Patent Application
20240254240
The present invention relates to a Tie2-agonistic antibody or antigen-binding fragment thereof binding to the Ig3 Fn3 (membrane proximal fibronectin type III) domain of human Tie2, in which, by binding of the antibody, homodimeric Tie2 may be formed into a polygonal assembly, and thus clustered and activated.
Angiogenesis occurs dynamically by various regulatory factors during development, growth, preservation, and homeostasis of an organism. As such, newly formed blood vessels serve as transport channels for various biomaterials, such as nutrients, oxygen, hormones, and the like, to surrounding cells. Functionally and structurally abnormal blood vessels are a direct or indirect cause of the onset and progression of various diseases. Tumor blood vessels worsen hypoxia due to functional and structural defects, resulting in tumor progression and metastasis to other tissues, and prevent anticancer drugs from being delivered well to the center of tumor tissue. In addition to cancer, defective blood vessels may be identified in various other diseases or disorders. Examples thereof include various eye diseases (e.g., diabetic macular edema, age-related macular degeneration), viral infections, and acute inflammatory responses such as sepsis, etc. Therefore, if a therapeutic agent that is able to normalize pathological blood vessels is present, application thereof to the treatment of various patients with vascular abnormalities is possible.
In order to inhibit abnormal angiogenesis and reduce vascular permeability, methods of directly activating Tie2 are being considered. Recombinant proteins that directly bind to the Tie2 receptor and induce Tie2 phosphorylation and activation are also being developed, and therapeutic effects thereof are being tested in a number of preclinical cancer and eye models. COMP-Ang1 and Vasculotide are representative examples. Although these agents exhibit anti-angiogenic and anti-invasive activities, they have the disadvantage of a very short half-life and unstable physicochemical properties. Moreover, a small molecule compound (AKB-9778) has been developed as an inhibitor of the dephosphorylating enzyme VE-PTP. VE-PTP serves to inactivate Tie2 by removing the phosphate group from phosphorylated Tie2. These compounds have the disadvantage of nonspecifically activating other receptors, but they indirectly increase Tie2 activity by inhibiting VE-PTP. Also, Tie2-activating antibodies have been developed (U.S. Pat. No. 6,365,154B1, US20170174789A1). These antibodies inhibit vascular leakage by increasing the survival rate of vascular endothelial cells. Interestingly, it is claimed that one of plant extracts may induce Tie2 activity and may be used as a skin care cosmetic (e.g., JP2011102273A, JP2018043949A, JP2015168656A).
Tie2 is an endothelial cell-specific receptor tyrosine kinase that promotes the growth and stability of blood vessels, and may be an attractive therapeutic target for ischemic and inflammatory vascular diseases. Tie2-agonistic antibodies and oligomeric angiopoietin (Angpt1) variants have been developed as potential therapeutic agents. However, the underlying mechanism for the role thereof in Tie2 clustering and activation has not been clearly identified. Moreover, Angpt1 variants have difficulties in production and storage.
Against this background, the inventors of the present application have made efforts to develop a Tie2-agonistic antibody, and thus developed a human Tie2-agonistic antibody and ascertained that such an antibody binds specifically to the Fn3 domain of Tie2, so that homodimeric Tie2 may be formed into a polygonal assembly and thus clustered and activated, thereby culminating in the present invention.
It is an object of the present invention to provide a Tie2-agonistic antibody or antigen-binding fragment thereof.
It is another object of the present invention to provide a nucleic acid encoding the antibody or antigen-binding fragment thereof.
It is still another object of the present invention to provide a vector including the nucleic acid, cells transformed with the vector, and a method of producing the same.
It is yet another object of the present invention to provide a composition for preventing or treating an angiogenic disease including the antibody or antigen-binding fragment thereof.
It is still yet another object of the present invention to provide a composition for co-administration with an additional therapeutic agent for an angiogenic disease, including the antibody or antigen-binding fragment thereof.
In order to accomplish the above objects, the present invention provides a Tie2-agonistic antibody or antigen-binding fragment thereof, in which the antibody binds to the Ig3 Fn3 (membrane proximal fibronectin type III) domain of human Tie2, and by binding of the antibody, homodimeric Tie2 is formed into a polygonal assembly, and thus clustered and activated.
Particularly, the present invention provides Fab including a heavy-chain variable region (VH) including the sequence of SEQ ID NO: 1, a heavy-chain constant region (CH) including the sequence of SEQ ID NO: 3, a light-chain variable region (VL) including the sequence of SEQ ID NO: 2, and a light-chain constant region (CL) including the sequence of SEQ ID NO: 4.
Particularly, the present invention provides a humanized antibody including a heavy-chain variable region including the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO: 7 and a light-chain variable region including the amino acid sequence of SEQ ID NO: 6 or SEQ ID NO: 8.
In addition, the present invention provides a nucleic acid encoding the antibody or antigen-binding fragment thereof.
In addition, the present invention provides a vector including the nucleic acid.
In addition, the present invention provides cells transformed with the vector.
In addition, the present invention provides a method of producing the antibody or antigen-binding fragment thereof, including (a) culturing the cells and (b) recovering the antibody or antigen-binding fragment thereof from the cultured cells.
In addition, the present invention provides a composition for preventing or treating an angiogenesis-related disease, including the antibody or antigen-binding fragment thereof as an active ingredient.
In addition, the present invention provides a composition for co-administration with an additional therapeutic agent for an angiogenic disease, including the antibody or antigen-binding fragment thereof. The present invention provides a method of preventing or treating an angiogenic disease, including administering the antibody or antigen-binding fragment thereof to a patient. The present invention provides the use of the antibody or antigen-binding fragment thereof for the manufacture of a medicament for preventing or treating an angiogenic disease.
In addition, the present invention provides an antibody polygonal assembly including a Tie2-agonistic antibody or antigen-binding fragment thereof and formed with homodimeric Tie2 by binding of the antibody to the Ig3 Fn3 (membrane proximal fibronectin type III) domain of human Tie2.
Unless otherwise defined, all technical and scientific terms used herein have the same meanings as typically understood by those skilled in the art to which the present invention belongs. In general, the nomenclature used herein is well known in the art and is typical.
The inventors of the present application developed a human Tie2-agonistic antibody hTAAB targeting the Tie2 Fn (membrane proximal fibronectin type III) domain. The Tie2/hTAAB complex structure operates in a new mode of Tie2 clustering.
hTAAB, which is a human Tie2-agonistic antibody, operates in a new mode of Tie2 clustering by forming a Tie2/hTAAB complex structure, and binds specifically to the Tie2 Fn3 domain, connecting Tie2 homodimers into a polygonal assembly. This structure is in contrast to the lateral Tie2 arrays observed in previous crystal lattices. Also, disruption of the Fn3-Fn3′ dimeric interface inactivates the clustering signal of Tie2 induced by hTAAB. These results highlight the importance of Fn3-mediated Tie2 homodimerization for an hTAAB-induced Tie2 polygonal assembly and provide insight into how Tie2 agonists induce Tie2 clustering and activation. Also, the success of constructing humanized antibodies based on the structure of hTAAB creates potential clinical possibilities.
Accordingly, an aspect of the present invention pertains to a Tie2-agonistic antibody or antigen-binding fragment thereof, in which the antibody binds to the Ig3 Fn3 (membrane proximal fibronectin type III) domain of human Tie2, and by binding of the antibody, homodimeric Tie2 is formed into a polygonal assembly, and thus clustered and activated.
In addition, the present invention pertains to an antibody polygonal assembly including a Tie2-agonistic antibody or antigen-binding fragment thereof and formed with homodimeric Tie2 by binding of the antibody to the Ig3 Fn3 (membrane proximal fibronectin type III) domain of human Tie2.
As used herein, the term “antibody” refers to an antibody that specifically binds to Tie2. The scope of the present invention includes not only the complete antibody form that specifically binds to Tie2, but also antigen-binding fragments of the antibody molecule.
A complete antibody has a structure having two full-length light chains and two full-length heavy chains, and each light chain is linked to a heavy chain by a disulfide bond. The heavy-chain constant region has gamma (γ), mu (μ), alpha (α), delta (δ), and epsilon (ε) types, and gamma 1 (γ1), gamma 2 (γ2), gamma 3 (γ3), gamma 4 (γ4), alpha 1 (α1), and alpha 2 (α2) subclasses. The constant region of the light chain has kappa (κ) and lambda (λ) types.
The antigen-binding fragment of an antibody or the antibody fragment is a fragment having an antigen-binding function, and includes Fab, F(ab′), F(ab′)2, and Fv. Among antibody fragments, Fab has a structure having light-chain and heavy-chain variable regions, a light-chain constant region, and a first heavy-chain constant region (CH1), and has one antigen-binding site. Fab′ differs from Fab in that Fab′ has a hinge region including at least one cysteine residue at the C-terminus of the heavy-chain CH1 domain. The F(ab′)2 antibody is produced by a disulfide bond between cysteine residues in the hinge region of Fab′. Fv is a minimal antibody fragment having only a heavy-chain variable region and a light-chain variable region. Two-chain Fv is configured such that a heavy-chain variable region and a light-chain variable region are linked by a non-covalent bond, and single-chain Fv (scFv) is configured such that a heavy-chain variable region and a light-chain variable region are generally linked by a covalent bond via a peptide linker therebetween, or are directly linked at the C-terminus, forming a dimeric structure, like the two-chain Fv. Such antibody fragments may be obtained using proteolytic enzymes (e.g., Fab may be obtained by restriction-cleaving a whole antibody with papain, and F(ab′)2 may be obtained by restriction-cleaving a whole antibody with pepsin), or may be constructed through genetic recombination technology.
In an embodiment, the antibody according to the present invention is in Fv form (e.g., scFv) or in intact antibody form. Also, the heavy-chain constant region may be any one selected from among isotypes such as gamma (γ), mu (μ), alpha (α), delta (δ), and epsilon (ε). For example, the constant region may be gamma 1 (IgG1), gamma 3 (IgG3), or gamma 4 (IgG4). The light-chain constant region may be kappa or lambda type.
As used herein, the term “heavy chain” is understood to include a full-length heavy chain and fragments thereof, the full-length heavy chain including a variable region domain H including an amino acid sequence having a variable region sequence sufficient to confer specificity to an antigen and three constant region domains CH1, CH2, and CH3. Also, the term “light chain” used herein is understood to include a full-length light chain and fragments thereof, the full-length light chain including a variable region domain VL including an amino acid sequence having a variable region sequence sufficient to confer specificity to an antigen and a constant region domain CL.
Examples of the antibody of the present invention include, but are not limited to, monoclonal antibodies, multispecific antibodies, human antibodies, humanized antibodies, chimeric antibodies, single-chain Fvs (scFVs), single-chain antibodies, Fab fragments, F(ab′) fragments, disulfide-liked Fvs (sdFVs), anti-idiotype (anti-Id) antibodies, epitope-binding fragments of these antibodies, and the like.
A monoclonal antibody s an antibody obtained from a population of substantially homogeneous antibodies, in which the individual antibodies that make up the population are identical, except for possible naturally-occurring mutations that may be present at low frequency. A monoclonal antibody is highly specific and is induced against a single antigenic site. In contrast to typical (polyclonal) antibodies, which commonly include different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen.
The term “epitope” refers to a protein determinant to which an antibody is able to specifically bind. The epitope is usually composed of a group of chemically active surface molecules, for example amino acids or sugar side-chains, and generally has specific three-dimensional structural features and specific charge properties. Conformational and nonconformational epitopes are distinguished in that binding to the former, but not the latter, is lost in the presence of a denaturing solvent.
A non-human (e.g., murine) antibody in a “humanized” form is a chimeric antibody including at least one amino acid sequence (e.g., CDR sequence) derived from at least one non-human antibody (donor or source antibody) that contains a minimal sequence derived from a non-human immunoglobulin. In most cases, the humanized antibody is a human immunoglobulin (recipient antibody), in which a residue from the hypervariable region of a recipient is replaced with a residue from the hypervariable region of a non-human species (donor antibody) having the desired specificity, affinity, and capability, for example, mice, rats, rabbits, or non-human primates. For humanization, residues within at least one framework domain (FR) of the variable region of the recipient human antibody may be replaced with corresponding residues from a non-human species donor antibody. This helps maintain the proper three-dimensional configuration of the grafted CDR (s), thereby improving affinity and antibody stability. The humanized antibody may include a new residue that does not appear in an additional recipient antibody or donor antibody, for example, to further refine antibody performance.
A “human antibody” is a molecule derived from human immunoglobulin, and means that all of the amino acid sequences constituting the antibody including a complementarity-determining region and a framework region are composed of human immunoglobulin.
A portion of the heavy chain and/or light chain is identical to or homologous with the corresponding sequence in an antibody derived from a particular species or belonging to a particular antibody class or subclass, whereas the remaining chain (s) includes a “chimeric” antibody (immunoglobulin) that is identical to or homologous with the corresponding sequence in an antibody derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies that exhibit the desired biological activity.
The “variable region” of the antibody as used herein is a light-chain or heavy-chain portion of an antibody molecule including the amino acid sequence of a complementarity-determining region (CDR; i.e., CDR1, CDR2, and CDR3) and a framework region (FR). VH refers to the variable region of a heavy chain, and VL refers to the variable region of a light chain.
The “complementarity-determining region” (CDR; i.e., CDR1, CDR2, and CDR3) is an amino acid residue of the antibody variable domain that is necessary for antigen binding. Each variable domain typically has three CDRs, identified as CDR1, CDR2, and CDR3.
The “framework region” (FR) is a variable domain residue other than the CDR residue. Each variable domain typically has four FRs, identified as FR1, FR2, FR3, and FR4.
The Tie2 antibody is monovalent or bivalent and contains a single chain or two chains. Functionally, binding affinity of the Tie2 antibody falls in the range of 10−5 M to 10−12 M. For example, binding affinity of the Tie2 antibody may be 10−6 M to 10−12 M, 10−7 M to 10−12 M, 10−8 M to 10−12 M, 10−9 M to 10−12 M, 10−5 M to 10−11 M, 10−6 M to 10−11 M, 10−7 M to 10−11 M, 10−8 M to 10−11 M, 10−9 M to 10−11 M, 10−10 M to 10−11 M, 10−5 M to 10−10 M, 10−6 M to 10−10 M, 10−7 M to 10−10 M, 10−8 M to 10−10 M, 10−9 M to 10−10 M, 10−5 M to 10−9 M, 10−6 M to 10−9 M, 10−7 M to 10−9 M, 10−8 M to 10−9 M, 10−5 M to 10−8 M, 10−6 M to 10−8 M, 10−7 M to 10−8 M, 10−5 M to 10−7 M, 10−6 M to 10−7 M, or 10−5 M to 10−6 M.
According to a specific embodiment of the present application, the antibody may be Fab including a heavy-chain variable region (VH) including the sequence of SEQ ID NO: 1, a heavy-chain constant region (CH) including the sequence of SEQ ID NO: 3, and a light-chain variable region (VL) including the sequence of SEQ ID NO: 2, and a light-chain constant region (CL) including the sequence of SEQ ID NO: 4.
In a specific embodiment according to the present invention, a humanized antibody hzTAAB, such as hzTAAB-H1 or hzTAAB-L1, was constructed. The humanized antibody hzTAAB may include a heavy-chain variable region including the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO: 7 and a light-chain variable region including the amino acid sequence of SEQ ID NO: 6 or SEQ ID NO: 8.
Specifically, in claim 3, the humanized antibody may include:
The antibody or antibody fragment according to the present invention may include not only the sequence of the anti-Tie2 antibody set forth herein, but also biological equivalents thereto, within a range that enables specific recognition of Tie2. For example, additional modifications may be made to the amino acid sequence of an antibody in order to further improve the binding affinity and/or other biological properties of the antibody. Such modifications include, for example, deletion, insertion, and/or substitution of the amino acid sequence residues of the antibody. The amino acid variations are based on the relative similarity of amino acid side-chain substituents with regard to, for example, hydrophobicity, hydrophilicity, charge, size, and the like. Based on analysis of the size, shape, and type of amino acid side-chain substituents, all of arginine, lysine, and histidine are positively charged residues, alanine, glycine, and serine have similar sizes, and phenylalanine, tryptophan, and tyrosine have similar shapes. Therefore, based on these considerations, arginine, lysine, and histidine may be regarded as biologically functional equivalents, alanine, glycine, and serine may be regarded as biologically functional equivalents, and phenylalanine, tryptophan, and tyrosine may be regarded as biologically functional equivalents.
Taking into consideration the above-described variations having equivalent biological activity, the amino acid sequence of the antibody of the present invention or the nucleic acid molecule encoding the same is to be understood as including a sequence showing substantial identity to the sequence set forth in the sequence number. When the sequence of the present invention and any other sequences are aligned so as to correspond to each other as closely as possible and the aligned sequence is analyzed using an algorithm commonly used in the art, “substantial identity” refers to sequences exhibiting at least 90% homology, most preferably at least 95% homology, at least 96% homology, at least 97% homology, at least 98% homology, or at least 99% homology. Alignment methods for sequence comparison are known in the art. The NCBI Basic Local Alignment Search Tool (BLAST) is accessible through NBCI and elsewhere, and may be used in conjunction with sequencing programs such as blastp, blasm, blastx, tblastn, and tblastx on the Internet. BLAST is available at www.ncbi.nlm.nih.gov/BLAST/. A method for comparing sequence homology using this program may be found at www.ncbi.nlm.nih.gov/BLAST/blast_help.html.
Based thereon, the antibody or antigen-binding fragment thereof according to the present invention may have 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or higher homology with a specified sequence or all of the sequences set forth herein. Such homology may be determined through sequence comparison and/or alignment using methods known in the art. For example, the percentage sequence homology of a nucleic acid or protein of the present invention may be determined using a sequence comparison algorithm (i.e., BLAST or BLAST 2.0), manual alignment, or visual inspection.
Another aspect of the present invention pertains to a nucleic acid encoding the antibody or antigen-binding fragment thereof.
The nucleic acid may include the sequence selected from the group consisting of SEQ ID NOS: 9 to 14.
An antibody or antigen-binding fragment thereof may be recombinantly produced by isolating a nucleic acid encoding the antibody or antigen-binding fragment thereof according to the present invention. The nucleic acid may be isolated and inserted into a replicable vector for further cloning (DNA amplification) or further expression. Based thereon, still another aspect of the present invention pertains to a vector including the nucleic acid.
Here, “nucleic acid” has a meaning comprehensively encompassing DNA (gDNA and cDNA) and RNA molecules, and nucleotides, which are the basic building blocks of nucleic acids, include not only natural nucleotides but also analogues in which sugar or base regions are modified. The sequences of the nucleic acids encoding the heavy- and light-chain variable regions of the present invention may be modified. Such modification includes addition, deletion, or non-conservative or conservative substitution of nucleotides.
DNA encoding the antibody is easily isolated or synthesized using typical techniques (e.g., using an oligonucleotide probe capable of specifically binding to DNA encoding the heavy and light chains of the antibody). Many vectors are available. A vector component generally includes, but is not limited to, at least one selected from among a signal sequence, an origin of replication, at least one marker gene, an enhancer element, a promoter, and a transcription termination sequence.
As used herein, the term “vector” refers to a means for expressing a target gene in a host cell, and includes a plasmid vector, a cosmid vector, a virus vector, such as a bacteriophage vector, an adenovirus vector, a retrovirus vector, and an adeno-associated virus vector, etc. In the vector, the nucleic acid encoding the antibody is operably linked with a promoter.
Here, “operably linked” means a functional linkage between a nucleic acid expression control sequence (e.g., a promoter, a signal sequence, or an array of transcription regulator binding sites) and a different nucleic acid sequence, whereby the control sequence serves to control the transcription and/or translation of the different nucleic acid sequence.
When a prokaryotic cell is used as a host, a strong promoter capable of promoting transcription (e.g., a tac promoter, lac promoter, lacUV5 promoter, lpp promoter, pLλ promoter, pRλ promoter, rac5 promoter, amp promoter, recA promoter, SP6 promoter, trp promoter, or T7 promoter), a ribosome-binding site for initiation of translation, and a transcription/translation termination sequence are generally included. In addition, for example, when a eukaryotic cell is used as a host, a promoter derived from the genome of a mammalian cell (e.g., a metallothionine promoter, B-actin promoter, human hemoglobin promoter, or human muscle creatine promoter) or a promoter derived from a mammalian virus (e.g., an adenovirus late promoter, vaccinia virus 7.5K promoter, SV40 promoter, cytomegalovirus (CMV) promoter, tk promoter of HSV, mouse mammary tumor virus (MMTV) promoter, LTR promoter of HIV, promoter of Moloney virus, promoter of Epstein-Barr virus (EBV), or promoter of Rous sarcoma virus (RSV)) may be used, and a polyadenylation sequence is generally used as a transcription termination sequence.
In some cases, the vector may be fused with another sequence in order to facilitate purification of the antibody expressed therefrom. Examples of the sequence that is fused therewith include glutathione S-transferase (Pharmacia, USA), maltose-binding protein (NEB, USA), FLAG (IBI, USA), and 6× His (hexa-histidine; Qiagen, USA).
The vector contains, as a selective marker, an antibiotic resistance gene that is commonly used in the art, for example, a gene conferring resistance to ampicillin, gentamicin, carbenicillin, chloramphenicol, streptomycin, kanamycin, geneticin, neomycin, or tetracycline.
Yet another aspect of the present invention pertains to cells transformed with the vector described above. Examples of the cells used to produce the antibody of the present invention may include, but are not limited to, prokaryotic cells, yeast cells, and higher eukaryotic cells.
Prokaryotic host cells, such as Escherichia coli, Bacillus subtilis and Bacillus thuringiensis as strains belonging to the genus Bacillus, Streptomyces, Pseudomonas (e.g., Pseudomonas putida), Proteus mirabilis, and Staphylococcus (e.g., Staphylococcus carnosus), may be used.
Here, animal cells are of greatest interest, and examples of useful host cell lines may include, but are not limited to, COS-7, BHK, CHO, CHOK1, DXB-11, DG-44, CHO/-DHFR, CV1, COS-7, HEK293, BHK, TM4, VERO, HELA, MDCK, BRL 3A, W138, Hep G2, SK-Hep, MMT, TRI, MRC 5, FS4, 3T3, RIN, A549, PC12, K562, PER.C6, SP2/0, NS-0, U20S, and HT1080.
Still yet another aspect of the present invention pertains to a method of producing the antibody or antigen-binding fragment thereof including (a) culturing the cells described above and (b) recovering the antibody or antigen-binding fragment thereof from the cultured cells.
The cells may be cultured in various media. Any commercially available medium may be used as a culture medium without limitation. All other essential supplements known to those skilled in the art may be contained in appropriate concentrations. Culture conditions, such as temperature, pH, etc., are already in use with the host cells selected for expression, as will be apparent to those skilled in the art.
For recovery of the antibody or antigen-binding fragment thereof, impurities may be removed by, for example, centrifugation or ultrafiltration, and the resultant product may be purified using, for example, affinity chromatography, etc. Other additional purification techniques, such as anion or cation exchange chromatography, hydrophobic interaction chromatography, hydroxyapatite chromatography, and the like, may be used.
Even yet another aspect of the present invention pertains to a composition for preventing or treating an angiogenic disease including the antibody or antigen-binding fragment thereof as an active ingredient.
Here, “angiogenesis” refers to the formation or growth of new blood vessels from previously existing blood vessels, and “angiogenesis-related disease” refers to a disease related to the occurrence or progression of angiogenesis. A disease may fall within the scope of angiogenesis-related diseases without limitation so long as it may be treated with the antibody. Examples of the angiogenesis-related disease may include, but are not limited to, cancer, metastasis, diabetic retinopathy, retinopathy of prematurity, corneal graft rejection, macular degeneration, neovascular glaucoma, erythrosis, proliferative retinopathy, psoriasis, hemophilic arthritis, capillary formation of atherosclerotic plaques, keloid, wound granulation, vascular adhesion, rheumatoid arthritis, osteoarthritis, autoimmune diseases, Crohn's disease, restenosis, atherosclerosis, intestinal adhesions, cat scratch disease, ulcer, liver cirrhosis, nephritis, diabetic nephropathy, diabetes mellitus, inflammatory diseases, and neurodegenerative diseases. Moreover, the cancer may be selected from the group consisting of esophageal cancer, stomach cancer, large intestine cancer, rectal cancer, oral cancer, pharynx cancer, larynx cancer, lung cancer, colon cancer, breast cancer, uterine cervical cancer, endometrial cancer, ovarian cancer, prostate cancer, testicular cancer, bladder cancer, renal cancer, liver cancer, pancreatic cancer, bone cancer, connective tissue cancer, skin cancer, brain cancer, thyroid cancer, leukemia, Hodgkin's lymphoma, lymphoma, and multiple myeloid blood cancer, but is not limited thereto.
As used herein, the term “prevention or prophylaxis” refers to any action that inhibits or delays the onset of a disease of interest by administering the antibody or the composition according to the present invention. The term “treatment or therapy” refers to any action that ameliorates or alleviates symptoms of a disease of interest by administering the antibody or the composition according to the present invention.
The composition including the antibody of the present invention may be a pharmaceutical composition and may further include appropriate vehicles, excipients, or diluents typically used in the art.
The pharmaceutical composition including pharmaceutically acceptable vehicles may be provided in a variety of oral or parenteral dosage forms such as tablets, pills, powders, granules, capsules, suspensions, oral solutions, emulsions, syrups, sterile aqueous solutions, non-aqueous solutions, suspensions, lyophilizates, and suppositories. In regard thereto, the pharmaceutical composition of the present invention may be formulated in combination with diluents or excipients, such as fillers, thickeners, binders, wetting agents, disintegrants, surfactants, etc. Solid formulations for oral administration may be in the form of tablets, pills, powders, granules, capsules, etc. In connection with these solids, the compound of the present invention may be formulated in combination with at least one excipient, such as starch, calcium carbonate, sucrose, lactose, or gelatin. Lubricants such as simple excipients, magnesium stearate, talc, etc. may be additionally used. Liquid formulations for oral administration may be suspensions, oral solutions, emulsions, syrups, etc. Various excipients such as simple diluents such as water or liquid paraffin, wetting agents, sweeteners, aromatics, preservatives, etc. may be included in liquid formulations. Moreover, the pharmaceutical composition of the present invention may be in a parenteral dosage form such as a sterile aqueous solution, non-aqueous solvent, suspension, emulsion, lyophilizate, suppository, etc. Injectable propylene glycol, polyethylene glycol, vegetable oils such as olive oil, and esters such as ethyl oleate may be suitable for non-aqueous solvents and suspensions. The basic materials for suppositories include Witepsol, Macrogol, Tween 61, cacao butter, laurin butter, and glycerogelatin.
The composition of the present invention is administered in a pharmaceutically effective amount. As used herein, the term “pharmaceutically effective amount” refers to an amount of a pharmaceutical composition sufficient to treat a disease at a reasonable benefit/risk ratio applicable to any medical treatment. The effective amount is determined depending on various factors including severity of the disease to be treated, the patient's age and gender, type of disease, activity of the drug, sensitivity to the drug, administration time, administration route, secretion rate, treatment period, co-administration of the drug, and other parameters known in the art. The composition of the present invention may be administered alone or in combination with the other therapeutics. As such, composition may be administered sequentially or simultaneously with conventional therapeutics. Also, the composition may be administered in a single dose or multiple doses. Taking these factors into full consideration, it is important to administer the minimum amount sufficient to obtain a maximum effect without side effects, and this dose may be readily determined by an expert in the field. The dose of the pharmaceutical composition of the present invention is not particularly limited, but varies depending on various factors, including the patient's health status and body weight, severity of the disease, type of drug, administration route, and administration time. The composition may be administered in a single dose or multiple doses per day into mammals, including rats, mice, livestock, humans, etc., by typically accepted routes, for example, orally, intrarectally, intravenously, subcutaneously, intrauterinely, or intracerebrovascularly.
A further aspect of the present invention pertains to a method of inhibiting angiogenesis or a method of preventing or treating an angiogenesis-related disease, including administering the antibody or the composition to a subject in need thereof.
The method of the present invention includes administering a pharmaceutically effective amount of a pharmaceutical composition to a subject in need of inhibition of angiogenesis. The subject may be a mammal such as a dog, bovine, horse, rabbit, mouse, rat, chicken, or human, but is not limited thereto. The pharmaceutical composition may be administered parenterally, subcutaneously, intraperitoneally, intrapulmonarily, or intranasally, and, as necessary, by an appropriate method including intralesional administration for topical treatment. The preferred dose of the pharmaceutical composition of the present invention varies depending on various factors, including the subject's health status and body weight, severity of the disease, type of drug, administration route, and administration time, and may be readily determined by those skilled in the art.
Still a further aspect of the present invention pertains to a pharmaceutical composition for preventing or treating cancer including the antibody, or a method of preventing or treating cancer including administering the antibody or the composition to a subject in need thereof. Here, the terms “antibody”, “prevention”, and “treatment” are as described above.
The type of cancer is not limited, so long as it is able to be treated with the antibody of the present invention. Particularly, the antibody of the present invention is capable of preventing the onset or progression of cancer by inhibiting angiogenesis. Examples of cancer include, but are not limited to, esophageal cancer, stomach cancer, large intestine cancer, rectal cancer, oral cancer, pharynx cancer, larynx cancer, lung cancer, colon cancer, breast cancer, uterine cervical cancer, endometrial cancer, ovarian cancer, prostate cancer, testicular cancer, bladder cancer, renal cancer, liver cancer, pancreatic cancer, bone cancer, connective tissue cancer, skin cancer, brain cancer, thyroid cancer, leukemia, Hodgkin's lymphoma, lymphoma, and multiple myeloid blood cancer.
Also, the antibody of the present invention may be used in combination with other antibodies or biologically active agents or materials for various purposes. Yet a further aspect of the present invention pertains to a composition for co-administration with an additional therapeutic agent for an angiogenic disease, including the antibody or antigen-binding fragment thereof.
Examples of the additional therapeutic agent for an angiogenic disease may include anti-angiogenic drugs, anti-inflammatory drugs, and/or anticancer drugs. Thereby, these may overcome each other's resistance and improve efficacy.
When the composition according to the present invention is co-administered with an additional therapeutic agent for an angiogenic disease, the Tie2 antibody and the additional therapeutic agent for an angiogenic disease may be administered sequentially or simultaneously. For example, an anti-angiogenic drug, an anti-inflammatory drug, and/or an anticancer drug may be administered to a subject and then the composition including the Tie2 antibody or antigen-binding fragment thereof as an active ingredient may be administered thereto, or the composition may be administered to a subject and then an anti-angiogenic drug, an anti-inflammatory drug, and/or an anticancer drug may be administered thereto. In some cases, the composition may be administered to a subject simultaneously with an anti-angiogenic drug, an anti-inflammatory drug, and/or an anticancer drug.
A better understanding of the present invention may be obtained through the following examples. These examples are merely set forth to illustrate the present invention, and are not to be construed as limiting the scope of the present invention, as will be apparent to those of ordinary skill in the art.
Recombinant Tie2 protein for mouse immunization was produced by cloning the gene encoding hTie2 Ig3-Fn3 (human Tie2 residues 349-738, GenBank accession number: AAH35514.2) into the pFuse-hIgG1-Fc vector (pFuse-hg1fc1, InvivoGen), followed by transient expression in Expi293F cells.
Particularly, Expi293F cells (2×106 cells/ml) were cultured in Expi293 expression medium (A1435103, ThermoFisher) and then transfected with a plasmid encoding hTie2 Ig3-Fn3 using an ExpiFectamine293 transfection kit (A14524, ThermoFisher). The cells were cultured for 5 days at 37° C. and 8% CO2 in a shaking incubator (orbital shaker, 125 rpm). After removal of cells by centrifugation, the culture supernatant including the secreted hTie2 Ig3-Fn3-Fc fusion protein was purified on an AKTA purification system (GE Healthcare) equipped with a HiTrap MabSelect SuRe affinity column (11003494, GE Healthcare). The purified hTie2Ig3-Fn3-Fc fusion protein was concentrated using an Amicon Ultra centrifugal filter (UFC8030, Millipore), and the buffer was replaced with PBS. The Fc tag of the fusion protein was removed by thrombin cleavage (27-0846-01, GE Healthcare) at 22° C. for 18 hours. The hTie2 Ig3-Fn3 protein was further purified by removing the cleaved Fc tag on a HiTrap MabSelect SuRe affinity column.
To prepare human Tie2 for crystallization, the gene encoding hTie2 Fn2-3 (residues 541-735) (described below) was cloned into pET-28a (69864, Novagen) and expressed in E. coli BL21 (DE3) RIL (230240, Agilent Technologies).
The cells were allowed to grow at 37° C. in LB medium supplemented with 50 μg/ml kanamycin until OD600 was 0.4. Protein expression was induced in 0.05 mM IPTG (isopropyl β-d-1-thiogalactopyranoside) and cultured at 18° C. for 15 hours. The cells were recovered by centrifugation, resuspended in lysis buffer (20 mM HEPES, pH 7.5, and 200 mM NaCl), and lysed by sonication on ice. After removal of cell debris by centrifugation (13,000×g at 4° C. for 0.5 hours), the supernatant was applied to a Ni-NTA agarose affinity column (30210, QIAGEN). After washing with wash buffer (20 mM HEPES, PH 7.5, 200 mM NaCl, and 50 mM imidazole) equivalent to 5 times the column volume, proteins were eluted with elution buffer (20 mM HEPES, pH 7.5, 200 mM NaCl, and 400 mM imidazole), and further purified by size-exclusion chromatography using a HiLoad16/600 Superdex 200 pg column (28-9893-35, GE Healthcare) equilibrated with 20 mM HEPES, pH 7.5, and 200 mM NaCl. To prepare chimeric hTAAB Fab for crystallization, the synthesized heavy and light chains for chimeric hTAAB Fab were cloned into a modified pBAD expression vector for periplasmic secretion. E. coli Top10F (Invitrogen) cells were transformed with plasmid pBAD-Fab and then allowed to grow at 37° C. in LB medium supplemented with 100 μg/ml ampicillin. Protein expression was induced with 0.2% arabinose at OD600 of 1.0, and the cells were allowed to grow at 30° C. for 15 hours. The cells were recovered by centrifugation, resuspended in lysis buffer (20 mM HEPES, pH 7.5, and 200 mM NaCl), and lysed by sonication on ice. After removal of cell debris by centrifugation (13,000×g at 4° C. for 30 minutes), the supernatant including soluble chimeric hTAAB Fab was applied to a Ni-NTA agarose affinity chromatography column (QIAGEN) and washed with wash buffer (20 mM HEPES, pH 7.5, 200 mM NaCl, and 50 mM imidazole) equivalent to 5 times the column volume. Proteins were eluted with elution buffer (20 mM HEPES, pH 7.5, 200 mM NaCl, and 400 mM imidazole) and further purified by size-exclusion chromatography using a HiLoad16/600 Superdex 200 pg column equilibrated with 20 mM HEPES, pH 7.5, and 200 mM NaCl. Purified proteins and antibodies were dispensed and stored at −80° C.
Five-week-old BALB/c mice were immunized with purified hTie2-Ig3-Fn3 (100 μg/injection) mixed with adjuvant twice a week for 6 weeks. Anti-Tie2 antibodies in the sera of immunized mice were assessed by hTie2 ELISA (enzyme-linked immunosorbent assay). When antibody titers (at a 1:5000 dilution) adequately increased (OD>1.0), B lymphocytes were isolated from the spleen of immunized mice and fused with cultured myeloma cells (SP2/0). The fused cells were cultured in HAT (hypoxanthine, aminopterin, and thymidine) medium, and hybridoma cells were selected and cultured with only fused myeloma cells and B lymphocytes.
B-cell hybridoma was maintained in DMEM (Dulbecco's Modified Eagle Medium) supplemented with 10% fetal bovine serum (FBS), penicillin (100 U/ml), and streptomycin (100 mg/ml). In order to produce anti-Tie2 antibodies in B-cell hybridoma, cells were washed with PBS and cultured in serum-free medium (SFM, 12045-076, Gibco) for 3 days.
The surviving hybridoma cells were dispensed in 96-well plates, and the culture supernatant was tested by hTie2 ELISA. For clone selection by limiting dilution, hybridoma pools showing+signals were selected.
Hybridoma cells (2×106 cells/ml) were cultured in DMEM containing 10% FBS, and total RNA was acquired using the RNeasy mini kit (Qiagen). RNA concentration was measured and cDNA was synthesized by reverse transcription (RT). Heavy- and light-chain variable region gene sequences were subjected to PCR using a Mouse Ig-Primer set (Novagen) and the synthesized cDNA as a template at 94° C. for 5 minutes, followed by 35 cycles of 94° C. for 1 minute, 50° C. for 1 minute, 72° C. for 2 minutes, and then 72° C. for 6 minutes with gradual cooling to 4° C. The PCR product obtained from each reaction was cloned into a TA vector and subjected to DNA sequencing, yielding nucleotide sequences encoding the heavy- and light-chain variable regions of each antibody.
The ECD of Tie2 forms dimers through membrane-proximal Fn3, regardless of ligand binding. Multimeric Angpt1 binding to ligand-binding domains (LBDs) cross-links these preformed Tie2 dimers into higher-order oligomers or “Tie2 clusters” for Tie2 activation and downstream signaling. However, the LBDs of preformed Tie2 homodimers are too far away (˜260 Å) for a single antibody targeting LBD to induce Tie2 clustering. Based on this concept, an anti-Tie2 antibody binding to the membrane-proximal Tie2 Fn domain was postulated to induce Tie2 oligomerization and activation, like multimeric Angpt1.
hTAAB, which is an hTie2-activating mouse monoclonal antibody that targets Ig3-Fn3 of hTie2, not mTie2, was produced.
Human-mouse chimeric IgG1, IgG2, and IgG4 antibodies of Tie2-activating antibody hTAAB were produced by cloning the heavy- or light-chain variable regions (VH or VL) of mouse hTAAB into backbone vectors expressing the human heavy- or light-chain constant regions (CH or CL). A DNA fragment encoding the heavy-chain variable region of mouse hTAAB was synthesized as the sequence “EcoRV-signal sequence-VH-NheI” (Bioneer, Inc). The synthesized DNA fragment was digested with EcoRV and NheI and then cloned into pFUSE-CHIg-hG1 (IgG1 isotype) and pFUSE-CHIg-hG2 (IgG2 isotype) vectors (InvivoGen). In order to construct human IgG4 chimeric antibody, DNA encoding the heavy-chain variable region (VH) of mouse hTAAB was amplified by PCR using primers including EcoRI and NheI sites for cloning. Then, the PCR product was subcloned into a modified pOptiVEC-TOPO vector expressing the heavy-chain constant region (CH) of human IgG4 antibody. The chimeric light-chain expression vector was constructed by PCR-amplifying a DNA fragment encoding the light-chain variable region of mouse hTAAB using primers including EcoRI and BsiWI restriction sites.
Human IgG1 heavy-chain constant region (CH1-CH3)
Human IgG2 heavy-chain constant region (CH1-CH3)
Human IgG4 heavy-chain constant region (CH1-CH3)
Next, the PCR product was subcloned into a modified pcDNA3.3-TOPO vector expressing the human kappa light-chain constant region.
Chimeric antibodies were produced using the Expi293 expression system (ThermoFisher). Expi293F cells were co-transfected with heavy- and light-chain expression vectors using the ExpiFectamine 293 transfection kit (A14524, ThermoFisher), after which the transfected cells were cultured in Expi293 expression medium for 5 days. The culture supernatant was filtered through a 0.45-μm filter, and antibodies were purified using an AKTA purification device (GE Healthcare) equipped with a HiTrap MabSelect SuRe column (11003494, GE Healthcare).
In order to delineate the epitope for hTAAB binding, the minimal domain of Tie2 for hTAAB binding was identified. Since hTie2 Ig3-Fn3 was used to immunize mice for antibody production, three recombinant proteins including Ig3-Fn3, Fn1-3, or Fn2-3 of hTie2 were produced (
The crystal structure of the hTie2 Fn2-3/chimeric hTAAB Fab complex at 2.1 Å resolution (Table 1) was determined by molecular replacement using durvalumab Fab (PDB: 5X8M) and Tie2 Fn2-3 structures (PDB: 5MYA chain B) models. The as search crystallographic asymmetric unit contained a 2-fold symmetric heterotetrameric hTie2 Fn2-3/chimeric hTAAB Fab complex (2:2 stoichiometry).
4953)
9.9 (50.9)a
aValues in parentheses refer to the highest resolution shell.
bRmerge = Σ Σ
I
I
Σ
Σ
I
cR = Σ
F
F
F
indicates data missing or illegible when filed
Two chimeric hTAAB Fabs bound to the lateral side of each hTie2 Fn3 domain at a tilt of approximately 15° relative to the plane perpendicular to the 2-fold axis (
These results show that hTAAB binding did not cause a change in conformation of the hTie2 homodimer. Four domains of chimeric hTAAB Fab (heavy-chain variable region (VH), heavy-chain constant region (CH), light-chain variable region (VL), and light-chain constant region (CL)) adopted a typical Ig domain fold composed of a pair of β sheets. Heavy-chain CDRs (HCDR1, HCDR2, and HCDR3) and light-chain CDRs (LCDR1, LCDR2, and LCDR3) were involved in contact with the hTie2 Fn3 domain (
Chimeric hTAAB Fab binds to hTie2 Fn3 through a large interaction interface with a total buried surface area of 897.5 Å2 composed of about 57% heavy-chain contacts (512.8 Å2; dark orange) and 43% light-chain contacts (384.7 Å2; light orange) (
The interactions of the A region are mainly mediated by ionic interactions and hydrogen bonds between the hTAAB heavy chain (HCDR1 and HCDR2) and the hTie2 Fn3 domain. Residues on hTAAB HCDR1 (S28, T30, S31, and W33) and HCDR2 (H52, D55, and E57) form multiple interactions with residues on hTie2 Fn3 βA [E643, N644, 1645 (main chain), K646, 1647 (main chain)] and βG (H727) (
In the B region, HCDR3, LCDR1, LCDR2, and LCDR3 of hTAAB cover a wide surface of hTie2 Fn3 by hydrophobic interactions, with a total buried surface area of 413.5 Å2A. Residues 1647, 1650, A707, V730, and L732 of hTie2 Fn3 form a network of hydrophobic core interactions with residues L100 and Y101 on HCDR3 and 131, Y49, A50, Y91, and A92 on LCDRs (
Interestingly, hTAAB light-chain residues involved in the C-region interactions are located on the β-strands of FRs (R46 on BC′, S53 on BC′, and R66 on BD), rather than the CDR loop. Most hTie2 Fn3 residues involved in hTAAB interactions are highly conserved among various species (
Consistent with previous Tie2 apo-structures (5MYB and Dimer2 model of 5UTK), the Fn3-Fn3′ interface is composed of hydrogen bonds between main-chain atoms of homotypic Fn3 BC′ (D682-K690), forming a continuous antiparallel ß-sheet (
Crystal structures and functional analysis using Fn2 mutants have suggested that Fn2 interactions are essential for lateral clustering of preformed Tie2 dimers. Surprisingly, even when the structure contained the Tie2 Fn2-3/hTAAB Fab complex and the space group for the protein crystal was different between two structures, the same interaction was observed between Fn2 domains of neighboring homodimers in the crystal packing (
Human umbilical vein endothelial cells (HUVECs; C2519A, Lonza) were maintained in EGM-2 endothelial proliferation medium (CC-3162; Lonza) and cultured at 37° C. and 5% CO2 in a humidified incubator. Expi293F cells (A14527, ThermoFisher) were maintained in Expi293 expression medium (A1435102, ThermoFisher) and cultured at 37° C. and 8% CO2 in a humidified shaking incubator.
Multimeric Angpt1 or COMP-Angpt1 is able to induce higher-order clustering of Tie2, which is key for activating Tie2 and downstream signaling thereof in ECs for vascular stabilization. The level of phosphorylation of Akt, which is a major downstream signaling protein of the Tie2 receptor, was measured using immunoblotting technology. Interestingly, not only hTAAB Fab but also hTAAB IgG1 induced concentration-dependent activation of Tie2 and Akt in primarily cultured HUVECs (
In order to mimic ligand-independent Tie2 dimers in a physiological cell membrane, a constitutive Tie2 dimer was artificially produced. The two residues D682 and N691 involved in the homotypic Fn3-Fn3′ interaction were mutated to cysteines (D682C and N691C) to introduce a disulfide bond (
The biological relevance and significance of Tie2/hTAAB polygonal assemblies in the cell membrane were evaluated. The Tie2 dimer (D682C/N691C) was used to construct a Tie2 monomer (V685D/V687D/K700E) along with a full-length Tie2-GFP construct by disrupting the Fn3-Fn3′ dimeric interface (
The Fv region of mouse hTAAB was humanized based on the Tie2 Fn2-3/chimeric hTAAB Fab complex structure and the model structure of IGHV1-46*01 and IGKV1-17*01 complexes.
The mouse hTAAB Fv sequence was compared with that of human germline genes using the IMGT/DomainGapAlign online tool from the International ImmunoGeneTics Information System (IMGT) (http://www.imgt.org). IGHV1-46*01 and IGKV1-17*01, which exhibited the highest sequence identity to heavy- and light-chain variable regions of mouse hTAAB, respectively, were selected as human framework (FR) donors. The CDRs (defined by IMGT numbering) of IGHV1-46*01 and IGKV1-17*01 were replaced with the counterparts in mouse hTAAB, producing hzTAAB-H1 and hzTAAB-L1. The selected residues critical for maintaining VH-VL pairing, CDR conformation, and affinity for Tie2 Fn3 were further substituted on hzTAAB-H1 and hzTAAB-L1, producing hzTAAB-H2 and hzTAAB-L2. The resulting humanized Fv genes (hzTAAB-H1, hzTAAB-H2, hzTAAB-L1, and hzTAAB-L2) were synthesized (Bioneer) and optimized for expression in mammalian cells. The human immunoglobulin kappa light-chain constant region (GenBank accession number: AAA58989.1) and the human immunoglobulin gamma 1 heavy-chain constant region (GenBank accession number: AWK57454.1) were first cloned into pOptiVEC-TOPO and pcDNA3.3-TOPO vectors, into which the synthesized variable regions of humanized light and heavy chains (hzTAAB-H1, hzTAAB-H2, hzTAAB-L1, or hzTAAB-L2) were subsequently cloned.
Expi293F Cells were Transfected with Plasmids containing humanized light and heavy chains using an ExpiFectamine 293 transfection kit (A14524, ThermoFisher). The cells were cultured for 5 days at 37° C. and 8% CO2 in a shaking incubator (orbital shaker, 125 rpm). The obtained culture supernatant was centrifuged to remove cells, and antibodies were isolated by affinity chromatography on a ProA column (Amicogen) equilibrated with PBS. The bound antibodies were eluted with 0.1 M glycine-HCl, pH 2.7, and neutralized with 1 M Tris-Cl, pH 9.0. The eluted antibodies were further purified by size-exclusion chromatography using a Superdex 200 Gain 10/300 GL column (28-9909-44, GE Healthcare) equilibrated with PBS. Antibody purity was evaluated using reducing and non-reducing SDS-PAGE, and purified antibodies were dispensed and stored at −80° C.
SWISS-MODEL homology modeling was performed with sequences of human germline IGHV1-46*01 and IGKV1-17*01 grafted with hTAAB CDRs using the structure of hTAAB Fv in the Tie2 Fn2-3/chimeric hTAAB Fab complex structure as a template. The resulting model with the highest QMEAN-Z (Qualitative Model Energy ANalysis-Z) score (−0.37) was aligned to the hTAAB Fv structure for further structure-based humanization.
Potent Tie2-agonistic activity of hTAAB is promising in clinical applications for vascular diseases. Therefore, attempts were made to humanize mouse hTAAB while maintaining the ability to bind to and activate Tie2 but minimizing immunogenicity, which is attributable to mouse origin thereof. Due to variation in length, sequence, and the number of disulfide bonds at the hinge between Fab and Fc domains, the hinge flexibility of IgG subclasses is slightly variable, and the Fab-Fab angle and Fab orientation relative to the Fc domain for each subclass are also variable.
Considering that the Fab-Fab angle and Fab orientation of hTAAB may be key determinants of polygonal assembly of Tie2, whether this hinge flexibility affects Tie2 activation was investigated. To this end, chimeric IgG1, IgG2, or IgG4 including the variable region of hTAAB was constructed (
Using the IMGT/Domain Gap Align tool from IMGT (International ImmunoGeneTics information system) (http://www.imgt.org), CDR boundaries were defined and human germline genes IGHV1-46*01 and IGKV1-17*01 were selected as human FR donors because they showed the highest sequence identities to the heavy-chain variable region (66%) and light-chain variable region (68%) of mouse hTAAB (
Binding kinetics of mouse hTAAB and humanized IgG1 for human Tie2 were measured by surface plasmon resonance (SPR) using a Biacore T200 system equipped with certified-grade CM5 series S sensor chips (BR100399, GE Healthcare). HEPES-buffered saline (0.01 M HEPES and 0.15 M NaCl) containing 3 mM EDTA (ethylenediaminetetraacetic acid) and 0.05% (v/v) P20 detergent (HBS-EP+) was used as reaction and running buffer (BR100669, GE Healthcare). Human Tie2 ECD (produced in-house; residues 23-735 of human Tie2, GenBank accession number: AAH35514.2) was immobilized on the surface of a CM5 sensor chip by amine coupling using 10 mM acetate at a pH of 5.5. Thereafter, mouse hTAAB and humanized IgG1 diluted in HBS-EP+buffer were applied over antigen-immobilized sensor chips at 7 different concentrations (0, 2, 4, 8, 16, 32, and 64 nM) for 300 seconds at a flow rate of 30 μl/min. Analytes bound to the sensor chips were dissociated by washing with HBS-EP+running buffer for 300 seconds. Both association (Kon, M−1s−1) and dissociation (Koff, s−1) constants were measured at 300-second intervals. The equilibrium dissociation constant (KD, M) was calculated as the ratio of off-rate to on-rate (Koff/kon). Kinetic parameters were determined with the global fitting function of Biacore Insight Evaluation Software using a 1:1-binding model.
Binding kinetics of mouse hTAAB and humanized IgG1 for mouse Tie2 were measured by BLI (biolayer interferometry) using the Octet system (ForteBio). Analysis was performed at 30° C. After hydration for 10 minutes in kinetics buffer (0.01% endotoxin-free BSA, 0.002% Tween-20, and 0.005% NaN3 in PBS), mouse hTAAB (10 μg/ml each) was loaded onto anti-mouse IgG Fc capture (AMC) biosensors (ForteBio). Ab-coated sensors were incubated with a 1600 nM solution of mouse Tie2 Ig3-Fn3 (residues 349-737) and thus association curves were recorded for 600 seconds. Dissociation was measured for 600 seconds in kinetics buffer.
Conventional CDR grafting was performed by simply replacing CDR portions in the selected human germline FR donors with corresponding CDRs of hybridoma mouse antibody hTAAB. In order to maintain the conformation of hTAAB HCDR2, S59 was replaced with a R59 residue flanking the HCDR2 of hTAAB heavy chains in the humanized antibody. The CDR-grafted variable regions of humanized Tie2-activating antibody (hzTAAB) heavy and light chains (hzTAAB-H1 and hzTAAB-L1) were cloned into a pOptiVEC-TOPO vector including the human Ig γ1 heavy-chain constant region (GenBank accession number: AWK57454.1) and a pcDNA3.3-TOPO vector including the human Ig κ light-chain constant region (GenBank accession number: AAA58989.1), respectively. After co-expression of hzTAAB-H1 and hzTAAB-L1 in HEK293F cells, the antibodies were purified to homogeneity as full-length IgG1 by protein A affinity chromatography and SEC (
Regarding structure-based humanization of hTAAB, homology modeling of hzTAAB-H1 and hzTAAB-L1 was performed using the Fv (variable fragment) structure of parental hTAAB in the crystal structure as a template. The parental hTAAB Fv structure was placed on the resulting hzTAAB-H1L1Fv model to identify FR residues critical for maintaining VH-VL pairing, CDR conformation, and binding affinity to hTie2 (
Following hzTAAB-H1L1, three other hzTAABs (hzTAAB-H1L2, hzTAAB-H2L1, and hzTAAB-H2L2) were produced depending on different combinations of heavy and light chains, all as full-length IgG1s in HEK293F cells (
Subsequently, phosphorylation of Tie2 and Akt upon hzTAAB treatment was examined and compared with the phosphorylation after treatment with hTAAB or 3H7H12G4. Consistent with the Tie2 binding affinity, previously developed 3H7H12G4 showed very low Tie2-agonistic activity compared to hTAAB (
Accordingly, hzTAAB-H2L2 potently induces survival, migration, and tube formation of ECs, and Tie2 translocation to cell-cell contact sites and FOX01 translocation from the nucleus to cytosol, to a similar extent to COMP-Angpt1 and parental hTAAB (
The inventors of the present application developed a human Tie2-agonistic antibody hTAAB targeting the Tie2 Fn (membrane proximal fibronectin type III) domain and a humanized antibody thereof. The Tie2/hTAAB complex structure operates in a new mode of Tie2 clustering. It can be confirmed that hTAAB operates in a new mode of Tie2 clustering by forming a Tie2/hTAAB complex structure, and binds specifically to the Tie2 Fn3 domain, connecting Tie2 homodimers into a polygonal assembly. The importance of Fn3-mediated Tie2 homodimerization for Tie2 polygonal assemblies induced by hTAAB can be confirmed and how the Tie2 agonist induces Tie2 clustering and activation can be understood. Also, potential clinical applicability can be confirmed by constructing a humanized antibody based on the structure of hTAAB.
Having described specific parts of the present invention in detail above, it will be obvious to those skilled in the art that these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. Accordingly, the substantial scope of the present invention will be defined by the appended claims and equivalents thereto.
An electronic file is attached.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0093451 | Jul 2021 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2022/006431 | 5/4/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63184901 | May 2021 | US |
