Classifications

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  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
  • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
  • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
  • C07K16/2887—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against CD20
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P35/00—Antineoplastic agents
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  • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
  • C12N5/10—Cells modified by introduction of foreign genetic material
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K49/00—Preparations for testing in vivo
  • A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
  • A61K49/08—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by the carrier
  • A61K49/10—Organic compounds
  • A61K49/14—Peptides, e.g. proteins
  • A61K49/16—Antibodies; Immunoglobulins; Fragments thereof
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  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
  • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
  • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
  • C07K16/2896—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against molecules with a "CD"-designation, not provided for elsewhere
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
  • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
  • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
  • C07K16/30—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants from tumour cells
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies
  • C07K16/18—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans
  • C07K16/28—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
  • C07K16/30—Immunoglobulins [IGs], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants from tumour cells
  • C07K16/3038—Kidney, bladder
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
  • C12N9/10—Transferases (2.)
  • C12N9/1048—Glycosyltransferases (2.4)
  • C12N9/1051—Hexosyltransferases (2.4.1)
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  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P21/00—Preparation of peptides or proteins
  • C12P21/005—Glycopeptides, glycoproteins
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K2039/505—Medicinal preparations containing antigens or antibodies comprising antibodies
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/10—Immunoglobulins specific features characterized by their source of isolation or production
  • C07K2317/14—Specific host cells or culture conditions, e.g. components, pH or temperature
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
  • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/40—Immunoglobulins specific features characterized by post-translational modification
  • C07K2317/41—Glycosylation, sialylation, or fucosylation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/70—Immunoglobulins specific features characterized by effect upon binding to a cell or to an antigen
  • C07K2317/73—Inducing cell death, e.g. apoptosis, necrosis or inhibition of cell proliferation
  • C07K2317/732—Antibody-dependent cellular cytotoxicity [ADCC]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

• the present invention relates to the field of glycosylation engineering of proteins. More particularly, the present invention relates to glycosylation engineering to generate proteins with improved therapeutic properties, including antibodies with increased antibody-dependent cellular cytotoxicity.
• Glycoproteins mediate many essential functions in human beings, other eukaryotic organisms, andsomeprokaryotes, including catalysis, signaling, cell- cell communication, and molecular recognition and association. They make up the majority of non-cytosolic proteins in eukaryotic organisms. (Lis et ah, Eur. J. Biochem. 218:1-21 (1993)). Many glycoproteins have been exploited for therapeutic purposes, and during the last two decades, recombinant versions of naturally-occurring, secreted glycoproteins have been a major product of the biotechnology industry.
• EPO erythropoietin
• therapeutic mAbs therapeutic monoclonal antibodies
• tPA tissue plasminogen activator
• IFN- ⁇ interferon- ⁇
• GM- CSF granulocyte-macrophage colony stimulating factor
• hCG human chorionic gonadotrophin
• the oligosaccharide component can significantly affect properties relevant to the efficacy of a therapeutic glycoprotein, includingphysical stability, resistance to protease attack, interactions with the immune system, pharrnacokinetics, and specific biological activity. Such properties may depend not only on the presence or absence, but also on the specific structures, of oligosaccharides. Some generalizations between oligosaccharide structure and glycoprotein function can be made. For example, certain oligosaccharide structures mediate rapid clearance of the glycoprotein from the bloodstream through interactions with specific carbohydrate bindingproteins, while others can be bound by antibodies and trigger undesired immune reactions . (Jenkins et al. , Nature Biotechnol. 14:975-81 (1996)).
• Mammalian cells are the preferred hosts for production of therapeutic glycoproteins, due to their capability to glycosylate proteins in the most compatible form for human application. (Gumming et al., Glycobiology 7:115- 30 (1991); Jenkins et al, Nature Biotechnol 14:975-81 (1996)). Bacteria very rarely glycosylate proteins, and like other types of common hosts, such as yeasts, filamentous fungi, insect and plant cells, yield glycosylation patterns associated with rapid clearance from the bloodstream, undesirable immune interactions, and in some specific cases, reduced biological activity. Among mammalian cells, Chinese hamster ovary (CHO) cells have been most commonly used during the last two decades.
• these cells allow consistent generation of genetically stable, highly productive clonal cell lines. They can be cultured to high densities in simple bioreactors using serum- free media, and permit the development of safe and reproducible bioprocesses.
• Other commonly used animal cells include baby hamster kidney (BHK) cells, NS0- and SP2/0-mouse myeloma cells. More recently, production from transgenic animals has also been tested. (Jenkins et al, Nature Biotechnol. 14:975-81 (1996)).
• All antibodies contain carbohydrate structures at conserved positions in the heavy chain constant regions, with each isotype possessing a distinct array of N-linked carbohydrate structures, which variably affect protein assembly, secretion or functional activity.
• N-linked carbohydrate structures which variably affect protein assembly, secretion or functional activity.
• the structure of the attached N-linked carbohydrate varies considerably, depending on the degree of processing, and can include high-mannose, multiply-branched as well as biantennary complex oligosaccharides. (Wright, A., and Morrison, S. L., Trends Biotech. 15:26-32 ( 1997)) .
• Unconjugatedmonoclonal antibodies can be useful medicines for the treatment of cancer, as demonstrated by the U.S. Food and Drug Administration's approval of Rituximab (RituxanTM; IDEC Pharmaceuticals, San Diego, CA, and Genentech Inc., San Francisco, CA), for the treatment of CD20 positive B-cell, low-grade or follicular Non-Hodgkin's lymphoma, and Trastuzumab (HerceptinTM; Genentech Inc,) forthe treatment of advanced breast cancer (Grillo-Lopez, A. -J., etal, Semin. Oncol. 26:66-13 (1999); Goldenberg, M. M., Gin. Ther.
• IgGl type antibodies the most commonly used antibodies in cancer immunotherapy, are glycoproteins that have a conservedN- linked glycosylation site at Asn297 in each CH2 domain.
• ADCC antibody dependent cellular cytotoxicity
• the present inventors showed previously that overexpression in Chinese hamster ovary (CHO) cells of ⁇ (l,4)-N-acetylglucosaminyltransferase III (GnTi ⁇ ), a glycosyltransferase catalyzing the formation of bisected oligosaccharides, significantly increases the in vitro ADCC activity of an anti- neuroblastoma chimeric monoclonal antibody (chCE7) produced by the engineered CHO cells.
• GnTi ⁇ Chinese hamster ovary
• chCE7 anti- neuroblastoma chimeric monoclonal antibody
• the antibody chCE7 belongs to a large class of unconjugated mAbs which have high tumor affinity and specificity, but have too little potency to be clinically useful when produced in standard industrial cell lines lacking the GnTHJ enzyme (Umana, P., et al, Nature Biotechnol. 77: 176-180 (1999)). That study was the first to show that large increases of maximal in vitro ADCC activity could be obtained by increasing the proportion of constant region (Fc)-associated, bisected oligosaccharides above the levels found in naturally occurring antibodies.
• Fc constant region
• the present inventors have now generated new glycosylation variants of the anti-CD20 monoclonal antibody (mAb) IDEC-C2B8 (Rituximab) and the anti-cancer mAb chG250 using genetically engineered mAb-producing cell lines that overexpress N-acetylglucosaminyltransferase III (GnTIII; EC 2.1.4.144) in a tetracycline regulated fashion.
• GnTIII is required for the synthesis of bisected oligosaccharides, which are found at low to intermediate levels in naturally- occurring human antibodies but are missing in mAbs produced in standard industrial cell lines.
• MabtheraTM the version of Rixtuximab marketed in Europe
• ADCC mouse-myeloma derived chG250 in biological activity.
• a ten-fold lower amount of the variant carrying the highest levels of bisected oligosaccharides was required to reach the maximal ADCC activity as MabtheraTM.
• the variant carrying the highest levels of bisected oligosaccharides mediated significant ADCC activity at a 125-fold lower concentration than that required to detect even low ADCC activity by the unmodified control chG250.
• a clear correlation was found between the level of GnTIII expression and ADCC activity.
• the claimed invention is directed to ahost cell engineered to produce a polypeptide having increased Fc-mediated cellular cytotoxicity by expression of at least one nucleic acid encoding ⁇ (l,4)-N- acetylglucosaminyltransferase UI (GnT IH), wherein the polypeptide produced by the host cell is selected from the group consisting of a whole antibody molecule, an antibody fragment, and a fusion protein which includes a region equivalent to the Fc region of an immunoglobulin, and wherein the GnT HI is expressed in an amount sufficient to increase the proportion of said polypeptide carrying bisected hybrid oligosaccharides or galactosylated complex oligosaccharides or mixtures thereof in the Fc region relative to polypeptides carrying bisected complex oligosaccharides in the Fc region.
• GnT IH nucleic acid encoding ⁇ (l,4)-N- acetylglucosaminyltransferas
• the polypeptide is IgG or a fragment thereof, most preferably, IgGl or a fragment thereof.
• the polypeptide is a fusion protein that includes a region equivalent to the Fc region of a human IgG.
• a nucleic acid molecule comprising at least one gene encoding GnTIII has been introduced into the host cell.
• at least one gene encoding GnTIII has been introduced into the host cell chromosome.
• the host cell has been engineered such that an endogenous
• GnT III gene is activated, for example, by insertion of a DNA element which increases gene expression into the host chromosome.
• the endogenous GnTIII has been activated by insertion of a promoter, an enhancer, a transcription factor binding site, atransposon, or aretroviral element or combinations thereof into the host cell chromosome.
• the host cell has been selected to carry a mutation triggering expression of an endogenous GnTIII.
• the host cell is the CHO cell mutant lee 10.
• the at least one nucleic acid encoding a GnTIII is operably linked to a constitutive promoter element.
• the host cell is a CHO cell, a BHK cell, a NS0 cell, a SP2/0 cell, or a hybridoma cell, a Y0 myeloma cell, a P3X63 mouse myeloma cell, aPER cell or a PER.C6 cell andsaid polypeptide is an anti- CD20 antibody.
• the host cell is a SP2/0 cell and the polypeptide is the monoclonal antibody chG250.
• the claimed invention is directed to a host cell that further comprises at least one transfected nucleic acid encoding an antibody molecule, an antibody fragment, or a fusion protein that includes a region equivalent to the Fc region of an immunoglobulin.
• the host cell comprises at least one transfected nucleic acid encoding an anti- CD20 antibody, the chimeric anti-human neuroblastoma monoclonal antibody chCE7, the chimeric anti-human renal cell carcinoma monoclonal antibody chG250, the chimeric anti-human colon, lung, and breast carcinoma monoclonal antibody ING- 1 , the humanized anti-human 17-1 A antigen monoclonal antibody 3622W94, the humanized anti-human colorectal tumor antibody A33, the anti- human melanoma antibody directed against GD3 ganglioside R24, or the chimeric anti-human squamous-cell carcinoma monoclonal antibody SF-25, an anti-human EGFR antibody, an anti-human EGFRvJH antibody, an anti-human PSMA antibody, and anti-human PSCA antibody, an anti-human CD22 antibody, an anti-human CD30 antibody, an anti-human CD33 antibody, an anti-human CD38 antibody, an anti-human CD20 antibody, the
• the claimed invention is directed to a method for producing a polypeptide in a host cell comprising culturing any of the above- described the host cells under conditions which permit the production of said polypeptide having increased Fc-mediated cellular cytotoxicity.
• the method further comprises isolating said polypeptide having increased Fc-mediated cellular cytotoxicity.
• the host cell comprises at least one nucleic acid encoding a fusion protein comprising a region equivalent to a glycosylated Fc region of an immunoglobulin.
• the proportion of bisected oligosaccharides in the Fc region of said polypeptides is greater than 50%, more preferably, greater than 70%.
• the proportion of bisected hybrid oligosaccharides or galactosylated complex oligosaccharides or mixtures thereof in the Fc region is greater than the proportion of bisected complex oligosaccharides in the Fc region of said polypeptide.
• polypeptide is an anti-semiconductor peptide
• CD20 antibody and the anti-CD20 antibodies produced by said host cell have a glycosylation profile, as analyzed by MALDI/TOF-MS, that is substantially equivalent to that shown in FIG. 2E.
• the polypeptide is the chG250 monoclonal antibody and the chG250 antibodies produced by said host cell have a glycosylaton profile, as analyzed by MALDI/TOF-MS, that is substantially equivalent to that shown in FIG. 7D.
• the claimed invention is directed to an antibody having increased antibody dependent cellular cytotoxicity (ADCC) produced by any of the methods described above.
• ADCC antibody dependent cellular cytotoxicity
• the antibody is selected from the group consisting of an anti-CD20 antibody, chCE7, ch-G250, a humanized anti-HER2 monoclonal antibody, ING-1, 3622W94, SF-25, A33, and R24.
• the polypeptide can be an antibody fragment that includes a region equivalent to the Fc region of an immunoglobulin, having increased Fc-mediated cellular cytotoxicity produced by any of the methods described above.
• the claimed invention is directed to a fusion protein that includes a region equivalent to the Fc region of an immunoglobulin and having increased Fc-mediated cellular cytotoxicity produced by any of the methods described above.
• the claimed invention is directed to a pharmaceutical composition
• a pharmaceutical composition comprising the antibody, antibody fragment, or fusion protein of the invention and a pharmaceutically acceptable carrier.
• the claimed invention is directed to a method for the treatment of cancer comprising administering a therapeutically effective amount of said pharmaceutical composition to a patient in need thereof.
• the invention is directed to an improved method for treating an autoimmune disease produced in whole or in part by pathogenic autoantibodies based on B-cell depletion comprising administering a therapeutically effective amount of immunologically active antibody to a human subject in need thereof, the improvement comprising administering a therapeutically effective amountof an antibody having increased ADCC prepared as described above.
• the antibody is an anti-CD20 antibody.
• autoimmune diseases or disorders include, but are not limited to, immune-mediated thrombocytopenias, such as acute idiopathic thrombocytopenic purpurea and chronic idiopathic thrombocytopenic purpurea, dermatomyositis, Sydenham's chorea, lupus nephritis, rheumatic fever, polyglandular syndromes, Henoch-Schonlein purpura, post-streptococcal nephritis, erythema nodosum, Takayasu's arteritis, Addison's disease, erythema multiforme, polyarteritis nodosa, ankylosing spondylitis, Goodpasture's syndrome, thromboangitis ubiterans, primary biliary cirrhosis, Hashimoto's thyroiditis, thyrotoxicosis , chroni c active hepatitis , poly
• atopic dermatitis atopic dermatitis
• systemic sclerodermaandsclerosis responses associated with inflammatory bowel disease (such as Crohn's disease and ulcerative colitis); respiratory distress syndrome (including adult respiratory distress syndrome; ARDS); dermatitis; meningitis; encephalitis; uveitis; colitis; glomerulonephritis; allergic conditions such as eczema and asthma and other conditions involving infiltration of T cells and chronic inflammatory responses; atherosclerosis; leukocyte adhesion deficiency; rheumatoid arthritis; systemic lupus erythematosus (SLE); diabetes mellitus (e.g.
• Type 1 diabetes mellitus or insulin dependent diabetes mellitus multiple sclerosis; Reynaud's syndrome; autoimmune thyroiditis; allergic encephalomyelitis; Sjorgen's syndrome; juvenile onset diabetes; and immune responses associated with acute and delayed hypersensitivity mediated by cytokines and T-lymphocytes typically found in tuberculosis, sarcoidosis, polymyositis, granulomatosis and vasculitis; pernicious amenia (Addison's disease); diseases involving leukocyte diapedesis; central nervous system (CNS) inflammatory disorder; multiple organ injury syndrome; hemolytic anemia (including, but not limited to cryoglobinemia or Coombs positive anemia); myastheniagravis; antigen-antibody complex mediated diseases; anti-glomerular basement membrane disease; antiphospholipid syndrome; allergic neuritis; Graves' disease; Lambert-Eaton myasthenic syndrome; pemphigoid bullous; pemphigus; autoimmune poly
• FIG. Indirect immunofluorescence assay showing the reactivity of the antibody preparation C2B8-25t to CD20 positive SB cells. Negative controls, including the HSB CD20 negative cell line and cells treated only with the secondary FITC-conjugated anti-human Fc polyclonal antibody are not shown.
• FIG. 2A-2E MALDI/TOF-MS spectra of the oligosaccharides derived from MabtheraTM (FIG.2A), C2B8-nt (FIG.2B), C2B8-2000t (FIG.2C), C2B8- 50t (FIG. 2D), and C2B8-25t (FIG. 2E) antibody samples. Oligosaccharides appear as [M+Na + ] and [M+K + ] ions.
• FIG. 3A and 3B Illustration of a typical human IgG Fc-associated oligosaccharide structure (A) and partial N-linked glycosylation pathway (B).
• the core of the oligosaccharide is composed of three mannose (M) and two N-acetylglucosamine (Gn) monosaccharide residues attached to Asn 297 .
• Galactose (G), fucose (F), and bisecting N-acetylglucosamine (Gn, boxed) can be present or absent. Terminal N-acetylneuraminic acid may be also present but it is not included in the figure.
• FIG.3B Partial N-linked glycosylation pathway leading to the formation of the major oligosaccharide classes (dotted frames). Bisecting N-acetylglucosamine is denoted as Gn b . Subscript numbers indicate how many monosaccharide residues are present in each oligosaccharide. Each structure appears together with its sodium-associated [M+Na + ] mass. The mass of those structures that contain fucose (f) are also included.
• FIG. 4A and 4B ADCC activities of Rituximab glycosylation variants.
• FIG.4A Activity of C2B8 samples derived from a single cell line but produced at increasing GnTIII expression levels (i.e., decreasing tetracycline concentrations). The samples are C2B8-2000t, C2B8-50t, C2B8-25t, and C2B8-nt (control mAb derived from a clone that does not express GnT ⁇ i (FIG 4B) ADCC activity of C2B8-50t and C2B8-25t compared to MabtheraTM.
• FIG. 5 Western blot analysis of the seven GnTIII expressing clones and the wild type. 30 ⁇ g of each sample were loaded on a 8.75% SDS gel, transferred to a PVDF membrane and probed with the anti-c-myc monoclonal antibody (9E10). WT refers to wt-chG250-SP2/0 cells.
• FIG. 6 SDS polyacrylamide gel electrophoresis of resolved purified antibody samples.
• FIG. 7A-7D MALDI/TOF-MS spectra of neutral oligosaccharide mixtures from chG250 mAb samples produced by clones expressing different GnT ⁇ i levels and wt-chG250-SP2/0 cells: WT (FIG. 7A), 2F1 (FIG. 7B), 3D3
• FIG. 8A-8D MALDI/TOF-MS spectra of neutral oligosaccharide mixtures from chG250 mAb samples produced by clones expressing different
• GnTIII levels 4E8, (FIG. 8A); 5G2, (FIG. 8B); 4G3, (FIG. 8C); 5H12, (FIG.
• FIG. 9 In vitro ADCC assay of antibody samples derived from control wt-chG250-SP2/- cells and GnTIII transected clones 3D3 and 5H12.
• antibody is intended to include whole antibody molecules, antibody fragments, or fusion proteins that include aregion equivalent to the Fc region of an immunoglobulin.
• region equivalent to the Fc region of an immunoglobulin is intended to include naturally occurring allelic variants of the Fc region of an immunoglobulin as well as variants having alterations which produce substitutions, additions, or deletions but which do not decrease substantially the ability of the immunoglobulin to mediate antibody dependent cellular cytotoxicity.
• one or more amino acids can be deleted from the N-terminus or C-terminus of the Fc region of an immunoglobulin without substantial loss of biological function.
• variants can be selected according to general rules known in the art so as to have minimal effect on activity. (See, e.g., Bowie, J. U. et al, Science 247:1306-10 (1990).
• glycoprotein-modifying glycosyl transferase refers to ⁇ (l,4)-N-acetylglucosaminyltransferase III (GnTIII).
• the terms engineer, engineered, engineering and glycosylation engineering are considered to include any manipulation of the glycosylation pattern of a naturally occurring polypeptide or fragment thereof.
• Glycosylation engineering includes metabolic engineering of the glycosylation machinery of a cell, including genetic manipulations of the oligosaccharide synthesis pathways to achieve altered glycosylation of glycoproteins expressed in cells.
• glycosylation engineering includes the effects of mutations and cell environment on glycosylation.
• the term host cell covers any kind of cellular system which can be engineered to generate modified glycoforms of proteins, protein fragments, or peptides of interest, including antibodies and antibody fragments.
• Host cells include cultured cells, e.g., mammalian cultured cells, such as CHO cells, BHK ceUs, NSO cells, SP2/0 cells, YO myeloma cells, P3X63 mouse myeloma cells, PER cells, PER.C6 cells or hybridoma cells, yeast cells, and insect cells, to name only a few, but also cells comprised within a transgenic animal or cultured tissue.
• Fc-mediated cellular cytotoxicity includes antibody-dependent cellular cytotoxicity and cellular cytotoxicity mediated by a soluble Fc-fusion protein containing a human Fc-region. It is an immune mechanism leading to the lysis of "antibody-targeted cells" by "human immune effector cells”, wherein:
• the "human immune effector cells” are a population of leukocytes that display Fc receptors on their surface through which they bind to the Fc- region of antibodies or of Fc-fusion proteins and perform effector functions. Such a population may include, but is not limited to, peripheral blood mononuclear cells (PBMC) and/or natural killer (NK) cells.
• PBMC peripheral blood mononuclear cells
• NK natural killer
• the "antibody-targeted cells” are cells bound by the antibodies or Fc- fusion proteins.
• the antibodies or Fc fusion-proteins bind to target cells via the protein part N-terminal to the Fc region.
• the term increased Fc-mediated cellular cytotoxicity is defined as either an increase in the number of "antibody-targeted cells” that are lysed in a given time, at a given concentration of antibody, or of Fc-fusion protein, in the medium surrounding the target cells, by the mechanism of Fc- mediated cellular cytotoxicity defined above, and/or a reduction in the concentration of antibody, or of Fc-fusion protein, in the medium surrounding the target cells, required to achieve the lysis of a given number of "antibody- targeted cells", in a given time, by the mechanism of Fc -mediated cellular cytotoxicity.
• Fc-mediated cellular cytotoxicity is relative to the cellular cytotoxicity mediated by the same antibody, or Fc-fusion protein, produced by the same type of host cells, using the same standard production, purification, formulation and storage methods, which are known to those skilled in the art, but that has not been produced by host cells engineered to express the glycosyltransferase GnTIII by the methods described herein.
• ADCC antibody having increased ADCC as determined by any suitable method known to those ofordinary skill in the art.
• One accepted in vitro ADCC assay is as follows:
• the assay uses target cells that are known to express the target antigen recognized by the antigen-binding region of the antibody;
• PBMCs peripheral blood mononuclear cells
• the assay is carried out according to following protocol: i) the PBMCs are isolated using standard density centrifugation procedures and are suspended at 5 x 10 6 cells/ml in RPMI cell culture medium; ii) the target cells are grown by standard tissue culture methods, harvested from the exponential growth phase with a viability higher than 90%, washed in RPMI cell culture medium, labelled with 100 micro-Curies of 51 Cr, washed twice with cell culture medium, and resuspended in cell culture medium at a density of 10 5 cells/ml; iii) 100 microliters of the final target cell suspension above are transferred to each well of a 96-well microtiter plate; iv) the antibody is serially-diluted from 4000 ng/ml to 0.04 ng ml in cell culture medium and 50 microliters of the resulting antibody solutions are added to the target cells in the 96-well microtiter plate, testing in triplicate various antibody concentrations covering the whole concentration range above; v) forthemaximumrelease
• "increased ADCC” is defined as either an increase in the maximum percentage of specific lysis observed within the antibody concentration range tested above, and/or a reduction in the concentration of antibody required to achieve one half of the maximum percentage of specific lysis observed within the antibody concentration range tested above.
• the increase in ADCC is relative to the ADCC, measured with the above assay, mediated by the same antibody, produced by the same type of host cells, using the same standard production, purification, formulation and storage methods, which are known to those skilled in the art, but that has not been produced by host cells engineered to overexpress the glycosyltransferase GnTIII.
• anti-CD20 antibody is intended to mean an antibody which specifically recognizes a jcell surface non-glycosylated phosphoprotein of 35,000 Daltons, typically designated as the human B lymphocyte restricted differentiation antigen Bp35, commonly referred to as CD20.
• the present invention provides methods for the generation and use of host cell systems for the production of glycoforms of antibodies or antibody fragments or fusion proteins which include antibody fragments with increased antibody-dependent cellular cytotoxicity. Identification of target epitopes and generation of antibodies having potential therapeutic value, for which modification of the glycosylation pattern is desired, and isolation of their respective coding nucleic acid sequence is within the scope of the invention.
• antibodies to target epitopes of interest include but are not limited to polyclonal, monoclonal, chimeric, single chain, Fab fragments and fragments produced by an Fab expression library. Such antibodies may be useful, e.g., as diagnostic or therapeutic agents. As therapeutic agents, neutralizing antibodies, i.e., those which compete for binding with a ligand, substrate or adapter molecule, are of especially preferred interest.
• various host animals are immunized by injection with the target protein of interest including, but not limited to, rabbits, mice, rats, etc.
• Various adjuvants may be used to increase the immunological response, depending on the host species, including but not limited to Freund's (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, saponin, oil emulsions, keyhole limpet hemocyanin, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and Corynebacterium parvum.
• BCG Bacille Calmette-Guerin
• Monoclonal antibodies to the target of interest may be prepared using any technique which provides for the production of antibody molecules by continuous cell lines in culture. These include, but are not limited to, the hybridoma technique originally described by Kohler and Milstein, Nature 256 ⁇ 95-91 (1975), the human B-cell hybridoma technique (Kosbor et al, Immunology Today 4:72 (1983); Cote et al, Proc. Natl. Acad. Sci. U.S.A. 80:2026-30 (1983 ) and the EBV-hybridoma technique (Cole etal, Monoclonal Antibodies and Cancer Therapy 11-96 (Alan R. Liss, Inc., 1985)).
• such fragments include, but are not limited to, F(ab') 2 fragments which can be produced by pepsin digestion of the antibody molecule and the Fab fragments which can be generated by reducing the disulfide bridges of the F(ab') 2 fragments.
• Fab expression libraries may be constructed (Huse et al, Science 246:1275-81 (1989) to allow rapid and easy identification of monoclonal Fab fragments with the desired specificity to the target protein of interest.
• the coding nucleic acid sequence is identified and isolated using techniques well known in the art.
• the present invention provides host cell expression systems for the generation of proteins having modified glycosylation patterns.
• the present invention provides host cell systems for the generation of glycoforms of proteins having an improved therapeutic value. Therefore, the invention provides host cell expression systems selected or engineered to increase the expression of a glycoprotein-modifying glycosyltransferase, namely ⁇ (l,4)-N- acetylglucosaminyltransferase UI (GnTIII).
• GnTIII glycoprotein-modifying glycosyltransferase
• such host cell expression systems may be engineered to comprise a recombinant nucleic acid molecule encoding GnTIII, operatively linked to a constitutive or regulated promoter system.
• host cell expression systems may be employed that naturally produce, are induced to produce, and/or are selected to produce GnTIII.
• the present invention provides a host cell that has been engineered to express at least one nucleic acid encoding GnTIII.
• the host cell is transformed or transfected with a nucleic acid molecule comprising at least one gene encoding GnTIII.
• the host cell has been engineered and/or selected in such way that endogenous GnTIII is activated.
• the host cell may be selected to carry a mutation triggering expression of endogenous GnTIII.
• the host cell is a CHO lee 10 mutant.
• the host cell may be engineered such that endogenous GnTIII is activated.
• the host cell is engineered such that endogenous GnTIII has been activated by insertion of a constitutive promoter element, a transposon, or a retroviral element into the host cell chromosome.
• any type of cultured cell line can be used as a background to engineer the host cell lines of the present invention.
• CHO cells, BHK cells, NS0 cells, SP2/0 cells, YO myeloma cells, P3X63 mouse myeloma cells, PER cells, PER.C6 cells or hybridoma cells, yeast cells, or insect cells are used as the background cell line to generate the engineered host cells of the invention.
• the invention is contemplated to encompass any engineered host cells expressing GnTIII as defined herein.
• One or several nucleic acids encoding GnTIII may be expressed under the control of a constitutive promoter or, alternately, a regulated expression system.
• Suitable regulated expression systems include, but are not limited to, a tetracycline-regulated expression system, an ecdysone-inducible expression system, a lac-switch expression system, a glucocorticoid-inducible expression system, a temperature-inducible promoter system, and a metallothionein metal- inducible expression system.
• nucleic acids encoding GnTIII are comprised within the host cell system, some of them may be expressed under the control of a constitutive promoter, while others are expressed under the control of a regulated promoter.
• the maximal expression level is considered to be the highest possible level of stable GnTIII expression that does not have a significant adverse effect on cell growth rate, and will be determined using routine experimentation. Expression levels are determined by methods generally known in the art, including Western blot analysis using a GnTIII specific antibody, Northern blot analysis using a GnTIII specific nucleic acid probe, or measurement of enzymatic activity.
• a lectin may be employed which binds to biosynthetic products of the GnTIII, for example, E 4 -PHA lectin.
• the nucleic acid may be operatively linked to a reporter gene; the expression levels of the GnTIII are determined by measuring a signal correlated with the expression level of the reporter gene.
• the reporter gene may transcribed together with the nucleic acid(s) encoding said GnTIII as a single mRNA molecule; their respective coding sequences may be linked either by an internal ribosome entry site (IRES) or by a cap-independent translation enhancer (CITE).
• the reporter gene may be translated together with at least one nucleic acid encoding said GnTIII such that a single polypeptide chain is formed.
• the nucleic acid encoding the GnTIII may be operatively linked to the reporter gene under the control of a single promoter, such that the nucleic acid encoding the GnTIII and the reporter gene are transcribed into an RNA molecule which is alternatively spliced into two separate messenger RNA (mRNA) molecules; one of the resulting mRNAs is translated into said reporter protein, and the other is translated into said GnTffl.
• mRNA messenger RNA
• nucleic acids encoding GnTIII may be arranged in such way that they are transcribed as one or as several mRNA molecules. If they are transcribed as a single mRNA molecule, their respective coding sequences may be linked either by an internal ribosome entry site (IRES) or by a cap-independent translation enhancer (CITE). They may be transcribed from a single promoter into an RNA molecule which is alternatively spliced into several separate messenger RNA (mRNA) molecules, which then are each translated into their respective encoded GnTIII.
• IRS internal ribosome entry site
• CITE cap-independent translation enhancer
• the present invention provides host cell expression systems for the generation of therapeutic antibodies, having an increased antibody-dependent cellular cytotoxicity, and cells which display the IgG Fc region on the surface to promote Fc-mediated cytotoxicity.
• the host cell expression systems have been engineered and/or selected to express nucleic acids encoding the antibody for which the production of altered glycoforms is desired, along with at least one nucleic acid encoding GnTIII.
• the host cell system is transfected with at least one gene encoding GnTIII.
• the transfected cells are selected to identify and isolate clones that stably express the GnTIII.
• the host cell has been selected for expression of endogenous GnTIII.
• cells may be selected carrying mutations which trigger expression of otherwise silent GnTIII.
• CHO cells are known to carry a silent GnT HI gene that is active in certain mutants, e.g., in the mutant LeclO.
• methods known in the art may be used to activate silent GnTIII, including the insertion of a regulated or constitutive promoter, the use of transposons, retroviral elements, etc.
• gene knockout technologies or the use of ribozyme methods may be used to tailor the host cell's GnTIII expression level, and is therefore within the scope of the invention.
• any type of cultured cell line can be used as background to engineer the host cell lines of the present invention.
• CHO cells, BHK cells, NSO cells, SP2/0 cells, YO myeloma cells, P3X63 mouse myeloma cells, PER cells, PER.C6 cells or hybridoma cells, yeast cell, or insect cells may be used.
• such cell lines are engineered to further comprise at least one transfected nucleic acid encoding a whole antibody molecule, an antibody fragment, or a fusion protein that includes a region equivalent to the Fc region of an immunoglobulin.
• a hybridoma cell line expressing a particular antibody of interest is used as background cell line to generate the engineered host cells of the invention.
• At least one nucleic acid in the host cell system encodes
• One or several nucleic acids encoding GnTIII may be expressed underthe control of a constitutive promoter, or alternately, a regulated expression system.
• Suitable regulated expression systems include, but are not limited to, a tetracycline-regulated expression system, an ecdysone-inducible expression system, a lac-switch expression system, a glucocorticoid-inducible expression system, a temperature-inducible promoter system, and a metallothionein metal- inducible expression system.
• nucleic acids encoding GnTIII are comprised within the host cell system, some of them may be expressed under the control of a constitutive promoter, while others are expressed under the control of a regulated promoter.
• the maximal expression level is considered to be the highest possible level of stable GnTIII expression that does not have a significant adverse effect on cell growth rate, and will be determined using routine experimentation. Expression levels are determined by methods generally known in the art, including Western blot analysis using a GnTIII specific antibody, Northern blot analysis using a GnTIII specific nucleic acid probe, or measurement of GnTIII enzymatic activity.
• a lectin may be employed which binds to biosynthetic products of GnTIII, for example, E 4 -PHA lectin.
• the nucleic acid may be operatively linked to a reporter gene; the expression levels of the glycoprotein-modifying glycosyl transferase are determined by measuring a signal correlated with the expression level of the reporter gene.
• the reporter gene may transcribed together with the nucleic acid(s) encoding said glycoprotein-modifying glycosyl transferase as a single mRNA molecule; their respective coding sequences may be linked either by an internal ribosome entry site (IRES) or by a cap-independent translation enhancer (CITE).
• the reporter gene may be translated together with at least one nucleic acid encoding GnTIII such that a single polypeptide chain is formed.
• the nucleic acid encoding the GnTIII may be operatively linked to the reporter gene under the control of a single promoter, such that the nucleic acid encoding the GnTIII and the reporter gene are transcribed into an RNA molecule which is alternatively spliced into two separate messenger RNA (mRNA) molecules; one of ithe resulting mRNAs is translated into said reporter protein, and the other is translated into said GnTIII.
• mRNA messenger RNA
• nucleic acids encoding a GnTIII may be arranged in such way that they are transcribed as one or as several mRNA molecules. If they are transcribed as single mRNA molecule, their respective coding sequences may be linked either by an internal ribosome entry site (IRES) or by a cap-independent translation enhancer (CITE). They may be transcribed from a single promoter into an RNA molecule which is alternatively spliced into several separate messenger RNA (mRNA) molecules, which then are each translated into their respective encoded GnTIII.
• IRS internal ribosome entry site
• CITE cap-independent translation enhancer
• a variety of host-expression vector systems may be utilized to express the coding sequence of the protein of interest and the coding sequence of the GnTIII.
• mammalian cells are used as host cell systems transfected with recombinant plasmid DNA or cosmid DNA expression vectors containing the coding sequence of the protein of interest and the coding sequence of the GnTIII.
• CHO cells, BHK cells, NSO cells, SP2/0 cells, YO myeloma cells, P3X63 mouse myeloma cells, PER cells, PER.C6 cells or hybridoma cells, yeast cells, or insect cells are used as host cell system.
• yeast cells transformed with recombinant yeast expression vectors containing the coding sequence of the protein of interest and the coding sequence of the GnTIII include, yeast cells transformed with recombinant yeast expression vectors containing the coding sequence of the protein of interest and the coding sequence of the GnTIII; insect cell systems infected with recombinant virus expression vectors (e.g., baculovirus) containing the coding sequence of the protein of interest and the coding sequence of the GnTIII; plant cell systems infected with recombinant virus expression vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or transformed with recombinant plasmid expression vectors (e.g., Ti plasmid) containing the coding sequence of the protein of interest and the coding sequence of the GnTHI; or animal cell systems infected with recombinant virus expression vectors (e.g., adenovirus, vaccinia virus) including cell lines engineered to contain multiple copies
• stable expression is generally preferred to transient expression because it typically achieves more reproducible results and also is more amenable to large scale production.
• host cells can be transformed with the respective coding nucleic acids controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker.
• appropriate expression control elements e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.
• engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media.
• the selectable marker in the recombinant plasmid confers resistance to the selection and allows selection of cells which have stably integrated the plasmid into their chromosomes and grow to form foci which in turn can be cloned and expanded into cell lines.
• a number of selection systems may be used, including, but not limited to, the herpes simplex virus thymidine kinase (Wigler et al, Cell 77:223 (1977)), hypoxanthine-guaninephosphoribosyltransferase (Szybalska& Szybalski, Proc. Natl. Acad. Sci. USA 48:2026 (1962)), and adenine phosphoribosyltransferase (Lowy et al, Cell22:Sll (1980)) genes, which can be employed in tk", hgprt" or aprt " cells, respectively.
• antimetabolite resistance can be used as the basis of selection for dhfr, which confers resistance to methotrexate (Wigler et al, Natl. Acad. Sci. USA 77:3561 (1989); O'Hare et al, Proc. Natl. Acad. Sci. USA 78: 1527 (1981)); gpt, which confers resistance to mycophenolic acid (Mulligan & Berg, Proc. Natl. Acad. Sci. USA 78:2012 (1981)); neo, which confers resistance to the aminoglycoside G-418 (Colberre-Garapin et al, J. Mol. Biol.
• hygro which confers resistance to hygromycin
• trpB which allows cells to utilize indole in place of tryptophan
• hisD which allows cells to utilize histinol in place of histidine
• the host cells which contain the coding sequence and which express the biologically active gene products may be identified by at least four general approaches; (a) DNA-DNA or DNA-RNA hybridization; (b) the presence or absence of "marker" gene functions; (c) assessing the level of transcription as measured by the expression of the respective mRNA transcripts in the host cell; and (d) detection of the gene product as measured by immunoassay or by its biological activity.
• the presence of the coding sequence of the protein of interest and the coding sequence of the GnTIII inserted in the expression vector can be detected by DNA-DNA or DNA-RNA hybridization using probes comprising nucleotide sequences that are homologous to the respective coding sequences, respectively, or portions or derivatives thereof.
• the recombinant expression vector/host system can be identified and selected based upon the presence or absence of certain "marker" gene functions (e.g. , thymidine kinase activity, resistance to antibiotics, resistance to methotrexate, transformation phenotype, occlusion body formation in baculovirus, etc.).
• certain "marker" gene functions e.g. , thymidine kinase activity, resistance to antibiotics, resistance to methotrexate, transformation phenotype, occlusion body formation in baculovirus, etc.
• a marker gene can be placed in tandem with the coding sequences under the control of the same or different promoter used to control the expression of the coding sequences. Expression of the marker in response to induction or selection indicates expression of the coding sequence of the protein of interest and the coding sequence of the GnTIII.
• transcriptional activity for the coding region of the protein of interest and the coding sequence of the GnTIII can be assessed by hybridization assays.
• RNA can be isolated and analyzed by Northern blot using a probe homologous to the coding sequences of the protein of interest and the coding sequence of the GnTIII or particular portions thereof.
• total nucleic acids of the host cell may be extracted and assayed for hybridization to such probes.
• the expression of the protein products of the protein of interest and the coding sequence of the GnTIII can be assessed immunologically, for example by Western blots, immunoassays such as radioimmuno-precipitation, enzyme-linked immunoassays and the like.
• the ultimate test of the success of the expression system involves the detection of the biologically active gene products.
• the present invention provides glycoforms of antibodies and antibody fragments having increased antibody-dependent cellular cytotoxicity.
• ADCC a lytic attack on antibody-targeted cells, is triggered upon binding of leukocyte receptors to the constant region (Fc) of antibodies. Deo etal, Immunology Today 18: 127(1997).
• Fc ⁇ Rs lymphocyte receptors
• Protein engineering studies have shown that Fc ⁇ Rs interact with the lower hinge region of the IgG CH2 domain. Lund et al, J. Immunol. 757:4963-69 (1996). However, Fc ⁇ R binding also requires the presence of oligosaccharides covalently attached at the conserved Asn 297 in the CH2 region. Lund et al, J. Immunol. 757:4963-69 (1996); Wright and Morrison, Trends Biotech.
• An IgG molecule carries two N-linked oligosaccharides in its Fc region, one on each heavy chain.
• an antibody is produced as a population of glycoforms which share the same polypeptide backbone but have different oligosaccharides attached to the glycosylation sites.
• the oligosaccharides normally found in the Fc region of serum IgG are of complex bi-antennary type (Wormald et al, Biochemistry 36: 130-38 (1997), with low level of terminal sialic acid and bisecting N-acetylglucosamine (GlcNAc), and a variable degree of terminal galact ⁇ sylation and core fucosylation.
• the CAMP ATH antigen is normally present at high levels on lymphoma cells, and this chimeric mAb has high ADCC activity in the absence of a bisecting GlcNAc.
• a bisecting GlcNAc is added by the enzyme ⁇ (l,4)-N-acetylglucosammyltransferasei ⁇ (GnTi ⁇ ). Schachter, Biochem. Cell Biol. 64: 163-81 (1986).
• the present inventors used a single antibody-producing CHO cell line, that was previously engineered to express, in an externally-regulated fashion, different levels of a cloned GnT in gene. This approach established for the first time arigorous correlation between expression of GnTHI and the ADCC activity of the modified antibody.
• C2B8 antibody modified according to the disclosed method had an about sixteen-fold higher ADCC activity than the standard, unmodified C2B8 antibody produced under identical cell culture and purification conditions.
• a C2B8 antibody sample expressed in CHO-tTA-C2B8 cells that do not have GnT ffl expression showed, a cytotoxic activity of about 31 % (at 1 ⁇ g/ml antibody concentration), measured as in vitro lysis of SB cells (CD20+) by human lymphocytes.
• C2B8 antibody derived from a CHO cell culture expressing GnT in at a basal, largely repressed level showed at 1 ⁇ g/ml antibody concentration a 33% increase in ADCC activity againstthe control at the same antibody concentration.
• increasing the expression of GnT in produced a large increase of almost 80% in the maximal ADCC activity (at 1 ⁇ g/ml antibody concentration) compared to the control at the same antibody concentration.
• Further antibodies of the invention having increased antibody-dependent cellular cytotoxicity include, but are not limited to, anti-human neuroblas oma monoclonal antibody (chCE7) produced by the methods of the invention, a chimeric anti-human renal cell carcinoma monoclonal antibody (ch-G250) produced by the methods of the invention, a humanized anti-HER2 monoclonal antibody (e.g., Trastuzumab (HERCEPTIN)) produced by the methods of the invention, a chimeric anti-human colon, lung, and breast carcinoma monoclonal antibody (ING-1) produced by the methods of the invention, a humanized anti- human 17-1 A antigen monoclonal antibody (3622 W94) produced by the methods of the invention, a humanized anti-human colorectal tumor antibody (A33) produced by the methods of the invention, an anti-human melanoma antibody (R24) directed against GD3 ganglioside produced by an anti-human neuroblas oma monoclonal antibody (chCE7)
• the present invention relates to a method for increasing the ADCC activity of therapeutic antibodies. This is achieved by engineering the glycosylation pattern of the Fc region of such antibodies, in particular by maximizing the proportion of antibody molecules carrying bisected complex oligosaccharides and bisected hybrid oligosaccharides N-linked to the conserved glycosylation sites in their Fc regions.
• This strategy can be applied to increase Fc-mediated cellular cytotoxicity against undesirable cells mediated by any molecule carrying a region that is an equivalent to the Fc region of an immunoglobulin, not only by therapeutic antibodies, since the changes introduced by the engineering of glycosylation affect only the Fc region and therefore its interactions with the Fc receptors on the surface of effector cells involved in the ADCC mechanism.
• Fc-containing molecules to which the presently disclosed methods can be applied include, but are not limited to, (a) soluble fusion proteins made of a targeting protein domain fused to the N- terminus of an Fc-region (Chamov and Ashkenazi, Trends Biotech. 14: 52(1996) and (b) plasma membrane-anchored fusion proteins made of a type H transmembrane domain that localizes to the plasma membrane fused to the N- terminus of an Fc region (Stumble, P.F., Nature Biotech. 16: 1357 (1998)).
• the targeting domain directs binding of the fusion protein to undesirable cells such as cancer cells, i.e., in an analogous fashion to therapeutic antibodies.
• undesirable cells such as cancer cells, i.e., in an analogous fashion to therapeutic antibodies.
• the application of presently disclosedmethodto enhance the Fc-mediated cellular cytotoxic activity mediated by these molecules would therefore be identical to the method applied to therapeutic antibodies.
• the undesirable cells in the body have to express the gene encoding the fusion protein.
• This can be achieved either by gene therapy approaches, i.e., by transfecting the cells in vivo with a plasmid or viral vector that directs expression of the fusion protein- encoding gene to undesirable cells, or by implantation in the body of cells genetically engineered to express the fusion protein on their surface.
• the later cells would normally be implanted in the body inside a polymer capsule (encapsulated cell therapy) where they cannot be destroyed by an Fc-mediated cellular cytotoxicity mechanism. However should the capsule device fail and the escaping cells become undesirable, then they can be eliminated by Fc-mediated cellular cytotoxicity.
• the presently disclosed method would be applied either by incorporating into the gene therapy vector an additional gene expression cassette directing adequate or maximal expression levels of GnT UI or by engineering the cells to be implanted to express adequate or maximal levels of GnT ffl.
• the aim of the disclosed method is to increase or maximize the proportion of surface-displayed Fc regions carrying bisected complex oligosaccharides and/or bisected hybrid oligosaccharides.
• VL and VH cDNA fragments were subcloned into pBluescript ⁇ KS(+), sequenced and directly joined by ligation to the human constant light (Ig ⁇ ) and heavy (IgGl) chain cDNAs, respectively, using unique restriction sites introduced at the variable and constant region junctions without altering the original amino acid residue sequence (Umana, P., et al, Nat Biotechnol. 77:176-180 (1999); Reff, M. E, et al, Blood 53:435-445 (1994)).
• GnTIII Establishment of two CHO cell lines, CHO-tet-GnTffl expressing different levels of GnTHI depending on the tetracycline concentration in the culture medium; and CHO-tTA, the parental cell line that does not express GnTHI has been described previously (Umana, P., et al, Nat Biotechnol 17: 116- 180 (1999); Umana, P., etal, Biotechnol Bioeng. (55:542-549 (1999)).
• Each cell line was cotianfected with vectors pC2B8L, pC2B8H, and pZeoSV2(+) (for Zeocin resistance; Invitrogen, Leek, The Netherlands) using a calcium phosphate method.
• Zeocin resistant clones were transferred to a 96-well plate and assayed for IDEC-C2B8 production using an ELISA assay specific for the human constant region (4).
• Three IDEC-C2B8 samples were obtained from parallel cultures of a selected clone (CHO-tet-GnTIII-C2B8), differing only in the tetracycline concentration added to the medium (25, 50 and 2000 ng/mL respectively) .
• CD20-positive cells SB cells; ATCC depositno. ATCC CCL120
• HSB cells CD20-negative cells
• HBSSB bovine serum albumin fraction V
• HBSSB bovine serum albumin fraction V
• AFITC-conjugated, anti-humanFc polyclonal antibody was used as a secondary antibody (SIGMA, St. Louis) for all samples. Cells were examined using a Leica fluorescence microscope (Wetzlar, Germany).
• Oligosaccharide profiling by MALDI/TOF-MS were derived from C2B8 antibody samples, MabTheraTM (European counterpart of Rituximab; kind gift from R Stahel, Universitatspital, Switzerland), C2B8-25t, C2B8-50t, C2B8-2000t, andC2B8-nt, (100 ⁇ g each) as previously described (Umana, P., et al, Nat Biotechnol. 77:176-180 (1999)).
• the antibody samples were first treated with Arthrobacter ureafaciens sialidase (Oxford Glycosciences, Abingson, UK) to remove any sialic acid monosaccharide residues.
• Acid N-linked oligosaccharides were then released from the desialylated antibody samples using peptide-N-glycosidase F (Oxford Glycosciences), purified using micro-columns, and analyzed by MALDI/TOF- MS in an Elite Voyager 400 spectrometer (Perseptive Biosystems, Farmingham, MA).
• PBMC Peripheral blood mononuclear cells
• CHO-tet-GnTi ⁇ cells with stable, tetracycline-regulated expression of GnTffl and stable, constitutive expression of IDEC-C2B8, were established and scaled- up forproduction of aset of antibody samples.
• parallel cultures from the same clone were grown under three different tetracycline concentrations, 25, 50 and 2000 ng/ml. These levels of tetracycline had previously been shown to result in different levels of GnTffl and bisected oligosaccharides (Umana, P., etal, Nat Biotechnol. 17: 176-180 (1999); Umana, P., et al, Biotechnol Bioeng.
• a C2B8-producing, control cell line that does not express GnTHI was also established and cultured under the same conditions as for the three parallel cultures of CHO-tet-GnTIH. After Protein A-affinity chromatography, mAb purity was estimated to be higher than 95% by SDS-PAGE and Coomassie-blue staining.
• the samples were named according to the tetracycline concentration added to the culture medium for their production: C2B8-25t,C2B8-50t, C2B8-2000t and C2B8-nt (i.e., no tetracycline for the non-bisected control).
• Sample C2B8-25t showedspecificantigen binding by indirect immunofluorescence using CD20-positive and CD20-negative cells (FIG. 1), indicating that the synthesized VL and VH gene fragments were functionally correct.
• Oligosaccharide profiling with MALDI/TOF-MS The glycosylation profile of each antibody sample was analyzed by MALDI/TOF-MS of the released, neutral oligosaccharide mix. In this technique, oligosaccharides of different mass appear as separate peaks in the spectrum and their proportions are quantitatively reflected by the relative peak heights (Harvey, D. J., Rapid Common Mass Spectrom. 7:614-619 (1993); Harvey, D. J., et al, Glycoconj J. 75:333-338 (1998)).
• Oligosaccharide structures were assigned to different peaks based on their expected molecular masses, previous structural data for oligosaccharides derived from IgGl mAbs produced in the same host, and information on the N-linked oligosaccharide biosynthetic pathway.
• GnTHI expression levels i.e., tetracycline concentration
• C2B8-nt which are derived from hosts that do not express GnTHI
• bisected structures amounted up to approximately 35% of the oligosaccharides pool in sample C2B8-2000t, i. e, at a basal level of GnTHI expression.
• ADCC activity ofIDEC-C2B8 glycosylated variants Different C2B8 mAb glycosylationvariants were compared for ADCC activity, measured as in vitro lysis of CD20-positive SB cells.
• sample C2B8-50t carried approximately equal levels ofbisected andnon-bisected oligosaccharides, but did not mediate significantly higher target-cell lysis.
• sample C2B8-25t which contained up to 80% of bisected oligosaccharide structures, was significantly more active than the rest of the samples in the whole antibody concentration range. It reached the maximal level of ADCC activity of sample C2B8-nt at a 10-fold lower antibody concentration (FIG. 4A).
• Sample C2B8-25t also showed a significant increase in the maximal ADCC activity with respect to the control (50% vs. 30% lysis).
• C2B8 antibody correlates with the proportion of molecules carrying bisected oligosaccharides in the Fc region.
• chCE7 an antibody with a low baseline level of ADCC activity, significant increases of activity could be obtained by increasing the fraction of bisected oligosaccharides above the levels found in naturally-occurring antibodies (Umana, P., etal, Nat Biotechnol. 77:176-180 (1999)).
• C2B8 mAb which already has high ADCC activity in the absence of bisected oligosaccharides.
• wt-chG250-SP2/0 myeloma cells weretransfectedby electroporation with a vector for constitutive expression of GnTHI operatively linked via an IRES to a puromycin resistance gene. 24 hours before electroporation culture medium was changed and cells were seeded at 5xl0 5 cells/ml. Seven million cells were centrifuged for 4 min at 1300 rpm at 4 °C. Cells were washed with 3 mL new medium and centrifuged again. Cells were resuspended in a volume of 0.3-0.5 ml of reaction mix, containing 1.25% (v/v) DMSO and 20-30 ⁇ g DNA in culture medium.
• the electroporation mix was then transferred to a 0.4 cm cuvette and pulsed at low voltage (250-300 V) and high capacitance (960 ⁇ F) using Gene Pulser from Bio Rad. After electroporation cells were quickly transferred to 6 mL 1.25% (v/v) DMSO culture medium in a T25 culture flask and incubated at 37 °C. Stable integrants were selected by applying 2 ⁇ g/mL puromycin to the medium two days after electroporation. After 2-3 weeks a stable, puromycin-resitant mixed population was obtained. Single-cell derived clones were obtained via FACS and were subsequently expanded and maintained under puromycin selection.
• chG250-SP2/0 cells were seeded at 3x10 s cells/mL in atotal volume of 130 ml culture medium, and cultivated in single Triple-flasks. Cells used for seeding were all in full exponential growth phase, therefore cells were considered to be at the same growth state when the production batches started. Cells were cultivated for 4 days. Supernatants containing the antibody were collected in the late exponential growth phase to ensure reproducibility.
• the chG250 monoclonal antibody was purified in two chromatographic steps. Culture supernatants containing the chG250 monoclonal antibody derived from each batch were first purified using a HiTrap Protein A affinity chromatography. Protein A is highly specific for the human IgG F c region.
• Oligosaccharide profiles were obtained by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI/TOF-MS), which accurately provides the molecular masses of the different oligosaccharide structures.
• MALDI/TOF-MS matrix-assisted laser desorption/ionization time of flight mass spectrometry
• This technique allows a quantitative analysis of proportions between different oligosaccharide structures within a mixture.
• Neutral oligosaccharides appeared predominantly as [M + Na + ] ions, however sometimes they were accompanied by smaller [M + K + ] ions, leading to an increase in mass of m/z of 16.
• the percentage of the structure appearing as potassium ion adducts depends on the content of the matrix and may thus vary between samples.
• a mixture of neutral N-linked oligosaccharides derived from each antibody preparation was analyzed using a 2,5-dehydrobenzoic acid (2,5-DHB) as matrix.
• 2,5-DHB 2,5-dehydrobenzoic acid
• Some of the peaks in the spectra were unequivocally assigned to specific oligosaccharide structures, because of known monosaccharide composition and unique mass. However, sometimes multiple structures could be assigned to a particular mass.
• MALDI enables the determination of the mass and cannot distinguish between isomers.
• Knowledge of the biosynthetic pathway and previous structural data enable, in most cases, the assignment of an oligosaccharide structure to a peak in the spectrum.
• the percentage of the nonbisected complex oligosaccharide type assigned to peak at m/z 1648, had the lowest values for the clones expressing the highest GnTffl levels (clones 4E6, 4E8, 5G2 and 5H12). These two peaks decreased in favor of the accumulation of bisected complex and bisected hybrid type oligosaccharides (FIGS. 7A-7D and 8A-8D). The percentage of bisected complex oligosaccharides was higher for the samples derived from the clones expressing lower amounts of G ⁇ THI. This is consistent with the fact that a higher GnTHI expression level probably shifts the biosynthetic flux to bisected hybrid structures, thereby decreasing the relative proportions of complex and complex bisected compound.
• Peaks m/z 1664, 1680, 1810 and 1826 can be assigned to either bisected hybrid type, to galactosylated complex oligosaccharides, or a mixture of them. Due to the fact that the wt-antibody preparation had a relatively low percentage of peak 1664, it was assumed that this peak, appearing in significant amounts in the antibody samples derived from the different clones, corresponded entirely to bisected hybrid structures (FIGS. 7A-7D and 8A-8D).
• the Calcein-AM retention method of measuring cytotoxicity measures the dye fluorescence remaining in the cells after incubation with the antibody.
• Four million G250 antigen-positive cells (target) were labelled with 10 ⁇ M Calcein-AM (Molecular Probes, Eugene, OR) in 1.8 mL RPMI-1640 cell culture medium (GIBCO BRL, Basel, Switzerland) supplemented with 10% fetal calf serum for 30 min at 37°C in a 5% CO 2 humidified atmosphere.
• the cells were washed twice in culture medium and resuspended in 12 mL AIMV serum free medium (GIBCO BRL, Basel, Switzerland).
• PBMC Peripheral blood mononuclear cells
• E:T ratio effector to target ratio
• 96-well plate was centrifuged at 700 x g for 5 min and the supernatants were discarded.
• the cell pellets were washed twice with Hank's balanced salt solution (HBSS) and lysed in 200 ⁇ L 0.05M sodium borate, pH 9, 0.1% Triton X-100. Retention of the fluorescent dye in the target cells was measured with a FLUOstarmicroplate reader (BMGLabTechnologies,Offenburg, Germany).
• the specific lysis was calculated relative to a total lysis control, resulting from exposure of the target cells to saponin (200 ⁇ g/mL in AIMV; SIGMA, Buchs, Switzerland) instead of exposure to antibody. Specific lysis (%) was calculated with the following formula:
• F med represents the fluorescence of target cells treated with medium alone and considers unspecific lysis by PMBCs
• F exp represents the fluorescence of cells treated with antibody
• F det represents the fluorescence of cells treated with saponin instead of antibody.
• Unmodified chG250 antibody did not mediate significant ADCC activity over the entire concentration range used in the assay (the activity was not significantly different from background).
• Augmented ADCC activity (close to 20%, see FIG. 9) at 2 g/mL was observed with the antibody sample derived from clone 3D3, which expressed intermediate GnTffl levels. The cytotoxic activity of this antibody samples did not grow at higher antibody concentrations.
• the antibody preparation derived from clone 5H 12 showed a striking increase over samples 3D3 and unmodified antibody in its ability to mediate ADCC against target cells.
• the maximal ADCC activity of this antibody preparation was around 50% and was remarkable in mediating significant ADCC activity at 125-fold less concentrated when comparing with the unmodified control sample.
• Immune-mediated, acquired pure red cell aplasia is a rare disorder frequently associated with other autoimmune phenomena.
• an anti-CD20 chimeric monoclonal antibody prepared by the methods of the present invention and having increased ADCC is administered to the subject as described in Zecca, M. et al, Blood 72:3995-97 (1997) (the entire contents of which are hereby incorporated by reference) .
• a subj ect with PRCA and autoimmune hemolytic anemia is given two doses of antibody, 375 mg/m 2 , per week.
• substitutive treatment with intravenous immunoglobulin is initiated. This treatment produces a marked depletion of B cells and a significant rise in reticulocyte count accompanied by increased hemoglobin levels.

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