a molecule (such as an antibody) which binds the molecule to be detected and is tagged with a detectable label (e.g. a radioactive isotope) and externally scanning the patient for localization of the label. 
     Other methods for identifying HER2 positive tumors are contemplated herein, including but not limited to measuring shed antigen, and detecting HER2 positive tumors indirectly, such as by evaluating downstream signaling mediated through HER2 receptor, gene expression profiling, etc. 
     Preferably, subjects are selected which have a HER2 positive tumor or sample which overexpresses HER2 as evaluated by immunohistochemistry (IHC) and/or has amplified HER2 gene as evaluated by FISH. 
     While the fusion polypeptide of the invention may be administered as single agent, the patient is preferably treated in combination with one or more chemotherapeutic agent(s). Preferably at least one of the chemotherapeutic agents is a taxoid. The combined administration includes coadministration or concurrent administration, using separate formulations or a single pharmaceutical formulation, and consecutive administration in either order, wherein preferably there is a time period while both (or all) active agents simultaneously exert their biological activities. Thus, the chemotherapeutic agent may be administered prior to, or following, administration of the fusion polypeptide. In this embodiment, the timing between at least one administration of the chemotherapeutic agent and at least one administration of the fusion polypeptide is preferably approximately 1 month or less, and most preferably approximately 2 weeks or less. Alternatively, the chemotherapeutic agent and the fusion polypeptide are administered concurrently to the patient, in a single formulation or separate formulations. Treatment with the combination of the chemotherapeutic agent (e.g. taxoid) and the fusion polypeptide may result in a synergistic, or greater than additive, therapeutic benefit to the patient. 
     The chemotherapeutic agent, if administered, is usually administered at dosages known therefor, or optionally lowered due to combined action of the drugs or negative side effects attributable to administration of the antimetabolite chemotherapeutic agent. Preparation and dosing schedules for such chemotherapeutic agents may be used according to manufacturers&#39; instructions or as determined empirically by the skilled practitioner. Where the chemotherapeutic agent is paclitaxel, preferably, it is administered every week (e.g. at 80 mg/m 2 ) or every 3 weeks (for example at 175 mg/m 2  or 135 mg/m 2 ). Suitable docetaxel dosages include 60 mg/m 2 , 70 mg/m 2 , 75 mg/m 2 , 100 mg/m 2  (every 3 weeks); or 35 mg/m 2  or 40 mg/m 2  (every week). 
     Various chemotherapeutic agents that can be combined are disclosed above. Preferred chemotherapeutic agents to be combined with the fusion polypeptide are selected from the group consisting of a taxoid (including docetaxel and paclitaxel), vinca (such as vinorelbine or vinblastine), platinum compound (such as carboplatin or cisplatin), aromatase inhibitor (such as letrozole, anastrazole, or exemestane), anti-estrogen (e.g. fulvestrant or tamoxifen), etoposide, thiotepa, cyclophosphamide, methotrexate, liposomal doxorubicin, pegylated liposomal doxorubicin, capecitabine, gemcitabine, COX-2 inhibitor (for instance, celecoxib), or proteosome inhibitor (e.g. PS342). 
     Most preferably, the fusion polypeptide is combined with a taxoid, such as paclitaxel or docetaxel, optionally in combination with at least one other chemotherapeutic agent, such as a platinum compound (for example carboplatin or cisplatin). 
     Where an anthracycline (e.g. doxorubicin or epirubicin) is administered to the subject, preferably this is given prior to and/or following administration of the fusion polypeptide, such as in the protocols disclosed in the Example below where an anthracycline/cyclophosphomide combination was administered to the subject following surgery, but prior to administration of the fusion polypeptide and taxoid. However, a modified anthracycline, such as liposomal doxorubicin (TLC D-99 (MYOCET®), pegylated liposomal doxorubicin (CAELYX®), or epirubicin, with reduced cardiac toxicity, may be combined with the fusion polypeptide. 
     Aside from the fusion polypeptide and the chemotherapeutic agent, other therapeutic regimens may be combined therewith. For example, a second (third, fourth, etc) chemotherapeutic agent(s) may be administered, wherein the second chemotherapeutic agent is either another, different taxoid chemotherapeutic agent, or a chemotherapeutic agent that is not a taxoid. For example, the second chemotherapeutic agent may be a taxoid (such as paclitaxel or docetaxel), a vinca (such as vinorelbine), a platinum compound (such as cisplatin or carboplatin), an anti-hormonal agent (such as an aromatase inhibitor or antiestrogen), gemcitabine, capecitabine, etc. Exemplary combinations include taxoid/platinum compound, gemcitabine/taxoid, gemcitabine/vinorelbine, vinorelbine/taxoid, capecitabine/taxoid, etc. “Cocktails” of different chemotherapeutic agents may be administered. 
     Other therapeutic agents that may be combined with the fusion polypeptide include any one or more of: a second, different HER2 antibody or fusion polypeptide (for example, a HER2 heterodimerization inhibitor such as pertuzumab, or a HER2 antibody which induces apoptosis of a HER2-overexpressing cell, such as 7C2, 7F3 or humanized variants thereof); an antibody directed against a different tumor associated antigen, such as EGFR, HER3, HER4; anti-hormonal compound or endocrine therapeutic, e.g., an anti-estrogen compound such as tamoxifen, or an aromatase inhibitor; a cardioprotectant (to prevent or reduce any myocardial dysfunction associated with the therapy); a cytokine; an EGFR inhibitor (such as TARCEVA®, IRESSA® or cetuximab); an anti-angiogenic agent (especially bevacizumab sold by Genentech under the trademark AVASTIN™); a tyrosine kinase inhibitor; a COX inhibitor (for instance a COX-1 or COX-2 inhibitor); non-steroidal anti-inflammatory drug, celecoxib (CELEBREX®); farnesyl transferase inhibitor (for example, Tipifarnib/ZARNESTRA® R115777 available from Johnson and Johnson or Lonafarnib SCH66336 available from Schering-Plough); HER2 vaccine (such as HER2 AutoVac vaccine from Pharmexia, or APC8024 protein vaccine from Dendreon, or HER2 peptide vaccine from GSK/Corixa); another HER targeting therapy (e.g. trastuzumab, cetuximab, ABX-EGF, EMD7200, gefitinib, erlotinib, CP724714, CI1033, GW572016, IMC-11F8, TAK165, etc); Raf and/or ras inhibitor (see, for example, WO 2003/86467); doxorubicin HCl liposome injection (DOXIL®); topoisomerase I inhibitor such as topotecan; taxoid; HER2 and EGFR dual tyrosine kinase inhibitor such as lapatinib/GW572016; TLK286 (TELCYTA®); EMD-7200; AB1007 (Factor XII heavy chain antibody, B7C9); everolimis (CERTICAN®); sirolimus (rapamycin, RAPAMUNE®); a body temperature-reducing medicament such as acetaminophen, diphenhydramine, or meperidine; hematopoietic growth factor, etc. 
     Suitable dosages for any of the above coadministered agents are those presently used and may be lowered due to the combined action (synergy) of the agent and fusion polypeptide. 
     In addition to the above therapeutic regimes, the patient may be subjected to radiation therapy. 
     VI. Deposit of Materials 
     The following hybridoma cell lines have been deposited with the American Type Culture Collection, 10801 University Boulevard, Manassas, Va. 20110-2209, USA (ATCC): 
                                                 Antibody Designation   ATCC No.   Deposit Date                          7C2   ATCC HB-12215   Oct. 17, 1996           7F3   ATCC HB-12216   Oct. 17, 1996           4D5   ATCC CRL 10463   May 24, 1990           2C4   ATCC HB-12697   Apr. 8, 1999                        
Further details of the invention are illustrated by the following non-limiting Examples. The disclosures of all citations in the specification are expressly incorporated herein by reference.
 
     EXAMPLES 
     Example 1 
     Molecular Cloning and Expression of Fusion Proteins 
     Anti-HER2-H60 and Anti-HER2-MicB fusion proteins were assembled using PCR. H60 was amplified from a Balb/C mouse spleen cDNA library and MicB was amplified from a human lung cDNA library using pairs of oligonucleotide primers designed to amplify the DNA sequence encoding the extracellular domain of H60 (or MicB). To facilitate cloning, the primers also introduced BamHI and SalI sites at the 5′ and 3′ end, respectively. The resulting PCR product included the sequence encoding the N-terminal base of the mature H60 or MicB protein and extended to the C-terminus (amino acid residues 30-213 for H60 or amino acid residues 16-297 for MicB). The N-terminal oligonucleotide also encoded a GGGGS linker that would join the C-terminal residue of the heavy chain of Anti-HER2 with the first residue of the mature H60 (or MicB) protein. Another pair of oligonucleotides was used to amplify DNA encoding the heavy chain of Anti-HER2 from a mammalian expression plasmid encoding 4D5 mIgG2a. These oligonucleotides introduced XbaI and BamHI sites at the 5′ and 3′ end, respectively. The two PCR reactions were performed separately, gel purified and then cloned back into the anti-HER2 heavy chain mammalian cell expression vector cut with XbaI and SalI sites. 
     The Anti-HER2-H60 and Anti-HER2-MicB fusion construct plasmids were co-transfected with another mammalian expression vector encoding the anti-HER2 immunoglobulin light chain of 4D5 mIgG2a into CHO cells. The fusion proteins and light chains assemble to form an antibody with two copies of either H60 or MicB. The supernatant was purified over ProteinA Sepharose®. The protein was eluted at 2 mM glycine pH 3 and buffer exchanged into Tris saline. 
     An additional anti-HER2-MicB plasmid with two substitutions at residue D265 and N297 was constructed as described above by swapping a heavy chain XbaI and BamHI insert containing the D265A and N297A mutations (designated Anti-HER2*-MicB). These two substitutions disrupt binding to murine FcγRI and murine FcγRIII. Ligation and subsequent transfection was also performed as previously described. 
     All fusion antibodies were resolved on 4-15% SDS-PAGE gels. At non-reducing condition, Anti-HER2-H60, Anti-HER2-MicB and Anti-HER2*-MicB fusion antibodies migrated at 250,000 dalton, suggesting that the fusion protein was dimeric and correctly folded. When 1 mM dithiothreitol was added to reduce disulfide bonding, the single 250,000 dalton dimeric molecule separated into two bands, migrating at 100,000 and 25,000 relative m.w. corresponding to the predicted 100K Anti-HER2 heavy chain-H60 (or MicB) fusion protein and the 25K m.w. light chain of Anti-HER2. Thus the H60 (or MicB) fusion molecule to Anti-HER2 and corresponding Fc domain D265A+N297A mutants were expressable as dimeric molecules and appeared to form intact Anti-HER2 antibody fused to two H60 (or MicB) molecules. 
     Example 2 
     The Fusion Proteins Bind HER2 and the NKG2D Receptor 
     Full-length murine NKG2D and DAP 10 were cloned and transfected into HEK 293 cells. Stable single clones were selected using G418 and cell surface expressions were verified by flow cytometry using polyclonal hamster sera against mNKG2D antigen. Murine FcγRI and FcγRIII stable cell lines on CHO cells were gifts from Presta and Shields. The specificities of the cell lines were verified by monoclonal antibodies (1F3.4.3 and 25H1.1.3) against Murine FcγRI and FcγRIII respectively. 
     An ELISA was developed to determine binding of Anti-HER2, Anti-HER2-H60, Anti-HER2-MicB and Anti-HER2*-MicB to mNKG2D. A soluble form of murine NKG2D representing residues 88-232 was cloned into a mammalian N′-FLAG tagged plasmid and expressed in CHO cells. It was expressed as glycosylated dimer on non-reduced SDS-PAGE gel. One microgram per milliliter of murine NKG2D in phosphate buffered saline was immobilized onto Nunc Immunosorp plates overnight at 4 degrees. The unbound protein was removed and free binding sites were blocked with a phosphate buffered saline solution containing 0.5% bovine serum albumin. Titrated amounts of Anti-HER2, Anti-HER2-H60, Anti-HER2-MicB, Anti-HER2*-MicB and mouse IgG2a control antibodies were added and incubated for one hour at room temperature. The unbound protein was removed by several washing with PBS 0.05% Tween 20 and then the goat anti-mouse F(ab′)2 horse radish peroxidase conjugated antibody was added. After 60 minutes the plates were washed as described above and a TMB substrate was added (KPL). 
     Titrated amounts of Anti-HER2 and Anti-HER2-H60 variants were assayed for binding. As expected, no binding to murine NKG2D was observed with Anti-HER2 or mIgG2a. In contrast, the Anti-HER2-H60 specifically bound immobilized NKG2D at EC 50 =0.2 nM. While Anti-HER2-MicB and Anti-HER2*-MicB bound to the captured mNKG2D at EC 50 =0.3 nM. Competition ELISA was also performed by adding increased concentration of soluble mNKG2D protein. As expected, soluble mNKG2D inhibited H60 and MicB ligand binding to captured NKG2D specifically. 
     In order to determine if all engineered variants of anti-HER2 and anti-HER2-H60 retained binding to the Her2 antigen, flow cytometry was performed on all variants to confirm their binding to BT474 cells. Flow cytometry assays were set up to determine if the various constructs stained Her2+ cells, mNKG2D transfectants, mFcγRI and mFcγRIII CHO stable and splenocytes from C57B16 mice. Her2+ monolayers of BT474 cells (a human epithelial breast cancer cells that express high levels of HER2 on the cell surface) were removed with trypsin and washed in phosphate buffered saline containing 2% fetal bovine serum. To 1×10 6  cells, titrated amount of Anti-HER2, Anti-HER2-H60, Anti-HER2-MicB and Anti-HER2*-MicB proteins were added and incubated on ice for 30 minutes and then washed twice with cold buffer. Fluorophore-conjugated goat anti-mouse F(ab′)2 were added for 30 minutes, washed again and analyzed by a FACS can or FACScalibur™ (BD). Control antibody mouse IgG2a was included to determine background binding. 
     BT474 cells incubated with the mouse IgG2a control antibody only showed background levels of staining, whereas titrated amount of anti HER2 showed positive staining of BT474 cells ( FIG. 5 ). Fusion antibodies including Anti-HER2-H60, Anti-HER2-MicB and Anti HER2*-MicB exhibited slightly (2- to 3-fold) lower staining of BT474 cells compared to anti-HER2 antibody. 
     To confirm the fusion protein binding to NKG2D, a stable mNKG2D transfectant in HEK293 cells was made. As expected, the Anti-HER2-H60 bound to the mNKG2D transfectant very well by flow cytometry (MFI=100). While the Anti-HER2-MicB and Anti-HER2*-MicB bound to the mNKG2D transfectant with an MFI=11 (the isotype MFI=4). But the Anti-HER2-MicB and Anti-HER2*-MicB bound to human NKG2D-CHO transfectant cells with MFI=61.7. 
     We also determined that H60 when fused to Anti-HER2 was able to bind mNKG2D on NK cells from splenocytes. Fusion antibodies were biotinylated and detected with fluorophore-conjugated strepavidin secondary antibody by FAC. As expected, no staining beyond background levels was observed with Anti-HER2, or the mouse IgG2a control antibody. In contrast, the Anti-HER2-H60 showed positive staining with a MFI=48.9. Furthermore, this staining could be blocked by mNKG2D extracellular domain protein or with an anti-mNKG2D antibody. The Anti-HER2-MicB and Anti-HER2*-MicB showed binding equivalent to the control, probably due to the lower affinity binding to the murine NKG2D receptor. 
     Example 3 
     Anti-Her2 Fusion Proteins Induce NK Cell-Mediated Killing Through NKG2D 
     NK cell mediated killing of cellular targets can occur through CD16 and NKG2D. We designed experiments to confirm that the fusion constructs act through NKG2D. We assayed for the ability to activate murine DX5+ NK cells and kill HER2+ BT474 cells. 
     To determine whether Anti-HER2-H60 (or MicB) activates NK cell killing through NKG2D or through CD16, we tested Fc mutations (D265A+N297A) that disrupt Fc binding to its receptors. We first confirmed that Anti HER2-H60 and Anti-HER2-MicB antibodies bind to mFcγRI. By flow cytometry, we found that Anti-HER2-H60 bound to mFcγRI and mFcγRIII CHO cells, but that its binding was unexpectedly attenuated. This attenuation is probably due to H60 hindering Fc binding. However, we observed that Anti-HER2-MicB binding to mFcγRI and mFcγRIII CHO cells was comparable to Anti-HER2 naked antibody. As expected, binding of Anti-HER2*-MicB to mFcγRI and mFcγRIII CHO cell was negligible. 
     We then added a 6.7 nM solution of mIgG2a, Anti-HER2, Anti-HER2-H60, Anti-HER2-MicB or Anti-HER2*-MicB to approximately 10,000 Her2 expressing cell line BT474 cell in 96 well microtiter plates and incubated at room temperature for 20 minutes. At the same time, spleens were removed from C57BL6 mice or murine FcγRIII knockout mice, and minced with glass coverslips to make single cell suspension. Cells were washed in cold PBS containing 0.5% bovine serum albumin. To isolate NK cells, DX5 magnetic beads were added (Miltenyi Biotec) and DX5 positive NK cells were isolated by magnetic separation. The cells were counted and adjusted to give a range of NK effector cells to target BT474 cell ratios. The NK cells were added to the target cells in microtiter wells and incubated for an additional 4 hours. After that the culture supernatant was harvested and assayed for lactate dehydrogenase using a commercial diagnostic kit (Roche). 
     With Anti-HER2 alone, we observed killing of BT474 cells at 15% with an E:T ratio of 50:1. Anti HER2-MicB doubled this killing to 30%. In contrast, when Anti-HER2*-MicB was assayed, killing was dropped to 15% at E:T ratio of 50:1. 
     To further demonstrate that killing was mediated via mNKG2D, anti-mouse CD16 antibody (2.4G2 from BD) or F(ab′)2 of anti-mNKG2D antibody (clone 191004 from R&amp;D systems) were added to the killing assay. The addition of anti-mouse CD16 completely inhibited Anti-HER2 killing but not anti HER2*-MicB induced killing, while F(ab′)2 of Anti-mNKG2D antibody completely inhibited Anti-HER2*-MicB mediated killing but not naked Anti-HER2 antibody ( FIG. 6   a ). These data confirmed that Anti-HER2*-MicB induced killing through a CD16-independent pathway that involved the NKG2D pathway. Alternatively, we used murine FcγRIII knockout mice splenic NK cells as effector cells to eliminate any CD16 mediated killing. As expected, Anti-HER2 did not induce any killing compared to mIgG2a, while Anti-HER2-H60 and Anti-HER2-MicB could still induce the killing at about 10% at the E:T ratio 20:1. Furthermore, these two fusion antibodies mediated killing could be completely blocked by anti-mNKG2D antibody ( FIG. 6   b ). 
     Example 4 
     In Vivo Therapeutic Use of Conjugate 
     To determine whether the H60 (MicB) and mNKG2D interaction could initiate the tumor killing in vivo, we tested our fusion antibodies in the BT474 xenograft model. 5 million BT474 cells were injected subcutaneously on day 1 in 0.1 ml PBS mixed with 0.1 ml Matrigel™ (Collaborative Research, Bedford, Mass.). 2-4 month old female athymic nude mice were injected subcutaneously with 17β-estradiol 60-day release pellets (0.75 mg/pellet; Innovative Research of America, Sarasota, Fla.) 24 hour before tumor cell injection. After the tumor volume reached 100 mm 3  (about 10-14 days), mice were randomly grouped. 5 mg/kg of mIgG2a, Anti-HER2 and 6 mg/kg of Anti-HER2-H60, Anti-HER2-MicB and Anti-HER2*-MicB were injected intraperitoneally. Tumor volume was measured weekly by using the formula: width×length×0.52 height. 
     A single dose of 5 mg/kg 4D5 mIgG2a resulted in near-complete inhibition of tumor growth at day 20. 4D5mIgG2a-MicB, which retained Fc function, resulted in near-complete inhibition comparable to that seen with 4D5. 4D5*-MicB, which knocked out Fc function, lost its ability to inhibit tumor growth. Finally, 4D5-H60, which had reduced binding to FcγRI and FcγRIII in vitro, had less anti-tumor activity than 4D5 ( FIG. 7 ). Serum samples were taken after administration of antibodies for 2, 7, 20 days and were measured for their PK. Comparable PK levels of all antibodies were found. 
     Throughout this specification and claims, the word “comprise,” or variations such as “comprises” or “comprising,” indicate the inclusion of any recited integer or group of integers but not the exclusion of any other integer or group of integers. 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention includes all such embodiments. 
     This specification contains numerous citations to literature and patents. Each is hereby incorporated by reference for all purposes, as if fully set forth.