Materials and methods for treating fibrosis in a mammal are disclosed. The methods comprise administering to a mammal a composition comprising a therapeutically effective amount of a zvegf3 antagonist in combination with a pharmaceutically acceptable delivery vehicle. Zvegf3 antagonists include anti-zvegf3 antibodies, mitogenically inactive receptor-binding zvegf3 variant polypeptides, and inhibitory polynucleotides. Within one embodiment of the invention the fibrosis is liver fibrosis.

Description of the Invention

DESCRIPTION OF THE INVENTION

The present invention provides materials and methods for reducing cell proliferation or extracellular matrix production, treating fibrosis, and reducing stellate cell activation in a mammal.

Within one aspect of the invention there is provided a method of reducing cell proliferation or extracellular matrix production in a mammal comprising administering to the mammal a composition comprising a zvegf3 antagonist in combination with a pharmaceutically acceptable delivery vehicle, wherein the zvegf3 antagonist is selected from the group consisting of anti-zvegf3 antibodies, mitogenically inactive receptor-binding zvegf3 variant polypeptides, and inhibitory polynucleotides, in an amount sufficient to reduce cell proliferation or extracellular matrix production. Within certain embodiments of the invention, proliferation of mesangial, endothelial, smooth muscle, fibroblast, osteoblast, osteoclast, stellate, or interstitial cells is reduced. Within other embodiments, the mammal is suffering from a fibroproliferative disorder of the liver, kidney, or bone.

Within another aspect of the present invention there is provided a method of treating fibrosis in a mammal comprising administering to the mammal a composition comprising a therapeutically effective amount of a zvegf3 antagonist in combination with a pharmaceutically acceptable delivery vehicle, wherein the zvegf3 antagonist is selected from the group consisting of anti-zvegf3 antibodies, mitogenically inactive receptor-binding zvegf3 variant polypeptides, and inhibitory polynucleotides. Within certain embodiment of the invention the fibrosis is liver fibrosis or kidney fibrosis.

Within a third aspect of the invention there is provided a method of reducing stellate cell activation in a mammal comprising administering to the mammal a composition comprising a zvegf3 antagonist in combination with a pharmaceutically acceptable delivery vehicle, wherein the zvegf3 antagonist is selected from the group consisting of anti-zvegf3 antibodies, mitogenically inactive receptor-binding zvegf3 variant polypeptides, and inhibitory polynucleotides, in an amount sufficient to reduce stellate cell activation. Within one embodiment, the stellate cells are liver stellate cells.

Within a fourth aspect of the invention there are provided pharmaceutical compositions for use within the above methods. In general, the compositions comprise a zvegf3 antagonist in combination with a pharmaceutically acceptable delivery vehicle, wherein the zvegf3 antagonist is selected from the group consisting of anti-zvegf3 antibodies, mitogenically inactive receptor-binding zvegf3 variant polypeptides, and inhibitory polynucleotides.

The present invention provides methods for treating fibrosis in a patient using zvegf3 antagonists. Zvegf3 is a protein that is structurally related to platelet-derived growth factor (PDGF) and the vascular endothelial growth factors (VEGF). This protein has also been designated "VEGF-R" (WIPO Publication WO 99/37671) and, more recently, "PDGF-C" (WO 00/18212). Zvegf3/PDGF-C is a multi-domain protein with significant homology to the PDGF/VEGF family of growth factors. Representative amino acid sequences of human and mouse zvegf3 are shown in SEQ ID NO:2 and SEQ ID NO:4, respectively. DNAs encoding these polypeptides are shown in SEQ ID NOS:1 and 3, respectively.

The term "zvegf3 protein" is used herein to denote proteins comprising the growth factor domain of a zvegf3 polypeptide (e.g., residues 235-345 of human zvegf3 (SEQ ID NO:2) or mouse zvegf3 (SEQ ID NO:4)), wherein said protein is mitogenic for cells expressing cell-surface PDGF .alpha.-receptor subunit. Zvegf3 has been found to bind to the .alpha..alpha. and .alpha..beta. isoforms of PDGF receptor. Zvegf3 proteins include homodimers and heterodimers as disclosed below. Using methods known in the art, zvegf3 proteins can be prepared in a variety of forms, including glycosylated or non-glycosylated, pegylated or non-pegylated, with or without an initial methionine residues, and as fusion proteins as disclosed in more detail below.

Structural predictions based on the zvegf3 sequence and its homology to other growth factors suggests that the polypeptide can form homomultimers or heteromultimers having growth factor activity, i.e., modulating one or more of cell proliferation, migration, differentiation, and metabolism. Experimental evidence confirms that biologically active zvegf3 is a dimeric protein. While not wishing to be bound by theory, the similarity of zvegf3 to other members of the PDGF/VEGF family suggests that zvegf3 may also form heteromultimers with other members of the family, including VEGF, VEGF-B, VEGF-C, VEGF-D, zvegf4 (SEQ ID NO:5), P1GF (Maglione et al., Proc. Natl. Acad. Sci. USA 88:9267-9271, 1991), PDGF-A (Murray et al., U.S. Pat. No. 4,899,919; Heldin et al., U.S. Pat. No. 5,219,759), or PDGF-B (Chiu et al., Cell 37:123-129, 1984; Johnsson et al., EMBO J. 3:921-928, 1984).

The zvegf3 polypeptide chain comprises a growth factor domain and a CUB domain. The growth factor domain is characterized by an arrangement of cysteine residues and beta strands that is characteristic of the "cystine knot" structure of the PDGF family. The CUB domain shows sequence homology to CUB domains in the neuropilins (Takagi et al., Neuron 7:295-307, 1991; Soker et al., ibid.), human bone morphogenetic protein-1 (Wozney et al., Science 242:1528-1534, 1988), porcine seminal plasma protein and bovine acidic seminal fluid protein (Romero et al., Nat. Struct. Biol. 4:783-788, 1997), and X. laevis tolloid-like protein (Lin et al., Dev. Growth Differ. 39:43-51, 1997).

An alignment of mouse and human zvegf3 polypeptide sequences is shown in FIG. 2 (see Original Patent). Analysis of the amino acid sequence shown in SEQ ID NO:2 indicates that residues 1 to 14 form a secretory peptide. The CUB domain extends from residue 46 to residue 163. A propeptide-like sequence extends from residue 164 to residue 234, and includes two potential cleavage sites at its carboxyl terminus, a dibasic site at residues 231-232 and a target site for furin or a furin-like protease at residues 231-234. The growth factor domain extends from residue 235 to residue 345. Those skilled in the art will recognize that domain boundaries are somewhat imprecise and can be expected to vary by up to .+-.5 residues from the specified positions. Potential proteolytic cleavage sites occur at residues 232 and 234. Processing of recombinant zvegf3 produced in BHK cells has been found to occur between residues 225 and 226. Signal peptide cleavage is predicted to occur after residue 14 (.+-.3 residues). This analysis suggests that the zvegf3 polypeptide chain may be cleaved to produce a plurality of monomeric species as shown in Table 1 (see Original Patent). Cleavage after Arg-234 is expected to result in subsequent removal of residues 231-234, with possible conversion of Gly-230 to an amide. Cleavage after Lys-232 is expected to result in subsequent removal of residue 231, again with possible conversion of Gly-230 to an amide. In addition, it may be advantageous to include up to seven residues of the interdomain region at the carboxyl terminus of the CUB domain. The interdomain region can be truncated at its amino terminus by a like amount. See Table 1. Corresponding domains in mouse and other non-human zvegf3s can be determined by those of ordinary skill in the art from sequence alignments.

Zvegf3 can thus be prepared in a variety of multimeric forms comprising a zvegf3 polypeptide as disclosed above. These zvegf3 polypeptides include zvegf3.sub.15-345, zvegf3.sub.46-345, zvegf3.sub.226-345, and zvegf3.sub.235-345. Variants and derivatives of these polypeptides can also be prepared as disclosed herein.

Zvegf3 proteins can be prepared as fusion proteins comprising amino- or carboxyl-terminal extensions, such as an amino-terminal methionine residue, an affinity tag, or a targeting polypeptide. For example, a zvegf3 protein can be prepared as a fusion with an affinity tag to facilitate purification. In principal, any peptide or protein for which an antibody or other specific binding agent is available can be used as an affinity tag. Affinity tags include, for example, a poly-histidine tract, protein A (Nilsson et al., EMBO J. 4:1075, 1985; Nilsson et al., Methods Enzymol. 198:3, 1991), glutathione S transferase (Smith and Johnson, Gene 67:31, 1988), Glu-Glu affinity tag (Grussenmeyer et al., Proc. Natl. Acad. Sci. USA 82:7952-4, 1985), substance P, Flag.TM. peptide (Hopp et al., Biotechnology 6:1204-1210, 1988), streptavidin binding peptide, maltose binding protein (Guan et al., Gene 67:21-30, 1987), cellulose binding protein, thioredoxin, ubiquitin, T7 polymerase, or other antigenic epitope or binding domain. Fusion of zvegf3 to, for example, maltose binding protein or glutatione S transferase can be used to improve yield in bacterial expression systems. In these instances the non-zvegf3 portion of the fusion protein ordinarily will be removed prior to use. Separation of the zvegf3 and non-zvegf3 portions of the fusion protein is facilitated by providing a specific cleavage site between the two portions. Such methods are well known in the art. Zvegf3 can also be fused to a targeting peptide, such as an antibody (including polyclonal antibodies, monoclonal antibodies, antigen-binding fragments thereof such as F(ab').sub.2 and Fab fragments, single chain antibodies, and the like) or other peptidic moiety that binds to a target tissue.

Variations can be made in the zvegf3 amino acid sequences shown in SEQ ID NO:2 and SEQ ID NO:4 to provide mitogenically inactive, receptor-binding polypeptides that act as zvegf3 antagonists. As used herein, the term "mitogenically inactive" means that the protein does not show statistically significant activity in a standard mitogenesis assay as compared to a wild-type zvegf3 control. Such variations include amino acid substitutions, deletions, and insertions. While not wishing to be bound by theory, it is believed that residues Arg260-Trp271 of human zvegf3 (SEQ ID NO:2) form a loop that define the ability of the protein to bind to PDGF-.beta. receptors, although binding is also permitted to alpha receptors. It is thus predicted that binding to either receptor subunit can be blocked or enhanced by mutations in this region. In addition, residues Leu311-His321 of SEQ ID NO:2 are predicted to form a loop (loop3) that may be mutated to block receptor binding. Peptides that mimic this region of the molecule may act as antagonists.

The effects of amino acid sequence changes can be predicted by computer modeling (using, e.g., the Insight II viewer and homology modeling tools; MSI, San Diego, Calif.) or determined by analysis of crystal structure (see, e.g., Lapthorn et al., Nature 369:455, 1994), and can be assessed using art-recognized mutagenesis procedures in combination with activity assays. Representative mutagenesis procedures include, for example, site-directed mutagenesis and alanine-scanning mutagenesis (Cunningham and Wells, Science 244, 1081-1085, 1989; Bass et al., Proc. Natl. Acad. Sci. USA 88:4498-4502, 1991). Multiple amino acid substitutions can be made and tested using known methods, such as those disclosed by Reidhaar-Olson and Sauer (Science 241:53-57, 1988) or Bowie and Sauer (Proc. Natl. Acad. Sci. USA 86:2152-2156, 1989). Other methods that can be used include phage display (e.g., Lowman et al., Biochem. 30:10832-10837, 1991; Ladner et al., U.S. Pat. No. 5,223,409; Huse, WIPO Publication WO 92/06204), region-directed mutagenesis (Derbyshire et al., Gene 46:145, 1986; Ner et al., DNA 7:127, 1988), and DNA shuffling as disclosed by Stemmer (Nature 370:389-391, 1994) and Stemmer (Proc. Natl. Acad. Sci. USA 91:10747-10751, 1994). The resultant mutant molecules are tested for mitogenic activity or other properties (e.g., receptor binding) to identify amino acid residues that are critical to these functions. Mutagenesis can be combined with high volume or high-throughput screening methods to detect biological activity of zvegf3 variant polypeptides, in particular biological activity in modulating cell proliferation. For example, mitogenesis assays that measure dye incorporation or .sup.3H-thymidine incorporation can be carried out on large numbers of samples. Competition assays can be employed to confirm antagonist activity.

Zvegf3 proteins, including full-length polypeptides, fragments, and fusion proteins, can be produced in genetically engineered host cells according to conventional techniques. Suitable host cells are those cell types that can be transformed or transfected with exogenous DNA and grown in culture, and include bacteria, fungal cells, and cultured higher eukaryotic cells (including cultured cells of multicellular organisms). Techniques for manipulating cloned DNA molecules and introducing exogenous DNA into a variety of host cells are disclosed by Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989, and Ausubel et al., eds., Current Protocols in Molecular Biology, Green and Wiley and Sons, NY, 1993. See, WO 00/34474. In general, a DNA sequence encoding a zvegf3 polypeptide is operably linked to other genetic elements required for its expression, generally including a transcription promoter and terminator, within an expression vector. The vector will also commonly contain one or more selectable markers and one or more origins of replication, although those skilled in the art will recognize that within certain systems selectable markers may be provided on separate vectors, and replication of the exogenous DNA may be provided by integration into the host cell genome. Selection of promoters, terminators, selectable markers, vectors and other elements is a matter of routine design within the level of ordinary skill in the art. Many such elements are described in the literature and are available through commercial suppliers. See, WO 00/34474.

Zvegf3 proteins can also comprise non-naturally occurring amino acid residues. Non-naturally occurring amino acids include, without limitation, trans-3-methylproline, 2,4-methanoproline, cis-4-hydroxyproline, trans-4-hydroxyproline, N-methylglycine, allo-threonine, methylthreonine, hydroxyethylcysteine, hydroxyethylhomocysteine, nitroglutamine, homoglutamine, pipecolic acid, tert-leucine, norvaline, 2-azaphenylalanine, 3-azaphenylalanine, 4-azaphenylalanine, and 4-fluorophenylalanine. Several methods are known in the art for incorporating non-naturally occurring amino acid residues into proteins. For example, an in vitro system can be employed wherein nonsense mutations are suppressed using chemically aminoacylated suppressor tRNAs. Methods for synthesizing amino acids and aminoacylating tRNA are known in the art. Transcription and translation of plasmids containing nonsense mutations is carried out in a cell-free system comprising an E. coli S30 extract and commercially available enzymes and other reagents. Proteins are purified by chromatography. See, for example, Robertson et al., J. Am. Chem. Soc. 113:2722, 1991; Ellman et al., Methods Enzymol 202:301, 1991; Chung et al., Science 259:806-809, 1993; and Chung et al., Proc. Natl. Acad. Sci. USA 90:10145-10149, 1993). In a second method, translation is carried out in Xenopus oocytes by microinjection of mutated mRNA and chemically aminoacylated suppressor tRNAs (Turcatti et al., J. Biol. Chem. 271:19991-19998, 1996). Within a third method, E. coli cells are cultured in the absence of a natural amino acid that is to be replaced (e.g., phenylalanine) and in the presence of the desired non-naturally occurring amino acid(s) (e.g., 2-azaphenylalanine, 3-azaphenylalanine, 4-azaphenylalanine, or 4-fluorophenylalanine). The non-naturally occurring amino acid is incorporated into the protein in place of its natural counterpart. See, Koide et al., Biochem. 33:7470-7476, 1994. Naturally occurring amino acid residues can be converted to non-naturally occurring species by in vitro chemical modification. Chemical modification can be combined with site-directed mutagenesis to further expand the range of substitutions (Wynn and Richards, Protein Sci. 2:395-403, 1993).

Zvegf3 polypeptides or fragments thereof can also be prepared through chemical synthesis according to methods known in the art, including exclusive solid phase synthesis, partial solid phase methods, fragment condensation or classical solution synthesis. See, for example, Merrifield, J. Am. Chem. Soc. 85:2149, 1963; Stewart et al., Solid Phase Peptide Synthesis (2nd edition), Pierce Chemical Co., Rockford, Ill., 1984; Bayer and Rapp, Chem. Pept. Prot. 3:3, 1986; and Atherton et al., Solid Phase Peptide Synthesis: A Practical Approach, IRL Press, Oxford, 1989.

Zvegf3 proteins are purified by conventional protein purification methods, typically by a combination of chromatographic techniques. See, in general, Affinity Chromatography: Principles & Methods, Pharmacia LKB Biotechnology, Uppsala, Sweden, 1988; and Scopes, Protein Purification: Principles and Practice, Springer-Verlag, New York, 1994. Proteins comprising a polyhistidine affinity tag (typically about 6 histidine residues) are purified by affinity chromatography on a nickel chelate resin. See, for example, Houchuli et al., Bio/Technol. 6: 1321-1325, 1988. Furthermore, the growth factor domain itself binds to nickel resin at pH 7.0-8.0 and 25 mM Na phosphate, 0.25 M NaCl. Bound protein can be eluted with a descending pH gradient down to pH 5.0 or an imidazole gradient. Recombinant zvegf3 growth factor domain protein can be purified using a combination of chromatography on a strong cation exchanger followed by a tandem column array comprising a strong anion exchanger followed by an immobilized metal affinity column in series. It has also been found that zvegf3 binds to various dye matrices (e.g., BLUE1, BLUE 2, ORANGE 1, ORANGE 3, and RED3 from Lexton Scientific, Signal Hill, Calif.) in PBS at pH 6-8, from which the bound protein can be eluted in 1-2 M NaCl in 20 mM boric acid buffer at pH 8.8. Protein eluted from RED3 may be passed over RED2 (Lexton Scientific) to remove remaining contaminants. Proteins comprising a glu-glu tag can be purified by immunoaffinity chromatography according to conventional procedures. See, for example, Grussenmeyer et al., ibid. Maltose binding protein fusions are purified on an amylose column according to methods known in the art.

As disclosed in more detail below, overexpression of zvegf3 in the livers of transgenic mice led to marked stellate cell activation and proliferation. At 8 weeks of age there was an accumulation of perisinusiodal extracellular matrix (ECM) that progressed to a perivenular ECM deposition at 22 weeks and possible early stages of cirrhosis characterized by fibrotic banding and hepatic nodule formation at 33 weeks of age. Thus, zvegf3 dimers appear to resemble the previously described PDGF isoforms in being potent mitogens of hepatic stellate cells and appearing to play a role in liver fibrosis. These transgenic mice thus provide a model for testing zvegf3 antagonists as well as other antifibrotic agents. In view of these and other experiments disclosed herein, it is expected that altered zvegf3 expression may initiate or exacerbate a variety of fibrotic conditions. In this context, inhibiting the action of zvegf3 using a zvegf3 antagonist will limit the progress of such conditions. While not wishing to be bound by theory, it is believed that the pro-fibrotic effects of zvegf3 are due at least in part to the induction of TGF-.beta. production.

Zvegf3 antagonists include, without limitation, anti-zvegf3 antibodies (including neutralizing antibodies), inhibitory polynucleotides (including antisense polynucleotides, ribozymes, and external guide sequences), and other peptidic and non-peptidic agents, including small molecule inhibitors and mitogenically inactive receptor-binding zvegf3 polypeptides. Such antagonists can be use to block the mitogenic effects of zvegf3 and thereby reduce, inhibit, prevent, or otherwise treat fibrosis, including, without limitation, scar formation, keloids, scleroderma, liver fibrosis, lung fibrosis, kidney fibrosis, pancreatic fibrosis, myelofibrosis, post-surgical fibrotic adhesions, fibroproliferative disorders of the vasculature, fibroproliferative disorders of the prostate, fibroproliferative disorders of bone, fibromatosis, fibroma, fibrosarcoma, and the like.

Of particular interest is the use of zvegf3 or zvegf3 antagonists for the treatment or repair of liver damage, including damage due to chronic liver disease, including chronic active hepatitis (including hepatitis C) and many other types of cirrhosis. Widespread, massive necrosis, including destruction of virtually the entire liver, can be caused by, inter alia, fulminant viral hepatitis; overdoses of the analgesic acetaminophen; exposure to other drugs and chemicals such as halothane, monoamine oxidase inhibitors, agents employed in the treatment of tuberculosis, phosphorus, carbon tetrachloride, and other industrial chemicals. Conditions associated with ultrastructural lesions that do not necessarily produce obvious liver cell necrosis include Reye's syndrome in children, tetracycline toxicity, and acute fatty liver of pregnancy. Cirrhosis, a diffuse process characterized by fibrosis and a conversion of normal architecture into structurally abnormal nodules, can come about for a variety reasons including alcohol abuse, post necrotic cirrhosis (usually due to chronic active hepatitis), biliary cirrhosis, pigment cirrhosis, cryptogenic cirrhosis, Wilson's disease, and alpha-1-antitrypsin deficiency. In cases of liver fibrosis it may be beneficial to administer a zvegf3 antagonist to suppress the activation of stellate cells, which have been implicated in the production of extracellular matrix in fibrotic liver (Li and Friedman, ibid.).

Fibrotic disorders of the kidney include, without limitation, glomerulonephritis (including membranoproliferative, diffuse proliferative, rapidly progressive, and chronic forms), diabetic glomerulosclerosis, focal glomerulosclerosis, diabetic nephropathy, lupus nephritis, tubulointerstitial fibrosis, membranous nephropathy, amyloidosis (which affects the kidney among other tissues), renal arteriosclerosis, and nephrotic syndrome. The glomerulus is a major target of many types of renal injury, including immunologic (e.g., immune-complex- or T-cell-mediated), hemodynamic (systemic or renal hypertension), metabolic (e.g., diabetes), "atherosclerotic" (accumulation of lipids in the glomerulus), infiltrative (e.g., amyloid), and toxic (e.g., snake venom) (Johnson, Kidney Int. 45:1769-1782, 1994). The renal structural changes in patients with diabetic nephropathy include hypertrophy of the glomerulus, thickening of the glomerular and tubular membranes (due to accumulated matrix), and increased amounts of matrix in the measangium and tubulointerstitium (Ziyadeh et al., Proc. Natl. Acad. Sci. USA 97:8015-8020, 2000). Glomerular hypertension due to intrarenal hemodynamic changes in diabetes can contribute to the progression of diabetic nephropathy (Ishida et al., Diabetes 48:595-602, 1999). Autoimmune nephritis can also lead to altered mesangial cell growth responses (Liu and Ooi, J. Immunol. 151:2247-2251, 1993). Infection by hepatitis-C virus can also result in idiopathic membranoproliferative glomerulonephritis (Johnson et al., N. Engl. J. Med. 328:465-470, 1993). While not wishing to be bound by theory, experiments have shown that the activity of zvegf3 is mediated by the .alpha..alpha. and .alpha..beta. PDGF receptor isoforms. PDGF receptors are widely expressed in most renal cell types, and their expression is upregulated in a number of kidney pathologies (e.g., Iida et al., Proc. Natl. Acad. Sci. USA 88:6560-6564, 1991). Stimulation of PDGF receptors has been implicated in fibroproliferative diseases of the kidney in a variety of animal models (e.g., Ooi et al., P.S.E.B.M. 213:230-237, 1996; Lindahl et al., Development 125:3313-3322, 1998; Lindahl and Betsholtz, Curr. Op. Nephr. Hypert. 7:21-26, 1998; and Betsholtz and Raines, Kidney Int. 51:1361-1369, 1997).

Fibrotic disorders of the lung include, for example, silicosis, asbestosis, idiopathic pulmonary fibrosis, bronchiolitis obliterans-organizing pneumonia, pulmonary fibrosis associated with high-dose chemotherapy, idiopathic pulmonary fibrosis, and pulmonary hypertension. These diseases are characterized by cell proliferation and increased production of extracellular matrix components, such as collagens, elastin, fibronectin, and tenascin-C.

Pancreatic fibrosis occurs in chronic pancreatitis. This condition is characterized by duct calcification and fibrosis of the pancreatic parenchyma. Like liver cirrhosis, chronic pancreatitis is associated with alcohol abuse. See, Fogar et al., J. Medicine 29:277-287, 1998.

Diseases of the skeleton that are due to modified growth and matrix production in the bone include, but are not limited to, osteopetrosis, hyperostosis, osteosclerosis, osteoarthritis, and endosteal bone formation in metastatic prostate cancer. Fibroproliferative disorders of bone are characterized by aberrant and ectopic bone formation, commonly seen as active proliferation of the major cell types participating in bone formation as well as elaboration by those cells of a complex bone matrix. Exemplary of such bone disorders is the fibrosis that occurs with prostate tumor metastases to the axial skeleton. In prostate tumor-related cancellous bone growth, prostate carcinoma cells can interact reciprocally with osteoblasts to produce enhanced tumor growth and osteoblastic action when they are deposited in bone (Zhau et al., Cancer 88:2995-3001, 2000; Ritchie et al., Endocrinology 138:1145-1150, 1997). Fibroproliferative responses of the bone originating in the skeleton per se include ostepetrosis and hyperstosis. A defect in osteoblast differentiation and function is thought to be a major cause in osteopetrosis, an inherited disorder characterized by bone sclerosis due to reduced bone resorption, marrow cavities fail to develop, resulting in extramedullary hematopoiesis and severe hematologic abnormalities associated with optic atrophy, deafness, and mental retardation (Lajeunesse et al., J. Clin Invest. 98:1835-1842, 1996). In osteoarthritis, bone changes are known to occur, and bone collagen metabolism is increased within osteoarthritic femoral heads. The greatest changes occur within the subchondral zone, supporting a greater proportion of osteoid in the diseased tissue (Mansell and Bailey, J. Clin. Invest. 101:1596-1603, 1998). As shown in more detail below, zvegf3 has been found to be produced by prostate cells and to stimulate an osteoblast cell line.

Fibroproliferative disorders of the vasculature include, for example, transplant vasculopathy, which is a major cause of chronic rejection of heart transplantation. Transplant vasculopathy is characterized by accelerated atherosclerotic plaque formation with diffuse occlusion of the coronary arteries, which is a "classic" fibroproliferative disease. See, Miller et al., Circulation 101: 1598-1605, 2000).

Antibodies used as zvegf3 antagonists include antibodies that specifically bind to a zvegf3 protein and, by so binding, reduce or prevent the binding of zvegf3 protein to the receptor and, consequently, reduce or block the receptor-mediated activity of zvegf3. As used herein, the term "antibodies" includes polyclonal antibodies, affinity-purified polyclonal antibodies, monoclonal antibodies, and antigen-binding fragments, such as F(ab').sub.2 and Fab proteolytic fragments. Genetically engineered intact antibodies or fragments, such as chimeric antibodies, Fv fragments, single chain antibodies and the like, as well as synthetic antigen-binding peptides and polypeptides, are also included. Non-human antibodies may be humanized by grafting non-human CDRs onto human framework and constant regions, or by incorporating the entire non-human variable domains (optionally "cloaking" them with a human-like surface by replacement of exposed residues, wherein the result is a "veneered" antibody). In some instances, humanized antibodies may retain non-human residues within the human variable region framework domains to enhance proper binding characteristics. Through humanizing antibodies, biological half-life may be increased, and the potential for adverse immune reactions upon administration to humans is reduced. Monoclonal antibodies can also be produced in mice that have been genetically altered to produce antibodies that have a human structure.

Methods for preparing and isolating polyclonal and monoclonal antibodies are well known in the art. See, for example, Cooligan et al. (eds.), Current Protocols in Immunology, National Institutes of Health, John Wiley and Sons, Inc., 1995; Sambrook et al., Molecular Cloning: A Laboratory Manual, second edition, Cold Spring Harbor, N.Y., 1989; and Hurrell (ed.), Monoclonal Hybridoma Antibodies: Techniques and Applications, CRC Press, Inc., Boca Raton, Fla., 1982. As would be evident to one of ordinary skill in the art, polyclonal antibodies can be generated by inoculating a variety of warm-blooded animals such as horses, cows, goats, sheep, dogs, chickens, rabbits, mice, and rats with a zvegf3 polypeptide or a fragment thereof.

Immunogenic polypeptides will comprise an epitope-bearing portion of a zvegf3 polypeptide (e.g., as shown in SEQ ID NO:2) or receptor. An "epitope" is a region of a protein to which an antibody can bind. See, for example, Geysen et al., Proc. Natl. Acad. Sci. USA 81:3998-4002, 1984. Epitopes can be linear or conformational, the latter being composed of discontinuous regions of the protein that form an epitope upon folding of the protein. Linear epitopes are generally at least 6 amino acid residues in length. Relatively short synthetic peptides that mimic part of a protein sequence are routinely capable of eliciting an antiserum that reacts with the partially mimicked protein. See, Sutcliffe et al., Science 219:660-666, 1983. Immunogenic, epitope-bearing polypeptides contain a sequence of at least six, often at least nine, more often from 15 to about 30 contiguous amino acid residues of a zvegf3 protein. Polypeptides comprising a larger portion of a zvegf3 protein, i.e. from 30 to 50 residues up to the entire sequence are included. It is preferred that the amino acid sequence of the epitope-bearing polypeptide is selected to provide substantial solubility in aqueous solvents, that is the sequence includes relatively hydrophilic residues, and hydrophobic residues are substantially avoided. Such regions include residues 43-48, 96-101, 97-102, 260-265, and 330-335 of SEQ ID NO:2. As noted above, it is generally preferred to use somewhat longer peptides as immunogens, such as a peptide comprising residues 80-104, 299-314, and 299-326 of SEQ ID NO:2. The latter peptide can be prepared with an additional N-terminal Cys residue to facilitate coupling.

The immunogenicity of a polypeptide immunogen may be increased through the use of an adjuvant, such as alum (aluminum hydroxide) or Freund's complete or incomplete adjuvant. Polypeptides useful for immunization also include fusion polypeptides, such as fusions of a zvegf3 polypeptide or a portion thereof with an immunoglobulin polypeptide or with maltose binding protein. If the polypeptide portion is "hapten-like", such portion may be advantageously joined or linked to a macromolecular carrier (such as keyhole limpet hemocyanin (KLH), bovine serum albumin (BSA), or tetanus toxoid) for immunization.

Alternative techniques for generating or selecting antibodies include in vitro exposure of lymphocytes to a polypeptide immunogen, and selection of antibody display libraries in phage or similar vectors (for instance, through use of immobilized or labeled polypeptide). Techniques for creating and screening such random peptide display libraries are known in the art (e.g., Ladner et al., U.S. Pat. No. 5,223,409; Ladner et al., U.S. Pat. No. 4,946,778; Ladner et al., U.S. Pat. No. 5,403,484 and Ladner et al., U.S. Pat. No. 5,571,698), and random peptide display libraries and kits for screening such libraries are available commercially, for instance from Clontech Laboratories (Palo Alto, Calif.), Invitrogen Inc. (San Diego, Calif.), New England Biolabs, Inc. (Beverly, Mass.), and Pharmacia LKB Biotechnology Inc. (Piscataway, N.J.). Random peptide display libraries can be screened using the zvegf3 sequences disclosed herein to identify proteins which bind to zvegf3.

Antibodies are determined to be specifically binding if they bind to their intended target (e.g., zvegf3 protein or receptor) with an affinity at least 10-fold greater than the binding affinity to control (e.g., non-zvegf3 or non-receptor) polypeptide or protein. In this regard, a "non-zvegf3 polypeptide" includes the related molecules VEGF, VEGF-B, VEGF-C, VEGF-D, P1GF, PDGF-A, and PDGF-B, but excludes zvegf3 polypeptides from non-human species. Due to the high level of amino acid sequence identity expected between zvegf3 orthologs, antibodies specific for human zvegf3 may also bind to zvegf3 from other species. The binding affinity of an antibody can be readily determined by one of ordinary skill in the art, for example, by Scatchard analysis (Scatchard, G., Ann. NY Acad. Sci. 51: 660-672, 1949). Methods for screening and isolating specific antibodies are well known in the art. See, for example, Paul (ed.), Fundamental Immunology, Raven Press, 1993; Getzoff et al., Adv. in Immunol 43:1-98, 1988; Goding (ed.), Monoclonal Antibodies: Principles and Practice, Academic Press Ltd., 1996; Benjamin et al., Ann. Rev. Immunol. 2:67-101, 1984.

Binding affinity can also be determined using a commercially available biosensor instrument (BIAcore.TM., Pharmacia Biosensor, Piscataway, N.J.), wherein protein is immobilized onto the surface of a receptor chip. See, Karlsson, J. Immunol. Methods 145:229-240, 1991 and Cunningham and Wells, J. Mol. Biol 234:554-563, 1993. This system allows the determination of on- and off-rates, from which binding affinity can be calculated, and assessment of stoichiometry of binding.

A variety of assays known to those skilled in the art can be utilized to detect antibodies that specifically bind to zvegf3 proteins or receptors. Exemplary assays are described in detail in Antibodies: A Laboratory Manual, Harlow and Lane (Eds.), Cold Spring Harbor Laboratory Press, 1988. Representative examples of such assays include: concurrent immunoelectrophoresis, radioimmunoassay, radioimmuno-precipitation, enzyme-linked immunosorbent assay (ELISA), dot blot or Western blot assays, inhibition or competition assays, and sandwich assays.

For therapeutic applications it is generally preferred to use neutralizing antibodies. As used herein, the term "neutralizing antibody" denotes an antibody that inhibits at least 50% of the biological activity of the cognate antigen when the antibody is added at a 1000-fold molar access. Those of skill in the art will recognize that greater neutralizing activity is sometimes desirable, and antibodies that provide 50% inhibition at a 100-fold or 10-fold molar access may be advantageously employed.

Zvegf3 antagonists further include antisense polynucleotides, which can be used to inhibit zvegf3 gene transcription and thereby inhibit cell activation and/or proliferation in vivo. Polynucleotides that are complementary to a segment of a zvegf3-encoding polynucleotide (e.g., a polynucleotide as set forth in SEQ ID NO:1) are designed to bind to zvegf3-encoding mRNA and to inhibit translation of such mRNA. Antisense polynucleotides can be targeted to specific tissues using a gene therapy approach with specific vectors and/or promoters, such as viral delivery systems as disclosed in more detail below.

Ribozymes can also be used as zvegf3 antagonists within the present invention. Ribozymes are RNA molecules that contain a catalytic center and a target RNA binding portion. The term includes RNA enzymes, self-splicing RNAs, self-cleaving RNAs, and nucleic acid molecules that perform these catalytic functions. A ribozyme selectively binds to a target RNA molecule through complementary base pairing, bringing the catalytic center into close proximity with the target sequence. The ribozyme then cleaves the target RNA and is released, after which it is able to bind and cleave additional molecules. A nucleic acid molecule that encodes a ribozyme is termed a "ribozyme gene." Ribozymes can be designed to express endonuclease activity that is directed to a certain target sequence in a mRNA molecule (see, for example, Draper and Macejak, U.S. Pat. No. 5,496,698, McSwiggen, U.S. Pat. No. 5,525,468, Chowrira and McSwiggen, U.S. Pat. No. 5,631,359, and Robertson and Goldberg, U.S. Pat. No. 5,225,337). An expression vector can be constructed in which a regulatory element is operably linked to a nucleotide sequence that encodes a ribozyme.

In another approach, expression vectors can be constructed in which a regulatory element directs the production of RNA transcripts capable of promoting RNase P-mediated cleavage of mRNA molecules that encode a zvegf3 polypeptide. According to this approach, an external guide sequence can be constructed for directing the endogenous ribozyme, RNase P, to a particular species of intracellular mRNA, which is subsequently cleaved by the cellular ribozyme (see, for example, Altman et al., U.S. Pat. No. 5,168,053; Yuan et at, Science 263:1269, 1994; Pace et al., WIPO Publication No. WO 96/18733; George et al., WIPO Publication No. WO 96/21731; and Werner et al., WIPO Publication No. WO 97/33991). An external guide sequence generally comprises a ten- to fifteen-nucleotide sequence complementary to zvegf3 mRNA, and a 3'-NCCA nucleotide sequence, wherein N is preferably a purine. The external guide sequence transcripts bind to the targeted mRNA species by the formation of base pairs between the mRNA and the complementary external guide sequences, thus promoting cleavage of mRNA by RNase P at the nucleotide located at the 5'-side of the base-paired region.

The growth factor domain of zvegf3 has been found to be the active (PDGF receptor-binding) species of the molecule. Proteolytic processing to remove the N-terminal portion of the molecule is required for activation. Thus, inhibitors of this proteolytic activation can also be used as zvegf3 antagonists within the present invention.

For pharmaceutical use, zvegf3 antagonists are formulated for topical or parenteral, particularly intravenous or subcutaneous, delivery according to conventional methods. In general, pharmaceutical formulations will include a zvegf3 antagonist in combination with a pharmaceutically acceptable vehicle, such as saline, buffered saline, 5% dextrose in water, or the like. Formulations may further include one or more excipients, preservatives, solubilizers, buffering agents, albumin to prevent protein loss on vial surfaces, etc. Methods of formulation are well known in the art and are disclosed, for example, in Remington: The Science and Practice of Pharmacy, Gennaro, ed., Mack Publishing Co., Easton, Pa., 19th ed., 1995. A "therapeutically effective amount" of a composition is that amount that produces a statistically significant effect, such as a statistically significant reduction in disease progression or a statistically significant improvement in organ function. The exact dose will be determined by the clinician according to accepted standards, taking into account the nature and severity of the condition to be treated, patient traits, etc. Determination of dose is within the level of ordinary skill in the art. The therapeutic formulations will generally be administered over the period required to achieve a beneficial effect, commonly up to several months and, in treatment of chronic conditions, for a year or more. Dosing is daily or intermittently over the period of treatment. Intravenous administration will be by bolus injection or infusion over a typical period of one to several hours. Sustained release formulations can also be employed. For treatment of pulmonary fibrosis, a zvegf3 antagonist can be delivered by aerosolization according to methods known in the art. See, for example, Wang et al., U.S. Pat. No. 5,011,678; Gonda et al., U.S. Pat. No. 5,743,250; and Lloyd et al., U.S. Pat. No. 5,960,792.

Other mitogenic factors, including EGF, TGF.beta., and FGF, have been implicated in the initiation or perpetuation of fibrosis. It may therefore be advantageous to combine a zvegf3 inhibitor with one or more inhibitors of these other factors.

Antibodies are preferably administered parenterally, such as by bolus injection or infusion (intravenous, intramuscular, intraperitoneal or subcutaneous) over the course of treatment. Antibodies are generally administered in an amount sufficient to provide a minimum circulating level of antibody throughout the treatment period of between approximately 20 .mu.g and 1 mg/kg body weight. In this regard, it is preferred to use antibodies having a circulating half-life of at least 12 hours, preferably at least 4 days, more preferably up to 14-21 days. Chimeric and humanized antibodies are expected to have circulatory half-lives of up to four and up to 14-21 days, respectively. In many cases it will be preferable to administer daily doses during a hospital stay, followed by less frequent bolus injections during a period of outpatient treatment. Antibodies can also be delivered by slow-release delivery systems, pumps, and other known delivery systems for continuous infusion. Dosing regimens may be varied to provide the desired circulating levels of a particular antibody based on its pharmacokinetics. Thus, doses will be calculated so that the desired circulating level of therapeutic agent is maintained. Daily doses referred to above may be administered as larger, less frequent bolus administrations to provide the recited dose averaged over the term of administration.

Those skilled in the art will recognize that the same principles will guide the use of other zvegf3 antagonists. The dosing regimen for a given antagonist will be determined by a number of factors including potency, pharmacokinetics, and the physicochemical nature of the antagonist. For example, non-peptidic zvegf3 antagonists may be administered enterally.

Therapeutic polynucleotides, such as antisense polynucleotides, can be delivered to patients or test animals by way of viral delivery systems. Exemplary viruses for this purpose include adenovirus, herpesvirus, retroviruses, vaccinia virus, and adeno-associated virus (AAV). Adenovirus, a double-stranded DNA virus, is currently the best studied gene transfer vector for delivery of heterologous nucleic acids. For review, see Becker et al., Meth. Cell Biol. 43:161-89, 1994; and Douglas and Curiel, Science & Medicine 4:44-53, 1997. The adenovirus system offers several advantages. Adenovirus can (i) accommodate relatively large DNA inserts; (ii) be grown to high-titer; (iii) infect a broad range of mammalian cell types; and (iv) be used with many different promoters including ubiquitous, tissue specific, and regulatable promoters. Because adenoviruses are stable in the bloodstream, they can be administered by intravenous injection.

By deleting portions of the adenovirus genome, larger inserts (up to 7 kb) of heterologous DNA can be accommodated. These inserts can be incorporated into the viral DNA by direct ligation or by homologous recombination with a co-transfected plasmid. When intravenously administered to intact animals, adenovirus primarily targets the liver. If the adenoviral delivery system has an E1 gene deletion, the virus cannot replicate in the host cells. However, the host's tissue (e.g., liver) will express and process (and, if a signal sequence is present, secrete) the heterologous protein.

An alternative method of gene delivery comprises removing cells from the body and introducing a vector into the cells as a naked DNA plasmid. The transformed cells are then re-implanted in the body. Naked DNA vectors are introduced into host cells by methods known in the art, including transfection, electroporation, microinjection, transduction, cell fusion, DEAE dextran, calcium phosphate precipitation, use of a gene gun, or use of a DNA vector transporter. See, Wu et al., J. Biol. Chem. 263:14621-14624, 1988; Wu et al., J. Biol. Chem. 267:963-967, 1992; and Johnston and Tang, Meth. Cell Biol. 43:353-365, 1994.

Activity of zvegf3 antagonists can be measured in vitro using assays (including cell-based assays) designed to measure zvegf3 activity. Antagonists will reduce the effects of zvegf3 within the assay. Ligand-receptor binding can be assayed by a variety of methods well known in the art, including receptor competition assays (Bowen-Pope and Ross, Methods Enzymol. 109:69-100, 1985) and through the use of soluble receptors, including receptors produced as IgG fusion proteins (U.S. Pat. No. 5,750,375). Receptor binding assays can be performed on cell lines that contain known cell-surface receptors for evaluation. The receptors can be naturally present in the cell, or can be recombinant receptors expressed by genetically engineered cells. Mitogenic activity can be measured using known assays, including .sup.3H-thymidine incorporation assays (as disclosed by, e.g., Raines and Ross, Methods Enzymol. 109:749-773, 1985 and Wahl et al., Mol Cell Biol. 8:5016-5025, 1988), dye incorporation assays (as disclosed by, for example, Mosman, J. Immunol. Meth. 65:55-63, 1983 and Raz et al., Acta Trop. 68:139-147, 1997) or cell counts. Suitable mitogenesis assays measure incorporation of .sup.3H-thymidine into (1) 20% confluent cultures to look for the ability of zvegf3 proteins to further stimulate proliferating cells, and (2) quiescent cells held at confluence for 48 hours to look for the ability of zvegf3 proteins to overcome contact-induced growth inhibition. Suitable dye incorporation assays include measurement of the incorporation of the dye Alamar blue (Raz et al., ibid.) into target cells. See also, Gospodarowicz et al., J. Cell. Biol. 70:395-405, 1976; Ewton and Florini, Endocrinol 106:577-583, 1980; and Gospodarowicz et al., Proc. Natl. Acad. Sci. USA 86:7311-7315, 1989.

The biological activities of zvegf3 antagonists can be studied in non-human animals by administration of exogenous compounds, by expression of zvegf3 antisense polynucleotides, and by suppression of endogenous zvegf3 expression through knock-out techniques. Viral delivery systems (disclosed above) can be employed. Zvegf3 antagonists can be administered or expressed individually, in combination with other zvegf3 antagonists, or in combination other compounds, including other growth factor antagonists. Test animals are monitored for changes in such parameters as clinical signs, body weight, blood cell counts, clinical chemistry, histopathology, and the like.

Effects of zvegf3 antagonists on liver and kidney fibrosis can be tested in known animal models, such as the db/db mouse model disclosed by Cohen et al., Diabetologia 39:270-274, 1996 and Cohen et al., J. Clin. Invest. 95:2338-2345, 1995, transgenic animal models (Imai et al., Contrib. Nephrot. 107:205-215, 1994), and the CCl.sub.4-induced cirrhosis model (Rojkind and Greenwel, Adv. Vet. Sci. Comp. Med. 37:333-355, 1993; Diaz-Gil et al., J. Hepatol. 30:1065-1072, 1999).

Effects on lung fibrosis can be assayed in a mouse model using bleomycin. The chemotherapy agent bleomycin is a known causative agent of pulmonary fibrosis in humans and can induce interstitial lung disease in mice, including an increase in the number of fibroblasts, enhanced collagen deposition, and dysregulated matrix remodeling. C57B1/6 mice are administered bleomycin by osmotic minipump for 1 week. There follows a period of inflammation, with cutaneous toxicity beginning approximately 4-7 days after bleomycin administration and continuing for about a week, after which the mice appear to regain health. About 3-4 weeks after the finish of bleomycin delivery, the mice are sacrificed, and the lungs are examined histologically for signs of fibrosis. Scoring is based on the extent of lung fibrotic lesions and their severity. Serum is assayed for lactic dehydrogenase, an intracellular enzyme that is released into the circulation upon general cell death or injury. Lung tissue is assayed for hydroxyproline as a measure of collagen deposition.
 

Claim 1 of 3 Claims

1. A method of reducing liver fibrosis caused by zvegf3 in a mammal, the method comprising administering to a mammal in need of said reducing a composition comprising a therapeutically effective amount of a zvegf3 antagonist in combination with a pharmaceutically acceptable delivery vehicle, wherein the zvegf3 antagonist is a monoclonal antibody that specifically binds to a zvegf3 dimeric protein consisting of two polypeptide chains, wherein each of said polypeptide chains consists of a sequence of amino acid residues as shown in SEQ ID NO:2 from amino acid residue X to amino acid residue 345, wherein X is an integer from 230 to 240, inclusive.

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