WO2023025215A1 - ANTIBODIES AND VARIANTS THEREOF AGAINST HUMAN CD16a - Google Patents

ANTIBODIES AND VARIANTS THEREOF AGAINST HUMAN CD16a Download PDF

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WO2023025215A1
WO2023025215A1 PCT/CN2022/114642 CN2022114642W WO2023025215A1 WO 2023025215 A1 WO2023025215 A1 WO 2023025215A1 CN 2022114642 W CN2022114642 W CN 2022114642W WO 2023025215 A1 WO2023025215 A1 WO 2023025215A1
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antibody
seq
antigen
nos
amino acid
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French (fr)
Inventor
Gang Liu
Zhongdao LI
Zhihui ZHAO
Cuiying SHAO
Bin Liu
Yi Jin
Liusong YIN
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Nanjing Jinsirui Science and Technology Biology Corp
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Nanjing Jinsirui Science and Technology Biology Corp
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Priority to EP22860561.4A priority Critical patent/EP4392453A4/en
Priority to KR1020247009137A priority patent/KR20240049331A/ko
Priority to US18/682,827 priority patent/US20240352128A1/en
Priority to CN202280057501.6A priority patent/CN117858902A/zh
Priority to JP2024512952A priority patent/JP2024532886A/ja
Publication of WO2023025215A1 publication Critical patent/WO2023025215A1/en
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    • 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
    • C07K16/2803—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 immunoglobulin superfamily
    • C07K16/283—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 immunoglobulin superfamily against Fc-receptors, e.g. CD16, CD32, CD64
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P35/00—Antineoplastic agents
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P37/00—Drugs for immunological or allergic disorders
    • A61P37/02—Immunomodulators
    • A61P37/04—Immunostimulants
    • 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
    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/22—Immunoglobulins specific features characterized by taxonomic origin from camelids, e.g. camel, llama or dromedary
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/20—Immunoglobulins specific features characterized by taxonomic origin
    • C07K2317/24—Immunoglobulins specific features characterized by taxonomic origin containing regions, domains or residues from different species, e.g. chimeric, humanized or veneered
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/30—Immunoglobulins specific features characterized by aspects of specificity or valency
    • C07K2317/33—Crossreactivity, e.g. for species or epitope, or lack of said crossreactivity
    • 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
    • C07K2317/50—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
    • C07K2317/569—Single domain, e.g. dAb, sdAb, VHH, VNAR or nanobody®
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2317/00—Immunoglobulins specific features
    • C07K2317/60—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments
    • C07K2317/64—Immunoglobulins specific features characterized by non-natural combinations of immunoglobulin fragments comprising a combination of variable region and constant region components
    • 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
    • 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
    • C07K2317/90—Immunoglobulins specific features characterized by (pharmaco)kinetic aspects or by stability of the immunoglobulin
    • C07K2317/92—Affinity (KD), association rate (Ka), dissociation rate (Kd) or EC50 value
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K2319/00—Fusion polypeptide

Definitions

  • Fc ⁇ receptors are cell surface receptors that bind the Fc region of immunoglobulin G (IgG) . These receptors form antibody-antigen complexes and play a part in effector cell responses. For example, cross-linking of activating Fc ⁇ receptors by immune complexes can result in the phagocytosis of pathogens, killing of foreign and transformed cells by-direct cytotoxicity, the clearance of toxic substances, and the initiation of an inflammatory response.
  • IgG recognizes targets through the antigen binding fragments and binds multiple types of Fc ⁇ Rs expressed on leukocytes with the Fc domain to elicit a cell-mediated response to treat leukemia, lymphomas, tumors, autoimmune disease and other diseases.
  • Fc ⁇ RIII also called CD16 is a low affinity receptor for the Fc portion of some IgGs known to be involved in antibody-dependent cellular cytotoxicity (ADCC) , is the best characterized membrane receptor responsible for triggering of target cell lysis by NK cells.
  • ADCC antibody-dependent cellular cytotoxicity
  • Human Fc ⁇ RIII exists as two isoforms, Fc ⁇ RIIIA (CD16a) and Fc ⁇ RIIIB (CD16b) , that share 96%sequence identity in their extracellular immunoglobulin-binding regions.
  • Fc ⁇ RIIIA (CD16a) is expressed on macrophages, mast cells, and NK cells as a transmembrane receptor.
  • Fc ⁇ RIIIB (CD16b) is present on polymorphonuclear granulocytes (PMN) as a glycosyl-phosphatidylinositol (GPI) -anchored receptor (Fc ⁇ RIIIB isoform) , which cannot trigger tumor cell killing.
  • PMN polymorphonuclear granulocytes
  • GPI glycosyl-phosphatidylinositol
  • Fc ⁇ RIIIB isoform
  • Fc ⁇ RIIIB exists as a soluble receptor in serum and upon binding to antibodies may trigger side-effects via the formation of immune complexes in vivo.
  • Fc ⁇ R-expressing effector cells have been shown to be involved in destroying tumor cells via ADCC. This has led to the development of several immunotherapeutic approaches to cancer therapy, which involve the use of Fc ⁇ R activities.
  • NK cells are professional cell killers and, unlike T cells, tend to exist in constitutively activated states not requiring additional (pre-) stimulation.
  • pre- additional
  • the present disclosure provides an isolated antibody, or an antigen-binding portion thereof, comprising: a monomeric variable domain comprising a CDR1 region, a CDR2 region, and a CDR3 region comprising the amino acid sequences of: SEQ ID NOs: 2, 3, and 4, respectively; or SEQ ID NOs: 6, 7, and 8, respectively; or SEQ ID NOs: 14, 15, and 16, respectively; or SEQ ID NOs: 14, 15, and 64, respectively; or SEQ ID NOs: 14, 15, and 66, respectively; or SEQ ID NOs: 18, 19, and 20, respectively; or SEQ ID NOs: 26, 27, and 28, respectively; or a variant thereof comprising up to about 3 amino acid substitutions in any one or more of the CDR1 region, the CDR2 region, and the CDR3 region.
  • the CDR1 region, the CDR2 region, and the CDR3 region comprises the amino acid sequences of: SEQ ID NOs: 2, 3, and 4, respectively; or SEQ ID NOs: 6, 7, and 8, respectively; or SEQ ID NOs: 18, 19, and 20, respectively; or SEQ ID NOs: 26, 27, and 28, respectively; or a variant thereof comprising up to about 3 amino acid substitutions in any one or more of the CDR1 region, the CDR2 region, and the CDR3 region.
  • the antibody or antigen-binding portion thereof specifically binds to human CD16a.
  • the antibody or antigen-binding portion thereof comprises or is a single domain antibody (sdAb) or a V H H domain.
  • the antibody or antigen-binding portion thereof is camelid, chimeric, human or humanized.
  • the monomeric variable domain comprises an amino acid sequence having at least 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99%identity to the amino acid sequence selected from the group consisting of SEQ ID NOs: 1, 5, 13, 17, 25, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, and 62.
  • the monomeric variable domain comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1, 5, 13, 17, 25, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, and 62.
  • the monomeric variable domain comprises an amino acid sequence having at least 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99%identity to the amino acid sequence selected from the group consisting of SEQ ID NOs: 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52.
  • the monomeric variable domain comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52.
  • the monomeric variable domain comprises an amino acid sequence having at least 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99%identity to the amino acid sequence selected from the group consisting of SEQ ID NOs: 42, 44, 45, 47, and 50. In certain of these embodiments, the monomeric variable domain comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 42, 44, 45, 47, and 50.
  • the present disclosure provides an isolated antibody, or an antigen-binding portion thereof, comprising a monomeric variable domain comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 1, 5, 13, 17, 25, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 5253, 54, 55, 56, 57, 58, 59, 60, 61, and 62.
  • the antibody can be a humanized antibody, and the monomeric variable domain can comprise the amino acid sequence selected from the group consisting of SEQ ID NOs: 42, 44, 45, 47, and 50.
  • the antibody or the antigen-binding portion thereof can further comprise an IgG Fc region fused with the monomeric variable domain.
  • the IgG Fc region can be a human IgG4 Fc region or a mouse IgG1 Fc region.
  • the human IgG4 Fc region may comprise an amino acid sequence of SEQ ID NO: 73.
  • the mouse IgG1 Fc region may comprise an amino acid sequence of SEQ ID NO: 74.
  • the present disclosure provides a bispecific molecule, an immunoconjugate, or a chimeric antigen receptor, comprising the antibody or antigen-binding portion thereof as described herein.
  • the present disclosure provides a nucleic acid molecule encoding the antibody or antigen-binding portion thereof, as described herein, or the bispecific molecule, an immunoconjugate, or a chimeric antigen receptor thereof.
  • the present disclosure provides an expression vector containing the nucleic acid molecule.
  • the present disclosure provides a host cell containing the expression vector.
  • the present disclosure provides a pharmaceutical composition
  • a pharmaceutical composition comprising the antibody or antigen-binding portion thereof as described herein, or the bispecific molecule, an immunoconjugate, or a chimeric antigen receptor as described herein, and a pharmaceutically acceptable carrier.
  • the pharmaceutical can further comprise a cytotoxic agent.
  • the present disclosure provides a method for treating a cancer disease in a subject, comprising administering to the subject a therapeutically effective amount of the pharmaceutical composition as described herein.
  • the cancer disease is selected from the group consisting of adrenal cancer, bladder cancer, breast cancer, colorectal cancer, gastric cancer, glioblastoma, kidney cancer, non-small-cell lung cancer, acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, hairy cell leukemia, Burkett's lymphoma, diffuse large B cell lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, non-Hodgkin’s lymphoma, small lymphocytic lymphoma, multiple myeloma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer, skin cancer, renal cell carcinoma, testicular cancer, and uterine cancer.
  • the present disclosure provides a method of promoting NK cell proliferation in a subject, comprising administering to the subject a therapeutically effective amount of the pharmaceutical composition as described herein.
  • Figs. 1A-1 and 1A-2 show FACS binding curves of certain embodiments of antibodies the present disclosure with human CD16a proteins.
  • Figs. 2A-1 and 2A-2 show FACS binding curves of certain embodiments of antibodies the present disclosure with human CD16b proteins.
  • Figs. 2B-1 shows FACS binding curves of certain embodiments of antibodies the present disclosure with human CD16a proteins.
  • Figs. 2B-2 shows FACS binding affinities certain embodiments of antibodies the present disclosure with human CD16b proteins.
  • Figs. 3 shows cytotoxicity assay results of certain embodiments of antibodies the present disclosure in triggering NK cells’ cytotoxicity.
  • Figs. 4A and 4B show binding affinities of certain humanized sdAbs of the present disclosure with human CD16a proteins.
  • Figs. 5A and 5B show binding affinities of certain humanized sdAbs of the present disclosure with human CD16b proteins.
  • Fig. 6A shows FACS binding curves and data of certain humanized sdAbs of the present disclosure with human CD16a proteins
  • Fig. 6B shows FACS binding curves and data of these humanized sdAbs with human CD16b proteins.
  • Fig. 7A shows FACS binding curves and data of certain humanized sdAbs of the present disclosure with human CD16a proteins
  • Fig. 7B shows FACS binding curves and data of these humanized sdAbs with human CD16b proteins.
  • Fig. 8A shows FACS binding curves and data of certain humanized sdAbs of the present disclosure with human CD16a proteins
  • Fig. 8B shows FACS binding curves and data of these humanized sdAbs with human CD16b proteins.
  • Fig. 9A shows FACS binding curves and data of certain humanized sdAbs of the present disclosure with human CD16a proteins
  • Fig. 9B shows FACS binding curves and data of these humanized sdAbs with human CD16b proteins.
  • Fig. 10A shows FACS binding curves and data of certain humanized sdAbs of the present disclosure with human CD16a proteins
  • Fig. 10B shows FACS binding curves and data of these humanized sdAbs with human CD16b proteins.
  • Figs. 11A and 11B show lactate dehydrogenase (LDH) cytotoxicity assay results with NK92/CD16a-158V/V cells of certain humanized sdAbs of the present disclosure with human CD16a proteins.
  • LDH lactate dehydrogenase
  • Fig. 12 shows lactate dehydrogenase (LDH) cytotoxicity assay results with NK92/CD16a-158V/V cells of certain humanized sdAbs of the present disclosure with human CD16a proteins by dose dependent response of reverse ADCC bioassay.
  • LDH lactate dehydrogenase
  • Figs. 13A and 13B show FACS Cyno binding curves and data of certain humanized sdAbs of the present disclosure with human CD16a proteins.
  • the present disclosure provides anti-CD16 llama single domain antibodies that exhibit specificity for Fc ⁇ RIIIA (CD16a) but do not bind with specificity to Fc ⁇ RIIIB (CD16b) .
  • the present disclosure further provides humanized sdAbs based on these llama sdAbs and fusion proteins thereof.
  • the antibodies (or binding molecules) of the present disclosure can activate NK cells upon binding, and can be used as a component of a bispecific or multispecific binding molecule directed against disease-associated cells.
  • antigen-binding portion of an antibody refers to one or more fragments of an antibody that retain the ability to bind to an antigen (e.g., a CD16a protein) .
  • an antigen e.g., a CD16a protein
  • This can include a heavy chain variable region containing a single variable domain, as well as a bigger molecule that includes such a domain and another polypeptide segment chemically linked to it.
  • single chain antibodies are also intended to be encompassed within the term “antigen-binding portion” .
  • an “isolated antibody” as used herein refers to an antibody that is substantially free of other antibodies having different antigenic specificities.
  • An isolated antibody that specifically binds a CD16a protein is substantially free of antibodies that do not bind to a CD16a protein.
  • An isolated antibody that binds a human CD16a may also bind other antigens, such as human CD16b protein or CD16a proteins from other species.
  • An isolated antibody can also be substantially free of other cellular material and/or chemicals.
  • CD16a binding protein As used herein, the terms “CD16a binding protein, ” “CD16a antibody, ” and “anti-CD16a antibody, ” are used interchangeably and refer to a variety of molecules that bind CD16a via an interaction with VL and/or VH domains (as distinct from Fc-mediated binding) .
  • Examples of CD16a binding proteins includes chimeric, humanized and human antibodies (e.g., comprising 2 heavy and 2 light chains) , fragments thereof (e.g., Fab, Fab′, F (ab′) 2, and Fv fragments) , bifunctional or multifunctional antibodies, single chain antibodies, fusion proteins (e.g., phage display fusion proteins) , “minibodies” (see, e.g., U.S. Pat. No. 5,837,821) and other antigen binding proteins comprising a VL and/or VH domain or fragment thereof.
  • minibodies see, e.g., U.S. Pat. No. 5,8
  • monoclonal antibody refers to a preparation of antibody molecules of single molecular composition.
  • single domain antibody refers to a single antigen-binding polypeptide comprising a single monomeric variable antibody domain having three complementary determining regions (CDRs) , which is capable of binding to an antigen without pairing with a corresponding CDR-containing polypeptide.
  • the single domain antibody is engineered from a camelid heavy chain antibodies (HCAb) , and is also called the V H H domain or fragment of the HCAb.
  • the single domain antibody is a kind of antigen-binding portion of a heavy chain only antibody.
  • the V H Hs may also be known as Nanobodies.
  • Camelid sdAb is one of the smallest known antigen binding antibody fragments (see, e.g., Hamers-Casterman et al., Nature 363: 446-8 (1993) ; Greenberg et al., Nature 374: 168-73 (1995) ; Hassanzadeh-Ghassabeh et al., Nanomedicine (Lond) , 8: 1013-26 (2013) ) .
  • particular single domain antibodies in the Examples of the present disclosure are referred to AR [digits and/or other symbols] , e.g., AR8866, AR8866-1.1, AR8804, AR8804-1.1, etc.
  • an antibody or molecule that “specifically binds to human CD16a” refers to an antibody or polypeptide molecule that binds to human CD16a protein but does not substantially bind to proteins that are not human CD16a proteins.
  • an antibody or molecule referred to herein as specifically binding to human CD16a should have a binding affinity against human CD16a of at least 100-fold higher than its binding affinity against human CD16b.
  • fused protein refers to an antibody molecule that include both a single domain antibody (e.g., V H H) part and an IgG constant region Fc (such as human IgG4 Fc region or mouse IgG1 Fc region) , where the two parts are chemically linked, e.g., by recombinant methods.
  • sdAbs can be directly fused to the IgG Fc region with the native hinge region of the IgG.
  • the sdAb is located upstream, i.e., closer to the N-terminus, of the IgG Fc in the fused antibody, where the sdAb and the IgG Fc region are intervened by the hinge region.
  • a fused antibody protein can be referenced herein as its constituent parts, e.g., AR8776-sdAb-hIgG4Fc refers to a fused protein or antibody made up by AR8776-sdAb fused with the human IgG4 Fc region.
  • camelid antibody is intended to include antibodies having variable regions (or more specifically the single domain antibodies or V H H fragments) in which both the framework and CDR regions are derived from camelid germline heavy chain only antibody sequences. Furthermore, if the antibody contains a constant region, the constant region can also be derived from camelid germline antibody sequences.
  • the camelid antibodies of the invention can include amino acid residues not encoded by camelid germline antibody sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo) .
  • the term “camelid antibody” is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species have been grafted onto camelid framework sequences.
  • chimeric antibody refers to an antibody made by combining genetic material from a nonhuman (e.g., camelid) source with genetic material from a human being. Or more generally, a chimeric antibody is an antibody having different parts produced from genetic material of different species.
  • humanized antibody refers to an antibody from non-human (e.g., camelid) species whose protein sequences have been modified to increase similarity to antibody variants produced naturally in humans.
  • percent “identity” as used herein in the context of two or more nucleic acids or proteins/peptides refer to two or more sequences or subsequences that have a specified percentage of nucleotides or amino acid residues that are the same, when compared and aligned (introducing gaps, if necessary) for maximum correspondence, not considering any conservative amino acid substitutions as part of the sequence identity.
  • the percent identity can be measured using sequence comparison software or algorithms or by visual inspection.
  • Various algorithms and software that can be used to obtain alignments of amino acid or nucleotide sequences are well-known in the art. These include, but are not limited to, BLAST, ALIGN, Megalign, BestFit, GCG Wisconsin Package, and variants thereof.
  • the term “subject” includes any human or nonhuman animal.
  • the term “nonhuman animal” includes all vertebrates, e.g., mammals and non-mammals. In certain embodiments, the subject is a human.
  • the CDRs of an antibody are defined by those skilled in the art using a variety of methods/systems. These systems and/or definitions have been developed and refined over a number of years and include Kabat, Chothia, IMGT, AbM, and Contact.
  • the Kabat definition is based on sequence variability and is commonly used.
  • the Chothia definition is based on the location of the structural loop regions.
  • the IMGT system is based on sequence variability and location within the structure of the variable domain.
  • the AbM definition is a compromise between Kabat and Chothia.
  • the Contact definition is based on analyses of the available antibody crystal structures.
  • An Exemplary system is a combination of Kabat and Chothia.
  • Protein and nucleic acid sequences for CD16a are reported in Genbank as accession numbers P08637 (protein) and X52645 (nucleic acid) and in SWISS-PROT as accession number CAA36870.
  • Protein and nucleic acid sequences for CD16b are reported in Genbank as accession numbers O75015 (protein) and X16863 (nucleic acid) and in SWISS-PROT as CAA34753.
  • Antibody targeting human CD16a (or anti-human CD16a antibody)
  • the present disclosure provides an isolated antibody, or an antigen-binding portion thereof, comprising a monomeric variable domain comprising a CDR1 region, a CDR2 region, and a CDR3 region comprising the amino acid sequences of: SEQ ID NOs: 2, 3, and 4, respectively; or SEQ ID NOs: 6, 7, and 8, respectively; or SEQ ID NOs: 14, 15, and 16, respectively; or SEQ ID NOs: 14, 15, and 64, respectively; or SEQ ID NOs: 14, 15, and 66, respectively; or SEQ ID NOs: 18, 19, and 20, respectively; or SEQ ID NOs: 26, 27, and 28, respectively; or a variant thereof comprising up to about 3 amino acid substitutions in any one or more of the CDR1 region, the CDR2 region, and the CDR3 region.
  • the CDR1 region, the CDR2 region, and the CDR3 region comprises the amino acid sequences of: SEQ ID NOs: 2, 3, and 4, respectively; or SEQ ID NOs: 6, 7, and 8, respectively; or SEQ ID NOs: 18, 19, and 20, respectively; or SEQ ID NOs: 26, 27, and 28, respectively; or a variant thereof comprising up to about 3 amino acid substitutions in any one or more of the CDR1 region, the CDR2 region, and the CDR3 region.
  • the antibody or antigen-binding portion thereof specifically binds to human CD16a.
  • the antibody or antigen-binding portion thereof comprises or is a single domain antibody (sdAb) or a V H H domain.
  • the antibody or antigen-binding portion thereof is camelid, chimeric, human or humanized.
  • the monomeric variable domain comprises an amino acid sequence having at least 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99%identity to the amino acid sequence selected from the group consisting of SEQ ID NOs: 1, 5, 13, 17, 25, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, and 62.
  • the monomeric variable domain comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 1, 5, 13, 17, 25, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, and 62.
  • the monomeric variable domain comprises an amino acid sequence having at least 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99%identity to the amino acid sequence selected from the group consisting of SEQ ID NOs: 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52.
  • the monomeric variable domain comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, and 52.
  • the monomeric variable domain comprises an amino acid sequence having at least 80%, 85%, 90%, 92%, 94%, 95%, 96%, 97%, 98%, or 99%identity to the amino acid sequence selected from the group consisting of SEQ ID NOs: 42, 44, 45, 47, and 50. In certain of these embodiments, the monomeric variable domain comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 42, 44, 45, 47, and 50.
  • the present disclosure provides an isolated antibody, or an antigen-binding portion thereof, comprising a monomeric variable domain comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 1, 5, 13, 17, 25, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 5253, 54, 55, 56, 57, 58, 59, 60, 61, and 62.
  • the antibody can be a humanized antibody, and the monomeric variable domain can comprise the amino acid sequence selected from the group consisting of SEQ ID NOs: 42, 44, 45, 47, and 50.
  • the antibody or antigen-binding portion thereof described herein can further comprise an IgG Fc region fused with the monomeric variable domain.
  • the IgG Fc region can be a human IgG4 Fc region or a mouse IgG1 Fc region.
  • the human IgG4 Fc region may comprise an amino acid sequence of SEQ ID NO: 73.
  • the mouse IgG1 Fc region may comprise an amino acid sequence of SEQ ID NO: 74.
  • the present disclosure provides a bispecific molecule, an immunoconjugate (or antibody drug conjugate) , or a chimeric antigen receptor, comprising the antibody or antigen-binding portion thereof as described herein.
  • bispecific molecule refers to an antibody of the present disclosure linked to at least one other functional molecule, e.g., another peptide or protein (e.g., another antibody or ligand for a receptor) .
  • a bispecific molecule can have at least two different binding sites or target molecules, and can includes molecules that have three or more specificities.
  • immunoconjugate refers to an antibody of the present disclosure conjugated to a therapeutic agent, such as cytotoxins, alkylating agents, DNA minor groove binders, DNA intercalators, DNA crosslinkers, histone deacetylase inhibitors, nuclear export inhibitors, proteasome inhibitors, topoisomerase I or II inhibitors, etc.
  • a therapeutic agent such as cytotoxins, alkylating agents, DNA minor groove binders, DNA intercalators, DNA crosslinkers, histone deacetylase inhibitors, nuclear export inhibitors, proteasome inhibitors, topoisomerase I or II inhibitors, etc.
  • the antibody and therapeutic agent can be are conjugated via a cleavable linker such as a peptidyl, disulfide,
  • chimeric antigen receptor refers to an engineered receptor that grafts a defined specificity onto an immune effector cell, typically a T cell, and augments T-cell function.
  • the new generation CAR comprises an extracellular binding domain comprising a single domain antibody, a hinge region, a transmembrane domain, and an intracellular signaling domain (mainly CD3-zeta’s cytoplasmic domain, which is the primary transmitter of T cell activation signals, plus one or more co-stimulatory domains) .
  • the CARs may further have factors that enhance T cell expansion, persistence, and anti-tumor activity, such as cytokines and co-stimulatory ligands.
  • the present disclosure provides a nucleic acid molecule encoding the antibody or antigen-binding portion thereof of any of the antibody (or antigen-binding portion thereof) , or the bispecific molecule, an immunoconjugate, or a chimeric antigen receptor of described herein.
  • a host cell e.g., a CHO cell, or a lymphocytic cell, or microorganisms, such as E. coli, and fungi, such as yeast
  • an expression vector containing the nucleic acid molecule can be used to produce antibodies of the present disclosure, preferably single domain antibodies.
  • Single domain antibody preparation involves immunization of a Camelid species with the antigen of interest such as CD16a, recovery of lymphocytes from the immunized animal, preparation of the cDNAs, generation of a phage display library using standard cloning protocols, and three to four rounds of phage screening to enrich antigen-specific binders.
  • a diverse single domain antibody library can also be prepared by introducing diversity into a V H H scaffold synthetically.
  • the single domain antibodies can also be isolated from phage display libraries expressing camelid single domain antibodies. Screening of phage libraries can be accomplished by various techniques known in the art. For example, a camelid single domain antibody library may be screened for antibodies binding to the coronavirus spike protein by solution panning with colorimetric plates coated with the receptor binding domain of CD16a protein over several rounds of selection with increasing stringency.
  • Isolates may be first expressed as single domain antibodies and screened for binding to the receptor binding domain by ELISA, and the selected isolates may then be cloned and expressed as single domain antibody linked to IgG4 or IgG1 Fc region, reanalyzed for binding to CD16a protein by ELISA and/or SPR and for functional activity and transfected in a CHO mammalian cell line for expression of the single domain antibodies.
  • DNA encoding single domain antibody or antigen-binding portion thereof of the present disclosure can be obtained by standard molecular biology techniques is inserted into one or more expression vectors such that the genes are operatively linked to transcriptional and translational regulatory sequences.
  • 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.
  • 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 genes. Such regulatory sequences are described, e.g., in Goeddel (Gene Expression Technology.
  • Preferred regulatory sequences for mammalian host cell expression include viral elements that direct high levels of protein expression in mammalian cells, such as promoters and/or enhancers derived from cytomegalovirus (CMV) , Simian Virus 40 (SV40) , adenovirus, e.g., the adenovirus major late promoter (AdMLP) and polyoma.
  • CMV cytomegalovirus
  • SV40 Simian Virus 40
  • AdMLP adenovirus major late promoter
  • nonviral regulatory sequences can be used, such as the ubiquitin promoter or ⁇ -globin promoter.
  • regulatory elements composed of sequences from different sources, such as the SR ⁇ promoter system, which contains sequences from the SV40 early promoter and the long terminal repeat of human T cell leukemia virus type 1 (Takebe et al., (1988) Mol. Cell. Biol. 8: 466-472) .
  • the expression vector and expression control sequences are chosen to be compatible with the expression host cell used.
  • the antibody encoding DNA can be inserted into the expression vector.
  • the recombinant expression vector can encode a signal peptide that facilitates secretion of the antibody chain from a host cell.
  • the antibody encoding DNA can be cloned into the vector such that the signal peptide is linked in-frame to the amino terminus of the antibody encoding DNA.
  • 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 expression vector (s) encoding the antibody chain can be transfected into a host cell by standard techniques.
  • the various forms of the term “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, calcium-phosphate precipitation, DEAE-dextran transfection and the like.
  • Mammalian host cells for expressing the antibodies of the present disclosure include HEK293 cells, Chinese Hamster Ovary (CHO cells) , 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, more preferably, 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.
  • the present disclosure provides a pharmaceutical composition
  • a pharmaceutical composition comprising one or more antibodies of the present invention, or the bispecific molecule, an immunoconjugate, or a chimeric antigen receptor described herein, together with a pharmaceutically acceptable carrier in accordance with conventional techniques.
  • composition may comprise one or more additional pharmaceutically active ingredients, such as another antibody, a drug, e.g., a cytotoxic or anti-tumor agent.
  • additional pharmaceutically active ingredients such as another antibody, a drug, e.g., a cytotoxic or anti-tumor agent.
  • the pharmaceutical compositions of the invention also can be administered in a combination therapy with, for example, another anti-cancer agent, another anti-inflammatory agent, etc.
  • pharmaceutically acceptable carrier includes pharmaceutically acceptable carriers, excipients or stabilizers.
  • solvents include but are not limited solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, surface active agents, thickening or emulsifying agents, solid binders, dispersion or suspension aids, solubilizers, colorants, flavoring agents, coatings, disintegrating agents, lubricants, sweeteners, preservatives, isotonic agents, and the like that are physiologically compatible.
  • suitable carrier is within the knowledge of an artisan skilled in the art.
  • the pharmaceutical composition can be suitable for intravenous, intramuscular, subcutaneous, parenteral, epidermal, and other routes of administration.
  • the active ingredient can be coated with a material or otherwise loaded in a material or structure to protect it from the action of acids and other natural conditions that may inactivate it.
  • parenteral administration means modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal, epidural and intrasternal injection and infusion.
  • an antibody of the invention can be administered via a non-parenteral route, such as a topical, epidermal or mucosal route of administration, e.g., intranasally, orally, vaginally, rectally, sublingually or topically.
  • the present disclosure provides a method for treating an immune-mediated disease such as cancer in a subject, e.g., a human or non-human mammal, comprising administering to the subject a therapeutically effective amount of the pharmaceutical composition described herein.
  • the cancer can be selected from the group consisting of adrenal cancer, bladder cancer, breast cancer, colorectal cancer, gastric cancer, glioblastoma, kidney cancer, non-small-cell lung cancer, acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, hairy cell leukemia, Burkett's lymphoma, diffuse large B cell lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, non-Hodgkin’s lymphoma, small lymphocytic lymphoma, multiple myeloma, melanoma, ovarian cancer, pancreatic cancer, prostate cancer, skin cancer, renal cell carcinoma, testicular cancer, and uterine cancer.
  • the present disclosure provides a method of promoting NK cell proliferation in a subject, comprising administering to the subject a therapeutically effective amount of the pharmaceutical composition described herein.
  • dosage regimens can be adjusted to provide the optimum desired response (e.g., a therapeutic response) .
  • Single bolus or divided doses can be administered based on the subject, the disease to be treated, etc.
  • Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subjects to be treated. Each unit contains a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Sustained release formulation can be used in which case less frequent administration is required.
  • the dosage may range from about 0.0001 to 100 mg/kg, and more usually 0.01 to 5 mg/kg, of the body weight of the subject.
  • dosages can be 0.3 mg/kg body weight, 1 mg/kg body weight, 3 mg/kg body weight, 5 mg/kg body weight or 10 mg/kg body weight or within the range of 1-10 mg/kg.
  • a suitable treatment regime can be once per week, once every two weeks, once every three weeks, once every four weeks, once a month, etc.
  • Example dosage regimens for an anti-CD16a antibody of the invention can include 1 mg/kg body weight or 3 mg/kg body weight via intravenous administration.
  • a “therapeutically effective amount” or “therapeutically effective amount” of an antibody targeting CD16a of the invention preferably results in a decrease in severity of disease symptoms, an increase in frequency and/or duration of disease symptom-free periods, prevention or reduction of likelihood of impairment or disability due to the disease affliction, or inhibition or delaying of the progression of disease.
  • a “therapeutically effective amount” of an antibody composition may inhibits tumor growth by at least about 20%, more preferably by at least about 40%, even more preferably by at least about 60%, and still more preferably by at least about 80%relative to untreated subjects.
  • the llama was immunized with recombinant human CD16a-His proteins (Acro Biosystems; catalog#: CDA-H52S1) under current animal welfare regulations.
  • the antigen was administrated in PBS solution or formulated as an emulsion with CFA (Complete Freund's adjuvant; primary immunization) or IFA (incomplete Freund's adjuvant; boost immunizations) .
  • CFA Complete Freund's adjuvant
  • IFA incomplete Freund's adjuvant
  • the animal received 6 injections of the emulsion, including the primary immunization with 200 ⁇ g of antigen in CFA emulsion, the subsequent 3 boosts with 100 ⁇ g of antigen in IFA emulsion at one-week interval and the following 2 injections with 50 ⁇ g of antigen in IFA emulsion at one-week interval.
  • a blood sample of 100 ml was collected.
  • Peripheral blood lymphocytes (PBLs) as the genetic source of the llama heavy chain antibodies (HCAbs) were isolated from the blood sample by gradient centrifugation.
  • Variable fragments targeting CD16a from AFM13 (Patent No.: US 9,035,026 B2, Affirmed GMBH, Germany) was incorporated into either human IgG4 or mouse IgG1 format as positive control (and reference antibody) , and normal human IgG4 or mouse IgG1 was set as isotype control, respectively.
  • the isolated RNA was reverse transcribed into cDNA with an oligo (dT) 20 primer using PRIMESCRIPT 1 st strand cDNA synthesis kit (Takara; catalog#: 6110A) according to the manufacturer’s protocol.
  • dT oligo
  • PRIMESCRIPT 1 st strand cDNA synthesis kit Takara; catalog#: 6110A
  • variable regions of the V H H fragments were amplified by two-step PCR methods.
  • the DNA products of the first PCR were used as templates in the second PCR.
  • the amplified second PCR products containing V H H PCR fragments were gel purified and enzyme digested followed by insertion into phagemid plasmids.
  • the recombinant plasmids were transferred into E. coli cells by electroporation, which generated the phage display library with size more than 1x10 9 .
  • the library phage was prepared according to a standard protocol and stored after filter sterilization at -80 °C as stock.
  • the constructed phage library was either screened with CHO-K1 cells (ATCC; catalog#: CCL-61) overexpressing human CD16a cells (constructed by Genscript) or first counter-screened with CHO-K1 cells overexpressing human CD16b cells (constructed by Genscript) followed by panning with CHO-K1 cells overexpressing human CD16a using a standard procedure developed by GenScript. At least two rounds of selections were performed and each selection output was analyzed for enrichment factor (number of phage present in elution relative to control) , diversity and percentage of CD16a positive CD16b negative or weak clones.
  • the anti-CD16a sdAb-Fc fusion protein constructs were generated by fusion of anti-CD16a sdAbs with human IgG4 (or mouse IgG1) Fc region.
  • the maxiprep of the constructs were prepared for CHO-3E7 cell transient expression.
  • the expressed anti-CD16a sdAb-Fc fusion proteins were purified by chromatography through a column containing Protein A agarose resin. 22 molecules were yielded.
  • CD16a and CD16b can exist as a soluble receptor in serum and, upon binding to antibodies, may trigger side-effects via the formation of immune complexes in vivo.
  • An antibody specific for CD16a would be particularly valuable in constructing bispecific or multispecific antibodies that are directed against disease-associated cells. In this case, the antibodies would mainly recruit NK cells and would not be bound by circulating soluble CD16b or diverted from NK cells binding by binding to neutrophils or activated eosinophils.
  • human CD16a (Acro Biosystems; catalog#: CDA-H52S1) or CD16b (Acro Biosystems; catalog#: CDB-H5227) was pre-coated onto ELISA plates (0.5 ⁇ g/ml, 100 ⁇ l) overnight at 4°C.
  • wells were incubated with 3x serial diluted sdAbs fusion proteins (with hIgG4 Fc region, SEQ ID NO: 73) , with initial concentration of 1.0 ⁇ g/ml, following with HRP-conjugated goat anti human IgG (H+L) (Rockland) for substrate TMB chromogenic reaction.
  • the bindings were quantified with optical densities readings at 450nm.
  • the sdAbs that showed specific affinity to human CD16a, but no or negligibly low affinity to CD16b were chosen for further screenings.
  • 7 sdAb molecules in total namely AR8804, AR8820, AR8776, AR8875, AR8866, AR8887, AR8861 (SEQ ID NO: 1, 5, 9, 13, 17, 21, 25) , were chosen for further verification. These selected leads were then fused to mouse IgG1 Fc for further study.
  • Example 3 The sdAbs’ NK cytotoxicity-triggering potency
  • AR8776, AR8804, AR8820, AR8861, AR8866, AR8875 and AR8887 sdAbs were relinked to mouse IgG1 Fc format (SEQ ID NO: 74) , and their affinity specificity for CD16a were verified through ELISA.
  • human CD16a (Acro Biosystems; catalog#: CDA-H52S1) was pre-coated onto ELISA plates (1 ⁇ g/ml, 100 ⁇ l) overnight at 4°C.
  • CD16b binding assay CD16b (Acro Biosystems; catalog#: CDB-H5227) was pre-coated onto ELISA plates (1 ⁇ g/ml, 100 ⁇ l) overnight at 4°C.
  • 11H1D3 an in-house mAb-mouse IgG1 antibody against human CD16a that proved to have high affinity with human CD16b, was exploited as positive sample in this experiment.
  • the ELISA experiment was followed by reverse ADCC assay to gauge the strength of these molecules to trigger NK cells’ cytotoxicity. Briefly, 10,000 human NK-92 158V/V cells were cocultured with mouse P815 target cells (SailyBio, Shanghai) pre-opsonized with 5ug/ml sdAbs at E/T ratio of 5: 1 for 4H. Afterwards, the percentage of specific lysis was calculated with LDH cytotoxicity kit (Roche) .
  • AFM-CD16a-mIgG1 (also written as CD16a-mLCK-IgG1) were used as reference control sample, while mouse IgG as isotype control.
  • humanized antibody production we fused the humanized anti-CD16a sdAbs to the N-terminus of human IgG4 (or mouse IgG1) Fc region to generate anti-CD16a sdAb-Fc fusion proteins.
  • the DNA sequence expressing each anti-CD16a sdAb-Fc fusion protein was inserted into pTT5 vector between EcoRI and HindIII restriction sites.
  • CHO-3E7 cells transfected with these expression plasmids were cultured at 37°C and 100 rpm for 6 days. The supernatant fraction was collected by centrifugation and the proteins were purified through Protein A column.
  • an antibody specific for CD16a would be particularly valuable in constructing bispecific or multispecific antibodies that are directed against disease-associated cells.
  • 41 purified humanized sdAbs-mIgG1 Fc fusion proteins derived were pre-coated onto ELISA plates (0.5 ⁇ g/ml, 100 ⁇ l) overnight at 4°C. On the next day, wells were incubated with 1.0 ⁇ g/ml primary antibodies, following with HRP-conjugated goat anti-mouse IgG (H+L) (Rockland; catalog#: 610-103-121) for substrate TMB chromogenic reaction.
  • Antibody-CD16a and CD16b bindings were quantified with optical densities readings at 450 nm (FIGS. 4A-4B, FIGS. 5A-5B) , and candidates having specific affinity to CD16a, were selected for further screenings.
  • AFM-CD16a-mIgG1 were used as reference control sample, while mouse IgG as isotype control.
  • the humanized sdAbs’ NK cytotoxicity-triggering potency
  • the strength of the humanized sdAbs to trigger NK cells’ cytotoxicity were gauged by way of reverse ADCC assay as described above. Briefly, 10,000 human NK-92 158V/V cells were cocultured with mouse P815 target cells (SailyBio, Shanghai) pre-opsonized with 0.008 ⁇ g/ml sdAbs-mIgG1 Fc fusion protein (pTT5-humanized sdAb-m IgG1Fc) at E/T ratio of 5: 1 for 4 hours. Afterwards, the percentage of specific lysis was calculated with LDH cytotoxicity kit (Roche) . AFM13-CD16a-mIgG1 was used as reference control, while mouse IgG as isotype control.
  • the selected leads of pTT5-AR8804-3.1 mIgG1Fc, pTT5-AR8804-3.3mIgG1Fc and pTT5-AR8820-1.3mIgG1Fc exhibited much higher activity than the reference antibody of AFM13-CD16a-mIgG1.
  • HEK293 cells expressing cyno monkey CD16a were harvested and incubated respectively with serially diluted anti-CD16a humanized sdAb-mIgG1Fcs (max. concentration: 100nM, 3-fold dilution) , followed by fluorophore (iFluor 647) -labeled goat anti mouse IgG (H+L) secondary antibodies (Jackson immuno research; catalog#: 115-605-062) .
  • the samples were then analyzed with flow cytometry.
  • Raw data was plotted with GraphPad Prism v6.02 software with four parameters, best-fit values program to analyze the EC 50 .

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WO2025108079A1 (zh) * 2023-11-21 2025-05-30 南京融捷康生物科技有限公司 一种抗CD16a的单域抗体及其用途
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