Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K16/00—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies
  • C07K16/18—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans
  • C07K16/28—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants
  • C07K16/2839—Immunoglobulins [IG], e.g. monoclonal or polyclonal antibodies against material from animals or humans against receptors, cell surface antigens or cell surface determinants against the integrin superfamily
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
  • A61P31/12—Antivirals
  • A61P31/14—Antivirals for RNA viruses
  • A61P31/18—Antivirals for RNA viruses for HIV
• • 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
  • C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
  • C12N15/09—Recombinant DNA-technology
  • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
• • 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
  • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
  • C07K2317/52—Constant or Fc region; Isotype
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07K—PEPTIDES
  • C07K2317/00—Immunoglobulins specific features
  • C07K2317/50—Immunoglobulins specific features characterized by immunoglobulin fragments
  • C07K2317/56—Immunoglobulins specific features characterized by immunoglobulin fragments variable (Fv) region, i.e. VH and/or VL
  • C07K2317/565—Complementarity determining region [CDR]
• • 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]
• • 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
  • C07K2317/734—Complement-dependent cytotoxicity [CDC]
• • 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
  • C07K2317/76—Antagonist effect on antigen, e.g. neutralization or inhibition of binding

Definitions

• ANTI- ⁇ LPHA-4- ⁇ ETA-7 ANTIBODIES 1. SEQUENCE LISTING [0001] The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on July 14, 2021, is named 483WO_SL.txt and is 106,797 bytes in size. 2. TECHNICAL FIELD [0002] The present application pertains to, among other things, novel anti- ⁇ 4 ⁇ 7 antibodies, polynucleotides encoding the antibodies, methods of making the same, and methods of use of these antibodies. 3.
• HIV human immunodeficiency virus
• cART combination antiretroviral therapy
• ⁇ 4 ⁇ 7 is a gut-homing integrin expressed on T cells (CD4+ or CD8+), B cells and other immune cells, and plays an important role in the pathogenesis of HIV infection. ⁇ 4 ⁇ 7 has also been reported to be incorporated into the envelope of HIV when the virions bud from the infected host cells (Guzzo et al., Sci. Immunol., 2017). [0005] The ⁇ 4 ⁇ 7 integrin is a heterodimeric receptor expressed on T cell subsets, B cells, NK cells and other immune cells.
• This integrin mediates the lymphocyte trafficking into gut-associated lymphoid tissues (GALT) by binding to its ligand mucosal addressin cell adhesion molecule 1 (MAdCAM-1) expressed on endothelial venules of intestinal mucosa.
• GALT gut-associated lymphoid tissues
• MAdCAM-1 mucosal addressin cell adhesion molecule 1
• High ⁇ 4 ⁇ 7 expressing CD4+ T cells are targets for HIV infection in vitro (Cicala et al., PNAS 2009), which are infected and therefore depleted during acute HIV infection (Sivro et al., Sci Transl Med 2018).
• ⁇ 4 ⁇ 7 present in HIV-infected CD4+ cells as well as in HIV virions could mediate their trafficking to GALT (Guzzo et al., Sci Immunol 2017).
• the present disclosure provides anti- ⁇ 4 ⁇ 7 antibodies and binding fragments thereof that specifically bind to human ⁇ 4 ⁇ 7.
• the amino acid sequences of exemplary CDRs, as well as the amino acid sequence of the VH and VL regions of the heavy and light chains of exemplary anti- ⁇ 4 ⁇ 7 antibodies are provided in the Detailed Description below.
• Polynucleotides comprising nucleotide sequences encoding the anti- ⁇ 4 ⁇ 7 antibodies of the disclosure are provided herein, as are vectors comprising polynucleotides.
• prokaryotic cells transformed with and eukaryotic cells transfected with a vector comprising a nucleotide sequence encoding a disclosed anti- ⁇ 4 ⁇ 7 antibody are provided herein, as well as eukaryotic (such as mammalian) host cells engineered to express the nucleotide sequences.
• Methods of producing antibodies, by culturing host cells and recovering the antibodies are also provided.
• the present disclosure provides methods of treating subjects, such as human subjects, diagnosed with HIV infection with an anti- ⁇ 4 ⁇ 7 antibody. The method generally involves administering to the subject an amount of an anti- ⁇ 4 ⁇ 7 antibody described herein effective to provide therapeutic benefit.
• the subject may be diagnosed with any clinical category of HIV infection.
• FIG.1 shows the blockade of adhesion of HuT78 cells to MAdCAM-1 by murine antibody Ab-m1.
• FIG.2 shows the functional cynomolgus monkey cross-reactivity of Ab-m1 using CHOK1-c ⁇ 4 ⁇ 7 (cyno ⁇ 4 ⁇ 7) cell adhesion assay to MAdCAM-1.
• FIG.3 shows Ab-m1 blocking of human MAdCAM-1 binding to primary human CD4+ memory T cells.
• FIG.4 shows binding of murine-human chimera Ab-c1 to human primary CD4+ memory T cells (h ⁇ 4 ⁇ 7+CD4+CD45RO+).
• FIG.5 shows the binding of liability engineered humanized anti- ⁇ 4 ⁇ 7 Ab-h1.9 scFv clones against human ⁇ 4 ⁇ 7 antigen displayed on yeast by flow cytometry.
• FIGS.6A-6F show ⁇ 4 ⁇ 7 expression analysis on samples from 45 HIV+ individuals and 10 healthy (HIV-) donors. Expression of ⁇ 4 ⁇ 7 (as % or as levels measured by MESF) on CD4+ and CD8+ T cells was compared among HIV+ and HIV- individuals. Only the comparisons that were significantly different by Mann-Whitney two-tailed test are shown in the figures.
• FIGS.7A-7G-2 show HIV virion capture with Ab-h1.9d-WT. All testing was done with a virion capture assay in a bead format.
• Ab-h1.9d-WT was tested with six laboratory grown HIV strains (FIGS.7A-7F) at 5 nM and 15 nM, whereas the negative control antibody was tested at 15 nM only. Amount of HIV p24 gag in the captured samples is shown in pg/mL in 10 ⁇ L assayed. Ab-h1.9d-WT was also tested with samples from two HIV-infected individuals with beads coated with 10 ⁇ g of the antibody (FIGS.7G-1 and 7G-2). Amount of HIV gag RNA in the input samples (FIG.7G-1) and in captured samples (FIG.7G-2) as detected by digital droplet PCR is shown in copies/mL.
• FIGS.8A-8E shows immune complexes (HIV virions with different antibodies) binding to Fc ⁇ Rs.
• Immune complexes were first formed by incubating antibodies (Ab-h1.9d-WT, Ab-h1.9d with LALA mutations to significantly reduce Fc ⁇ R binding, Ab-Vedo, and isotype negative control) with HIV NL4-3, and then captured on Fc ⁇ Rs immobilized on a plate.
• Fc ⁇ RI, and Fc ⁇ RIIIa V158
• Fc ⁇ RIIa H131
• Fc ⁇ RIIa R131
• Fc ⁇ RIIIa F158
• FIGS.9A-9C show ⁇ 4 ⁇ 7- and Fc-dependence of Ab-h1.9d-WT-mediated uptake of ⁇ 4 ⁇ 7-coated beads in THP-1 cells. Phagocytosis scores of immune complexes (containing ⁇ 4 ⁇ 7 coated beads and the indicated anti- ⁇ 4 ⁇ 7 or control antibody) in THP-1 cells treated with the complexes for 3 h are plotted.
• FIG.9A shows data from one representative experiment.
• FIG.9B shows normalized data from 3 independent experiments. Significance was determined using one-way ANOVA coupled to Tukey’s multiple comparisons test.
• FIG.9C shows representative images of Ab-h1.9d-WT immune complex treated cell with 3 internalized ⁇ 4 ⁇ 7-coated beads, acquired by imaging cytometry.
• FIG.10 shows binding of anti- ⁇ 4 ⁇ 7 antibodies to ⁇ 4 ⁇ 7+GFP+VLPs (viral like particles). Binding of Abs to VLPs was determined using ELISA. Ab-h1.9d-WT, Ab-h1.9d-LALA and Ab-Vedo bound to a4b7+GFP+VLPs coated plated with similar EC50 values. Representative data from two independent experiments is shown.
• FIGS.11A-11B show ⁇ 4 ⁇ 7- and Fc-dependence of Ab-h1.9d-WT-mediated ⁇ 4 ⁇ 7+GFP+VLP (viral like particles) uptake by THP-1 cells.
• FIG.11A shows ⁇ 4 ⁇ 7+GFP+VLP uptake by THP-1 cells as a percentage of GFP+ cells measured by flow cytometry.
• FIG 11B shows inhibition of ⁇ 4 ⁇ 7+GFP+VLP uptake by Latrunculin A (Lat A).
• Lat A Latrunculin A
• THP-1 cells were pretreated with Lat A for 2 h and then incubated with VLPs and antibodies as in FIG 11A. Mean ⁇ s.d.
• FIGS.12A-12B show inhibition of interaction of HIV gp120 with ⁇ 4 ⁇ 7 by different antibodies.
• FIG.12A shows binding of RPMI 8866 cells to the HIV gp120-V2 WT peptide, but not the control peptide.
• RPMI 8866 cells constitutively express ⁇ 4 ⁇ 7 on the cell surface.
• HIV gp120 V2 WT peptide and HIV gp120 V2 control peptide were identical in sequence except four amino acids reported to mediate the binding between ⁇ 4 ⁇ 7 and gp120 were mutated in the control peptide.
• FIG.12B shows inhibition of binding of HIV gp120 peptides to RPMI 8866 cells expressing ⁇ 4 ⁇ 7 by different antibodies. Ab-h1.9d-WT was more potent than Ab-Vedo in inhibiting the binding of HIV gp120-V2 WT peptide to RPMI 8866 cells expressing ⁇ 4 ⁇ 7.
• FIG.13 shows the percentage of human and cynomolgus CD4+ and CD8+ T subsets bound by Ab-h1.9d-WT.
• the binding of Ab-h1.9d-WT to human and cynomolgus CD4+ and CD8+ T cells was assessed by flow cytometry analysis.
• the percentage of ⁇ 4 ⁇ 7+ T cell subsets bound by Ab-h1.9d-WT were determined.
• the data were obtained from 3 human and 5 cynomolgus donors.
• FIGS.14A-14F show binding specificity of Ab-h1.9d-WT to various integrins.
• Binding specificity of Ab-h1.9d-WT was assessed on recombinant cells expressing human (14A, 14C and 14E) or cynomolgus integrins (14B, 14D and 14F). Binding to target integrin ⁇ 4 ⁇ 7 (FIG.14A/14B) in comparison to ⁇ 4 ⁇ 1 (FIG.14C/14D) and ⁇ E ⁇ 7 (FIG.14E/14F) integrins.
• Ab-Nata and etrolizumab-derived Ab-Etro were used as ⁇ 4 and ⁇ 7 integrin specific positive controls, respectively and Ab-Ctet as an isotype control. FACS binding results are represented as MFI for titrated mAbs.
• FIG.15 shows non-specific binding evaluation of Ab-h1.9d-WT in HEK293 cells.
• Non-specific binding of Ab-h1.9d-WT to HEK293 cells was assessed by flow cytometry analysis. A positive control showed high binding whereas negligible binding was observed for both Ab-h1.9d-WT and isotype control Ab-cTet at 100 ⁇ g/mL test concentration.
• Percentage HEK293 cells bound to test mAbs (A) and MFI of binding intensity by test mAbs (B) are presented.
• N 2.
• FIGS.16A-16B show internalization of ⁇ 4 ⁇ 7 complex with Ab-h1.9d-WT or Ab-Vedo on human primary cells.
• FIG.16A shows internalization of Ab-h1.9d-WT on CD4+ T and CD8+ T na ⁇ ve cells from peripheral blood human donors. Dot plots from two donors indicating the percentage of ⁇ 4 ⁇ 7 cells upon treatment with Ab-h1.9d-WT at 4 or 37°C at 18 hours post treatment. The remaining ⁇ 4 ⁇ 7 on the cell surface was detected with Alexa-647 labeled anti- ⁇ 7 Ab-Etro.
• FIGS.17A-17B show Ab-h1.9d-WT blocks MAdCAM-1 co-stimulation signal on human primary CD4+ T cells.
• FIG.17A the activation of human primary CD4+ T cells by anti-CD3 and MAdCAM-1 in the presence of isotype control Ab and Ab-h1.9d-WT was measured as percentage of Ki67+CD25+ cells (Ki67+ on X axis, CD25+ on Y axis) by flow cytometry analysis. The data is from a representative donor.
• FIG.17B the activation of human primary CD4+ T cells by anti-CD3 and MAdCAM-1 in the presence of isotype control Ab, Ab-h1.9d-WT and Ab-Vedo was measured as percentage of Ki67+CD25+ cells (on Y axis). Data is from 6 individual healthy donors. Statistical analysis was performed using two-tailed parametric paired t test: **P ⁇ 0.01, ****P ⁇ 0.0001). [0028] FIG.18 shows Ab-h1.9d-WT does not block VCAM-1 mediated cell adhesion. Cell adhesion blockade by Ab-h1.9d-WT to VCAM-1 was determined using HuT78 cell adhesion assay.
• FIGS.19A-19B show binding of Ab-h1.9d-WT to human Fc ⁇ R-expressing cells in comparison to Ab-Vedo via flow cytometry.
• FIGS.20A-20B show reporter-based ADCC and ADCP activity of Ab-h1.9d-WT.
• Ab-Ritu was used as a positive control in the assays. Results are represented by luminescence (RLU); high signal indicates ADCC and ADCP activity.
• FIG.21 shows CDC Activity of Ab-h1.9d-WT.
• FIG.22 shows cytotoxicity-based ADCC activity of Ab-h1.9d-WT. The ability of Ab-h1.9d-WT to induce Fc mediated in-vitro ADCC was assessed using HuT78 cells as target cells and human primary NK cells from two donors as effector cells in FACS-based cytotoxicity assay.
• Target cell killing is represented by percentage ADCC for both donors.
• DETAILED DESCRIPTION [0033] Without being bound by theory, embodiments of the invention, are hypothesized to exert viral control against HIV infection via two major mechanisms of action: 1) Fab-dependent mechanism: blocking interaction of ⁇ 4 ⁇ 7 with its ligands such as MAdCAM-1and HIV gp120, thus inhibiting the co-stimulation of CD4+ T cells mediated by the signaling of these ligands, and suppressing HIV replication in these stimulated cells (Nawaz et al., Mucosal Immunol.2018, Livia et al., PNAS. 2020), HIV infection of gut tissues (Guzzo et.
• ⁇ 4 ⁇ 7 integrin is usually in a resting (inactive) state with low affinity for its ligands. Once it is activated, it can bind to its ligands (e.g MAdCAM-1 and gp120) with high-affinity (Ye et al., Blood, 2012; Lertjuthaporn et al., PloS One, 2018).
• ligands e.g MAdCAM-1 and gp120
• high-affinity Ye et al., Blood, 2012; Lertjuthaporn et al., PloS One, 2018.
• a motif in the V2 region of HIV gp120 mimics MAdCAM-1 and is capable of binding to ⁇ 4 ⁇ 7 (Peachman et al., PloS One, 2015).
• LFA-1 lymphocyte function-associated antigen-1
• ⁇ 4 ⁇ 7 induces the activation of lymphocyte function-associated antigen-1 (LFA-1), potentially inducing the formation of virological synapses and thus enhancing HIV cell-to-cell transmission (Arthos et al. Nat Immunol 2008).
• LFA-1 lymphocyte function-associated antigen-1
• Cell-to-cell transmission is critical for promoting viral spread in tissues, and is more important than cell-free virus for viral transmission.
• embodiments of the invention can reduce ⁇ 4 ⁇ 7-mediated cell-to-cell transmission of HIV by disrupting the interaction of ⁇ 4 ⁇ 7 with gp120, inducing the internalization of the ⁇ 4 ⁇ 7-antibody bound complex to the cells, or may inactivate ⁇ 4 ⁇ 7.
• embodiments of the invention demonstrate the ability to inhibit HIV replication and viral spread in tissues.
• embodiments of the invention do not induce the emergence of viral resistance mutations that are usually associated with a treatment targeting a viral protein due to the high mutation frequency of HIV. 6.1.
• the antibodies described herein are, in many embodiments, described by way of their respective polypeptide sequences. Unless indicated otherwise, polypeptide sequences are provided in N ⁇ C orientation.
• polynucleotides described herein are, in many embodiments, described by way of their respective polynucleotide sequences.
• polypeptide sequences in 5’ ⁇ 3’ orientation.
• the conventional three or one-letter abbreviations for the genetically encoded amino acids may be used, as noted in TABLE 1, below.
• Certain sequences are defined by structural formulae specifying amino acid residues belonging to certain classes (e.g., aliphatic, hydrophobic, etc.). The various classes to which the genetically encoded amino acids belong as used herein are noted in TABLE 2, below. Some amino acids may belong to more than one class. Cysteine, which contains a sulfhydryl group, and proline, which is conformationally constrained, are not assigned classes.
• Abbreviations used throughout the various exemplary embodiments include those provided in TABLE 3, below:
• the disclosure concerns antibodies that specifically bind ⁇ 4 ⁇ 7 heterodimeric integrin receptor (also known as a4b7, LPAM-1, lymphocyte Peyer's patch adhesion molecule 1, and a dimer of Integrin alpha-4 and Integrin beta-7).
• ⁇ 4 ⁇ 7 heterodimeric integrin receptor also known as a4b7, LPAM-1, lymphocyte Peyer's patch adhesion molecule 1, and a dimer of Integrin alpha-4 and Integrin beta-7.
• the term “antibody” refers to an immunoglobulin molecule that specifically binds to a particular antigen, e.g., ⁇ 4 ⁇ 7.
• the anti- ⁇ 4 ⁇ 7 antibodies of the disclosure bind to human ⁇ 4 ⁇ 7 and thereby modulate the immune system.
• Anti- ⁇ 4 ⁇ 7 antibodies of the disclosure comprise complementarity determining regions (CDRs), also known as hypervariable regions, in both the light chain and the heavy chain variable domains. The more highly conserved portions of variable domains are called the framework (FR).
• CDRs complementarity determining regions
• FR framework
• the amino acid position/boundary delineating a hypervariable region of an antibody can vary, depending on the context and the various definitions known in the art.
• variable domains within a variable domain may be viewed as hybrid hypervariable positions in that these positions can be deemed to be within a hypervariable region under one set of criteria while being deemed to be outside a hypervariable region under a different set of criteria. One or more of these positions can also be found in extended hypervariable regions.
• the disclosure provides antibodies comprising modifications in these hybrid hypervariable positions.
• the variable domains of native heavy and light chains each comprise four FR regions, largely by adopting a ⁇ -sheet configuration, connected by three CDRs, which form loops connecting, and in some cases forming part of, the ⁇ -sheet structure.
• the CDRs in each chain are held together in close proximity by the FR regions and, with the CDRs from the other chain, contribute to the formation of the target binding site of antibodies. See Kabat et al., Sequences of Proteins of Immunological Interest (National Institute of Health, Bethesda, Md.1987).
• the antibodies of the disclosure may be polyclonal, monoclonal, genetically engineered, and/or otherwise modified in nature, including but not limited to chimeric antibodies, humanized antibodies, human antibodies, single chain antibodies, etc. In various embodiments, the antibodies comprise all or a portion of a constant region of an antibody.
• the constant region is an isotype selected from: IgA (e.g., IgA1 or IgA2), IgD, IgE, IgG (e.g., IgG1, IgG2, IgG3 or IgG4), and IgM.
• the anti- ⁇ 4 ⁇ 7 antibodies described herein comprise an IgG1.
• the anti- ⁇ 4 ⁇ 7 antibodies comprise an IgG2.
• the anti- ⁇ 4 ⁇ 7 antibodies comprise an IgG4.
• the “constant region” of an antibody includes the natural constant region, allotypes or variants, such as any of T250Q, L234A, L235A, D356E, L358M, M428L, and/or A431G in human IgG1.
• the light constant region of an anti- ⁇ 4 ⁇ 7 antibody may be a kappa ( ⁇ ) light region or a lambda ( ⁇ ) region.
• a ⁇ light region can be any one of the known subtypes, e.g., ⁇ 1, ⁇ 2, ⁇ 3, or ⁇ 4.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a kappa ( ⁇ ) light region.
• monoclonal antibody as used herein is not limited to antibodies produced through hybridoma technology.
• a monoclonal antibody is derived from a single clone, including any eukaryotic, prokaryotic, or phage clone, by any means available or known in the art.
• Monoclonal antibodies useful with the present disclosure can be prepared using a wide variety of techniques known in the art including the use of hybridoma, recombinant, and phage display technologies, or a combination thereof.
• chimeric antibody refers to an antibody having variable sequences derived from a non-human immunoglobulin, such as a rat or a mouse antibody, and human immunoglobulin constant regions, typically chosen from a human immunoglobulin template.
• “Humanized” forms of non-human (e.g., murine) antibodies comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin sequence.
• the humanized antibody can also comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin consensus sequence.
• “Human antibodies” include antibodies having the amino acid sequence of a human immunoglobulin and include antibodies isolated from human immunoglobulin libraries or from animals transgenic for one or more human immunoglobulins and that do not express endogenous functional immunoglobulins. Human antibodies can be made by a variety of methods known in the art including phage display methods using antibody libraries derived from human immunoglobulin sequences.
• Anti- ⁇ 4 ⁇ 7 antibodies of the disclosure include full-length (intact) antibody molecules.
• the anti- ⁇ 4 ⁇ 7 antibodies may be antibodies whose sequences have been modified to alter at least one constant region-mediated biological effector function.
• an anti- ⁇ 4 ⁇ 7 antibody may be modified to reduce at least one constant region-mediated biological effector function relative to the unmodified antibody, e.g., reduced binding to one or more of the Fc receptors (Fc ⁇ R) such as Fc ⁇ RI, Fc ⁇ RIIa, Fc ⁇ RIIb, Fc ⁇ RIIIa and/or Fc ⁇ RIIIb.
• Fc ⁇ R binding can be reduced by mutating the immunoglobulin constant region segment of the antibody at particular regions necessary for Fc ⁇ R interactions (See, e.g., Canfield and Morrison, 1991, J. Exp.
• the anti- ⁇ 4 ⁇ 7 antibodies described herein include antibodies that have been modified to acquire or improve at least one constant region-mediated biological effector function relative to an unmodified antibody, e.g., to enhance Fc ⁇ R interactions (See, e.g., US Patent Appl. No. 2006/0134709).
• an anti- ⁇ 4 ⁇ 7 antibody of the disclosure can have a constant region that binds Fc ⁇ RI, Fc ⁇ RIIa, Fc ⁇ RIIb, Fc ⁇ RIIIa and/or Fc ⁇ RIIIb with greater affinity than the corresponding unmodified constant region.
• Additional substitutions that can modify Fc ⁇ R binding and/or ADCC effector function of an anti- ⁇ 4 ⁇ 7 antibody include the K322A substitution or the L234A and L235A double substitution in the Fc region. See, e.g., Hezareh, et al. J. Virol., 75 (24): 12161-12168 (2001).
• the anti- ⁇ 4 ⁇ 7 antibodies of the disclosure can comprise modified (or variant) CH2 domains or entire Fc domains that include amino acid substitutions that increase binding to Fc ⁇ RIIb and/or reduced binding to Fc ⁇ RIIIa as compared to the binding of a corresponding wild-type CH2 or Fc region.
• a variant CH2 or variant Fc domain may include one or more substitutions at position 263, position 266, position 273, and position 305.
• the anti- ⁇ 4 ⁇ 7 antibodies comprise one or more substitutions selected from V263L, V266L, V273C, V273E, V273F, V273L, V273M, V273S, V273Y, V305K, and V305W, relative to the wild-type CH2 domain.
• variant CH2 or variant Fc domains that can afford increased binding to Fc ⁇ RIIb and/or reduced binding to Fc ⁇ RIIIa as compared to the binding of a corresponding wild-type CH2 or Fc region include those found in Vonderheide, et al. Clin.
• Anti- ⁇ 4 ⁇ 7 antibodies that comprise a human IgG4 constant region can comprise the S228P mutation, which has been reported to prevent Fab arm exchange. See, e.g., Silva, JP et al. Journal of Biological Chemistry, 290(9), 5462-5469 (2015).
• the anti- ⁇ 4 ⁇ 7 antibodies include modifications that increase or decrease their binding affinities to the fetal Fc receptor, FcRn, for example, by mutating the immunoglobulin constant region segment at particular regions involved in FcRn interactions.
• an anti- ⁇ 4 ⁇ 7 antibody of the IgG class is mutated such that at least one of amino acid residues 250, 314, and 428 of the heavy chain constant region is substituted alone, or in any combinations thereof.
• the substituting amino acid residue can be any amino acid residue other than threonine, including, but not limited to, alanine, cysteine, aspartic acid, glutamic acid, phenylalanine, glycine, histidine, isoleucine, lysine, leucine, methionine, asparagine, proline, glutamine, arginine, serine, valine, tryptophan, or tyrosine.
• the substituting amino acid residue can be any amino acid residue other than leucine, including, but not limited to, alanine, cysteine, aspartic acid, glutamic acid, phenylalanine, glycine, histidine, isoleucine, lysine, methionine, asparagine, proline, glutamine, arginine, serine, threonine, valine, tryptophan, or tyrosine.
• the substituting amino acid residues can be any amino acid residue other than methionine, including, but not limited to, alanine, cysteine, aspartic acid, glutamic acid, phenylalanine, glycine, histidine, isoleucine, lysine, leucine, asparagine, proline, glutamine, arginine, serine, threonine, valine, tryptophan, or tyrosine.
• An exemplary substitution known to modify Fc effector function is the Fc substitution M428L, which can occur in combination with the Fc substitution T250Q. Additional specific combinations of suitable amino acid substitutions are identified in Table 1 of U.S. Patent No.7,217,797.
• Anti- ⁇ 4 ⁇ 7 antibodies with high affinity for human ⁇ 4 ⁇ 7 may be desirable for therapeutic and diagnostic uses. Accordingly, the present disclosure contemplates antibodies having a high binding affinity to human ⁇ 4 ⁇ 7.
• the anti- ⁇ 4 ⁇ 7 antibodies binds to human ⁇ 4 ⁇ 7 with an affinity of at least about 100 nM, but may exhibit higher affinity, for example, at least about 90 nM, 80 nM, 70 nM, 60 nM, 50 nM, 40 nM, 30 nM, 25 nM, 20 nM, 15 nM, 10 nM, 7 nM, 6 nM, 5 nM, 4 nM, 3 nM, 2 nM, 1 nM, 0.1 nM, 0.01 nM, or even higher.
• the antibodies bind human ⁇ 4 ⁇ 7 with an affinity in the range of about 1 pM to about 10 nM, of about 100 pM to about 10 nM, about 100 pM to about 1 nM, or an affinity ranging between any of the foregoing values.
• Affinity of anti- ⁇ 4 ⁇ 7 antibodies for human ⁇ 4 ⁇ 7 can be determined using techniques well known in the art or described herein, such as for example, but not by way of limitation, ELISA, isothermal titration calorimetry (ITC), surface plasmon resonance, or fluorescent polarization assay.
• Anti- ⁇ 4 ⁇ 7 antibodies generally comprise a heavy chain comprising a variable region (VH) having three complementarity determining regions (“CDRs”) referred to herein (in N ⁇ C order) as VH CDR#1, VH CDR#2, and VH CDR#3, and a light chain comprising a variable region (VL) having three complementarity determining regions referred to herein (in N ⁇ C order) as VL CDR#1, VL CDR#2, and VL CDR#3.
• CDRs complementarity determining regions
• VL variable region having three complementarity determining regions referred to herein (in N ⁇ C order) as VL CDR#1, VL CDR#2, and VL CDR#3.
• anti- ⁇ 4 ⁇ 7 antibodies include these exemplary CDRs and/or VH and/or VL sequences, as well as antibodies that compete for binding human ⁇ 4 ⁇ 7 with such antibodies.
• an anti- ⁇ 4 ⁇ 7 antibody is suitable for administration to humans.
• the anti- ⁇ 4 ⁇ 7 antibody is humanized.
• the amino acid sequences of the CDRs of an anti- ⁇ 4 ⁇ 7 antibody are selected from the sequences of TABLE 4.
• Specific exemplary embodiments of anti- ⁇ 4 ⁇ 7 antibodies with the above CDRs are described herein.
• an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:12, 13, 14, 15, 16, and 17.
• an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:32, 33, 34, 35, 36, and 37. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:42, 43, 44, 45, 46, and 47. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:52, 53, 54, 55, 56, and 57. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:62, 63, 64, 65, 66, and 67.
• an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:72, 73, 74, 75, 76, and 77. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody has the CDRs of SEQ ID NOS:82, 83, 84, 85, 86, and 87. [0065] In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain and a VL chain selected from the sequences of TABLE 5: [0066] In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to SEQ ID NO:10; and a VL chain corresponding in sequence to SEQ ID NO:11.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to any one of SEQ ID NOS:20, or 22-23; and a VL chain corresponding in sequence to any one of SEQ ID NOS:25, or 27-28.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to a variant of SEQ ID NO:21; and a VL chain corresponding in sequence to a variant of SEQ ID NOS:26.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to SEQ ID NO:40; and a VL chain corresponding in sequence to SEQ ID NO:41.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to SEQ ID NO:50; and a VL chain corresponding in sequence to SEQ ID NO:51.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to SEQ ID NO:60; and a VL chain corresponding in sequence to SEQ ID NO:61.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to SEQ ID NO:70; and a VL chain corresponding in sequence to SEQ ID NO:71.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH chain corresponding in sequence to SEQ ID NO:80; and a VL chain corresponding in sequence to SEQ ID NO:81.
• Certain mutations of a VH or VL sequence in an anti- ⁇ 4 ⁇ 7 antibody described herein would be understood by a person of skill to afford anti- ⁇ 4 ⁇ 7 antibodies within the scope of the disclosure. Mutations may include amino acid substitutions, additions, or deletions from a VH or VL sequence as disclosed herein while retaining significant anti- ⁇ 4 ⁇ 7 activity.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH sequence having at least 85%, at least 90%, at least 93%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the VH sequence of any one of the antibodies shown in TABLE 5.
• An anti- ⁇ 4 ⁇ 7 antibody can comprise a VH sequence having up to 8, up to 7, up to 6, up to 5, up to 4, up to 3, or up to 2 mutations compared with the VH sequence of any one of the antibodies shown in TABLE 5.
• an anti- ⁇ 4 ⁇ 7 antibody can comprise a VH sequence having 5 or fewer, 4 or fewer, 3 or fewer, or 2 or fewer mutations compared with the VH sequence of any one of the antibodies shown in TABLE 5.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VH sequence having a single amino acid substitution.
• the mutation in the VH sequence is located in VH CDR#1, VH CDR#2, or VH CDR#3.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VL sequence having at least 85%, at least 90%, at least 93%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% sequence identity to the VL sequence of any one of the antibodies shown in TABLE 5.
• An anti- ⁇ 4 ⁇ 7 antibody can comprise a VL sequence having up to 8, up to 7, up to 6, up to 5, up to 4, up to 3, or up to 2 mutations compared with the VL sequence of any one of the antibodies shown in TABLE 5.
• an anti- ⁇ 4 ⁇ 7 antibody can comprise a VL sequence having 5 or fewer, 4 or fewer, 3 or fewer, or 2 or fewer mutations compared with the VL sequence of any one of the antibodies shown in TABLE 5.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a VL sequence having a single amino acid substitution.
• the mutation in the VL sequence is located in VL CDR#1, VL CDR#2, or VL CDR#3.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain amino acid sequence, and/or a light chain amino acid sequence selected from the sequences of TABLE 6.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:90; and a light chain corresponding in sequence to SEQ ID NO:100.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:92; and a light chain corresponding in sequence to SEQ ID NO:100.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:94; and a light chain corresponding in sequence to SEQ ID NO:100.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:96; and a light chain corresponding in sequence to SEQ ID NO:100.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:98; and a light chain corresponding in sequence to SEQ ID NO:100.
• Post-translational modifications to the sequences of an anti- ⁇ 4 ⁇ 7 antibody may occur, such as cleavage of one or more (e.g., 1, 2, 3, or more) amino acid residues on the C-terminal end of the antibody heavy chain, creating a truncated form.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:91; and a light chain corresponding in sequence to SEQ ID NO:100.
• an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:93; and a light chain corresponding in sequence to SEQ ID NO:100. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:95; and a light chain corresponding in sequence to SEQ ID NO:100. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:97; and a light chain corresponding in sequence to SEQ ID NO:100. In some embodiments, an anti- ⁇ 4 ⁇ 7 antibody comprises a heavy chain corresponding in sequence to SEQ ID NO:99; and a light chain corresponding in sequence to SEQ ID NO:100.
• the anti- ⁇ 4 ⁇ 7 antibodies compete for binding human ⁇ 4 ⁇ 7 in in vitro assays with a reference antibody.
• the anti- ⁇ 4 ⁇ 7 antibodies compete for binding human ⁇ 4 ⁇ 7 on cells expressing human ⁇ 4 ⁇ 7.
• the reference antibody may be any of the anti- ⁇ 4 ⁇ 7 antibodies described herein.
• the reference antibody is an antibody provided for in TABLES 4-6.
• the reference antibody is an antibody provided for in TABLE 8.
• the reference antibody is selected from a research grade antibody generated using amino acid sequences from an anti-human ⁇ 4 ⁇ 7 antibody or an antibody having an amino acid sequence equivalent thereto, such as vedolizumab.
• the anti- ⁇ 4 ⁇ 7 antibodies antagonize, e.g., inhibit, human ⁇ 4 ⁇ 7 heterodimer of one ⁇ 4 (SEQ ID NOS:1-2) and one ⁇ 7 (SEQ ID NOS:3-4).
• ⁇ 4 ⁇ 7 receptor antagonism can occur by a number of mechanisms, for example, by inhibiting binding of ⁇ 4 ⁇ 7 by at least one of its ligands, such as human MAdCAM-1 (SEQ ID NO:5) or human VCAM-1 (SEQ ID NO:6).
• the anti- ⁇ 4 ⁇ 7 antibodies described herein bind to human ⁇ 4 ⁇ 7.
• Cross reactivity of the antibodies for binding to ⁇ 4 ⁇ 7 from other species may offer advantages, such as the ability to test in monkey animal models for biological activity.
• animal model testing may be used to screen anti- ⁇ 4 ⁇ 7 antibodies to select properties related to efficacy, e.g., favorable pharmacokinetics, or those related to safety, e.g., decreased hepatic toxicity.
• the anti- ⁇ 4 ⁇ 7 antibodies bind to cynomolgus ⁇ 4 ⁇ 7 as well as human ⁇ 4 ⁇ 7.
• Assays for competition include, but are not limited to, a radioactive material labeled immunoassay (RIA), an enzyme-linked immunosorbent assay (ELISA), a sandwich ELISA, fluorescence activated cell sorting (FACS) assays, and surface plasmon resonance assays.
• RIA radioactive material labeled immunoassay
• ELISA enzyme-linked immunosorbent assay
• FACS fluorescence activated cell sorting
• surface plasmon resonance assays a detectable label, such as a fluorophore, biotin or an enzymatic (or even radioactive) label to enable subsequent identification.
• cells expressing human ⁇ 4 ⁇ 7 are incubated with unlabeled test antibody, labeled reference antibody is added, and the intensity of the bound label is measured. If the test antibody competes with the labeled reference antibody by binding to an overlapping epitope, the intensity will be decreased relative to a control reaction carried out without test antibody.
• concentration of labeled reference antibody that yields 80% of maximal binding (“conc80%”) under the assay conditions e.g., a specified density of cells
• a competition assay carried out with 10X conc80% of unlabeled test antibody and conc80% of labeled reference antibody is first determined, and a competition assay carried out with 10X conc80% of unlabeled test antibody and conc80% of labeled reference antibody.
• Ki inhibition constant
• IC50 concentration of test antibody that yields a 50% reduction in binding of the reference antibody
• Kd dissociation constant of the reference antibody, a measure of its affinity for human ⁇ 4 ⁇ 7.
• Antibodies that compete with anti- ⁇ 4 ⁇ 7 antibodies disclosed herein can have a Ki from 10 pM to 10 nM under assay conditions described herein.
• a test antibody is considered to compete with a reference antibody if it decreases binding of the reference antibody by at least about 20% or more, for example, by at least about 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or even more, or by a percentage ranging between any of the foregoing values, at a reference antibody concentration that is 80% of maximal binding under the specific assay conditions used, and a test antibody concentration that is 10-fold higher than the reference antibody concentration.
• Another aspect of the present disclosure includes anti- ⁇ 4 ⁇ 7 antibody binding fragments that are capable of specifically binding human ⁇ 4 ⁇ 7.
• these anti- ⁇ 4 ⁇ 7 binding fragments comprise at least one and up to all CDRs of the anti- ⁇ 4 ⁇ 7 antibodies disclosed herein.
• antibody binding fragments include by way of example and not limitation, Fab, Fab', F(ab')2, Fv fragments, single chain Fv fragments and single domain fragments.
• An anti- ⁇ 4 ⁇ 7 antibody or binding fragment thereof may have one or more amino acids inserted into one or more of its CDRs, for example as described in Jung and Plückthun, 1997, Protein Engineering 10:9, 959-966; Yazaki et al., 2004, Protein Eng. Des Sel.17(5):481-9. Epub 2004 Aug 17; and U.S. Pat. Appl. No.2007/0280931.
• the present disclosure encompasses polynucleotide molecules encoding immunoglobulin light and heavy chain genes for anti- ⁇ 4 ⁇ 7 antibodies, vectors comprising such polynucleotides, and host cells capable of producing the anti- ⁇ 4 ⁇ 7 antibodies of the disclosure.
• An anti- ⁇ 4 ⁇ 7 antibody of the disclosure can be prepared by recombinant expression of immunoglobulin light and heavy chain genes in a host cell.
• a host cell is transfected with one or more recombinant expression vectors carrying DNA fragments encoding the immunoglobulin light and heavy chains of the antibody such that the light and heavy chains are expressed in the host cell and, optionally, secreted into the medium in which the host cells are cultured, from which medium the antibodies can be recovered.
• DNA fragments encoding the light and heavy chain variable regions are first obtained. These DNAs can be obtained by amplification and modification of germline DNA or cDNA encoding light and heavy chain variable sequences, for example using the polymerase chain reaction (PCR).
• DNA fragments encoding anti- ⁇ 4 ⁇ 7 antibody-related VH and VL segments are obtained, these DNA fragments can be further manipulated by standard recombinant DNA techniques, for example to convert the variable region genes to full-length antibody chain genes, to Fab fragment genes or to a scFv gene.
• a VL- or VH-encoding DNA fragment is operatively linked to another DNA fragment encoding another protein, such as an antibody constant region or a flexible linker.
• the term “operatively linked,” as used in this context, is intended to mean that the two DNA fragments are joined such that the amino acid sequences encoded by the two DNA fragments remain in-frame.
• the isolated DNA encoding the VH region can be converted to a full-length heavy chain gene by operatively linking the VH-encoding DNA to another DNA molecule encoding heavy chain constant regions (CH1, CH2, CH3 and, optionally, CH4).
• heavy chain constant regions CH1, CH2, CH3 and, optionally, CH4.
• the sequences of human heavy chain constant region genes are known in the art (See, e.g., Kabat, E.A., et al., 1991, Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No.91-3242) and DNA fragments encompassing these regions can be obtained by standard PCR amplification.
• the heavy chain constant region can be an IgG1, IgG2, IgG3, IgG4, IgA, IgE, IgM or IgD constant region, but in certain embodiments is an IgG1 or IgG4.
• the VH-encoding DNA can be operatively linked to another DNA molecule encoding only the heavy chain CH1 constant region.
• the isolated DNA encoding the VL region can be converted to a full-length light chain gene (as well as a Fab light chain gene) by operatively linking the VL-encoding DNA to another DNA molecule encoding the light chain constant region, CL.
• the sequences of human light chain constant region genes are known in the art (See, e.g., Kabat, et al., 1991, Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No.91-3242) and DNA fragments encompassing these regions can be obtained by standard PCR amplification.
• the light chain constant region can be a kappa or lambda constant region, but in certain embodiments is a kappa constant region.
• DNAs encoding partial or full-length light and heavy chains, obtained as described above, are inserted into expression vectors such that the genes are operatively linked to transcriptional and translational control sequences.
• the term “operatively linked” is intended to mean that an antibody gene is ligated into a vector such that transcriptional and translational control sequences within the vector serve their intended function of regulating the transcription and translation of the antibody gene.
• the expression vector and expression control sequences are chosen to be compatible with the expression host cell used.
• the antibody light chain gene and the antibody heavy chain gene can be inserted into separate vectors or, more typically, both genes are inserted into the same expression vector. [0089]
• the antibody genes are inserted into the expression vector by standard methods (e.g., ligation of complementary restriction sites on the antibody gene fragment and vector, or blunt end ligation if no restriction sites are present).
• the expression vector Prior to insertion of the anti- ⁇ 4 ⁇ 7 antibody-related light or heavy chain sequences, the expression vector can already carry antibody constant region sequences.
• one approach to converting the anti- ⁇ 4 ⁇ 7 monoclonal antibody-related VH and VL sequences to full-length antibody genes is to insert them into expression vectors already encoding heavy chain constant and light chain constant regions, respectively, such that the VH segment is operatively linked to the CH segment(s) within the vector and the VL segment is operatively linked to the CL segment within the vector.
• the recombinant expression vector can encode a signal peptide that facilitates secretion of the antibody chain from a host cell.
• the antibody chain gene can be cloned into the vector such that the signal peptide is linked in-frame to the amino terminus of the antibody chain gene.
• the signal peptide can be an immunoglobulin signal peptide or a heterologous signal peptide (i.e., a signal peptide from a non-immunoglobulin protein).
• the recombinant expression vectors of the disclosure carry regulatory sequences that control the expression of the antibody chain genes in a host cell.
• the term “regulatory sequence” is intended to include promoters, enhancers and other expression control elements (e.g., polyadenylation signals) that control the transcription or translation of the antibody chain genes.
• the recombinant expression vectors of the disclosure can carry additional sequences, such as sequences that regulate replication of the vector in host cells (e.g., origins of replication) and selectable marker genes.
• the selectable marker gene facilitates selection of host cells into which the vector has been introduced.
• the expression vector(s) encoding the heavy and light chains is transfected into a host cell by standard techniques.
• transfection are intended to encompass a wide variety of techniques commonly used for the introduction of exogenous DNA into a prokaryotic or eukaryotic host cell, e.g., electroporation, lipofection, calcium-phosphate precipitation, DEAE- dextran transfection and the like.
• prokaryotic or eukaryotic host cells e.g., electroporation, lipofection, calcium-phosphate precipitation, DEAE- dextran transfection and the like.
• expression of antibodies is performed in eukaryotic cells, e.g., mammalian host cells, of optimal secretion of a properly folded and immunologically active antibody.
• Exemplary mammalian host cells for expressing the recombinant antibodies of the disclosure include Chinese Hamster Ovary (CHO cells) (including DHFR- CHO cells, described in Urlaub and Chasin, 1980, Proc. Natl. Acad. Sci. USA 77:4216-4220, used with a DHFR selectable marker, e.g., as described in Kaufman and Sharp, 1982, Mol. Biol.159:601-621), NSO myeloma cells, COS cells and SP2 cells.
• Chinese Hamster Ovary CHO cells
• DHFR-CHO cells described in Urlaub and Chasin, 1980, Proc. Natl. Acad. Sci. USA 77:4216-4220, used with a DHFR selectable marker, e.g., as described in Kaufman and Sharp, 1982, Mol. Biol.159:601-621
• NSO myeloma cells COS cells and SP2 cells.
• the antibodies When recombinant expression vectors encoding antibody genes are introduced into mammalian host cells, the antibodies are produced by culturing the host cells for a period of time sufficient to allow for expression of the antibody in the host cells or secretion of the antibody into the culture medium in which the host cells are grown. Antibodies can be recovered from the culture medium using standard protein purification methods. Host cells can also be used to produce portions of intact antibodies, such as Fab fragments or scFv molecules. It is understood that variations on the above procedure are within the scope of the present disclosure. For example, it can be desirable to transfect a host cell with DNA encoding either the light chain or the heavy chain (but not both) of an anti- ⁇ 4 ⁇ 7 antibody of this disclosure.
• Recombinant DNA technology can also be used to remove some or all of the DNA encoding either or both of the light and heavy chains that is not necessary for binding to human ⁇ 4 ⁇ 7.
• the molecules expressed from such truncated DNA molecules are also encompassed by the antibodies of the disclosure.
• the host cell can be co-transfected with two expression vectors of the disclosure, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide.
• the two vectors can contain identical selectable markers, or they can each contain a separate selectable marker.
• a single vector can be used which encodes both heavy and light chain polypeptides.
• a polynucleotide encoding one or more portions of an anti- ⁇ 4 ⁇ 7 antibody has been obtained, further alterations or mutations can be introduced into the coding sequence, for example to generate polynucleotides encoding antibodies with different CDR sequences, antibodies with reduced affinity to the Fc receptor, or antibodies of different subclasses.
• the anti- ⁇ 4 ⁇ 7 antibodies of the disclosure can also be produced by chemical synthesis or by using a cell-free platform. 6.5.
• a polypeptide of the disclosure can be purified by any method known in the art for purification of a protein.
• the polypeptides may be purified as a monomer or as a dimer, e.g., as a anti- ⁇ 4 ⁇ 7 antibody comprising two polypeptides.
• an anti- ⁇ 4 ⁇ 7 antibody can be further purified. 6.6. Methods of Use 6.6.1.
• anti-human ⁇ 4 ⁇ 7 antibodies demonstrate favorable binding affinity, specificity, and potency towards ⁇ 4 ⁇ 7, as well as favorable binding profiles on primary immune cells, Fc ⁇ R binding, and lack of ADCC and ADCP activity on human ⁇ 4 ⁇ 7+ cells.
• These anti-human ⁇ 4 ⁇ 7 antibodies were shown to bind to ⁇ 4 ⁇ 7 in the virions of different laboratory-grown HIV strains as well as from patients’ HIV samples, and subsequently form immune complexes. These immune complexes can bind to different Fc ⁇ Rs and taken up by a human monocytic cell line THP-1 by phagocytosis.
• the anti- ⁇ 4 ⁇ 7 antibodies, binding fragments, and/or pharmaceutical compositions comprising them may be used therapeutically to induce viral suppression of HIV infection or to reduce viral load in an HIV infected subject by Fc-dependent and Fab-dependent mechanisms.
• viral suppression of HIV infection involves reducing function of the HIV virus and/or reducing replication of the HIV virus.
• the disclosed anti-human ⁇ 4 ⁇ 7 antibodies may be used in a method of treating HIV infection in a subject in need thereof. In some embodiments, the method involves reducing viral load in the subject. In some embodiments, the viral load in the subject is reduced to undetectable levels.
• the subject is a human subject infected with HIV.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody that antagonizes ⁇ 4 ⁇ 7 to provide therapeutic benefit.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody which binds to HIV virions.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody which binds to ⁇ 4 ⁇ 7 in HIV virions to form immune complexes.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody forming immune complexes with HIV virions.
• these immune complexes are taken up by APCs by phagocytosis.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody which blocks the interaction of ⁇ 4 ⁇ 7 with its ligands such as MadCAM-1 and with HIV gp120.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody that blocks the interaction of ⁇ 4 ⁇ 7 with HIV gp120, inhibiting the cell-to-cell HIV transmission.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody that blocks CD4 T cell stimulation mediated by MadCAM-1 or HIV gp120.
• the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody which suppresses HIV replication in the CD4 T cells costimulated by MadCAM-1 or HIV gp120. In some embodiments, the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody which induces viral suppression of HIV replication. In some embodiments, the method involves administering to a human subject having HIV infection an anti- ⁇ 4 ⁇ 7 antibody which induces HIV suppression that is immune-mediated. 6.7. Table of Sequence Descriptions [00103] A correlation of sequences disclosed in the incorporated Sequence Listing and their brief descriptions is shown in TABLE 7. 7.
• Example 1 Generation of Anti-Human ⁇ 4 ⁇ 7 Antibodies 7.1.1.
• Hybridoma screening [00107] Hybridoma-based techniques were utilized to generate an initial panel of mouse anti-human ⁇ 4 ⁇ 7 antibodies. Mice were immunized with HEK293, CHO-K1 or BaF3 recombinant cells expressing human ⁇ 4 ⁇ 7 in addition to adjuvant. The selection of candidate hybridoma derived antibodies was based on criteria of TABLE 9: [00108] A panel of functional hybridoma mAbs was identified from this screen, with all candidates displaying a favorable profile.
• Purified antibodies were characterized through binding and functional assays to determine isoform and species cross-reactivity. Binding screening [00110] Purified antibodies were characterized for isoform and species cross-reactivity by FACS with BaF3-h ⁇ 4 ⁇ 7, BaF3-h ⁇ E ⁇ 7, BaF3-c ⁇ E ⁇ 7, BaF3, CHOK1-c ⁇ 4 ⁇ 7, CHOK1-m ⁇ 4 ⁇ 7 and CHOK1-h ⁇ 4 ⁇ 1 cell lines at a concentration of 1 ⁇ g/ml. The FACS profiles, including that of exemplary mAb Ab-m1, is summarized in TABLE 10. Functional validation [00111] Purified antibody was characterized by adhesion assay to MadCAM-1 in HuT78 cells.
• Ab-m1 showed potential blocking potency in the MadCAM-1 assay and was therefore functionally validated. Data from three independent experiments for Ab-m1 is summarized in TABLE 11. Representative data is shown in FIG.1. Functional characterization [00112] Further functional characterization of Ab-m1 was performed using an adhesion assay to MadCAM-1 in CHOK1-c ⁇ 4 ⁇ 7, to check for cyno cross-reactivity. The adhesion assay data in CHOK1-c ⁇ 4 ⁇ 7 is summarized in TABLE 11 above. Representative data is shown in FIG.2. [00113] To determine the affinity of Ab-m1 binding to human ⁇ 4 ⁇ 7, FACS-based titrations were performed in BaF3-h ⁇ 4 ⁇ 7.
• EC50 was determined, as summarized in TABLE 12.
• Epitope binning was performed by competitive FACS using comparator antibodies conjugated with Alexa488 fluorophore in the presence of 50x excess of non-labeled Abs indicated in the TABLE 13.
• Ab-m1 was characterized as belonging to a vedolizumab (Ab-Vedo) like group based on the percentage of binding inhibition of Alexa488-labeled Abs by the non-labeled Abs (TABLE 13).
• Candidate Profiling [00115] The affinity of mAbs binding to human ⁇ 4 ⁇ 7 was confirmed in primary human CD4+memory T cells.
• Antibody VH and VL fragments were separately amplified from their hybridoma total RNA by RT-PCR using mouse Ig primer set (Novagen, 69831-3). Positive PCR products of appropriate size were inserted to T-vector for sequencing and identification of VH and VL regions (TABLE 14). Full length antibody sequences were built using combinations of VH/VL sequences together with theoretical constant region sequences. [00118] After primer designing, VL/VHs were individually amplified and cloned into expression vectors to make chimeric antibody constructs via homologous recombination. The amino acid sequences of CDRs in VH and VL are shown in TABLE 14.
• Chimeric antibodies were produced by transient transfection in HEK293 cells. After expression, proteins were purified. A high percentage monomer for the chimeric antibodies was confirmed by SEC-HPLC.
• Ab-c1 is a chimeric antibody having Ab-m1’s variable regions and human IgG1/k constant regions. The affinity of Ab-c1 binding to human primary CD4+CD45RO+ T cells was determined by FACS with the binding EC50 value of 3.9 pM from one representative human whole blood (shown in FIG.4 and TABLE 15). The ability of Ab-c1 to block ⁇ 4 ⁇ 7 integrin binding to MadCAM-1 was also evaluated in HuT78 cells and CHOK1-c ⁇ 4 ⁇ 7 cells (TABLE 15).
• Purified chimeric antibody Ab-c1 was further characterized by FACS with BaF3-h ⁇ 4 ⁇ 7, BaF3-h ⁇ E ⁇ 7, BaF3-c ⁇ E ⁇ 7, BaF3, CHOK1-c ⁇ 4 ⁇ 7 and CHOK1-h ⁇ 4 ⁇ 1 cell lines at one concentration (1 ⁇ g/ml) to confirm its binding specificity and cynomolgus cross-reactivity.
• the FACS profile of tested chimera is summarized in TABLE 16.
• HuT78 was used to investigate whether chimeric Ab-c1 was capable of blocking MadCAM-1 mediated adhesion to h ⁇ 4 ⁇ 7 integrin. As shown in TABLE 17, Ab-c1 demonstrates the capacity to inhibit HuT78 cell adhesion to MadCAM-1. [00123] CHOK1-c ⁇ 4 ⁇ 7 was used to investigate whether chimeric antibodies could inhibit MadCAM-1 mediated adhesion to c ⁇ 4 ⁇ 7. As shown in TABLE 17, the Ab-c1 demonstrates the capacity to inhibit CHOK1-c ⁇ 4 ⁇ 7 cell adhesion to MadCAM-1. 7.1.4.
• Antibody Ab-m1 was selected based on binding and potency on both HuT78 cells and human primary CD4+ T memory cells, cyno cross-reactivity, CDR sequence diversity, binding selectivity, sequence liability (i.e. glycosylation), and epitope group. See TABLE 18 for specified characteristics.
• Humanized antibodies were designed from assembling VH and VL fragments in accordance with TABLE 19, and incorporating human IgG1 and kappa constant regions.
• These humanized anti- ⁇ 4 ⁇ 7 mAbs were produced, having good expression, showing >95% monomers by SEC. Identity was confirmed by MS, and stability of the humanized anti- ⁇ 4 ⁇ 7 was measured by DSC.
• Antibody Ab-h1.9 was selected for generating variant VH and VL chains having reduced chemical liability with respect to deamidation, isomerization, oxidation, glycosylation, hydrolysis and cleavage.
• the sequence of Ab-h1.9 VH is: and the sequence of Ab-h1.9 VL is: G wherein selected liability mutation sites are underlined and CDRs bolded.
• Liabilities are present in VH-CDR2, VH-CDR3, and VL-CDR1.
• Two rounds of liability free anti- ⁇ 4 ⁇ 7 clone selection using biotinylated human ⁇ 4 ⁇ 7 extracellular domain protein were performed. Colonies from each library were sequenced, and those having additional liabilities in any CDR were removed. Clones from each library were screened for binding to surface ⁇ 4 ⁇ 7 antigen on yeast by FACS, in comparison to parental Ab-h1.9.
• Liability-engineered clones that were identified as binding similarly as parental (FIG.5) are presented in TABLE 21. These liability-engineered clones along with their variable regions were converted to IgG format.
• Ab-h1.9d-HuIgG1 is human IgG1/kappa type antibody having a HC of SEQ ID NO:90 featuring a canonical human heavy chain constant region, and a LC of SEQ ID NO:100 featuring a canonical human kappa light chain constant region.
• Ab-h1.9d-HuIgG1 may also have a C-terminal lysine truncated HC of SEQ ID NO:91.
• Ab-h1.9d-WT is an IgG1/kappa type antibody having a HC of SEQ ID NO:92 featuring variant CH3 substitutions D356E and L358M, and a LC of SEQ ID NO:100.
• Ab-h1.9d-WT may also have a C-terminal lysine truncated HC of SEQ ID NO:93.
• Ab-h1.9d-LALA is an IgG1/kappa type antibody having a HC of SEQ ID NO:94 featuring variant CH2 substitutions L234A and L235A, and variant CH3 substitutions D356E and L358M, and a LC of SEQ ID NO:100.
• Ab-h1.9d-LALA may also have a C-terminal lysine truncated HC of SEQ ID NO:95.
• Ab-h1.9d-QL is an IgG1/kappa type antibody having a HC of SEQ ID NO:96 featuring variant CH2 substitution T250Q, and variant CH3 substitutions D356E, L358M, and M428L, and a LC of SEQ ID NO:100.
• Ab-h1.9d-QL may also have a C-terminal lysine truncated HC of SEQ ID NO:97.
• Ab-h1.9d-LALA/QL is an IgG1/kappa type antibody having a HC of SEQ ID NO:98 featuring variant CH2 substitution T250Q, and variant CH3 substitutions L234A, L235A, D356E, L358M, and M428L, and a LC of SEQ ID NO:100.
• Ab-h1.9d-LALA/QL may also have a C-terminal lysine truncated HC of SEQ ID NO:99.
• CD4+ and CD8+ T cell subsets were defined as: CD28+CD45RO- na ⁇ ve cells, CD28-CD45RO- terminal effector cells, CD28-CD45RO+ effector memory cells, CD28+CD45RO+CCR7+ central memory cells, and CD28+CD45RO+CCR7- transient memory cells. 7.2.2.
• a panel of six strains (BCF06, CMU08, NL4-3, RU507, YBF30, and IIIB) representing different groups, genetic subtypes, and co-receptor usage (TABLE 23), were produced in activated primary human PBMCs [e.g. activated by OKT3 antibody or phytohemagglutinin (PHA)] in the presence of retinoic acid (RA) to induce the expression of ⁇ 4 ⁇ in the cells.
• activated primary human PBMCs e.g. activated by OKT3 antibody or phytohemagglutinin (PHA)
• RA retinoic acid
• Protein G-conjugated immunomagnetic beads (Dynabeads, Thermo Fisher) were armed with the appropriate antibody and then incubated with virus stock of each HIV strain ( ⁇ 2 ng p24 gag/reaction).
• the armed beads were washed to remove unbound virus particles, and subsequently treated with Triton X-100 to lyse the captured virions for p24 gag quantification.
• the viral titer copies/mL
• Protein G-conjugated immunomagnetic beads armed with 10 ⁇ g of the appropriate antibody were incubated with 400 ⁇ L of patient sera for 2 hours. Beads were then washed to remove unbound virus particles, and RNA of the bound virions was subsequently extracted using Qiagen’s viral RNA extraction kit per manufacturer’s instructions.
• Copy number of the captured virions from patients’ samples was subsequently quantified by digital droplet PCR using primers and probe targeting conserved region in LTR-gag for HIV subtype B.
• Ab-h1.9d-WT was tested in a virion capture assay modified to a 96-well plate format. Serially diluted antibody was added to a prewashed PierceTM Protein G coated plate (Thermo Fisher). After incubation, the plates were washed to remove unbound antibodies. Viral stock of each HIV strain (approximately 2 ng p24 gag) was added to each well and incubated.
• Ab-h1.9d-WT was also able to capture virions from HIV-1 patients’ samples (viral input shown in FIG.7G-1), as indicated by the higher number of HIV RNA copy number in samples reacted with Ab-h1.9d-WT compared to those with the negative control antibody (FIG.7G-2).
• Ab-h1.9d-WT was next tested in a virion capture assay modified to a 96-well plate format to determine its EC50 values for capturing HIV virions. The EC50 values were similar for all the viruses tested and ranged from 0.12 nM (0.019 ⁇ g/mL) to 0.25 nM (0.038 ⁇ g/mL) (TABLE 23).
• HIV IIIB strain could be captured by Ab-h1.9d-WT (FIG.7F) and Ab-Vedo (data not shown) using the bead format assay, but its EC50 values could not be determined by the plate format assay due to the low titer of the viral stock.
• IIIB strain could be captured by Ab-h1.9d-WT and Ab-Vedo in bead assay format, but its EC50 values could not be determined in plate assay format due to the low titer of the viral stock.
• Ab-h1.9d-WT is a potent anti- ⁇ 4 ⁇ 7 antibody that can bind to ⁇ 4 ⁇ 7 on the envelope of virions of all the HIV strains and HIV-1 patients’ samples tested. 7.4.
• Example 4 Binding of Immune complexes of Ab-h1.9d-WT and HIV virions to Fc ⁇ Rs 7.4.1. Materials and Methods [00142] To test if the immune complexes formed by Ab-h1.9d-WT and HIV virions could bind to Fc ⁇ Rs in vitro, the appropriate antibody was first mixed with HIV NL4-3 virus (prepared in activated human PBMC in the presence of RA to induce the expression of ⁇ 4 ⁇ 7) to form immune complexes, which were subsequently incubated with His-tagged Fc ⁇ Rs immobilized on nickel coated plates [for Fc ⁇ RI and Fc ⁇ RIIIa (V158), which have relatively higher affintiy to Ab-h1.9d-WT, as shown in TABLE 32], or biotinylated Fc ⁇ Rs immobilized on neutravidin coated plates to increase the sensitivity of the detction [for Fc ⁇ RIIa (H131 or R131) and Fc ⁇ RIIIa (F158), which have relatively lower affinity to Ab
• HIV virion by itself did not bind to the Fc ⁇ Rs (data not shown), nor immune complexes formed by HIV virions and Ab-h1.9d-LALA, an antibody identical to Ab-h1.9d-WT except it has engineered LALA mutations in its Fc domain to significantly reduce its binding to Fc ⁇ Rs (FIGS.8A-8E).
• the immune complexes formed by HIV virions and Ab-Vedo demonstrated minimal binding to Fc ⁇ Rs (FIGS.8A-8E). This is consistent with the significantly lower binding affinity of Ab-Vedo to different Fc ⁇ Rs than Ab-h1.9d-WT due to the engineered mutations in the Fc domain of Ab-Vedo.
• THP-1 cells were cultured at 37°C, 5% CO2 in RPMI media (Gibco) supplemented with 10% FBS (Sigma).
• NeutrAvidin-labeled fluorescent beads were incubated with biotinylated ⁇ 4 ⁇ 7 for 1-24 h at 4°C. Bead-protein conjugation reactions occurred at a ratio of 2 mg ⁇ 4 ⁇ 7 protein per 1 ml of stock beads, unless otherwise stated. Protein conjugated beads were washed twice with 1x PBS containing 1% BSA (Sigma), then diluted 100x prior to use. Successful conjugation of protein to beads was confirmed in phagocytosis assays comparing anti- ⁇ 4 ⁇ 7 with isotype control conditions.
• Phagocytosis assays using protein coated beads and THP-1 cells were adapted from a previously described study (Ackerman et al 2011). Assays were performed in 96 well plates. Immune complexes were formed by combining 10 ul of prepared ⁇ 4 ⁇ 7 coated beads with 10 ul of the indicated antibody (10 ⁇ g/ml). These were incubated for 1-2 h at 37°C, 5% CO2. THP-1 cells (100,000/well) were then incubated with immune complexes for the indicated amount of time in a final volume of 200 ul.
• phagocytosis score (MFI x percent bead positive cells)/1000. Normalization: Data from 3 independent experiments were normalized and plotted on one graph.
• Imaging Flow Cytometry Internalization of beads were confirmed using imaging flow cytometry. Fixed cells were analyzed on ImagestreamX Mark II imaging flow cytometer (Luminex Corp.) at 40x magnification and medium sensitivity and medium speed setting. Fluorescent beads were imaged using 488 nm (5 mW)/560-595nm (excitation/emission).
• Live/dead stain was imaged using 405 nm (5mW)/ 430-480nm (excitation/emission).
• Brightfield image was collected in channel 2 (camera 1).
• Data was analyzed using IDEAS analysis software v6.1 (Luminex Corp.). Standard gating strategy was used to find appropriate cell populations. Briefly, focused cells were identified using high (>40) gradient RMS (root mean square) for brightfield image sharpness. Single cells were identified by high aspect ratio and low object area of brightfield image. Cellular object area was identified in the brightfield image and 4 pixels were eroded from the cell boundary to define an 'intracellular mask'. Cells with positive fluorescence signal in the intracellular mask were identified as true internalization events.
• THP-1 cells have been reported to phagocytose antibody-fluorescent bead immune complexes in an Fc/Fc ⁇ R-dependent manner (Ackerman et al., 2011). Therefore, THP-1 cells were used to investigate whether Ab-h1.9d-WT mediates phagocytosis of ⁇ 4 ⁇ 7-coated fluorescent beads.
• Cells treated for 3 h with ⁇ 4 ⁇ 7-beads/Ab-h1.9d-WT antibody immune complexes displayed significant uptake of fluorescent beads relevant to Ab-h1.9d-LALA and Ab-Vedo (featuring LALA) by flow cytometry (FIGS.9A-9B). LALA mutations are known to drastically reduce IgG Fc binding to Fc ⁇ Rs.
• VLPs viral like particles
• each well of a high binding flat-bottomed 96-well plate was coated with 50 ⁇ L of ⁇ 4 ⁇ 7+GFP+VLPs at a concentration of 7.5x107 particles/mL in PBS and incubated overnight at 4°C.
• the wells were washed with PBS+1% FBS and blocked with 100 ⁇ L of a superblock solution for 30 min at room temperature (RT).
• each well was incubated with 50 ⁇ L of 4-fold serially diluted primary antibody in PBS+1% FBS for 1 h at RT, followed by washing and incubation with 50 ⁇ L of an HRP-conjugated donkey anti-human IgG-Fc ⁇ -specific secondary antibody in PBS+1% FBS for 1 h at RT.
• TMB substrate was added to each well for color development, and the reaction was stopped by adding 2N H2SO4.
• the optical density (OD) for each well was measured by a plate reader at 450 nm.
• ⁇ 4 ⁇ 7+GFP+VLPs/anti-a4b7 immunocomplex in THP-1 cells 5x104 THP-1 cells were mixed in a flat-bottomed 96-well plate without or with an antibody at the final concentration of 1 ⁇ g/ml and ⁇ 4 ⁇ 7+ GFP+VLPs at the cell-to-particle ratio of 1:100 in 100 ⁇ L volume of RPMI, 10% FBS. The plate was incubated for 16 h at 37°C in a CO2 incubator.
• Cells were then resuspended and transferred to a V-bottom 96-well plate to wash once with 200 ⁇ L of PBS, 2% FBS through centrifugation. Cell pellet was resuspended in 200 ⁇ L of PBS, 0.5% paraformaldehyde and subjected to the determination of percent GFP+ cells by flow cytometry.
• THP-1 cells 0.5x106/mL were pretreated with or without Latrunculin A (Lat A) at a final concentration of 240 nM or with 0.1% DMSO (control) for 2 h at 37°C in a CO2 incubator, followed by the incubation with or without antibody and ⁇ 4 ⁇ 7+GFP+VLPs, as indicated above. 7.6.2.
• VLPs viral like particles generated from mammalian cells have dynamic sizes ranging from 0.1 to 0.2 microns. Thus, they are more similar in size to virions than the fluorescence-labeled beads used in the previous experiments and were utilized as a tool to model the internalization/uptake of ⁇ 4 ⁇ 7+virions/Ab immune complex by THP-1 cells.
• the purified ⁇ 4 ⁇ 7-expressing GFP+VLPs was evaluated for their ability to bind anti- ⁇ 4 ⁇ 7 Abs via ELISA.
• Example 7 Ab-h1.9d-WT Demonstrated No Neutralization Activity against HIV 7.7.1.
• Some Abs that can bind to HIV virions e.g. HIV broad neutralizing antibodies, are capable of blocking viral infection.
• HIV Neutralization Assay [00159] HIV virus (prepared with PHA and RA) corresponding to approximately 150,000 RLU (previously determined by viral titration on TZM-bl cells) was preincubated with serially diluted antibodies. TZM-bl cells containing DEAE-dextran were added to the mixture containing pre-incubated HIV and antibodies, and then incubated for 48 hours at 37°C. The cells were treated with Bright-Glo (Promega), and luciferase signal was measured. 7.7.2.
• Example 8 Inhibition of the Interaction of ⁇ 4 ⁇ 7 with HIV gp120 by Different Antibodies 7.8.1. Materials and Methods [00162] The interaction between ⁇ 4 ⁇ 7 and HIV gp120 has been reported to activate LFA-1, potentially facilitating cell-to-cell transmission of HIV (Arthos et al. Nat Immunol 2008).
• an ⁇ 4 ⁇ 7/gp120 binding assay was set up using ⁇ 4 ⁇ 7-expressing RPMI 8866 cells binding to a HIV gp120-V2 peptide immobilized on a plate according to a published method (Peachman et al., PloS One). NeutrAvidin coated high capacity 96-well plate (Thermo Fisher) was coated with biotinylated HIV gp120-V2 WT or gp120-V2 control peptide (TABLE 24).
• the sequences of the two biotinylated peptides were identical except four amino acids reported to mediate binding between ⁇ 4 ⁇ 7 and gp120 were mutated in the control peptide. [00163] * Amino acids different between the two peptides are shown in bold. [00164] Before adding the antibody-cell mixture, the peptide-coated plates were washed to remove the unbound peptides. To generate the antibody-cell mixture stock, RPMI 8866 cells (8 x 106 cells/mL) were resuspended in a cold blocking buffer supplemented with MnCl2 at a final concentration of 2 mM to activate the conformation of ⁇ 4 ⁇ 7.
• Ab-Vedo had an IC50 value (0.042 ⁇ 0.023 ⁇ g/mL) higher than that of Ab-h1.9d-WT when tested in the same assay, indicating that it was less potent than Ab-h1.9d-WT in blocking this interaction (FIG 12B).
• IC50 value 0.042 ⁇ 0.023 ⁇ g/mL
• Ab-h1.9d-WT can effectively disrupt the interaction of ⁇ 4 ⁇ 7 with gp120, potentially inhibiting the cell-to-cell viral spread.
• Ab-h1.9d-WT blocked the binding of RPMI 8866 cells to the HIV gp120-V2 WT peptide with an IC50 value of 0.022 ⁇ 0.016 ⁇ g/mL (FIG.12B).
• HuT78 cells expressing endogenous ⁇ 4 ⁇ 7 were cultured in IMDM media containing 20% FBS, Penicillin (50 units/mL)/Streptomycin (50 ⁇ g/mL). HuT78 cells were harvested, washed 1x and resuspended in DPBS at 1.5 x 106 cells/mL. Cells (7.5 x 104 in 50 ⁇ L) were added to each well of MSD high binding plate(s).
• Fetal bovine serum at 6.7% (diluted in DPBS) was added and plate(s) were incubated at 37°C for one hour.
• Supernatant was removed and 25 ⁇ L of titrated Ab-h1.9d-WT antibody or isotype control prepared through 1:4 fold 8-point dilutions ranging from 1.5 ⁇ g/mL to 0.000091 ⁇ g/mL (in DPBS buffer containing 5% FBS, and 1mM MnCl2) were added to each well and then plates were incubated at 37°C for one hour.
• Plates were washed 2x with DPBS and 25 ⁇ L of goat anti-human Ab sulfo tag at a 1:500 dilution in 5% FBS/DPBS/1 mM MnCl2 was added to each well, followed by incubation at 37°C for 30 minutes. Cells were washed twice with DPBS and then 150 ⁇ L of 2x MSD read buffer T was added to each well. Plate(s) were read on Sector Imager 6000 reader and binding curves and binding EC50 values were generated using GraphPad Prism 7.0 software.
• CD4+ na ⁇ ve CD4+CD45RA+CCR7+ cells
• CD4+ memory CD4+CD45RA-cells
• CD8+ na ⁇ ve CD8+CD45RA+CCR7+ cells
• CD8+ memory CD8+CD45RA-cells a.
• Human PBMC 3 donors b.
• Cynomolgus PBMC 5 donors [00173] The average binding EC50 values range from 10 to165 pM on all the T cell subsets evaluated. Ab-h1.9d-WT binds very similarly to human and cynomolgus CD4+ and CD8+ T cells or their subsets , since the mean EC50 values for each corresponding cell-type vary only by 2- to 3-fold between these two species. [00174] The binding of Ab-h1.9d-WT to human and cynomolgus monkey CD4+ and CD8+ T subsets was also analyzed to compare percentage of Ab-h1.9d-WT bound T cell subsets, shown in FIG.13.
• Recombinant cells expressing individual human and cynomolgus monkey heterodimeric integrin ⁇ 4 ⁇ 7, ⁇ 4 ⁇ 1 and ⁇ E ⁇ 7 enabled the evaluation of binding specificity of Ab-h1.9d-WT.
• Ab-h1.9d-WT was also evaluated for non-specific binding to human epithelial HEK293 cells.
• Integrin Binding Specificity Assay [00179] Various human and cynomolgus integrins ( ⁇ 4 ⁇ 7, ⁇ 4 ⁇ 1 or ⁇ E ⁇ 7) expressing CHO-K1 or BAF3 cells, except for cynomolgus ⁇ 4 ⁇ 1 were harvested, counted and prepared in FACS buffer (DPBS, w/o Ca+2/Mg+2, 1% BSA) at a density of 1.5 x 106 cells per milliliter. A 100 ⁇ L containing 1.5 x 105 cells was added to each well of a 96-well U-bottom plate and centrifuged to remove supernatant.
• FACS buffer DPBS, w/o Ca+2/Mg+2, 1% BSA
• CHO-K1 cells expressing cynomolgus ⁇ 4 ⁇ 1 an antibody staining cocktail containing 25 ⁇ L of CD29-APC and CD49d-BV421 mixture each at 1:25 dilution, and 25 ⁇ L of Ab-h1.9d-WT, assay control or isotype control prepared by 1:5 fold serial dilutions in FACS buffer were added to each well of a 96-well U-bottom to reconstitute cynomolgus ⁇ 4 ⁇ 1 cell pellets.
• HEK293G cells were cultured in complete DMEM (DMEM + 10% FBS + 1% Na Pyruvate). Cells were harvested using non-enzymatic dissociation buffer (Gibco, Cat 13151-014), counted and resuspended at 1.5 x 106 cells/mL in FACS buffer (2% BSA/PBS). To each well of a 96-well U-bottom plate, 7.5 x 104 cells were dispersed.
• Ab-h1.9d-WT has binding specificity for both human and cynomolgus ⁇ 4 ⁇ 7.
• Non-Specific HEK293 Cell Binding [00183] Ab-h1.9d-WT was also evaluated for non-specific binding to human epithelial HEK293 cells. As demonstrated in FIG.15, Ab-h1.9d-WT did not exhibit any non-specific binding to HEK293 cells at high concentration (100 ⁇ g/mL), comparable to a control antibody, while a positive control mAb displayed strong non-specific binding to these cells. 7.11.
• Example 11 Rabbit and Rodent Binding Cross-Reactivity of Ab-h1.9d-WT 7.11.1.
• PBMCs Peripheral blood mononuclear cells
• Frozen PBMCs were thawed, counted and reconstituted at 1 x 106 cells/mL in RPMI media + 10% FBS and 100 ⁇ L of cells were plated at 1 x 105 cells per well. The plated cells were then incubated at 4°C or placed in 37°C, 5% CO2 incubator for 30 minutes to acclimate plate temperature. Human PBMCs were pre-incubated with 100 ⁇ L of 2x conc. unlabeled Ab-h1.9d-WT antibody at 1.25 ⁇ g/mL (final 0.625 ⁇ g/mL) for one hour at 4°C.
• Cells were centrifuged, washed and resuspended in 200 ⁇ L of RPMI + 10% FBS and incubated at 4°C or 37°C, 5% CO2 for 18 hours. Following incubation, cells were washed 2x with FACS buffer (PBS + 1% FBS), and then stained with CD4+ (Biolegend 317410), CD8+ (Biolegend 344710), and CD45RA (Biolegend 304130) with or without the AF647 labeled noncompeting anti- ⁇ 7 antibody for 30 minutes. Cell fluorescence was acquired by flow cytometry (LSR-Fortessa).
• Example 13 MAdCAM-1 Ligand Blockade By Ab-h1.9d-WT 7.13.1. Materials and Methods MAdCAM-1 Ligand Blockade Assay [00192] For FACS-based assay, HuT78 cells or human PBMCs were harvested, washed 1x with DPBS, adjusted to a density of 1.5 x 106 cells/mL and resuspended in FACS buffer (DPBS, w/o Ca+2/Mg+2, 1% BSA/1mM MnCl2). Cells at 1 x 105 (100 ⁇ L)/well were dispensed into a 96-well U-bottom plate and centrifuged to remove supernatant.
• DPBS w/o Ca+2/Mg+2, 1% BSA/1mM MnCl2
• Flow data (FCS 3.0 files) was analyzed using FlowJo Version 10 software, binding curves and inhibition IC50 values were generated using GraphPad Prism 7.0 software.
• 96-well flat-bottom plates (Greiner, Cat 655077) were coated with 100 ⁇ L of 20 ⁇ g/mL MAdCAM-1 hFc or isotype control (final concentration 2 ⁇ g/well) using coating buffer (PBS w/o Ca+2/Mg+2, 0.1% BSA) at 4oC for overnight.
• plate(s) were washed 2x with 200 ⁇ L of wash buffer (PBS w/Ca+2/Mg+2, 0.1% BSA) then blocked at 37°C for one hour using blocking buffer (PBS w/Ca+2/Mg+2, 1% BSA).
• wash buffer PBS w/Ca+2/Mg+2, 0.1% BSA
• blocking buffer PBS w/Ca+2/Mg+2, 1% BSA.
• dilutions of Ab-h1.9d-WT and isotype control were prepared and HuT78 cells harvested.
• a 2x initial concentration was prepared at 5 ⁇ g/mL and then serial 1:4.57-point dilutions (final concentrations ranging from 2.5 to 0.0003 ⁇ g/mL) were performed in duplicate or triplicate.
• the cells were counted, washed and resuspended at a 2 x 106 cells/mL in assay media (IMDM, 1% BSA) to which a final concentration of 2 mM MnCl2 was added and 100,000 cells were dispensed to each well of 96-well plates.
• IMDM assay media
• the diluted antibodies were then added to the cells and the mixture was incubated at 37 ⁇ C, 5% CO2 for 30 minutes.
• the blocking solution from MAdCAM-1 hFc coated plates was decanted and 100 ⁇ L/well of pre-incubated HuT78 cells and mAb mixture was distributed into each well of MAdCAM-1 hFc coated plates.
• CD4+ T cell activation and proliferation assay [00199] 96-well flat bottom tissue culture plates were coated with 200 ng/well anti-CD3 antibody (Biolegend) in HBSS at 4°C overnight. On the following day, the anti-CD3 coated plates were washed once with HBSS and incubated with 200 ng/well MAdCAM-1 (R&D systems) for 1 hour at 37°C. Following the incubation, the plates were washed once with 200 ul of HBSS and 50,000 CD4+ T cells were added to each well in the presence or absence of 1 ⁇ g/ml testing antibodies.
• MAdCAM-1-mediateed gut-homing of ⁇ 4 ⁇ 7+CD4+ T cells plays a central role in HIV infection of GALT (gut-associated lymphoid tissues). In addition to this role, MAdCAM-1 has also been reported to deliver a co-stimulation signal to human primary CD4+ T cells and promote HIV replication (Nawaz et. al., Mucosal Immunology 2018).
• VCAM-1 Ligand Blockade Assay Plates (96-well flat-bottom, Greiner, Cat 655077) were coated on Day 1 with 100 ⁇ L of 20 ⁇ g/mL VCAM-1 hFc or isotype control (final concentration 2 ⁇ g/well) using coating buffer (PBS w/o Ca+2Mg+2, 0.1% BSA) at o / 4 C overnight. On Day 2, plate(s) were washed 3x with 200 ⁇ L of wash buffer (PBS w/ Ca+2 +2 /Mg , 0.1% BSA) then blocked at 37°C for 1h or longer using blocking buffer (PBS w/ Ca+2 +2 /Mg , 1% BSA).
• coating buffer PBS w/o Ca+2Mg+2, 0.1% BSA
• HuT78 cells were harvested.
• a 2x initial concentration of antibody was prepared at 4 ⁇ g/mL and then 1:4 fold serial dilutions in assay medium (IMDM, 1% BSA) were made.
• HuT78 cells were counted, washed and resuspended at a 2 x 106 cells/mL in assay medium to which a final concentration of 2 mM MnCl2 was added and 100,000 cells were dispensed to each well of 96-well plates.
• the diluted antibodies were then added to the cells and the mixture was incubated at 37 ⁇ C, 5% CO2 for 30 minutes.
• VCAM-1 hFc coated plates The blocking solution from VCAM-1 hFc coated plates was decanted, and 100 ⁇ L of pre-incubated HuT78 cells and mAb mixture were distributed into each well of VCAM-1 hFc coated plates. Plate(s) were incubated at 37°C, 5% CO2 for 30 minutes and then were washed gently 3x using washing buffer. Post-washing, 100 ⁇ L/well of a mixture (containing 50 ⁇ L of CellTiter-Glo reagent and 50 ⁇ L assay medium) was added to each well. Plate(s) were placed on orbital shaker for two minutes then incubated at RT for 10 minutes. Plate luminescence was read on luminescence plate reader (Topcount, Perkin Elmer).
• Luminescence signals were plotted to determine IC50 values in GraphPad Prism 7.0 using 4-parameter curve fit analysis. 7.15.2. Results
• ⁇ 4 ⁇ 7 can also bind to VCAM-1 expressed on endothelial cells (TABLE 30).
• Natalizumab Ab-nata an anti- ⁇ 4 mAb, capable of blocking ⁇ 4 ⁇ 7 and ⁇ 4 ⁇ 1 binding to VCAM-1 caused progressive multifocal leukoencephalopathy (PML) due to its blockade of trafficking of circulating lymphocytes to the brain.
• PML progressive multifocal leukoencephalopathy
• Example 16 Ab-h1.9d-WT Binding Affinity to Human and Cynomolgus Monkey Fc ⁇ RI, Fc ⁇ RIIa, Fc ⁇ RIIb, Fc ⁇ RIIIa and FcRn 7.16.1.
• Materials and Methods [00207] Ab-h1.9d-WT was evaluated by BIAcore for its binding affinity to a panel of recombinant human and cynomolgus monkey Fc ⁇ R extracellular domain (ECD) proteins in comparison to antibody IgG1 control, Trastuzumab. [00208] Ab-h1.9d-WT binding to human Fc ⁇ Rs was also evaluated via flow cytometry by using CHO-K1 cells engineered to express various cell surface human Fc ⁇ Rs.
• ECD extracellular domain
• Binding of Ab-h1.9d-WT to human and cynomolgus FcRn was evaluated by BIAcore at pH 6.0 and pH 7.4 using recombinant human and cynomolgus FcRn ECD protein (TABLE 31).
• N 3 Human and Cynomolgus Monkey Fc ⁇ R1, Fc ⁇ RIIa, Fc ⁇ RIIb, and Fc ⁇ RIIIa Surface Plasmon Resonance (SPR) Binding Assay
• Binding kinetics of Ab-h1.9d-WT for His tagged human Fc ⁇ Rs were determined by SPR measurements made on Biacore T200 instrument (GE Healthcare) at 25 ⁇ C using anti-His capture.
• Analyte concentrations ranged from 0.78 to 200 nM for hu and cynomolgus Fc ⁇ RI cynomolgus Fc ⁇ RIII, 46.9 to 12000 nM for hu and cynomolgus Fc ⁇ RII and 7.8 to 4000 nM for Fc ⁇ RIII (2-fold serial dilution).
• a buffer only injection was included for double referencing.
• Bound Fc ⁇ Rs dissociation was monitored for one to five minutes (one minute for Fc ⁇ RIIb, Fc ⁇ RIIa, three minutes for Fc ⁇ RIIIa and five minutes for Fc ⁇ RI).
• CHO-K1 expressing hFc ⁇ R cells were grown in 150 cm2 culture flasks and loaded with a specific amount of fluorophore, CellTrace CFSETM and CellTrace VioletTM (Molecular Probes) according to manufacturer instructions to establish a unique fluorescence footprint (barcoding method) for each line.
• N 3 [00215] While both Ab-h1.9d-WT and trastuzumab exhibited binding to both cynomolgus Fc ⁇ RI and cynomolgus Fc ⁇ RIII, no measurable binding parameters could be determined for cynomolgus Fc ⁇ RIIa and cynomolgus Fc ⁇ RII receptors likely due to their weak binding to these receptors.
• Target ⁇ 4 ⁇ 7 expressing RPMI8866 cells were grown and maintained in culture media (RPMI1640, 2 mM L-glutamine and 10% FBS). Log phase cells were harvested, counted, washed and resuspended at a 6 x 105 cells/mL stock in assay medium (RPMI1640 containing low IgG serum) and placed at 37°C, 5% CO2 until ready for use.
• Ab-h1.9d-WT and control mAbs were prepared at a 3x initial concentration of 30 ⁇ g/mL then serially (2 pt.) diluted at 1:100 in Costar 3956 dilution plates.
• Antibodies 25 ⁇ L were mixed with an equal volume of target RPMI8866 cells (25 ⁇ L) in duplicate according to plate layout(s).
• Effector Jurkat cells stably expressing the human Fc ⁇ RIIIa V158 variant and an NFAT response element driving expression of firefly luciferase from PromegaTM were thawed rapidly and adjusted to 3 x 106 cells/mL in assay media.
• Jurkat effectors 25 ⁇ L were then added to the 96-well assay plates containing RPMI8866 targets and antibody.
• Control wells included media alone, Effector (E) and Target (T) alone, E + T, E + mAb (30 ⁇ g /mL) or T + mAb (30 ⁇ g/mL). All wells were adjusted to 75 ⁇ L per well according to plate layout(s). The final cell numbers were 75,000 Jurkat effector cells/well and 15,000 RPMI8866 target cells/well corresponding to an E:T ratio of 5:1.
• the final antibody concentrations per well were 67 nM (10 ⁇ g/mL), 0.67 nM (0.1 ⁇ g/mL) and 0.0067 nM (0.001 ⁇ g/mL). Plates were incubated at 37°C, 5% CO2 for six hours during which Bio-Glo TM buffer and substrate (Cat 7110) was equilibrated to RT prior to use. At the end of the incubation, Bio-Glo substrate was reconstituted with buffer to form enzyme/substrate solution (Bio-Glo reagent). An equal volume of 75 ⁇ L/well Bio-Glo was added to all wells. Plates were then incubated at RT for 10 minutes.
• Target ⁇ 4 ⁇ 7 expressing RPMI8866 cells were grown and maintained in culture media (RPMI1640, 2 mM L-glutamine and 10% FBS). Log phase cells were harvested, counted, washed and resuspended at a 2 x 105 cells/mL stock in assay medium (RPMI1640 containing low IgG serum) and placed at 37°C, 5% CO2 until ready for use.
• Ab-h1.9d-WT and control mAbs were prepared at a 3x initial concentration of 30 ⁇ g/mL then serially (2 pt.) diluted at 1:100 in Costar 3956 dilution plates.
• Antibodies 25 ⁇ L were mixed with an equal volume of target cells (25 ⁇ L) in duplicate according to plate layout(s).
• Effector Jurkat cells stably expressing the human Fc ⁇ RIIa H131 variant and an NFAT response element driving expression of firefly luciferase from PromegaTM were thawed rapidly and adjusted to 1 x 106 cells/mL in assay media.
• Jurkat effectors 25 ⁇ L were then added to the 96-well assay plates containing RPMI8866 targets and antibody.
• Control wells included media alone, Effector (E) and Target (T) alone, E + T, E + mAb (30 ⁇ g /mL) or T + mAb (30 ⁇ g/mL). All wells were adjusted to 75 ⁇ L per well according to plate layout(s). The final cell numbers were 25,000 Jurkat effector cells/well and 5,000 target cells/well corresponding to an E:T ratio of 5:1.
• the final antibody concentrations per well were 67 nM (10 ⁇ g/mL), 0.67 nM (0.1 ⁇ g/mL) and 0.0067 nM (0.001 ⁇ g/mL).
• Bio-Glo TM buffer and substrate (Cat 7110) was equilibrated to RT prior to use.
• Bio-Glo substrate was reconstituted with buffer to form enzyme/substrate solution (Bio-Glo reagent).
• An equal volume of 75 ⁇ L/well Bio-Glo was added to all wells. Plates were then incubated at RT for 10 minutes. Plate luminescence was read on a luminescence plate reader (Topcount, Perkin Elmer). Luminescence signal was plotted as RLU using GraphPad Prism 7.0 software.
• RPMI8866 cells were grown and maintained in culture media (RPMI1640, 2 mM L-glutamine and 10% FBS). Log phase cells were harvested, counted, washed and resuspended in assay medium (RPMI1640 minus phenol red, Cat 11835-030) at a 4 x 106 cells/mL stock and placed at 37°C, 5% CO2 until ready for use. Ab-h1.9d-WT and control mAbs were prepared at a 3x initial concentration of 45 ⁇ g/mL and 0.45 ⁇ g/mL in Costar 3956 dilution plates.
• Human donor serum (HMN19169 and HMN19170) was thawed using cold running water and immediately placed on ice. Antibodies, controls (25 ⁇ L) and media were added to assay plates (Costar 3599). Donor serum (25 ⁇ L each), the target cells (25 ⁇ L) and diluted mAbs (25 ⁇ L) were mixed at the final volume of 75 ⁇ L per well containing 33% serum complement, 1 x 105 cells and 15 ⁇ g/mL mAb. Plate(s) were then incubated at 37°C, 5% CO2 for two hours.
• Target ⁇ 4 ⁇ 7 expressing HuT78 cells were harvested, washed 2x with PBS (w/o Ca+2/Mg+2, 1% BSA) and resuspended in PBS at 1 x 107 cells/mL then labeled with CFSE at RT for eight minutes at a final concentration of 2 ⁇ M. After incubation, FBS was added at a 10% final concentration to quench labeling. Cells were washed 2x with RPMI + 10% FBS media and then CFSE labeled HuT78 cells were incubated with 100 ⁇ L of a 2x conc.
• NK and HuT78 cell mixtures were washed 2x with PBS and resuspended at 1 x 106 cells/mL with azide-free and protein-free PBS containing 1 ⁇ L of FVD dye/mL and incubated at RT for 20 minutes.
• Cells were washed 2x with FACS buffer, resuspended in 200 ⁇ L of 0.5% PFA in PBS and plate was read on FACS (Canto II, BD).
• Flow data FCS 3.0 files
• All HuT78 target cells live and dead were gated to determine % dead targets within the total target cell population.
• % ADCC 100 x [% dead targets in (E + T +Ab) mix - % dead targets in (E + T) mix] / [100 - % dead targets in (E +T) mix].
• Percentage ADCC was graphed using GraphPad Prism 7.0 software. 7.17.2. Results ADCC Reporter Activity, ADCP Reporter Activity, and CDC [00224] As expected, Ab-Ritu demonstrated strong concentration-dependent in vitro ADCC and ADCP activity; however, Ab-h1.9d-WT and isotype control did not show any of these activities at three concentrations (10, 0.1, 0.001 ⁇ g/mL) tested (FIGS.20A and 20B).
• Ab-h1.9d-WT did not induce any in vitro cell cytotoxicity at 10 ⁇ g/mL (67 nM) concentration when the assay was performed using NK effector cells isolated from two different donors with Fc ⁇ RIIIa V158 genotype (FIG.22).
• Ab-h1.9d-WT binds to human Fc ⁇ Rs as shown above (Example 12), it does not induce undesired Fc-mediated ADCC, ADCP and CDC activities against uninfected ⁇ 4 ⁇ 7+ cells in vitro. 7.18.
• Example 18 Homology modeling of Ab-h1.9d-WT binding site on the target 7.18.1.
• Ab-h1.9d-WT is a potent anti- ⁇ 4 ⁇ 7 antibody that can bind to ⁇ 4 ⁇ 7 on the envelope of virions of all laboratory grown HIV strains and HIV patients’ samples tested.
• the immune complexes formed by Ab-h1.9d-WT and HIV virions could bind to different Fc ⁇ Rs through its Fc domain, a step that could enable it to be taken up by APCs by phagocytosis to induce the proposed "vaccination effect" for HIV control.
• Ab-h1.9d-WT binds HIV virions, it does not neutralize HIV infection, which is consistent with the notion that ⁇ 4 ⁇ 7 is not a viral receptor on host cells.
• Ab-h1.9d-WT By targeting ⁇ 4 ⁇ 7 integrin, a host protein, on the HIV viral envelope, Ab-h1.9d-WT may exhibit a higher barrier to resistance compared to other antibodies targeting the HIV virally encoded gp120/41 glycoprotein in the viral envelope such as HIV broadly neutralizing antibodies. [00231] Ab-h1.9d-WT can disrupt the interaction between ⁇ 4 ⁇ 7 and its ligands such as MadCAM-1 or HIV gp120 through an Fab-dependent mechanism, inhibiting the CD4 T cell co-stimulation mediated by MadCAM-1 and gp120, and potentially inhibiting HIV replication in these stimulated cells.
• Ab-h1.9d-WT can potentially inhibit cell-to-cell HIV viral transmission by an Fab-mediated mechanism through its ability to disrupt the interaction between ⁇ 4 ⁇ 7 and HIV gp120.
• Ab-Vedo demonstrated lower activity in capturing HIV virions and disruption of the interaction between ⁇ 4 ⁇ 7 and HIV gp120.
• Ab-Vedo was capable of binding HIV virions to form immune complexes, these immune complexes bound to Fc ⁇ Rs with a much lower affinity than complexes formed by Ab-h1.9d-WT due to the engineered mutations in Ab-Vedo Fc domain to reduce Fc functions.
• Vedolizumab demonstrated modest efficacy in two clinical studies for HIV studies. This efficacy can be attributable to Fab-dependent (e.g., antibody binding to ⁇ 4 ⁇ 7 disrupting its interactions with its ligands such as MAdCAM-1and HIV gp120, thus inhibiting the CD4 T cell co-stimulation and the HIV replication in these stimulated cells, and cell-to-cell viral transmission), but not Fc-dependent mechanism of actions.
• the reduced binding affinity of vedolizumab to Fc ⁇ Rs renders it deficient in mediating Fc-dependent mechanisms.
• Ab-h1.9d-WT which has intact Fc functionality, may be positively differentiated from vedolizumab for its ability to induce sustained HIV viral suppression through its Fc-dependent mechanisms of action.
• the binding of the immune complexes formed by HIV virions and anti- ⁇ 4 ⁇ 7 antibodies (with intact Fc domain) to Fc ⁇ Rs on APCs is required to induce new and durable HIV-specific immune responses (vaccination effect).
• Ab-h1.9d-WT can mediate the uptake of ⁇ 4 ⁇ 7-coated beads or ⁇ 4 ⁇ 7-expressing GFP+VLPs (viral like particles) in an ⁇ 4 ⁇ 7- and Fc-dependent manner in THP-1 cells.
• Ab-h1.9d-WT demonstrates activity in several proposed mechanisms of action for HIV control, including those that are Fc-dependent or Fab-dependent. Therefore, Ab-h1.9d-WT is predicted to be a more potent agent than vedolizumab for sustained reduction of HIV viral load due to its higher affinity to ⁇ 4 ⁇ 7 and its intact Fc functionality to induce “vaccination effect”.
• Key attributes of Ab-h1.9d-WT from a comprehensive in vitro characterization are summarized in TABLE 35.
• Ab-h1.9d-WT is an antagonistic anti- ⁇ 4 ⁇ 7 human IgG1/k monoclonal antibody that binds to ⁇ 4 ⁇ 7 but not to ⁇ 4 ⁇ 1 and minimally to ⁇ E ⁇ 7.
• Ab-h1.9d-WT binds strongly to both human and cynomolgus monkey CD4+ and CD8+ T subsets, demonstrating excellent cynomolgus binding cross- reactivity. However, Ab-h1.9d-WT does not bind to rodent PBMCs. Ab-h1.9d-WT selectively blocks ⁇ 4 ⁇ 7/MAdCAM-1 interaction with high potency without inhibiting ⁇ 4 ⁇ 7/VCAM-1 interaction. Ab-h1.9d-WT is capable of blocking MAdCAM-1-mediated co-stimulation of human primary CD4+ T cells.
• Ab-h1.9d-WT binds to human Fc ⁇ Rs (a necessary prerequisite for Fc-mediated "vaccination effect" in vivo) without triggering ADCC, ADCP and CDC activities against uninfected ⁇ 4 ⁇ 7+ cells in vitro. Lack of in vitro Fc effector activities by Ab-h1.9d-WT may be partly explained by the reduced cell surface ⁇ 4 ⁇ 7 expression due to antibody- induced target internalization. Additionally, Ab-h1.9d-WT can mediate the uptake of ⁇ 4 ⁇ 7-coated beads or ⁇ 4 ⁇ 7-expressing VLPs (viral like particles) in an ⁇ 4 ⁇ 7-dependent and Fc-dependent manner in THP-1 cells.
• Ab-h1.9d-WT exhibits the intended in vitro pharmacological properties necessary for clinical candidacy.
• Ab-h1.9d-WT is a potent ⁇ 4 ⁇ 7-selective antagonist that is differentiated and improved from vedolizumab.
• the key attributes of Ab-h1.9d-WT in comparison to Ab-Vedo are shown in TABLES 36-40 and summarized in Table 41.
• An anti-human ⁇ 4 ⁇ 7 antibody which comprises (i) a VH chain region comprising three CDRs; and (ii) a VL chain region comprising three CDRs, wherein: 2.
• the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 1-7 which comprises a heavy chain having an amino acid sequence of SEQ ID NO:92 or SEQ ID NO:93, and a light chain having an amino acid sequence of SEQ ID NO:100.
• the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 1-8 comprising a variant CH2 domain having amino acid substitutions L234A and/or L235A.
• the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 1-9 comprising a variant CH2 domain having an amino acid substitution T250Q, and/or a variant CH3 domain having an amino acid substitution M428L. 11.
• a polynucleotide comprising a nucleotide sequence encoding an anti-human ⁇ 4 ⁇ 7 antibody, wherein the antibody comprises (i) a VH chain region comprising three CDRs; and (ii) a VL chain region comprising three CDRs, wherein: 12.
• An expression vector comprising the polynucleotide of embodiment 11. 13.
• a eukaryotic host cell engineered to express the polynucleotide of embodiment 11.
• a method of producing an anti-human ⁇ 4 ⁇ 7 antibody comprising: (a) culturing the eukaryotic host cell of embodiment 15 and (b) recovering the anti-human ⁇ 4 ⁇ 7 antibody. 17.
• a method of producing an anti-human ⁇ 4 ⁇ 7 antibody comprising: (a) culturing the prokaryotic host cell of embodiment 19 and (b) recovering the anti-human ⁇ 4 ⁇ 7 antibody. 21.
• a method of inducing viral suppression of HIV infection in an HIV-infected subject comprising administering to the subject an amount of the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 1-10. 22. The method of embodiment 21, wherein the viral suppression is immune-mediated. 23. A method of treating HIV infection in an HIV-infected subject, comprising administering to the subject an amount of the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 1-10. 24. An anti-human ⁇ 4 ⁇ 7 antibody, which suppresses HIV. 25. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 24, which inhibits HIV replication and/or HIV infection. 26.
• 28. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 24, which inhibits CD4 T cell co-stimulation.
• 29. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 28, wherein CD4 T cell co-stimulation is mediated by MAdCAM-1 or HIV gp120.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 25 which inhibits HIV replication in CD4 T cells. 31.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 30, wherein the CD4 T cells are MAdCAM-1 stimulated CD4 T cells or HIV gp120 stimulated CD4 T cells.
• 33. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 32, wherein the ⁇ 4 ⁇ 7 ligand is MAdCAM-1.
• 34. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 32, wherein the ⁇ 4 ⁇ 7 ligand is HIV gp120.
• 35. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 34 which inhibits gp120-mediated cell-to-cell transmission of HIV. 36.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 37, wherein the immune complex binds to a Fc ⁇ R on an antigen presenting cell (APC).
• APC antigen presenting cell
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 39, wherein the immune complex is taken up by the APC by phagocytosis. 41.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 40 which induces an HIV-specific immune response.
• 42. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 40 or 41, which induces a vaccination effect against HIV.
• ATI antiretroviral treatment interruption
• the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 24-46 having a set of six complementary determining regions (CDRs) or the variable heavy chain region and variable light chain region from an antibody selected from Ab-m1, Ab-c1, Ab-h1.1, Ab-h1.2, Ab-h1.3, Ab-h1.4, Ab-h1.5, Ab-h1.6, Ab-h1.7, Ab-h1.8, Ab-h1.9, Ab-h1.9a, Ab-h1.9b, Ab-h1.9c, Ab- h1.9d, or Ab-h1.9e. 48.
• the anti-human ⁇ 4 ⁇ 7 antibody of any one of embodiments 1-10 which suppresses HIV.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 48 which inhibits HIV replication and/or HIV infection. 50.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 48 which inactivates and/or reduces activation of human ⁇ 4 ⁇ 7 on cells expressing human ⁇ 4 ⁇ 7. 51.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 48 which induces internalization of human ⁇ 4 ⁇ 7 on cells expressing human ⁇ 4 ⁇ 7. 52.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 48 which inhibits CD4 T cell co-stimulation.
• 53. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 52, wherein CD4 T cell co-stimulation is mediated by MAdCAM-1 or HIV gp120.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 49 which inhibits HIV replication in CD4 T cells. 55.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 54 wherein the CD4 T cells are MAdCAM-1 stimulated CD4 T cells or HIV gp120 stimulated CD4 T cells.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 48 which disrupts interaction of ⁇ 4 ⁇ 7 with at least one of its ligands.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 56 wherein the ⁇ 4 ⁇ 7 ligand is MAdCAM-1.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 56, wherein the ⁇ 4 ⁇ 7 ligand is HIV gp120.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 58 which inhibits gp120-mediated cell-to-cell transmission of HIV. 60.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 48 which binds to an HIV virion.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 60 wherein the antibody binding to the HIV virion forms an immune complex.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 61 wherein the immune complex binds to a Fc ⁇ R on a cell.
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 61, wherein the immune complex binds to a Fc ⁇ R on an antigen presenting cell (APC).
• APC antigen presenting cell
• the anti-human ⁇ 4 ⁇ 7 antibody of embodiment 64 which induces an HIV-specific immune response.
• 66. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 64 or 65, which induces a vaccination effect against HIV.
• 68. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 67, wherein the viral control results in reduced viral load.
• 70. The anti-human ⁇ 4 ⁇ 7 antibody of embodiment 67, wherein the viral control results in delay in viral rebound after an antiretroviral treatment interruption (ATI).
• ATI antiretroviral treatment interruption

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