Patent Application
20230303711
The present invention relates to the technical field of bio-immunology, particularly to a fully human anti-CD47 IgG antibody, and more particularly to CD47 antibodies that do not cause significant hemagglutination of human red blood cells, hemoglobin reduction, anemia and/or platelet reduction, methods for preparing these antibodies and use of these monoclonal antibodies in the manufacture of medicaments.
CD47, also known as integrin-associated protein (IAP), is a transmembrane glycoprotein that is extensively expressed on the cell surface and belongs to the immunoglobulin superfamily (Johansen and Brown, J. Biol. Chem. 2007). CD47 binds to its ligand signal regulatory protein α (SIRPα), thereby inhibiting macrophages' phagocytosis (Matozaki T, et al., Trends Cell Biol. 2009). Studies have confirmed that CD47 is overexpressed in many malignancies, such as acute myeloid leukemia (AML), B-cell and T-cell acute leukemia and non-Hodgkin lymphoma, and evades immune surveillance by sending “don't eat me” signals to macrophages, and high expression of CD47 is associated with poor clinical prognosis (Willingham et al. Proc Natl Acad Sci USA. 2012).
U.S. patent application 2009/0191202 discloses that professor Weissman's team from Stanford University conducted an experiment with a xenograft animal model of orthotopic immunodeficient mice and found that the administration of anti-CD47 monoclonal antibodies could inhibit the growth and metastasis of large tumors and cure small tumors. U.S. patent application 2016/0251435 discloses the use of anti-CD47 monoclonal antibodies in the treatment of tumors. The patent application WO2013056352 describes the use of humanized anti-human SIRPα full-length monoclonal antibodies and antibody fragments derived therefrom in the treatment of hematological tumors, particularly leukemia. Blocking the CD47-SIRPα signaling pathway can promote the phagocytosis of tumor cells by macrophages, providing a new means for tumor immunotherapy.
The present invention provides antibodies that recognize and bind to CD47. In some embodiments, the antibodies disclosed herein are capable of recognizing and binding to human CD47. The antibodies disclosed herein can prevent CD47 from interacting with SIRPα without causing significant hemagglutination of red blood cells. The antibodies provided herein are collectively referred to as “CD47 antibodies”.
In some embodiments, the CD47 antibodies disclosed herein exhibit a variety of desirable properties, such as, according to non-limiting embodiments, specifically recognizing human or macaque CD47, effectively blocking the interaction between CD47 and its ligand SIRPα without causing significant hemagglutination of red blood cells, and having effective antitumor activity.
In some embodiments, the present invention provides an antibody or an antigen-binding fragment that specifically binds to human integrin-associated protein (CD47) and that comprises 1, 2, 3, 4, 5 or 6 of the below described VH CDR1, VH CDR2, CDR3, VL CDR1, VL CDR2 and VL CDR3, wherein:
In some embodiments, the present invention provides an antibody or an antigen-binding fragment that specifically binds to human integrin-associated protein (CD47) and that comprises 1, 2, 3, 4, 5 or 6 of the below described VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2 and VL CDR3 wherein:
In some embodiments, the present invention provides an antibody or an antigen-binding fragment that specifically binds to human integrin-associated protein (CD47) and that comprises 1, 2, 3, 4, 5 or 6 of the following sequences:
In some embodiments, the present invention provides an antibody or an antigen-binding fragment that specifically binds to human integrin-associated protein (CD47) and that comprises:
In some embodiments, the antibody or the antigen-binding fragment comprises a heavy chain variable region VH, which comprises an amino acid sequence selected from any one of SEQ ID NOs: 11, 36-44, 50 and 56, or an amino acid sequence having at least 90% sequence identity to an amino acid sequence of any one of SEQ ID NOs: 11, 36-44, 50 and 56.
In some embodiments, the antibody or the antigen-binding fragment comprises a light chain variable region VL, which comprises an amino acid sequence selected from any one of SEQ NOs: 12-13, 45-49, 51-55 and 65, or an amino acid sequence having at least 90% sequence identity to an amino acid sequence of any one of SEQ ID NOs: 12-13, 45-49, 51-55 and 65.
In some embodiments, the present invention provides an antibody or an antigen-binding fragment that specifically binds to human integrin-associated protein (CD47) and that comprises VH CDR1 set forth in SEQ ID NO: 14, VH CDR2 set forth in SEQ ID NO: 17, VH CDR3 set forth in SEQ ID NO: 23, VL CDR1 set forth in SEQ ID NO: 30, VL CDR2 set forth in SEQ ID NO: 32, and VL CDR3 set forth in SEQ ID NO: 34.
In some embodiments, the antibody or the antigen-binding fragment comprises a heavy chain variable region VH, which comprises one or more amino acid residue mutations according to Kabat numbering selected from the group consisting of:
In some embodiments, the antibody or the antigen-binding fragment comprises a heavy chain variable region VH, which comprises an amino acid sequence selected from any one of SEQ ID NOs: 11 and 50, or an amino acid sequence having at least 90% sequence identity to an amino acid sequence of any one of SEQ ID NOs: 11 and 50.
In some embodiments, the antibody or the antigen-binding fragment comprises a light chain variable region VL, which comprises an amino acid sequence selected from any one of SEQ ID NOs: 13, 45-49, 51-55 and 65, or an amino acid sequence having at least 90% sequence identity to an amino acid sequence of any one of SEQ ID NOs: 13, 45-49, 51-55 and 65.
In some embodiments, the antibody or the antigen-binding fragment comprises a heavy chain variable region VH and a light chain variable region VL; the VH comprises an amino acid sequence selected from SEQ ID NOs: 11 and 50, and the VL comprises an amino acid sequence selected from SEQ ID NOs: 13 and 65.
In some embodiments, the CD47 antibody disclosed herein specifically recognizes and binds to human or macaque CD47; the antibody comprises a heavy chain variable region of an amino acid sequence selected from any one of SEQ ID NOs: 11, 36-44 and 50 and/or a light chain variable region of an amino acid sequence selected from any one of SEQ ID NOs: 12, 13, 45-49, 51-55 and 65.
In some embodiments, the antibody or the antigen-binding fragment comprises a heavy chain H and a light chain L; the heavy chain H comprises an amino acid sequence selected from any one of SEQ ID NOs: 60 and 62-63, and the light chain L comprises an amino acid sequence selected from any one of SEQ ID NOs: 61 and 64.
In some embodiments, the CD47 antibody disclosed herein block at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 95%, or at least 99% of the interaction between CD47 and SIRPα occurred in the absence of the CD47 antibody.
In some embodiments, the antibody comprises a heavy chain constant region and/or a light chain constant region; the heavy chain constant region comprises an amino acid sequence selected from SEQ IO NOs: 3 and 4, and the light chain constant region comprises an amino acid sequence selected from SEQ ID NO: 5.
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EYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLTC
LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRW
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In some embodiments, the CD47 antibodies disclosed herein do not cause significant cell agglutination; for example, the CD47 antibodies disclosed herein do not cause significant hemagglutination of red blood cells. In some embodiments, if the level of agglutination occurred in the presence of the CD47 antibodies disclosed herein decreases by at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 99% compared to the level of agglutination occurred in the presence of the existing CD47 antibody Hu5P9-G4, the CD47 antibodies disclosed herein are shown not to cause significant agglutination. In some embodiments, the CD47 antibodies disclosed herein do not cause significant cell agglutination when at an antibody concentration between 400 μM and 800 nM.
In some embodiments, the antibodies disclosed herein are also significantly effective in tumor models compared to known antibodies in the art. For example, the ability of macrophages to phagocytose tumor cells is increased by at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90% or at least 99% in the presence of the CD47 antibodies disclosed herein.
In some embodiments, the antibody or the antigen-binding fragment is of an IgG isotype selected from the group consisting of IgG1 isotype, IgG2 isotype, IgG3 isotype and IgG4 isotype. In some embodiments, the antibody or the antigen-binding fragment is of an IgG isotype selected from IgG4P and IgG4PE. IgG4P refers to the mutation of the Ser228 site of the hinge region of IgG4 into Pro to prevent chain exchange. IgG4PE refers to the mutation of the Ser228 site of the hinge region of IgG4 into Pro to prevent chain exchange and the mutation of Leu235 of the constant region into Glu to alter the interaction with an Fc receptor.
In some embodiments, the antibody is chimeric, humanized or fully human. In some embodiments, the antibody binds to human CD47.
In some embodiments, the CD47 antibody or antigen-binding fragment is an isolated CD47 antibody or antigen-binding fragment.
In some embodiments, the CD47 antibody or antigen-binding fragment disclosed herein is a monoclonal antibody or fragment thereof.
In some embodiments, the CD47 antibodies or antigen-binding fragments disclosed herein can be used in the manufacture of medicaments for treating cancer or infection. In some embodiments, the CD47 antibodies or antigen-binding fragments disclosed herein can be used in the manufacture of medicaments for treating solid tumors or hematological tumors. In some embodiments, the CD47 antibodies or antigen-binding fragments disclosed herein can be used in the manufacture of medicaments for treating non-Hodgkin lymphoma (NHL), acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), multiple myeloma (MM), breast cancer, ovarian cancer, head and neck cancer, bladder cancer, melanoma, colorectal cancer, pancreatic cancer, lung cancer, leiomyoma, leiomyosarcoma, glioma, glioblastoma, breast cancer, ovarian cancer, lung cancer, prostate cancer, melanoma, colorectal cancer, head and neck cancer, bladder cancer, esophageal cancer, liver cancer and renal cancer. In some embodiments, the CD47 antibodies or antigen-binding fragments disclosed herein can be used in the manufacture of medicaments for treating diffuse large B-cell lymphoma or follicular lymphoma.
In some embodiments, the CD47 antibodies disclosed herein can be used to treat, delay the progression of, avoid relapses of, or alleviate the symptoms of cancer or other neoplastic conditions. For example, the CD47 antibodies disclosed herein can be used to treat hematological malignancies and/or tumors, e.g., hematological malignancies and/or tumors. For example, the CD47 antibodies disclosed herein can be used to treat CD47+ tumors. By way of non-limiting example, the CD47 antibodies disclosed herein can be used to treat non-Hodgkin lymphoma (NHL), acute lymphocytic leukemia (ALL), acute myelogenous leukemia (ANIL), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), multiple myeloma (MM), breast cancer, ovarian cancer, head and neck cancer, bladder cancer, melanoma, colorectal cancer, pancreatic cancer, lung cancer, leiomyoma, leiomyosarcoma, glioma, glioblastoma, etc. Solid tumors include, for example, breast cancer, ovarian cancer, lung cancer, prostate cancer, melanoma, colorectal cancer, head and neck cancer, bladder cancer, esophageal cancer, liver cancer and renal cancer. For example, the CD47 antibodies disclosed herein can be used to treat diffuse large B cell lymphoma or follicular lymphoma.
As used herein, “hematological cancer” includes leukemia, lymphoma, myeloma, etc. “Leukemia” refers to hematologic cancer that produces too many white blood cells that are not effective against infection, which crowd out other components that constitute the blood, such as platelets and red blood cells. Cases of leukemia can be acute or chronic. By ways of non-limiting example, leukemia can include acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), myeloproliferative diseases/tumors (MPDS) and myelodysplastic syndrome. “Lymphoma” can include Hodgkin lymphoma, indolent and aggressive non-Hodgkin lymphoma, Burkitt lymphoma, follicular lymphoma (small cell and large cell), etc. Myeloma can include multiple myeloma (MM), giant cell myeloma, heavy chain myeloma and light chain or Bence-Jones myeloma.
Exemplary monoclonal antibodies of the present invention include, for example, the antibodies disclosed herein. Exemplary antibodies include ones having a heavy chain variable region of an amino acid sequence selected from any one of SEQ ID NOs: 11, 36-44, 50 and 56 and a light chain variable region of an amino acid sequence selected from any one of SEQ ID NOs: 12, 13, 45-49, 51-55 and 65. The antibodies also include ones having a heavy chain variable region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or higher identity to at least one of the sequences SEQ ID NOs: 11, 36-44. 50 and 56 and a light chain variable region having at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or higher identity to at least one of the sequences SEQ NOs: 12, 13, 45-49, 51-55 and 65. These antibodies exhibit specificity for human CD47 and can prevent CD47 from interacting with SIRPα without causing significant hemagglutination of red blood cells.
In some embodiments, the present invention also provides a biomaterial, which is
The pharmaceutical compositions disclosed herein can comprise the antibodies disclosed herein and pharmaceutically acceptable carriers. These pharmaceutical compositions can be contained in a kit, such as a diagnostic kit.
The present invention also provides a method for alleviating the symptoms of cancer or other neoplastic conditions by administering to a subject in need one or more monoclonal antibodies that hind to CD47 or immunologically active fragments thereof; the antibodies will not cause significant hemagglutination of red blood cells after administration. The antibody should be administered at a dose sufficient to alleviate the symptoms of cancer or other neoplastic conditions in the subject. In some embodiments, the subject is a human. In some embodiments, the antibodies or the immunologically active fragments thereof prevent CD47 from interacting with SIRPα.
In some embodiments, the CD47 antibodies disclosed herein are used in combination with one or more other agents. Suitable other agents include existing drugs and/or surgical therapies for particular applications (such as cancer). For example, the CD47 antibodies used in combination with one or more other chemotherapeutic or antitumor agents. Alternatively, the other chemotherapeutic agent is radiotherapy. In some embodiments, the chemotherapeutic agent is an apoptosis inducer. In some embodiments, the chemotherapeutic agent induces an asymmetry loss of cross plasma membrane phospholipid, e.g., causing cell surface exposure of phosphatidylserine (PS). In some embodiments, the chemotherapeutic agent induces endoplasmic, reticulum (ER) stress. In some embodiments, the chemotherapeutic agent is a proteasome inhibitor. In some embodiments, the chemotherapeutic agent induces the translocation of ER proteins to the cell surface. In some embodiments, the chemotherapeutic agent induces the translocation and cell surface exposure of calreticulin.
In some embodiments, the anti-CD47 antibody and the other agent are formulated into a single therapeutic composition, and the anti-CD47 antibody and the other agent are administered simultaneously. Alternatively, the anti-CD47 antibody and the other agent are separated from each other, for example, are each formulated into a separate therapeutic composition, and the anti-CD47 antibody and the other agent are administered simultaneously, or the anti-CD47 antibody and the other agent are administered at different times during a treatment regimen. For example, the CD47 antibody is administered prior to the administration of the other agent, the CD47 antibody is administered subsequent to the administration of the other agent, or the CD47 antibody and the other agent are administered in an alternating manner. In the present invention, the anti-CD47 antibody and the other agent are administered in single doses or in multiple doses.
In some embodiments, provided is the use of the antibody or the antigen-binding fragment, the composition and the biomaterial disclosed herein in the manufacture of medicaments for treating cancer or infection.
It will be understood by those skilled in the art that the antibodies disclosed herein can be widely used. For example, the antibodies disclosed herein can be used as therapeutic agents, reagents in diagnostic kits or diagnostic tools, or reagents in competitive experiments to produce therapeutic agents.
The present invention provides antibodies that specifically bind to CD47. In some embodiments, the antibodies disclosed herein are capable of specifically binding to human CD47. These antibodies are collectively referred to herein as anti-CD47 antibodies. Unless otherwise stated herein, the amino acid residues in the variable regions and constant regions of antibodies are numbered according to the Kabat scheme (Kabat et al., 1991, EU indexes in Sequences of Proteins of Immunological Interest).
Some properties of the antibodies disclosed herein include: a) specifically binding to CD47 (e.g., human CD47 and macaque CD47); b) blocking the interaction between CD47 and SIRPα; c) not having significant hemagglutination activity; d) being capable of promoting the phagocytosis of tumor cells by macrophages; and/or e) showing effective antitumor activity in mouse models of human cancer.
Thus, the antibodies disclosed herein play an important role in the treatment of a variety of cancers.
Many existing CD47 antibodies block SIRPα; however, the existing antibodies that block SIRPα can cause an unwanted side effect—hemagglutination. Other existing antibodies (such as 2D3) do not cause hemagglutination; however, these antibodies do not block SIRPα either, rendering them ineffective in the promotion of phagocytosis. Therefore, cell agglutination is a major limitation on the uses of the existing full-length IgG antibodies to therapeutically target CD47. Therefore, there is an urgent need for CD47 antibodies that are capable of blocking SIRPα without causing cell aggregation.
The CD47 antibodies disclosed herein avoid unwanted hemagglutination, thereby increasing the effectiveness of therapeutic targeting CD47, and maintain the ability to block the interaction between CD47 and SIRPα, thereby promoting phagocytosis of CD47-expressing cells. In some embodiments, the CD47 antibodies disclosed herein (e.g., Antibody L12 and Antibody L12-6) do not agglutinate cells at significant levels. For example, the CD47 antibodies disclosed herein do not agglutinate RBCs at significant levels.
The CD47 antibodies disclosed herein bind to human CD47 and block its interaction with SIRPα (
The antibody disclosed herein binds to the CD47 epitope with an equilibrium dissociation constant (KD) of less than or equal to 1 μM, e.g., less than or equal to 100 nM, such as less than or equal to 10 nM, or less than or equal to 1 nM. For example, the CD47 antibodies provided herein exhibit KD values of less than 1 nM.
The CD47 antibodies disclosed herein serve to modulate, block, inhibit, reduce, antagonize, neutralize or interfere with the functional activity of the widely distributed CD47. Functional activities of CD47 include, for example, signaling via the interaction with SIRPα, modulating (e.g., increasing) intracellular calcium ion concentration upon cell adhesion to the extracellular matrix, interacting with the C-terminal cell binding domain of thrombospondin, interacting with fibrinogen, and interacting with various integrins. For example, the CD47 antibodies completely or partially inhibit the functional activity of CD47 by partially or completely modulating, blocking, inhibiting, reducing, antagonizing, neutralizing or interfering with the binding of CD47 to SIRPα.
Unless otherwise defined, scientific and technical terms used in the present invention have the meanings that are commonly understood by those skilled in the art. Generally, the nomenclature and techniques used in cell culture, molecular biology and protein purification described herein are well known and commonly used in the art. Standard techniques are used for recombinant DNA, oligonucleotide synthesis and cell culture and transformation (e.g., electroporation and lipofection). Enzymatic reactions and purification techniques are performed according to the manufacturer's instructions, or methods commonly used in the art or described herein. The aforementioned techniques and methods are generally used as described in various comprehensive and specific documents that are well known in the art and that are cited and discussed in this specification. See, e.g., Sambrook et al., Molecular Cloning: A Laboratory Manual (the 2nd edition, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989)).
As used in this disclosure, unless otherwise stated, the following terms shall be understood to have the following meanings: The terms “red blood cell” and “erythrocyte” are synonymous and are used interchangeably.
The term “agglutination” refers to clumping of cells, while the term “hemagglutination” refers to clumping of a particular type of cells (i.e., red blood cells). Therefore, hemagglutination is one type of agglutination. In the hemagglutination assay described herein, red blood cells form in a given well a form that can be a “button”, a “halo” or an intermediate between the two. The term “in a line” means that masses of red blood cells flow in a line upon tilting the 96-well plate 45°. The term “significant hemagglutination activity” refers to the presence of any halo form in the well upon addition of the antibodies described herein.
The term “antibody” as used herein refers to immunoglobulin (Ig) molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen-binding site that specifically binds to (immunoreacts with) an antigen. By “specifically bind” or “immunoreact” or “directed against” is meant that the antibody reacts with one or more antigenic determinants of the target antigen and does not react with other polypeptides, or binds to other polypeptides with very low affinity (KD>10−6 g/mL). Antibodies include, but are not limited to, monoclonal antibodies, chimeric antibodies, dAbs (domain antibodies), single-chain antibodies, Fab, Fab- and F(ab′)2 fragments, Fv and Fab expression libraries.
The basic antibody structural unit is known to comprise a tetramer. Each tetramer (or “full-length antibody”) is composed of two identical pairs of polypeptide chains, each pair having one “light” chain (about 25 kDa) and one “heavy” chain (about 50-70 kDa). The amino-terminal portion of each chain includes a variable region of about 100 to 110 or more amino acids primarily responsible for antigen recognition. The carboxy-terminal portion of each chain defines a constant region primarily responsible for effector function. In general, antibody molecules obtained from humans relate to any of the classes IgG, IgM, IgA, IgE and IgD, which differ from each other by the nature of the heavy chain present in the molecule. Certain classes also have subclasses, such as IgG1, IgG2, and others. Furthermore, in humans, the light chain may be a κ chain or a λ chain.
As used herein, the term “monoclonal antibody” (mAb) refers to a population of antibody molecules that contain only one molecular species of the antibody molecules consisting of a unique light chain gene product and a unique heavy chain gene product. In particular, the complementarity-determining regions (CDRs) of the monoclonal antibody are identical in all the molecules of the population. MAbs contain an antigen-binding site capable of immunoreacting with a particular epitope of an antigen.
The term “single-chain antibody” (scFv) refers to an antibody in which its heavy chain variable region (VH) and light chain variable region (VL) are linked by a linker of 15-20 amino acids.
The term “antigen-binding site” or “binding portion” refers to the portion of an immunoglobulin molecule that is involved in antigen binding. The antigen-binding site is formed from amino acid residues of the N-terminal variable (“V”) region of the heavy (“H”) chain and the light (“L”) chain. Three highly differentiated branches (referred to as “hypervariable regions”) in the heavy chain variable region (VH) and light chain variable region (VL) are located between more conserved branches (referred to as “framework regions” or “FRs”). Thus, the term “FR” refers to amino acid sequences that naturally occur between or adjacent to hypervariable regions in immunoglobulins. In an antibody molecule, the three hypervariable regions of a light chain and the three hypervariable regions of a heavy chain are arranged relative to each other in three-dimensional space to form an antigen-binding surface. The antigen-binding surface is complementary to the three-dimensional surface of the bound antigen, and the three hypervariable regions of each of the heavy chains and light chains are referred to as “complementarity-determining regions” or “CDRs”. The alignment of amino acids to each domain can be in accordance with the definitions of Kabat Sequences of Proteins of Immunological Interest (National Institutes of Health (1987 and 1991)) or Chothia and Lesk's articles (J. Mol. Biol, 196:901-917 (1987); Chothia et al., Nature 342:878-883 (1989)).
The term “epitope” as used herein includes any protein determining region that can specifically hind to an immunoglobulin or a fragment thereof or a T cell receptor. The epitope determinant generally consists of chemically active surface groups of molecules (such as amino acids or sugar side chains), and usually has specific three-dimensional structural properties and specific charge properties.
As used herein, the term “specific binding” refers to the type of non-covalent interactions that occur between an immunoglobulin molecule and an antigen for which the immunoglobulin is specific. The strength or affinity of an immunological binding interaction can be expressed in terms of the equilibrium dissociation constant (KD) of the interaction, where a smaller KD represents a greater affinity. The immunological binding properties of the selected polypeptides may be quantified using methods well known in the art. One such method requires the measurement of the rates of antigen-binding site/antigen complex formation and dissociation, where those rates depend on the concentration of the complex partners, the affinity of the interaction and geometric parameters that affect the rates equally in both directions. Thus, both “association rate constant” (kon) and “dissociation rate constant” (koff) can be determined by calculating the concentration and the actual association and dissociation rates. (see Nature 361:186-87 (1993)). The ratio kon/koff can eliminate all the parameters that are independent of the affinity and is equal to the equilibrium dissociation constant KD. (generally see Davies et al. (1990) Annual Rev Biochem 59:439-473). Specific binding can be measured by radiolig and binding assays, surface plasmon resonance (SPR), flow cytometry binding assay, or similar assays known to those skilled in the art. When the equilibrium dissociation constant (KD)≤1 μM (e.g., less than or equal to 100 nM, less than or equal to 10 nM, or less than or equal to 1 nM), the antibodies disclosed herein specifically bind to CD47.
An “isolated” antibody is one that is isolated and/or recovered from a component of its natural environment. Contaminant components of its natural environment are substances that would interfere with diagnostic or therapeutic uses of the antibody, and can include enzymes, hormones, and other proteinaceous or non-proteinaceous solutes. In some embodiments, the antibody is purified to the following extent: (1) the percentage, by weight, of the antibody is greater than 95%, e.g., greater than 99%, as measured by the Lowry method; (2) at least 15 residues of the N-terminal or internal amino acid sequence can be obtained by using a. spinning cup sequenator; or (3) the antibody is homogeneous, as determined by reducing or non-reducing SDS-PAGE with Coomassie blue or silver staining. Isolated antibodies include antibodies in situ within recombinant cells. Typically, an isolated antibody will be prepared through at least one or more purification steps. In some embodiments, the purity of the isolated antibody is at least about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 99%, or within the range between any two of these values (inclusive), or any values therein.
The term “polypeptide” is used herein as a generic term to refer to native proteins, fragments or analogs of a polypeptide sequence. Thus, native protein fragments and analogs are members of the polypeptide genus.
The term “sequence identity” or “sequence homology” means that two polynucleotides or amino acid sequences are identical (i.e., are identical on a nucleotide-by-nucleotide or residue-by-residue basis) over the comparison window. The term “percentage of sequence identity” is calculated by comparing two optimally aligned sequences over the comparison window, determining the number of positions at which the identical nucleic acid base (e.g., T, C, G, U or I) or amino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the comparison window (i.e., the window size), and then multiplying the result by 100 to yield the percentage of sequence identity.
As used herein, the twenty conventional amino acids and their abbreviations follow conventional usage. See Immunology-A Synthesis (the 2nd edition, Eds. E. S. Golub and D. R. Gren, Sinauer Associates, Sunderland 7 Mass. (1991)). Stereoisomers (e.g., D-amino acids) of the twenty conventional amino acids, unnatural amino acids (such as αor α-disubstituted amino acids), N-alkyl amino acids, lactic acid, and other unconventional amino acids can also be suitable components for the polypeptides of the present disclosure. Examples of unconventional amino acids include: 4-hydroxyproline, γ-carboxyglutamate, ε-N,N,N-trimethyllysine, ε-N-acetyllysine, O-phosphoserine, N-acetylserine, N-formylmethionine, 3-methylhistidine, 5-hydroxylysine, σ-N-methylarginine and other similar amino acids and imino acids (e.g., 4-hydroxyproline). In the polypeptide notation used herein, the left-hand direction is the amino-terminal direction and the right-hand direction is the carboxy-terminal direction, in accordance with standard usage and convention. The conventional (natural) amino acids include alanine (three-letter symbol: Ala, one-letter symbol: A), arginine (Arg, R), asparagine (Asn, N), aspartic acid (Asp, D), cysteine (Cys, C), glutamine (Gln, Q), glutamic acid (Glu, E), glycine (Gly, G), histidine (His, H), isoleucine (Ile, I), leucine (Leu, L), lysine (Lys, K), methionine (Met, M), phenylalanine (Phe, F), proline (Pro, P), serine (Ser, S), threonine (Thr, T), tryptophan (Trp, W), tyrosine (Tyr, Y), and valine (Val, V).
Similarly, unless otherwise stated, the left-hand end of a single-stranded polynucleotide sequence is the 5′ end, and the left-hand direction of a double-stranded polynucleotide sequence is referred to as the 5′ direction. The direction of 5′ to 3′ addition of nascent RNA transcripts is referred to as the transcription direction; sequence regions on the DNA strand which have the same sequence as the RNA and are 5′ to the 5′ end of the RNA transcript are referred to as “upstream sequences”; sequence regions on the DNA strand which have the same sequence as the RNA and are 3′ to the 3′ end of the RNA transcript are referred to as “downstream sequences”. The term “substantially identical” when applied to polypeptides means that two peptide sequences, when optimally aligned, such as by the program GAP or BESTFIT using default gap weights, share at least 80% sequence identity, preferably at least 90% sequence identity, more preferably at least 95% sequence identity, and most preferably at least 99% sequence identity.
In some embodiments, residue positions that are not identical differ by conservative amino acid substitutions.
Minor variations in the amino acid sequences of antibodies or immunoglobulin molecules are contemplated by the present disclosure, provided that the identity of the amino acid sequences retains at least 75%, such as at least 80%, 90%, 95%, and as another example 99%. In some embodiments, the variations are conservative amino acid substitutions. Conservative amino acid substitutions are ones that occur within a family of amino acids that are related in their side chains. Genetically encoded amino acids are generally classified into the following categories: (1) acidic amino acids are aspartate and glutamate; (2) basic amino acids are lysine, arginine and histidine; (3) non-polar amino acids are alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan; and (4) uncharged polar amino acids are glycine, asparagine, glutamine, cysteine, serine, threonine and tyrosine. Amino acids of the other families include (i) serine and threonine of the aliphatic-hydroxy family; (ii) asparagine and glutamine of the amide-containing family; (iii) alanine, valine, leucine and isoleucine of the aliphatic family; and (iv) phenylalanine, tryptophan and tyrosine of the aromatic family. In some embodiments, conservative amino acid substitution groups are valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, glutamic acid-aspartic acid, and asparagine-glutamine. For example, it is reasonable to expect that the single replacement of leucine with isoleucine or valine, aspartate with glutamate, threonine with serine, or the similar replacement of an amino acid with a structurally related amino acid, will not have a major effect on the binding or properties of the resulting molecule, particularly when the replacement does not involve an amino acid within a binding site. Whether an amino acid change results in a functional peptide can be readily determined by determining the specific activity of the polypeptide derivative. The determination is described in detail herein. Fragments or analogs of antibodies or immunoglobulin molecules can be readily prepared by those of ordinary skill in the art.
In some embodiments, the amino acid substitutions have the following effects: (1) reducing susceptibility to proteolysis, (2) reducing susceptibility to oxidation, (3) altering the binding affinity for formation of protein complexes, (4) altering binding affinity, and (5) conferring or improving other physicochemical or functional properties of such analogs. Analogs can include various muteins whose sequences differ from the naturally occurring peptide sequences. For example, single or multiple amino acid substitutions (preferably conservative amino acid substitutions) may be made in the naturally occurring sequence (preferably in a portion of the polypeptide outside the domains that form intermolecular contacts). A conservative amino acid substitution should not significantly alter the structural characteristics of the parent sequence (e.g., a replacement amino acid should not tend to disrupt a helix that occurs in the parent sequence, or disrupt other types of secondary structures that characterize the parent sequence). Examples of secondary and tertiary structures of artificially recognized polypeptides are described in Proteins, Structures and Molecular Principles (Ed. Creighton, W. H. Freeman and Company, New York (1984)); Introduction to Protein Structure (Eds. C. Branden and J. Tooze, Garland Publishing, New York, N.Y. (1991)); and Thornton et al., Nature 354:105(1991).
The term “agent” as used herein means a chemical compound, a mixture of chemical compounds, a biological macromolecule, or an extract made from biological material.
As used herein, the term “label” or “labeled” refers to incorporation of a detectable marker, e.g., by incorporation of a radiolabeled amino acid or attachment to a polypeptide of biotinyl moieties that can be detected by marked avidin (e.g., streptavidin containing a fluorescent marker or having enzymatic activity that can be detected by optical or calorimetric methods).
In certain instances, the label or labels may also be therapeutic. Various methods for labeling polypeptides and glycoproteins are known in the art and can be used. Examples of labels for polypeptides include, but are not limited to: radioisotopes or radionuclides (e.g., 3H, 14C, 15N, 35S, 90Y, 99Tc, 111In, 125I and 131I), fluorescent labels (e.g., FITC, rhodainine and lanthanide phosphor), enzymatic labels (e.g., horseradish peroxidase, β-galactosidase, luciferase and alkaline phosphatase), chemiluminescent labels, biotinyl groups and predetermined polypeptide epitopes recognized by secondary reporter genes (e.g., leucine zipper pair sequences, secondary antibody-binding sites, metal binding domains and epitope tags). In some embodiments, the labels are connected by spacer arms of various lengths to reduce potential steric hindrance.
The term “agent” or “drug” refers to a compound or composition that is capable of inducing the desired therapeutic effect when properly administered to a patient.
The term “antitumor agent” as used herein refers to an agent having the functional property of inhibiting in a human the development or progression of a tumor, particularly a malignant (cancerous) lesion, such as cancer, sarcoma, lymphoma or leukemia. Inhibition of metastasis is a property of antineoplastic drugs in many cases.
Other chemical terms herein are used according to conventional usage in the art, such as The McGraw-Hill Dictionary of Chemical Terms (Ed. Parker, S., McGraw-Hill, San Francisco (1985)).
The antibodies disclosed herein have the ability to bind to CD47 to inhibit the binding of SIRPα to CD47, to reduce CD47-SIRPα-mediated signaling, to promote phagocytosis, and to inhibit tumor growth and/or metastasis. For example, inhibition can be determined using the cellular assay described herein in the examples.
Exemplary antibodies disclosed herein include Antibody 17, Antibody L12, Antibody 6Y-G1, Antibody 6Y-G4, etc., as well as other similar antibodies having the same or similar CDR regions.
The VH CDRs of Antibody 17 include SEQ ID NO: .14 (VH CDR1), SEQ ID NO: 17 (VH CDR2) and SEQ ID NO: 23 (VH CDR3), and the VL CDRs include SEQ ID NO: 31 (VL CDR1), SEQ NO: 33 (VL CDR2) and SEQ ID NO: 35 (VL CDR3). The VH CDRs are the hypervariable regions of the heavy chains and the VL CDRs are the hypervariable regions of the light chains.
In some embodiments, the present invention makes substitutions at one or more amino acid sites of VH CDR1, VH CDR2 and/or VH CDR3 based on Antibody 17. In some embodiments, the substitutable sites (parents) of VH CDR1, VH CDR2 and/or VH CDR3 and the amino acids that can be used for substitution are shown in one or more in Table 1. “Position” in Table 1 represents amino acid sites of the amino acid sequence set forth in SEQ ID NO: 11 numbered from left to right; for example, position 30 represents the 30th amino acid “D”, from left to right, in the amino acid sequence set forth in SEQ ID NO: 11.
The VH CDRs of Antibody L12 and Antibody L12-6 include SEQ ID NO: 14 (VH CDR1), SEQ ID NO: 17 (VH CDR2) and SEQ ID NO: 23 (VH CDR3), and the VL CDRs include SEQ ID NO: 30 (VL CDR1), SEQ ID NO: 32 (VL CDR2) and SEQ ID NO: 34 (VL CDR3).
It has been confirmed by experiment that the VH CDR1 sequence may also be SEQ ID NO: 15 or 16. The VH CDR2 sequence may also be SEQ ID NO: 18, 19, 20, 21 or 22. The VH CDR3 sequence may also be SEQ ID NO: 24, 25, 26, 27, 28 or 29. Other CDR sequences can be achieved by amino acid substitutions as shown in Table 1. In some embodiments, 1, 2 or 3 amino acids are substituted.
In addition to changes in the CDRs, proper changes can also be made to the amino acids of framework regions. For example, L12-1-VH; L12-2-VH, L12-3-VH, L12-6-1-VH, L12-6-VH, L12-8-VH or L12-9-VH produced by making two mutations (R81K and R82aS) relative to the framework region of the heavy chain of Antibody L12 is also a suitable heavy chain variable region. In some embodiments, the heavy chain variable region of the CD47 antibody may have a K at position 81 or an S at position 82a (according to Kabat numbering). Other framework region mutations are also present in different antibody sequences.
Accordingly, the present invention provides heavy chain framework regions having R81K and/or R82aS (according to Kabat numbering) mutations.
Exemplary antibodies of the present invention include ones that comprise a heavy chain variable region of a sequence selected from SEQ ID NOs: 11, 36-44, 50 and 56 and a light chain variable region of a sequence selected from SEQ ID NOs: 12-13, 45-49, 51-55 and 65. In particular, exemplary antibodies include Antibody 17, Antibody 3-3, Antibody 3-6, Antibody 3, Antibody 6, Antibody 10, Antibody 11, Antibody 16, Antibody 18, Antibody 24, Antibody 25, Antibody L1, Antibody L2, Antibody L5, Antibody L12-1-1, Antibody L12, Antibody L24, Antibody L26, Antibody L12-1, Antibody L12-2, Antibody L12-3, Antibody L12-4, Antibody L12-5, Antibody L12-6-1, Antibody L12-6, Antibody L12-7, Antibody L12-8, Antibody L12-9, Antibody L12-10 and Antibody L12-11, and also ones with suitable sequence identity to the sequences of the antibodies described above, for example, sharing at least 80% sequence identity, preferably at least 90% sequence identity, more preferably at least 95% sequence identity, and most preferably at least 99% sequence identity. In some embodiments, these sequences with identity at least do not have varied CDRs.
In some embodiments, Antibody 1,12 is subjected to human framework adaptation. In some embodiments, framework mutations fix the VH of Antibody L12 are shown as the underlined amino acids of L12-1-VH, L12-2-VH, L12-3-VH, L12-6-1-VH, L12-6-VH, L12-8-VH or L12-9-VH in Table 3. In some embodiments, framework mutations for the VL of Antibody L12 are shown as the underlined amino acids of L12-1-1-VL, L12-1-VL, L12-2-VL, L12-3-VL, L12-4-VL, L12-5-VL, L12-6-1-VL, L12-7-VL, L12-8-VL, L12-9-VL, L12-10-VL air L12-11-VL in Table 3.
The present invention further comprises an antibody that binds to the same epitope as the anti-CD47 antibodies disclosed herein. For example, the antibodies disclosed herein specifically bind to an epitope that comprises one or more amino acid residues on human CD47 (see, e.g., GenBank accession No. Q08722.1).
Provided below is an exemplary human CD47 ECD amino acid sequence SEQ ID NO: 1 (GenBank accession No. Q08722.1 (GI: 1171879)), which is incorporated herein by reference. The signal sequence (amino acids 1-18) is underlined.
MWPLVAALLLGSACCGSAQLLFNKTKSVEFTFCNDTVVIPCFVTNMEAQN
The ability of the antibodies disclosed herein to modulate, block, inhibit, reduce, antagonize, neutralize or otherwise interfere with CD47- and/or CD47/SIRPα-mediated signaling can be assessed using methods including measuring CD47- and/or CD47/SIRPα-mediated signaling in the presence of one or more antibodies described herein. These assays can include competitive binding assays or can measure a biological readout, for example, the ability to promote phagocytosis of CD47-expressing cells by macrophages (as described in Example 3).
The antibodies disclosed herein can be produced using various methods known in the art (e.g., Antibodies: A Laboratory Manual, Harlow E and Lane D, 1988, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., which is incorporated herein by reference). Fully human antibodies are antibody molecules in which the entire sequences (including the CDRs) of both the light and heavy chains are derived from a human gene. Such antibodies are referred to herein as “human antibodies” or “fully human antibodies”. Human monoclonal antibodies can be produced by using the trioma technique, the human B-cell hybridoma technique (see Kozbor et al., 1983 Immunol Today 4:72), and the EBV hybridoma technique (see Cole et al., 1985. In: Monoclonal Antibodies And Cancer Therapy, Alan R. Liss, Inc., pp. 77-96) to produce human monoclonal antibodies. Human monoclonal antibodies can be utilized and can be produced by using human hybridomas (see Cote et al., 1983. Proc Natl Acad Sci USA 80:2026-2030) or by transforming human B-cells with Epstein Barr Virus in vitro (see Cole et al., 1985. In: Monoclonal Antibodies And Cancer Therapy, Alan R. Liss, Inc., pp. 77-96).
Antibodies can be purified by known techniques, such as affinity chromatography using protein A or protein G, which provides primarily the IgG fraction of immune serum. In addition, the specific antigen targeted by the immunoglobulin, or an epitope thereof, can be immobilized on a column to purify the immune specific antibody by immunoaffinity chromatography. For purification of immunoglobulins, reference can be made to the D. Wilkinson's article (The Scientist, published by the Scientist, Inc., Philadelphia. Pa., Vol. 14, No. 8 (Apr. 17, 2000), pp. 25-28).
The CD47 antibodies disclosed herein can be monoclonal antibodies. Monoclonal antibodies that modulate, block, inhibit, reduce, antagonize, neutralize or otherwise interfere with CD47- and/or CD47/SIRPα-mediated cell signaling are produced, for example, by immunizing an animal with, for example, membrane-bound and/or soluble CD47 (e.g., human CD47 or an immunogenic fragment, derivative or variant thereof). Alternatively, the animal is immunized with cells transfected with a vector containing a nucleic acid molecule encoding CD47 such that CD47 is expressed and associated with the surface of the transfected cells. Alternatively, the antibodies are obtained by screening a library that contains antibody or antigen-binding domain sequences for binding to CD47. The library is prepared by expressing fusions of the proteins or peptides fused with the phage coat protein on the surface of assembled phage particles and incorporating encoding DNA sequences into the phage particles (i.e. “phage displayed library”). Screening was then performed by binding reaction with CD47.
For preparing monoclonal antibodies using, for example, hybridoma methods, see, e.g., those described by Kohler and Milstein, Nature, 256:495 (1975). In the hybridoma method, a mouse, a hamster or other appropriate host animal, is typically immunized with an immunizing agent to elicit lymphocytes that produce or are capable of producing antibodies that specifically bind to the immunizing agent. Alternatively, the lymphocytes can be immunized in vitro.
The immunizing agent generally includes a protein antigen, a fragment thereof or a fusion protein thereof. Generally, if a human cell is desired, a peripheral blood lymphocyte is used, or if a cell of non-human mammalian origin is desired, a spleen cell or lymph node cell is used. The lymphocyte is then fused with an immortalized cell line using a suitable fusing agent, such as polyethylene glycol, to form a hybridoma cell (Goding, Monoclonal Antibodies: Principles and Practice, Academic Press, (1986) pp. 59-103). Immortalized cell lines are usually rat or mouse myelorna cell lines. The hybridoma cell may be cultured in a suitable culture medium preferably containing one or more substances that inhibit the growth or survival of unfused immortalized cells. For example, if the parent cells lack hypoxanthine-guanine phosphoribosyltransferase (HGPRT or HPRT), the culture medium for the hybridoma generally contains hypoxanthine, aminopterin and thymine (“HAT medium”), which prevent the growth of HGPRT-deficient cells.
The monoclonal antibody can also be prepared by recombinant DNA methods, such as those described in U.S. Pat. No, 4,816,567. DNA encoding the monoclonal antibody disclosed herein can be isolated and sequenced using conventional methods (e.g., by using oligonucleotide probes that can specifically bind to genes encoding the heavy and light chains of murine antibodies). The hybridoma cell described herein serves as a preferred source of such DNA. Once isolated, the DNA can be placed into expression vectors, which are then transfected into a host cell such as a Chinese hamster ovary (CHO) cell, a human embryonic kidney (HEK) 293 cell, a simian COS cell, a PER. NS0 cell, a SP2/0 cell, a YB2/0 cell or a myeloma cell that does not otherwise produce immunoglobulins, thereby obtaining a synthetic monoclonal antibody in the recombinant host cell. The DNA can also be modified, for example, by substituting the coding sequence for human heavy and light chain constant domains for the homologous murine sequences (see U.S. Pat, No, 4,816,567; Morrison, Nature 368. 812-13(1994)) or by covalently linking the immunoglobulin coding sequence to all or part of the coding sequence for a non-immunoglobulin polypeptide. Such a non-immunoglobulin polypeptide can be substituted for the constant domains of the antibodies disclosed herein, or can be substituted for the variable domains of one antigen-binding site of the antibodies disclosed herein to produce chimeric bivalent antibodies.
Antibody-producing cell lines can be selected, constructed and cultured using techniques well known to those skilled in the art. These techniques are described in various laboratory manuals and main publications, such as Recombinant DNA Technology for Production of Protein Therapeutics in Cultured Mammalian Cells, D. L. Hacker, F. M. Wurm, Reference Module in Life Sciences, 2017, which is incorporated by reference in its entirety, including the supplements.
In some embodiments, the DNA encoding the antibody can be designed and synthesized according to the antibody amino acid sequence described herein by conventional methods, inserted into an expression vector, and transfected into a host cell. The transfected host cell is then cultured in a medium to produce the monoclonal antibody. In some embodiments, the vector expressing the antibody comprises at least one promoter element, an antibody coding sequence, a transcription termination signal and a poly-A tail. Other elements include enhancers, Kozak sequences, and donor and recipient sites flanking the inserted sequence for RNA splicing. Efficient transcription can be obtained by early and late promoters of SV40, long terminal repeats from retroviruses such as RSV, HTLV1 HIV1, and early promoters of cytomegalovirus, and promoters from other cells such as actin promoter can also be used. Suitable expression vectors may include pIRES1neo, pRetro-Off, pRetro-On, PLXSN, or Plncx, pcDNA3.1 (+/−), pcDNA/Zeo (+/−), pcDNA3.1/Hygro(+/−), PSVL, PMSG, pRSVcat, pSV2dhfr, pBC12MI, pCS2. etc. Commonly used mammalian cells include 293 cells, Cos1 cells, Cos7 cells, CV1 cells, murine L cells, CHO cells and the like.
In some embodiments, the inserted gene fragment should comprise a screening label, common ones of which include screening genes such as dihydrofolate reductase, glutamine synthetase, neomycin resistance and hygromycin resistance, to facilitate the screening and separation of cells that have been successfully transfected. The constructed plasmid is transfected to a host cell without the above genes, and the successfully transfected cells are cultured in large quantities in a selective culture medium to produce the desired target protein.
In some embodiments, the DNA sequences encoding the CD47 antibodies disclosed herein can be obtained using the amino acid sequences of the antibodies in combination with the conventional methods in the art. In some embodiments, the DNA sequence encoding the heavy chain of Antibody 6Y-G4 is set forth in SEQ ID NO: 57, wherein the underlined portions encode VH CDRs; the amino acid sequence encoding the heavy chain of Antibody 6Y-G4 is set forth in SEQ ID NO: 60.
SEQ ID NO: 57 is shown below:
ggagctggatccggcagcctcctggcaagggcctggagtggatcggctac
atctactattccggcaacaccaattacaacccttccctgaagagccgggt
ttctggagagatattggggccagggtaccctcgtgaccgtgtccagcgct
In some embodiments, the DNA sequence encoding the light chain of Antibody 6Y-G4 is set forth in SEQ ID NO: 58, wherein the underlined portions encode VL CDRs; the amino acid sequence encoding the light chain of Antibody 6Y-G4 light chain is set forth in SEQ ID NO: 61.
SEQ ID NO: 58 is shown below:
actggtatcagcagaggcctggcgaggcccctaagctgctgatctttgcc
gcttccagcctgcggagcggcgtgcctagcaggttctccggcagcggctc
In some embodiments, the amino acid sequence of the heavy chain of Antibody 6Y-G1 is set forth in SEQ ID NO: 62.
In some embodiments, the amino acid sequence of the light chain of Antibody 6Y-G1 is set forth in SEQ ID NO: 61.
In some embodiments, the amino acid sequence of the heavy chain of Antibody 17 is set forth in SEQ ID NO: 63.
In some embodiments, the amino acid sequence of the light chain of Antibody 17 is set forth in SEQ ID NO: 64.
In some embodiments, the amino acid sequence of the heavy chain of Antibody L12 is set forth in SEQ ID NO: 63. In some embodiments, the amino acid sequence of the light chain of Antibody L12 is set forth in SEQ ID NO: 61.
The antibodies disclosed herein include fully human antibodies or humanized antibodies. These antibodies are suitable for administration to humans without causing immune responses in humans to the administered immunoglobulins.
The CD47 antibodies are produced, for example, through phage display methods using antibodies that contain only human sequences. Such methods are well known in the art, for example, in WO92/01047 and U.S. Pat. No. 6,521,404. In this method, a natural or recombinant CD47 or a fragment thereof is used to screen a combinatorial library of phage carrying random pairs of light and heavy chains. In another approach, the CD47 antibodies can be produced through a method in which at least one step comprises immunizing a transgenic non-human animal with human CD47 protein. In such approaches, some of the endogenous heavy and/or k light chain loci of transgenic non-human animals have been disabled and are incapable of the rearrangement required to produce genes encoding immunoglobulins in response to an antigen. In addition, at least one human heavy chain locus and at least one human light chain locus have been stably transfected into the animal. Thus, in response to the administered antigen, the human loci rearrange to provide genes encoding human variable regions immunospecific for the antigen. Thus, the transgenic mouse produces, upon immunization, B cells that secrete fully human immunoglobulins.
The production of antibodies with reduced immunogenicity is also achieved via humanization techniques, chimerization techniques and display techniques using appropriate libraries. It should be understood that murine antibodies or antibodies from other species can be humanized or primatized using techniques well known in the art. See. e.g., Winter and Harris Immunol Today 14:43 46(1993) and Wright et al., Crit. Reviews in Immunol. 12125-168(1992). The antibodies of interest can be engineered by recombinant DNA techniques to substitute CH1, CH2, CH3, hinge domains and/or framework domains with the corresponding human sequences (see WO 92102190 and U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,761; 5,693,792; 5,714,350 and 5, 777,085). The use of Ig cDNAs for the construction of chimeric immunoglobulin genes is also known in the art (Liu et al., P.N.A.S. 84:3439 (1987) and J. Immunol. 139:3521 (1987)). mRNA is isolated from hybridomas or other cells that produce the antibody and used to produce cDNA. The cDNA of interest can be amplified by polymerase chain reaction using specific primers (U.S. Pat. Nos. 4,683,195 and 4,683,202). Alternatively, a library is constructed and screened to isolate the sequence of interest. The DNA sequences encoding the variable regions of the antibody are then fused to human constant region sequences. The sequences of the human constant region genes can be found in Kabat et al., Sequences of Proteins of immunological Interest (N.I.H. publication no. 91-3242 (1991)). The human C region genes can be readily obtained from known clones. The choice of isotype will be guided by the desired effector functions, such as activity of complement fixation or activity in antibody-dependent cellular cytotoxicity. Preferred isotypes are IgG1 and IgG2. Either of the human light chain constant regions, i.e., k or λ, can be used, and the chimeric humanized antibody is then expressed using conventional methods.
In some embodiments, antibody fragments such as Fv, F(ab′)2 and Fab can be prepared by cleavage of an intact protein, e.g., by using protease or chemical cleavage, including but not limited to: (i) digesting the antibody molecule with pepsin to obtain a F(ab′)2 fragment; (ii) obtaining a Fab fragment by reducing the disulfide bond of the F(ab′)2 fragment; (iii) treating the antibody molecule with papain and a reducing agent to produce a Fab fragment, and (iv) a Fv fragment.
The consensus sequence J region of the heavy and light chains can be used to design oligonucleotides for use as primers to introduce useful restriction sites into the J region for subsequent linkage of V region fragments to human C region fragments. The C region cDNA can be modified by site-directed mutagenesis to place a restriction site at a similar position in the human sequence.
The CD47 antibodies disclosed herein can be expressed by vectors comprising DNA fragments encoding the antibodies described above. including plasmids, retroviruses, YAC, EBV-derived episomes and the like. A suitable vector is typically one that encodes a functionally complete human heavy chain constant region (CH) or light chain constant region (CL) immunoglobulin sequence, with appropriate restriction sites so that any VH or VL sequence can be readily inserted and expressed. In such vectors, splicing typically occurs between the splice donor site in the inserted J region and the splice acceptor site before the human C region, and also at the splice regions that occur within the human CH exons. Polyadenylation and transcription termination occur at natural chromosomal sites downstream of the coding regions. The resulting chimeric antibody can be linked to any strong promoter, including retroviral LTRs, such as the SV-40 early promoter (Okayama et al., Mol. Cell. Rio. 3:280(1983)), Rous sarcoma virus LTR (Gorman et al., P.N.A.S. 79:6777(1982)), and Moloney murine leukemia virus LTR (Grosschedl et al., Cell 41:885 (1985)). In addition, natural Ig promoters and the like can be used.
Relevant effector functions of the antibodies disclosed herein can be modified to improve, for example, the efficacy of the antibodies in treating diseases and disorders associated with CD47 signaling. For example, one or more mutations can be introduced into the Fe region of the antibody to silence effector function, thereby reducing the likelihood of killing normal cells.
In some embodiments, the antibody described herein is of the IgG isotype. In some embodiments, a constant region of the antibody is of a human IgG1 isotype and has an amino acid sequence set forth in SEQ ID NO: 3. In some embodiments, amino acid Asn297 (Kabat numbering) on the constant region of human IgG1 is modified to avoid glycosylation of the antibody, e.g., Asn297Ala (N297A). In some embodiments, amino acid Leu235 (Kabat numbering) on the antibody constant region is modified to alter Fc receptor interactions, e.g., Leu235Glu (L235E) or Leu235Ala (L235A). In some embodiments, amino acid Leu234 (Kabat numbering) on the antibody constant region is modified to alter Fc receptor interactions, e.g., Leu234Ala (L234A). In some embodiments, amino acids 234 and 235 on the antibody constant region are modified simultaneously, e.g., Leu234Ala and Leu235Ala (L234A/L235A) (EU indexes in Kabat et al., 1991., Sequences of Proteins of Immunological Interest).
In some embodiments, a constant region of the antibody is of a human IgG4 isotype and has an amino acid sequence set forth in SEQ ID NO: 4.
In some embodiments, the hinge region within the human IgG4 constant region is modified to avoid or reduce chain exchange, e.g., Ser228Pro (S228P). In other embodiments, amino acid 235 on the human IgG4 constant region is modified to alter Fc receptor interactions, e.g., Leu235Glu (L235E). In some embodiments, the hinge region and amino acids 235 within the constant region of human IgG4 are modified, e.g., Ser228Pro and Leu235Glu (S228P/L235E). In some embodiments, amino acid Asn297 (boxed, Kabat numbering) on the constant region of human IgG4 is modified to avoid glycosylation of the antibody, e.g., Asn297Ala (N297A). In some embodiments, amino acids Ser228, Leu235 and Asn297 on the human IgG4 constant region are modified (e.g., S228P/L235E/N297A).
In some embodiments, CD47 antibodies including the present invention can be used to diagnose, prognose, monitor, treat, alleviate and/or prevent a disease or pathology associated with abnormal CD47 expression, activity and/or signaling in a subject. A treatment regimen can be carried out by identifying a subject (e.g., a human patient) suffering from a disease or condition associated with abnormal CD47 expression, activity and/or signaling (such as cancer or other neoplastic conditions), or at risk of developing a disease, using standard methods, In some embodiments, provided is a method for treating a disease or condition involving abnormal CD47 expression, activity and/or signaling, which comprises administering to a subject in need of treatment for the disease or condition an effective amount of an antibody disclosed herein or a formulation thereof. The administration of the antibody may eliminate or inhibit or interfere with the expression, activity and/or signaling function of the target (e.g., CD47). The administration of the antibody may eliminate or inhibit or interfere with the binding of the target (e.g., CD47) to an endogenous ligand (e.g., SIRPα) to which it naturally binds. For example, the antibody binds to the target and modulates, blocks, inhibits, reduces, antagonizes, neutralizes or interferes with CD47 expression, activity and/or signaling.
In some embodiments, the disease or condition involving abnormal CD47 expression, activity, and/or signaling includes hematologic cancer and/or a solid tumor. The hematologic cancers include, for example, leukemia, lymphoma and myeloma. In some embodiments, certain forms of leukemia include acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML) and myeloproliferative diseases/tumors (MPDS) and myelodysplastic syndrome. In some embodiments, certain forms of lymphoma include Hodgkin lymphoma, indolent and aggressive non-Hodgkin lymphoma, Burkitt lymphoma and follicular lymphoma (small cell and large cell). In some embodiments, certain forms of myeloma include multiple myeloma (MM), giant cell myeloma, heavy chain myeloma, and light chain or Bence-Jones myeloma. The solid tumor includes, for example, breast cancer, ovarian cancer, lung cancer, pancreatic cancer, prostate cancer, melanoma, colorectal cancer, lung cancer, head and neck cancer, bladder cancer, esophageal cancer, liver cancer and renal cancer.
Symptoms associated with cancer and other neoplastic conditions include, for example, inflammation, fever, general malaise, fever, pain, often localized to the inflamed area, loss of appetite, weight loss, edema, headache, fatigue, rash, anemia, muscle weakness, muscle fatigue and abdominal symptoms (e.g., abdominal pain, diarrhea, or constipation).
A therapeutically effective amount of the antibody disclosed herein typically relates to an amount required to achieve a therapeutic goal. The amount required for administration depends on the binding affinity of the antibody for its specific antigen, the severity of the disease, disorder or condition, the route of administration, the rate at which the antibody administered in the subject is depleted from free volume, and the like. In some embodiments, a common range of the therapeutically effective dose of the antibody or the antibody fragment disclosed herein is from about 0.1 mg/kg to about 100 mg/kg. In some embodiments, the antibody disclosed herein is administered to a subject at a dose of about 0.1 mg/kg, about 0.5 mg/kg, about 1 mg/kg, about 2 mg/kg, about 5 mg/kg, about 10 mg/kg, about 15 mg/kg, about 20 mg/kg, about 25 mg/kg, about 30 mg/kg, about 50 mg/kg, about 75 mg/kg, about 100 mg/kg or more, or a range between any two of these values (inclusive). The common dosing frequency ranges, for example, from once daily to once weekly.
In other embodiments, antibodies against CD47 can be used in methods known in the art related to CD47 localization and/or quantification (e.g., for determining the level of CD47 and/or both CD47 and SIRPα in a suitable physiological sample, for diagnostic methods, for protein imaging, etc.). In a given embodiment, an antibody that comprises an antigen-binding domain derived from an antibody and that is specific for CD47 or a derivative, fragment, analog or homolog thereof is used as a pharmaceutically active compound (hereinafter “therapeutic agent”).
In other embodiments, CD47 polypeptides can be isolated using antibodies specific for CD47 via standard techniques such as immunoaffinity, chromatography or immunoprecipitation. Antibodies (or fragments thereof) against the CD47 protein can be used to detect the proteins in biological samples. In some embodiments, CD47 may be detected in a biological sample as part of a clinical testing procedure, e.g., to determine the efficacy of a given treatment regimen. Coupling (i.e., physically linking) the antibody to a detectable substance can facilitate detection. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials and radioactive materials. Examples of suitable enzymes include horseradish peroxidase, alkaline phosphatase, β-galactosidase, or acetylcholinesterase; examples of suitable prosthetic group complexes include streptavidin/biotin and avidin/biotin; examples of suitable fluorescent materials include umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; one example of a luminescent material includes luminol; examples of bioluminescent materials include luciferase, luciferin and aequorin, and examples of suitable radioactive materials include 125I, 131I, 35S or 3H.
In other embodiments, the antibodies disclosed herein can be used as agents for detecting the presence of CD47 and/or both CD47 and SIRPα proteins (or protein fragments thereof) in a sample. In some embodiments, the antibodies comprise a detectable label. The antibodies are polyclonal antibodies, or more preferably monoclonal antibodies. An intact antibody or a fragment thereof (e.g., Fab, scFv, or F(ab′)2) is used. The detection method of the embodiments can be used to detect an analyte mRNA, protein or genomic DNA in a biological sample in vitro as well as in vivo. For example, in vitro detection techniques for detecting an analyte mRNA include Northern hybridization and in situ hybridization. In vitro detection techniques for detecting an analyte protein include enzyme-linked immunosorbent assays (ELISAs), Western blots, immunoprecipitations and immunofluorescence. In vitro detection techniques for detecting an analyte genomic DNA include Southern hybridization. (ELISA: Theory and Practice: Methods in Molecular Biology, Vol. 42, J. R. Crowther Human Press, Totowa, N.J., 1995; Immunoassay, E. Diamandis and T. Christopoulus, Academic Press, Inc., San Diego, Calif., 1996; Practice and Theory of Enzyme Immunoassays, P. Tijssen, Elsevier Science Publishers, Amsterdam, 1985). In addition, in vivo techniques for detecting an analyte protein include introducing a labeled anti-analyte protein antibody into a subject. For example, the antibody can be labeled with a radioactive marker, the presence and location of which in the subject can then be detected by standard imaging techniques.
The antibodies disclosed herein and derivatives, fragments, analogs and homologs thereof can be incorporated into pharmaceutical compositions suitable for administration. The principles and considerations involved in preparing such compositions, as well as guidelines in the choice of components, are well known in the art, see, e.g., Remington's Pharmaceutical Sciences: The Science And Practice Of Pharmacy, the 19th edition, Mack Pub. Co., Easton, Pa.: 1995; Drug Absorption Enhancement: Concepts, Possibilities, Limitations, And Trends, Harwood Academic Publishers, Langhorne, Pa., 1994; and Peptide And Protein Drug Delivery, Advances in Parenteral Sciences, Vol. 4, 1991, M. Dekker, New York.
Such compositions typically comprise the antibody and a pharmaceutically acceptable carrier. In some embodiments, an antibody fragment is used as the smallest inhibitor fragment that specifically binds to the binding domain of the target protein. For example, a peptide that is based on the variable region sequence of an antibody and retains the ability to bind to a target protein sequence is used.
As used herein, the term “pharmaceutically acceptable carrier” is intended to include any and all solvents, stabilizers, buffers, dispersion media, coatings, antibacterial agents, isotonic and absorption delaying agents, and the like that are compatible with pharmaceutical administration. Suitable carriers are described in the latest edition of Remington's Pharmaceutical Sciences. Such carriers or diluents can include, but are not limited to, water, saline. Ringer's solution, glucose solution and 5% human serum albumin.
The formulations to be used for in vivo administration must be sterile. This can be readily achieved by filtration through sterile filtration membranes.
The pharmaceutical compositions of the embodiments are generally compatible with their intended routes of administration. Examples of the routes of administration include parenteral administration, such as intravenous, intradermal, subcutaneous, oral (e.g., inhalational), transdermal (i.e., topical), transmucosal and rectal administration. The pharmaceutical compositions can comprise one or more of the following components: sterile diluents for injection, such as water, saline solutions, fixed oils, polyethylene glycols, glycerol, propylene glycol or other synthetic solvents; antibacterial agents, such as benzyl alcohol or methylparaben; antioxidants, such as ascorbic acid or sodium bisulfite; chelating agents, such as ethylenediamine tetraacetic acid (EDTA); buffers, such as histidine hydrochloride, acetates, citrates or phosphates; tonicity-adjusting agents, such as sodium chloride or dextrose; stabilizers, such as arginine, methionine, trehalose, sucrose or sorbitol; and surfactants, such as tween 20 or tween 80. The pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. The pharmaceutical compositions can be packaged in ampoules, disposable syringes or multiple-dose vials made of glass or plastic. In some embodiments, the pharmaceutical compositions suitable for injection include sterile aqueous solutions (herein water-soluble solutions) or dispersions and sterile powders for the instant preparation of sterile injectable solutions or dispersions. In use, the compositions must be sterile and should be fluid to the extent that easy syringability exists. The composition must be stable under the conditions of manufacture and storage and must be able to prevent the contamination of microorganisms such as bacteria and fungi. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminum monostearate and gelatin.
For transmucosal or transdermal administration, penetrants appropriate for the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art, and include, for example, detergents, bile salts and fusidic acid derivatives for transmucosal administration. Transmucosal administration can be accomplished through the use of nasal sprays or suppositories. For transdermal administration, one or more of the antibodies may be formulated into ointments, salves, gels, or creams as generally known in the art.
The pharmaceutical compositions are formulated in dosage unit form for ease of administration and uniformity of dosage. As used herein, dosage unit form refers to physically separable units that are suitable as unitary dosages for a subject to be treated; each unit contains a predetermined amount of one or more of the antibodies calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier.
The pharmaceutical compositions can be placed in a container or dispenser and packaged together with instructions for administration.
The pharmaceutical compositions disclosed herein can also comprise other active ingredients, preferably those with complementary activities that do not adversely affect each other, depending on the particular condition to be treated. In some embodiments, the compositions can comprise an agent that enhances its function, such as a cytotoxic agent, cytokine, chemotherapeutic agent or growth inhibitory agent. Such active ingredients are suitably present in combination in amounts that are effective for the intended purpose.
In one embodiment, one or more active ingredients, including the CD47 antibodies, can be administered in combination therapy, i.e., in combination with other agents, such as therapeutic agents (e.g., one or more cytokines and growth factor inhibitors, immunosuppressive agents, anti-inflammatory agents, metabolic inhibitors, enzyme inhibitors and/or cytotoxic or cytostatic agents). The term “in combination” as used herein means that the agents are administered substantially contemporaneously, simultaneously or sequentially. In some embodiments, such combination therapies may advantageously utilize lower doses of the administered therapeutic agents, thus avoiding possible toxicities or complications associated with various monotherapies.
In some embodiments, the antibodies disclosed herein are used as vaccine adjuvants against autoimmune disorders, inflammatory diseases, etc. The vaccines can be a wide variety of antigens. The antigens are derived from the targeted autoantigens, i.e., autoantigens involved in autoimmunity, such as myelin basic protein; inflammatory autoantigens, such as amyloid peptide protein or transplant antigens, such as alloantigens. The antigens may comprise peptides or polypeptides derived from proteins, as well as fragments of any of the following: sugars, proteins, polynucleotides or oligonucleotides, autoantigens, amyloid peptide proteins, transplant antigens, allergens or other macromolecular components. In some embodiments, more than one antigen is comprised in the antigenic composition.
Citation of publications and patent documents herein is not intended as an admission that any is pertinent prior art, nor does it constitutes any admission as to the contents or date of the same. Now, the present invention has been described in the written description, and it should be understood by those skilled in the art that the present invention may be practiced in various embodiments. The above specification and the examples below are intended to be illustrative rather than limiting the claims disclosed herein. All the publications, patents, and patent applications cited herein are incorporated herein by reference in their entirety for all purposes.
The materials, reagents, etc. used in the following examples can be commercially available or obtained using known methods unless otherwise stated. In the following examples, Antibody L12-6 is the same antibody as Antibody 6Y-G1.
CHO-CD47 cell construction process: a HindIII/EcoRI window was designed to introduce a polynucleic acid encoding CD47 (see Uniprot, Q08722 for the sequence) into the pcDNA3.1(+) (Invitrogen, V790-20) plasmid, and then CHO cells (ATCC #CCL-61) were transfected with the plasmid by single digestion with Pvul. Stable CHO-CD47 cell lines were obtained by screening.
The Jurkat cells were purchased from Cell Bank of Chinese Academy of Sciences, Shanghai, under catalog No. Clone E6-1.
The IgG antibodys was purchased from BioXCell, under catalog No. BE0297.
The macaque CD47-Fc was purchased from Creative BioMart, and its model number was CD47-745C.
Preparation of CD47 antigens: A CD47 recombinant protein was constructed by adding a 6×HIS tag (HHHHHH, SEQ ID NO: 2) or human Fc (underlined in SEQ ID NO: 3) (referring to R&D system) to the C-terminus of the human CD47 extracellular domain (ECD) protein (SEQ ID NO: 1). The ECD region of human CD47 was genetically synthesized together with 6×HIS or Fc and subcloned into the mammalian expression vector pcDNA3.1(+) (Invitrogen, V790-20). After transient transfection of HEK293F cells, a His-tagged human CD47-ECD protein (CD47-His) purified by nickel-based immobilized metal affinity chromatography and a secreted Fc-tagged human CD47-ECD protein (CD47-Fc) purified by immobilized metal affinity chromatography (IMAC) using a protein A column (GE Healthcare) were obtained.
Combinations of VH and VL for 30 single-chain antibodies (scFvs) are shown in Table 2. The C-terminus of VH and the N-terminus of VL were linked by a linker whose sequence is set forth in SEQ ID NO: 10 (GGGGSGGGGSGGGGS). The heavy chain variable regions of the antibodies are indicated by antibody number +“-VH”, e.g., 17-VH; the light chain variable regions of the antibodies are indicated by antibody number +“-VL”, e.g., 17-VL; the single-chain antibodies (scFvs) are indicated by antibody number +“-ScFv”, e.g., 17-ScFv (which is obtained by linking the C-terminus of 17-VH (set forth in SED ID NO: 11) and the N-terminus of 17-VL (set forth in SED ID NO: 12) by a linker set forth in SED ID NO: 10).
Combinations of VH and VL of 30 full-length IgG1 antibodies are shown in Table 2. VH and CH constitute the heavy chains of the antibodies, and VL and CL constitute the light chains of the antibodies. The sequence of CH is set forth in SED ID NO: 3, and the sequence of CL is set forth in SED ID NO: 5. The heavy chain variable regions of the antibodies are indicated by antibody number +“-VH”, e.g., 17-VH; the light chain variable regions of the antibodies are indicated by antibody number +“-VL”, e.g., 17-VL; the full-length IgG1 antibodies were indicated by “antibody”+antibody number, e.g., Antibody 17 (whose heavy chain is composed of 17-VH (set forth in SED ID NO: 11) and the CH set forth in SED ID NO: 3. and whose light chain is composed of 17-VL (set forth in SED ID NO: 12) and the CL set forth in SED ID NO: 5).
The amino acid sequence of the heavy chain of Antibody 6Y-G4 is set forth in SEQ ID NO: 60, and the amino acid sequence of the light chain is set forth in SEQ ID NO: 61.
The corresponding sequences of the VHs and VLs in Table 2 are shown in Table 3. The heavy chain CDRs are shown in Table 4 and the light chain CDRs are shown in Table 5.
Plasmid pcDNA3.1 (+) (Invitrogen, V790-20) was engineered using conventional techniques to carry a DNA sequence encoding the above amino acid sequences. The plasmid was then transiently transfected into HEK293F cells, and the HEK293F cells were allowed to express antibodies of the above amino acid sequences. CD47 antibodies were obtained after purification by immobilized metal affinity chromatography (IMAC) using a protein A column (GE Healthcare), and sequencing showed that their sequences were in agreement with the expected ones. They were subjected to biological activity determination.
In terms of clearing target cells, the primary Fc-dependent functions of an antibody (e.g., the CD47 antibody) are complement-dependent cytotoxicity (CDC) initiated by the binding of C1q to the Fc region; antibody-dependent cellular cytotoxicity (ADCC) mediated by the interaction between the Fc region and Fcγ receptors (FcγRs), primarily FcγRIIIa, on immune effector cells (e.g., NK cells and neutrophils); and antibody-dependent cellular phagocytosis (ADCP) by macrophages through the recognition of opsinized target cells via FcγRI. Antibody subclasses differ in their abilities to mediate Fc-dependent effector activities. In humans, the IgG1 and IgG3 subclasses have high potency for CDC due to binding C1q. In addition, the IgG1 subclass has the highest affinity for FcγRs and is therefore the most effective in terms of ADCC and Fc-dependent ADCP. The IgG4 subclass does not have the ability to bind to C1q and has greatly reduced FcγR binding affinity and therefore has significantly diminished effector function.
Antibody 6Y-G4 of the IgG4P subclass having mutation 5228P for stabilizing the hinge region of the antibody was prepared according to Antibody 6Y-G1 (the CH of 6Y-G1 set forth in SEQ ID NO: 3 was replaced with the CR set forth in SEQ ID NO: 4, and the other sequences were unchanged), further diminishing the antibody Fc effect.
17-ScFv was prepared as an example. The method of preparing a ScFV in the present invention is described below.
A nucleotide sequence encoding 17-ScFv (set forth in SEQ ID NO: 59) was linked to the pcDNA3.1(+) plasmid vector using restriction endonuclease Hind III/EcoRI. The plasmid vector was then transiently transfected into HEK293F cells, and the HEK293F cells were allowed to express the antibody of the above amino acid sequence. Antibody 17-ScFv was obtained after purification by immobilized metal affinity chromatography (IMAC) using a protein A column, and sequencing showed that its sequence was in agreement with the expected one.
Other ScFvs were similarly prepared and purified, and sequencing showed that their sequences were in agreement with the expected ones.
The sequence of SEQ ID NO: 59 is shown below:
The binding activity of 17-ScFv to CHO-CD47 or Jurkat cell surface CD47 was tested (
Antibodies 17-ScFv and Hu5F9-G4 (the heavy chain of Hu5F9-G4 is composed of a variable region set forth in SEQ ID NO: 8 and a constant region set forth in SEQ ID NO: 4, and the light chain is composed of a variable region set forth in SEQ ID NO: 9 and a constant region set forth in SEQ ID NO: 5) were diluted with PBS to various concentrations (20, 10, 5, 2.5, 1.25, 0.625, 0.313, 0.156, 0.078, 0.039, 0.02 and 0.01 μg/mL) and incubated with CHO-CD47 or Jurkat cell surface CD47 at 4° C. for 30 min, and the cells were washed once with PBS. Goat anti-human IgG Fc-PE (eBioscience, catalog No. 2183639) fluorescent secondary antibody was added, and the cells were incubated at 4° C. for 15 min and washed twice with PBS. The PE-A mean fluorescence signal value was measured on a flow cytometer.
The ability of 17-ScFv to block the binding of SIRPα to CHO-CD47 cell surface CD47 was determined using the FACS technique. Antibody 17-ScFv was diluted with PBS to various concentrations (160, 80, 40, 20, 10, 5, 2,5, 1.25 and 0.625 μg/mL). Antibodies Hu5F9-G4 and IgG (diluted with PBS to various concentrations: 40, 20, 10, 5, 2.5, 1.25, 0.625, 0.313, 0.156 and 0.078 μg/mL) were incubated with CHO-CD47 cell surface CD47 at 4° C. for 30 min, and the cells were washed once with PBS. SIRPα-Fc-Bio (6.5 μg/mL) was added, and the cells were incubated at 4° C. for 15 min and washed once with PBS. Then Streptavidin PE (eBioscience, catalog No. 1992345) fluorescent secondary antibody was added, and the cells were incubated at 4° C. for 15 min and washed twice with PBS. The PE-A mean fluorescence signal value was measured on a flow cytometer.
Using ELISA competition method, 17-ScFv or 18 antibodies (Antibody 3, Antibody 3-3, Antibody 3-6, Antibody 6, Antibody 10, Antibody 11, Antibody 16, Antibody 18, Antibody 24, Antibody 25, Antibody L12, Antibody L1, Antibody L5, Antibody L24, Antibody L26, Antibody 17, Antibody 6Y-G1, and Antibody 6Y-G4), a positive control (Antibody Hu5F9-G4) and a negative control (antibody IgG) were diluted with PBS to various concentrations (12, 6, 3, 2, 1.5, 1.2, 0.75, 0.375, 0.188 and 0.094 μg/mL) and incubated with CD47-His (2 μg/mL) antigen coating on an ELISA plate at room temperature for 1 h, and the plate was washed four times with PBST. Then SIRPα-Fc-Bio (0.1 μg/mL) (prepared according to Thermo Scientific. EZ-Link® NHS-Biotin Reagents kit) ligand was added and incubated with the CD47-His antigen at room temperature for 1 h, and the plate was washed four times with PBST. Chemiluminescence reactions of the bound SIRPα-Fc-Bio with HRP-conjugated streptavidin secondary antibody were carried out, and the OD450 values were measured using a plate reader. The IC50 of the antibodies was calculated from the OD450 values, thereby determining the SIRPα blocking activity of the antibodies.
The CD47 antibodies were tested for hemagglutination. 5 mL of fresh blood from a healthy human donor was collected into a tube containing heparin sodium anticoagulant. The PBMCs (for other purposes) were isolated first using a lymphocyte-isolating solution, and then 1 mL of red blood cells at the bottom of the tube was collected into 6 mL of normal saline. The red blood cells were washed and centrifuged at 2000 rpm for 5 min; the wash procedure was repeated until the supernatant was not significantly red. Then the red blood cells were resuspended in normal saline to prepare a 2% red blood cell suspension. At room temperature, 50 of a CD47 antibody serially diluted 2-fold in PBS (the maximum concentration was 800 nM; 12 gradients in total) was mixed with 50 μL of the 2% red blood cell suspension, and the mixture was added to a 96-well U-plate and incubated for 4 h. Then the hemagglutination caused by the antibody was assessed by titling 45° the 96-well U-plate and observing the flow of masses of red blood cells; if the cells flow in a line, it means that no hemagglutination occurred. Most of the tested CD47 antibodies induced hemagglutination when at high concentrations (Antibody 17 caused significant hemagglutination) and did not cause hemagglutination when at about 6 nM. Antibody L12, Antibody 6Y-G1 (i.e., Antibody L12-6) and Antibody 6Y-G4 did not cause any hemagglutination (
The binding activity of the CD47 antibodies to human CD47 and macaque CD47 was determined by ELISA. Antibody 17, Antibody L12, Antibody 6Y-G1, Antibody 6Y-G4 and Antibody Hu5F9-G4 were diluted 3-fold with PBS from 5 μg/mL to 8 concentrations and then incubated with human or macaque CD47-Fc (2 μg/mL) antigen coating on an ELISA plate at room temperature for 1 h, and the plate was washed four times with PBST. Then HRP-anti-kappa (1:10000, sigma) secondary antibody was added and incubated with the antibodies at room temperature for 1 h, and the plate was washed four times with PBST. Chemiluminescence reactions of the bound HRP-anti-kappa with TMB substrate were carried out, and the OD450 values were measured using a plate reader. The EC50 of the antibodies was calculated from the OD450 values, thereby determining the binding activity of the antibodies to human or macaque CD47.
The binding activity of 11 antibodies (Antibody L12-1, Antibody L12-2, Antibody L12-3, Antibody L12-4, Antibody L12-5, Antibody L12-6, Antibody 1,12-7; Antibody L12-9, Antibody L12-10, Antibody L12-11, and Antibody L12) and Hu5F9-G4 to human CD47 was determined by Fortebio.
A protein A sensor was pre-wetted in PBS for 10 min for later use. The test antibodies were diluted to 10 μg/mL with PBST haying a pH of 6.8 and containing 0.5% BSA (hereinafter referred to as dilution buffer). The PA sensor was immobilized in the antibodies until the signal was about 1.7 nm. CD47-His antigen was diluted with the dilution buffer to 50; 25, 12.5 and 6.25 nM. The dilution buffer, the antigen dilutions at the gradient concentrations, a regeneration buffer (1 M MgCl2 at pH 8.4) and a neutralization buffer (PBST) were sequentially added to the corresponding columns in a 96-well plate, and the following steps were performed: (1) Baseline: 60 seconds of baseline detection in the dilution buffer; (2) Association: 100 seconds of association in the serial dilutions of the antigen and a sample blanks (dilution buffer); (3) Dissociation: 700 seconds of dissociation in the dilution buffer; (4) Regeneration: 5 seconds of regeneration in the regeneration buffer; (5) Neutralization: 5 seconds of neutralization in the neutralization buffer; and (6) 3 Regeneration-Neutralization cycles.
The data was processed and analyzed using Data Analysis 8.2; and the sample data was fitted after reference (sample blank) signal subtraction to obtain an affinity constant (KD). The affinity results of the antibodies are summarized in Table 8. The results show that the 11 antibodies had similar binding affinities for CD47 antigen.
An in vitro phagocytosis assay was carried out to assess whether the CD47 antibodies promote phagocytosis of CD47-expressing target cells by macrophages. Briefly, in the presence of CD47 antibodies (0.7 nM), RAW264.7 macrophages (2×105 cells/mL) (Cell Resource Center, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, 3111C0001CCC000146) and CFSE-labeled Raji cells (4×105 cells/mL) (Promega, JA1595) were plated to a 24-well plate in a ratio of 1:2 and incubated in the dark at 37° C. for 2 h. Upon completion of incubation, the cells were washed twice with PBS and the RAW264.7 cells were trypsinized. The digested macrophages were transferred to 1.5 mL EP tubes and centrifuged at 2000 rpm for 5 min. The supernatant was removed and 100 μL of APC-F4/80 fluorescent antibody (eBiosciences) was added to each tube. The cells were incubated in the dark at 4° C. for 30 min, centrifuged at 2000 rpm for 5 min and washed twice with PBS buffer. The cells were obtained on a BD C6 flow cytometer. The phagocytosis index was analyzed. The phagocytosis index was calculated as: phagocytosis index=number of CFSE positive macrophages (i.e. number of macrophages that phagocytosed tumor cells)/per 5000 macrophages. Antibodies 6Y-G1, 6Y-G4, 17, L12 and Hu5F9-G4 showed potent phagocytosis-enhancing abilities (
Prior to the present invention, known CD47-binding molecules that block SIRPα and contain a Fc domain (e.g., CD47 antibodies and recombinant SIRPα-Fc fusion proteins) all induce red blood cell and platelet reduction to varying degrees. Therefore, the effects of the antibodies disclosed herein on blood cells were assessed in cynomolgus monkeys. A total of 8 normal cynomolgus monkeys that met the experimental requirements were selected. Half of the monkeys were female. The males weighed from 3,70 to 5.30 kg, and the females weighed from 2.75 to 3.55 kg. The monkeys were simple randomly divided into 4 groups, with 2 animals in each group (a male and a female) according to body weight. The negative control group was given normal saline. The test samples were Antibody 6Y-G1 (i.e., Antibody L12-6) and Hu5F9-G4 and AB6.12-G1. The vehicle for intravenous infusion was normal saline. The drugs were administered 5 times by intravenous infusion once a week at doses of 1→10→10→30→30 mg/kg in a volume of 10 mL/kg. After the administrations were completed, the animals were observed until day 42.
The antitumor effect of the test drug Antibody L12 in a tumor model of the human blood tumor MV4-11 system was evaluated. NOD.SCID mice (GemPharmatech Co., Ltd., weighing 18-22 g, at 6-8 weeks of age) were inoculated with MV4-11 cells (ATCC) via tail vein, and a tumor model of the human blood tumor MV4-11 system was created about 4 weeks after the inoculation. The mice were divided into groups of 6: test AB6.12-G1 0.2 mg/mouse; Hu5F9-G4 0.2 mg/mouse; Antibody L12 0.2 mg/mouse; and vehicle (normal saline) control group. The mice were intraperitoneally injected with the drugs three times a week over three weeks. The therapeutic effects were evaluated according to increase in life span (ILS). The safety was evaluated according to change in animal body weight and mortality during administration.
The antitumor activity of Antibody 6Y-G4 was evaluated in a Raji model of lymphoma. Raji cells were implanted subcutaneously in NOD/SCID mice, which were randomized into 3 groups (8 mice per group, day 0). Group 1: vehicle control (normal saline); Group 2: Hu5F9-G4 (positive control); Group 3: 6Y-G4. Treatment with each antibody or vehicle (buffer only) began when tumors were palpable (50 mm3, day 4). The mice were sacrificed when their tumor volumes reached about 3000 mm3. Tumor volumes were measured every 3 days. Antibodies were administered intraperitoneally (IP) at 100 μg/dose 3 times a week over 3 weeks (a total of 9 doses per mouse). Treatment began on day 4 and ended on day 21. As shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010761404.8 | Jul 2020 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2021/109446 | 7/30/2021 | WO |
