# Patent

## Title
Growth factor binding constructs materials and methods

## Abstract

The present invention provides materials and methods for antagonizing the function of vascular endothelial growth factor receptors, platelet derived growth factor receptors and other receptors. Soluble binding constructs able to bind vascular endothelial growth factors, platelet derived growth factors, and other ligands are provided.

## Background
This application is a divisional of U.S. patent application Ser. No. 11/075,047, filed Mar. 7, 2005, now U.S. Pat. No. 7,422,741, which the priority benefit of U.S. Provisional Application No. 60/550,907, filed Mar. 5, 2004, incorporated herein by reference in its entirety.


BACKGROUND
The vascular endothelial growth factor (VEGF) proteins and their receptors (VEGFRs) play important roles in both vasculogenesis, the development of the embryonic vasculature from early differentiating endothelial cells, angiogenesis, the process of forming new blood vessels from pre-existing ones, and lymphangiogenesis, the process of forming new lymph vessels. The platelet derived growth factor (PDGF) proteins and their receptors (PDGFRs) are involved in regulation of cell proliferation, survival and migration of several cell types.
Dysfunction of the endothelial cell regulatory system is a key feature of cancer and various diseases associated with abnormal vasculogenesis, angiogenesis, and lymphangiogenesis.
Angiogenesis occurs in embryonic development and normal tissue growth, repair, and regeneration, and also in the female reproductive cycle, establishment and maintenance of pregnancy, and in repair of wounds and fractures. In addition to angiogenesis which takes place in the healthy individual, angiogenic events are involved in a number of pathological processes, notably tumor growth and metastasis, and other conditions in which blood vessel proliferation, especially of the microvascular system, is increased, such as diabetic retinopathy, psoriasis and arthropathies. Inhibition of angiogenesis is useful in preventing or alleviating these pathological processes.
Although therapies directed to blockade of VEGF/PDGF signaling through their receptors has shown promise for inhibition of angiogenesis and tumor growth, medicine needs new compounds and therapies for the treatment of such diseases.
SUMMARY OF THE INVENTION
The present invention relates to novel compositions and methods of use thereof for the inhibition of aberrant angiogenesis and lymphangiogenesis, and inhibition of other effects of members of the PDGF/VEGF family of growth factors: VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D, each of which is able to bind at least one growth factor receptor tyrosine kinase and stimulate phosphorylation of the same. The compositions of the invention include binding constructs that bind one or more PDGF/VEGF molecules. The binding constructs include one or more binding units. In some embodiments, the binding unit comprises a polypeptide, e.g., a fragment of a growth factor receptor tyrosine kinase extracellular domain. The invention also provides nucleic acids encoding such binding constructs. Binding units are not limited to receptor fragments, nor are they limited to polypeptides, but rather comprise any species that binds a growth factor. Administration of the compositions of the invention to patients inhibits growth factor stimulation of VEGF receptors and/or PDGF receptors (e.g., inhibits phosphorylation of the receptors) and thereby inhibits biological responses mediated through the receptors including, but not limited to, PDGFR- and/or VEGFR-mediated angiogenesis and lymphangiogenesis.
Each member of the growth factor genus described above binds with high affinity to, and stimulation phosphorylation of, at least one PDGF receptor or VEGF receptor (or receptor heterodimer) selected from VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-alpha, and PDGFR-beta. This statement refers to well known properties of the growth factors toward their cognate receptors, and is not meant as a limiting feature per se of the binding constructs of the invention. (For example, VEGF-A has been shown to bind to VEGFR-1 and VEGFR-2 and induce tyrosine phosphorylation of both receptors and initiate downstream receptor signaling.) However, preferred binding units of the invention do more than simply bind their target growth factors: a preferred binding construct also inhibits the growth factor(s) to which it binds from stimulating phosphorylation of at least one (and preferably all) of the receptor tyrosine kinases to which the growth factor(s) bind. Stimulation of tyrosine phosphorylation is readily measured using in vitro cell-based assays and anti-phosphotyrosine antibodies. Because phosphorylation of the receptor tyrosine kinases is an initial step in a signaling cascade, it is a convenient indicator of whether the binding construct is capable of inhibiting growth factor-mediated signal transduction that leads to cell migration, cell growth, and other responses. A number of other cell based and in vivo assays can be used to confirm the growth factor neutralizing properties of binding constructs of the invention.
As described herein, binding constructs can be chemically modified (e.g., heterologous peptide fusions, glycosylation, pegylation, etc.) to impart desired characteristics, while maintaining their specific growth factor binding properties. An exemplary peptide fusion comprises a immunoglobulin constant domain fragment. Exemplary desired characteristics imparted by chemical modifications include increased serum half life, increased solubility in an aqueous medium, and the ability to target a specific cell population, e.g., cancer cells.
Binding constructs and units that are “specific” for a particular growth factor are binding constructs and units that specifically recognize a circulating, active form of the growth factor. Preferably, the binding constructs specifically bind other forms of the growth factors as well. By way of example, VEGF-A exists in multiple isoforms, some of which circulate and others of which associate with heparin sulfate proteoglycans on cell surfaces. Binding constructs that are specific for VEGF-A bind to at least a circulating isoform, preferably all circulating isoforms, and more preferably, bind other major isoforms as well. By way of another example, VEGF-C is translated as a prepro-molecule with extensive amino-terminal and carboxy-terminal propeptides that are cleaved to yield a “fully processed” form of VEGF-C that binds and stimulates VEGFR-2 and VEGFR-3. Binding constructs specific for VEGF-C bind to at least the fully processed form of VEGF-C, and preferably also bind to partly processed forms and unprocessed forms.
Additional description is used herein when a more specialized meaning is intended. For example, VEGF-B167 is heparin bound whereas VEGF-B186 is freely secreted. An binding construct of the invention that minimally binds the circulating isoform is said to be specific for VEGF-B, and such a binding construct preferably also binds the heparin bound form. A binding construct of the invention that is “specific for heparin-bound VEGF-B” or “specific for VEGF-B167” is a binding construct that differentially recognizes the heparin bound isoform, compared to the freely circulating isoform. A binding construct of the invention that is specific for VEGF-B186” is a binding construct that differentially recognizes the circulating form, compared to the heparin bound form. Binding constructs specific for each isoform of a growth factor are contemplated as components of some embodiments of the binding constructs of the invention.
The designations “first” and “second” and “third” in respect to the binding units of the binding constructs is for ease and clarity in description only, and is not meant to signify a particular order, e.g., order in the amino acid sequence of a polypeptide binding construct.
A binding construct comprising two or more binding units may further comprise a linker connecting adjacent binding units. The linker may take on a number of different forms. Preferably, the linker comprises a peptide which allows adjacent binding units to be linked to form a single polypeptide.
The invention also includes compositions comprising a polypeptide, binding construct, or nucleic acid encoding the same, together with a pharmaceutically acceptable carrier. Such compositions may further comprise a pharmaceutically acceptable diluent, adjuvant, or carrier medium.
Nucleic acids (polynucleotides) of the invention include nucleic acids that constitute binding units, e.g., aptamers, and also nucleic acids that encode polypeptide binding units and constructs, which may be used for such applications as gene therapy and recombinant in vitro expression of polypeptide binding constructs. In some embodiments, nucleic acids are purified or isolated. In some embodiments, polynucleotides further comprise a promoter sequence operatively connected to a nucleotide sequence encoding a polypeptide, wherein the promoter sequence promotes transcription of the sequence that encodes the polypeptide in a host cell. Polynucleotides may also comprise a polyadenylation sequence.
Vectors comprising polynucleotides are also aspects of the invention. Such vectors may comprise an expression control sequence operatively connected to the sequence that encodes the polypeptide, and the vector may be selected from the group consisting of a lentivirus vector, an adeno-associated viral vector, an adenoviral vector, a liposomal vector, and combinations thereof. In some embodiments, the vector comprises a replication-deficient adenovirus, said adenovirus comprising the polynucleotide operatively connected to a promoter and flanked by adenoviral polynucleotide sequences. Host cells comprising the polynucleotides, vectors and other nucleic acids, and methods for using the same to express and isolate the binding constructs and units are also aspects of the invention.
For binding units of a binding construct that comprises an aptamer, the aptamer may be generated by preparing a library of nucleic acids; contacting the library of nucleic acids with a growth factor, wherein nucleic acids having greater binding affinity for the growth factor (relative to other library nucleic acids) are selected and amplified to yield a mixture of nucleic acids enriched for nucleic acids with relatively higher affinity and specificity for binding to the growth factor. The processes may be repeated, and the selected nucleic acids mutated and rescreened, whereby a growth factor aptamer is be identified. Nucleic acids may be screened to select for molecules that bind to more than growth factor.
In one aspect of the invention, the binding construct comprises a purified polypeptide comprising an amino acid sequence at least 95% identical to a vascular endothelial growth factor receptor 3(VEGFR-3) fragment, wherein the VEGFR-3 fragment comprises an amino acid sequence consisting of a portion of SEQ ID NO: 6, wherein the carboxy-terminal residue of the fragment is selected from the group consisting of positions 211 to 247 of SEQ ID NO: 6. The fragment, and the polypeptide comprising the same, specifically bind to at least one growth factor selected from the group consisting of human vascular endothelial growth factor-C (VEGF-C), and human vascular endothelial growth factor-D (VEGF-D). In some embodiments the VEGFR-3 fragments has an amino terminal amino acid selected from the group consisting of positions 1 to 47 of SEQ ID NO: 6. In some embodiments, the polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NOS: 36 and 38. In some embodiments, the fragment has an amino acid sequence selected from the group consisting of positions 1-226 and 1-229 of SEQ ID NO: 6. In some embodiments, the polypeptide is part of a binding construct, and the polypeptide is operatively connected with a second polypeptide that binds at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D. In some embodiments, the second polypeptide is selected from the group consisting of a polypeptide comprising a vascular endothelial growth factor receptor extracellular domain fragment, a platelet derived growth factor receptor extracellular domain fragment, and a polypeptide comprising an antigen binding fragment of an antibody that immunoreacts with the at least one of said growth factors. In some embodiments, at least one of the polypeptides is encoded by a polynucleotide comprising a nucleotide sequence selected from the group consisting of SEQ ID NOS: 35 and 37.
In another aspect of the invention, a binding construct comprises a purified polypeptide comprising an amino acid sequence at least 95% identical to a VEGFR-2 fragment, wherein the VEGFR-2 fragment comprises an amino acid sequence consisting of a portion of SEQ ID NO: 4, wherein the amino terminal amino acid of the VEGFR-2 fragment is selected from the group consisting of positions 106-145 of SEQ ID NO: 4, wherein the carboxy terminal amino acid of the VEGFR-2 fragment is selected from the group consisting of positions 203 to 240 of SEQ ID NO: 4, and wherein the VEGFR-2 fragment and the polypeptide bind VEGF-C or VEGF-D. In some embodiments, the polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 22, 24, and 26. In some embodiments, the fragment consists of an amino acid sequence selected from the group consisting of residues 118-220, 118-226, and 118-232 of SEQ ID NO: 4. In some embodiments, the polypeptide is part of a binding construct, and the polypeptide is operatively connected with a second polypeptide that binds at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D. In some embodiments, the second polypeptide is selected from the group consisting of a polypeptide comprising a vascular endothelial growth factor receptor extracellular domain fragment, a platelet derived growth factor receptor extracellular domain fragment, and a polypeptide comprising an antigen binding fragment of an antibody that immunoreacts with the at least one of said growth factors. In some embodiments, at least one of the polypeptides is encoded by a polynucleotide comprising a nucleotide sequence selected from the group consisting of SEQ ID NOS: 21, 23, and 25.
In still another aspect, the invention provides a binding construct comprising a first polypeptide operatively connected to a second polypeptide. The first and second polypeptides each binds at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D polypeptides. The amino acid sequence of the first polypeptide differs from the amino acid sequence of the second polypeptide. The first and second polypeptides comprise members independently selected from the group consisting of:
(a) a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-1 extracellular domain amino acid sequence comprising positions 27-758 of SEQ ID NO: 2;
(b) a fragment of (a) that binds VEGF-A, VEGF-B, or PlGF;
(c) a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-2 extracellular domain amino acid sequence comprising positions 20-764 of SEQ ID NO: 4;
(d) a fragment of (c) that binds VEGF-A, VEGF-C, VEGF-E or VEGF-D;
(e) a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-3 extracellular domain amino acid sequence comprising residues 24-775 of SEQ ID NO: 6;
(f) a fragment of (e) that binds VEGF-C or VEGF-D;
(g) a polypeptide comprising an amino acid sequence at least 90% identical to the neuropilin-1 extracellular domain amino acid sequence comprising residues 22-856 of SEQ ID NO: 113;
(h) a fragment of (g) that binds VEGF-A, VEGF-B, VEGF-C, VEGF-E, or PlGF;
(i) a polypeptide comprising an amino acid sequence at least 90% identical to the neuropilin-2 extracellular domain amino acid sequence comprising residues 21-864 of SEQ ID NO: 115;
(j) a fragment of (i) that binds VEGF-A, VEGF-C, or PlGF;
(k) a polypeptide comprising an amino acid sequence at least 90% identical to the platelet derived growth factor receptor alpha extracellular domain amino acid sequence comprising residues 24-524 of SEQ ID NO: 117;
(l) a fragment of (k) that binds PDGF-A, PDGF-B, or PDGF-C;
(m) a polypeptide comprising an amino acid sequence at least 90% identical to the platelet derived growth factor beta extracellular domain amino acid sequence comprising residues 33 to 531 of SEQ ID NO: 119;
(n) a fragment of (m) that binds PDGF-B or PDGF-D; and
(o) a polypeptide comprising an antigen binding fragment of an antibody that binds to at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D.
In one embodiment, the binding construct of the invention comprises a first polypeptide comprising a fragment of a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-2 extracellular domain amino acid sequence comprising positions 20-764 of SEQ ID NO: 4, wherein the fragment binds VEGF-A, VEGF-C, VEGF-E or VEGF-D. It is contemplated that the binding construct further comprises a second polypeptide comprising a fragment of a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-1 extracellular domain amino acid sequence comprising positions 27-758 of SEQ ID NO: 2; wherein the fragment binds VEGF-A, VEGF-B, or PlGF. Additionally, it is contemplated that the binding construct further comprises a third polypeptide operatively connected to the first or second polypeptide, wherein the third polypeptide comprises a fragment of a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-3 extracellular domain amino acid sequence comprising residues 24-775 of SEQ ID NO: 6, wherein the fragment binds VEGF-C or VEGF-D.
As described herein in greater detail, the extracellular domain of VEGFR or PDGFR have immunoglobulin-like domain structure. In a related embodiment, the binding construct of the invention comprises a first, second and third polypeptide as described above, wherein: (a) the first polypeptide comprises an amino acid sequence at least 90% identical to a fragment of the VEGFR-2 extracellular domain, wherein the fragment comprises immunoglobulin-like domain 2 amino acid sequence; (b) the second polypeptide comprises an amino acid sequence at least 90% identical to a fragment of the VEGFR-1 extracellular domain, wherein the fragment comprises immunoglobulin-like domain 3 amino acid sequence; and (c) the third polypeptide comprises an amino acid sequence at least 90% identical to a fragment of the VEGFR-3 extracellular domain, wherein said fragment comprises VEGFR-3 immunoglobulin-like domain 1 amino acid sequence.
In another aspect, the invention provides a binding construct comprising: a) a first amino acid sequence at least 90% identical to a fragment of the VEGFR-3 extracellular domain, wherein said fragment comprises VEGFR-3 immunoglobulin-like domain 1 amino acid sequence; (b) a second amino acid sequence at least 90% identical to a fragment of the VEGFR-2 extracellular domain, wherein the fragment comprises immunoglobulin-like domain 2 amino acid sequence; and, (c) a third amino acid sequence at least 90% identical to a fragment of the VEGFR-1 extracellular domain, wherein the fragment comprises immunoglobulin-like domain 3 amino acid sequence; wherein the first, second, and third amino acid sequences are operatively connected, and wherein the binding construct binds to at least VEGF-A and VEGF-C. In one embodiment, the binding construct comprises an amino acid sequence at least 95% identical to the amino acid sequence set out in SEQ ID NO: 128. In a related embodiment, the binding construct comprises the amino acid sequence of SEQ ID NO: 128.
In a second embodiment, the binding construct of the invention comprises a first polypeptide comprising a fragment of a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-3 extracellular domain amino acid sequence comprising residues 24-775 of SEQ ID NO: 6, wherein the fragment binds VEGF-C or VEGF-D. It is contemplated that the binding construct of the invention comprises a second polypeptide comprising a fragment of a polypeptide comprising an amino acid sequence at least 90% identical to the VEGFR-2 extracellular domain amino acid sequence comprising positions 20-764 of SEQ ID NO: 4, wherein the fragment binds VEGF-A, VEGF-C, VEGF-E or VEGF-D.
In a related embodiment, the binding construct of the invention comprises a first and second polypeptide as described above, wherein: (a) the first polypeptide comprises an amino acid sequence at least 90% identical to a fragment of the VEGFR-3 extracellular domain, wherein said fragment comprises VEGFR-3 immunoglobulin-like domain 1 amino acid sequence; and, (b) the second polypeptide comprises an amino acid sequence at least 90% identical to a fragment of the VEGFR-2 extracellular domain, wherein the fragment comprises immunoglobulin-like domains 2 and 3 amino acid sequence.
In another aspect, the invention provides a binding construct comprising: a) a first amino acid sequence at least 90% identical to a fragment of the VEGFR-3 extracellular domain, wherein said fragment comprises VEGFR-3 immunoglobulin-like domain 1 amino acid sequence; and, (b) a second amino acid sequence at least 90% identical to a fragment of the VEGFR-2 extracellular domain, wherein the fragment comprises immunoglobulin-like domain 2 amino acid sequence; and an immunoglobulin-like domain 3 amino acid sequence; wherein the first, second, and third amino acid sequences are operatively connected, and wherein the binding construct binds to at least VEGF-A and VEGF-C. It is further contemplated that the construct binds VEGF-D. In one embodiment, the binding construct comprises an amino acid sequence at least 95% identical to the amino acid sequence set out in SEQ ID NO: 125. In a related embodiment, the binding construct comprises the amino acid sequence of SEQ ID NO: 125.
Preferably, the binding units of a binding construct are not exclusively (antibody) antigen binding fragments. In some embodiments, the binding construct comprises at least one non-antigen binding fragment binding unit. In some embodiments, the binding units all comprise antigen binding fragments. Exemplary Bispecific antibodies are provided in co-owned, concurrently (Mar. 5, 2004) filed U.S. Provisional Patent Application No. 60/550,511: “Multivalent Antibody Materials And Methods For VEGF/PDGF Family Of Growth Factors,” and related, co-filed International Patent Application No. PCT/US05/07742, both applications incorporated herein by reference it their entirety.
Every method of using binding constructs of the invention, and nucleic acids encoding the same, whether for therapeutic, diagnostic, or research purposes, is another aspect of the invention.
For example, the invention further contemplates use of the binding constructs of the invention as a method for screening for inhibition of growth factor binding to receptor and decrease in receptor activation. In one aspect the invention provides a method of screening a binding construct for growth factor neutralization activity comprising: contacting a growth factor and a growth factor receptor in the presence and absence of a binding construct; and, measuring binding between the growth factor and the growth factor receptor in the presence and absence of the binding construct, wherein reduced binding in the presence of the binding construct indicates growth factor neutralization activity for the binding construct; wherein the growth factor comprises at least one member selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D and combinations thereof; wherein the receptor is at least one member selected from the group consisting of VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-α, PDGFR-β; an extracellular domain fragment of any of said receptors that is effective to bind to the growth factor; a chimeric receptor comprising the extracellular domain fragment; and combinations thereof; and wherein the binding construct comprises a polypeptide or binding construct or a polynucleotide or vector according to the invention.
It is further contemplated in the screening method that the contacting is performed in a cell free system and the measuring of the binding comprises: measuring growth factor bound to the growth factor receptor. In a related embodiment, the contacting comprises contacting a cell that expresses the receptor with the growth factor; and wherein the measuring comprises: measuring growth factor receptor phosphorylation, wherein the phosphorylation is indicative of binding; measuring a growth factor-mediated cellular response in the cell, wherein the cellular response is indicative of binding between the growth factor and the receptor.
The substances are useful for any disorder where one PDGF/VEGF family member is overexpressed and especially useful if two or more are overexpressed.
For example, the invention includes a method of inhibiting fibrosis comprising administering to a mammalian subject in need of inhibition of fibrosis a binding construct of the invention.
For example, one aspect of the invention is a method for inhibiting angiogenesis or lymphangiogenesis comprising administering to a mammalian subject in need of inhibition of angiogenesis or lymphangiogenesis a binding construct according to the invention, in an amount effective to inhibit angiogenesis or lymphangiogenesis. Methods to determine the extent of inhibition of angiogenesis and lymphangiogenesis are described herein.
The invention further contemplates a method for inhibiting angiogenesis or lymphangiogenesis comprising administering to a mammalian subject in need of inhibition of angiogenesis or lymphangiogenesis a binding construct according to the invention, wherein the subject has a disease characterized by neoplastic cell growth exhibiting angiogenesis or lymphangiogenesis, and the binding construct is administered in an amount effective to inhibit the neoplastic cell growth. Neoplastic cell growth as used herein refers to multiplication of the cells which is uncontrolled and progressive. Cancers, especially vascularized cancers, are examples of neoplastic cell growth that is treatable using materials and methods of the invention.
It is further contemplated that the method of the invention is used wherein the subject has a disease characterized by aberrant angiogenesis or lymphangiogenesis, wherein the disease is selected from the group consisting of inflammation (chronic or acute), an infection, an immunological disease, arthritis, rheumatoid arthritis, diabetes, retinopathy, psoriasis, arthopathies, congestive heart failure, plasma leakage, fluid accumulation due to vascular permeability, lymphangioma, and lymphangiectasis.
The binding constructs also may be used to treat or prevent cancer associated disorders such as cancer associated ascites formation.
In one aspect, the invention provides a method of inhibiting endothelial or smooth muscle cell proliferation in a mammal, comprising administering to a mammal a composition, said composition comprising a polypeptide or binding construct, or a polynucleotide or vector encoding a binding construct, in an amount effective to inhibit endothelial cell proliferation in the mammal.
In some embodiments, the mammal to which the composition is administered has a neoplastic disease characterized by endothelial or smooth muscle cell growth. In some embodiments the neoplastic disease is selected from the group consisting of carcinomas, squamous cell carcinomas, lymphomas, melanomas, and sarcomas. Other cancers may be targeted as well as discussed herein. The composition is preferably administered in an amount effective to inhibit tumor growth or metastasis.
The method may also comprise the step of screening a mammal to identify a neoplastic disorder characterized by endothelial cell proliferation. In some embodiments, the subject of the method is a human, in other a non-human mammal, and in still others a non-mammalian species. In some embodiments, the screening step comprises screening the mammal for elevated serum levels of at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D polypeptides. In some embodiments, the screening step comprises obtaining a tissue sample from the tumor and detecting elevated levels of at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D polypeptides, or elevated levels of at least one receptor capable of binding the same. The method may also comprise the step of selecting a binding construct, wherein the binding construct binds to one or more of the elevated growth factors identified in the screening step, for use in the administration step.
The methods of the invention may also be carried out with more than one binding construct, or at least one binding construct in combination with another therapeutic. For example, other therapeutics that may be used in combination with the binding constructs of the invention include anti-sense RNA, RNA interference, bispecific antibodies, other antibody types, and small molecules, e.g., chemotherapeutic agents, which target growth factors and/or their receptors. A cytokine, radiotherapeutic agent, or radiation therapy may also be used in combination with a binding construct. The chemotherapeutic agent or radiotherapeutic agent may be a member of the class of agents including an anti-metabolite; a DNA-damaging agent; a cytokine or growth factor; a covalent DNA-binding drug; a topoisomerase inhibitor; an anti-mitotic agent; an anti-tumor antibiotic; a differentiation agent; an alkylating agent; a methylating agent; a hormone or hormone antagonist; a nitrogen mustard; a radiosensitizer; and a photosensitizer. Specific examples of these agents are described elsewhere in the application. Combination therapies are preferably synergistic, but they need not be, and additive therapies are also considered aspects of the invention.
In addition to their use in methods, the binding constructs may be combined or packaged with other therapeutics in kits or as unit doses. Neoplastic diseases are not the only diseases that may be treated with the binding constructs. The binding constructs may be used as therapeutics for any disease associated with abnormally high levels of growth factor expression.
This summary of the invention is not intended to be limiting or comprehensive, and additional embodiments are described in the drawings and detailed description, including the examples. All such embodiments are aspects of the invention. Moreover, for the sake of brevity, various details that are applicable to multiple embodiments have not been repeated for every embodiment. Variations reflecting combinations and rearrangements of the embodiments described herein are intended as aspects of the invention. In addition to the foregoing, the invention includes, as an additional aspect, all embodiments of the invention narrower in scope in any way than the variations specifically mentioned above. For example, for aspects described as a genus or range, every subgenus, subrange or species is specifically contemplated as an embodiment of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic depiction of vascular endothelial growth factor receptors and ligands that bind the same.
FIG. 2 is an autoradiograph of a PAGE from binding assays of VEGFR-2 fragment binding constructs using either radiolabeled VEGF-A or VEGF-C constructs.
FIG. 3 is an autoradiograph of a PAGE from binding assays of VEGFR-3 fragment binding constructs using a radiolabeled VEGF-C construct.



While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described herein in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and the equivalents falling within the spirit and scope of the disclosure as defined by the appended claims.
DETAILED DESCRIPTION
The present invention provides novel binding constructs, compositions, and materials and methods for making and using the same. The binding constructs bind growth factors that exert angiogenic, lymphangenic, and other effects in vivo, and are useful for modulating those effects and also for purifying, isolating, and characterizing the growth factors.
I. BINDING CONSTRUCTS
For the purposes of this invention, a “binding construct” comprises one or more binding units associated with each other by covalent or other forms of attachment. A “binding unit” binds a growth factor ligand, i.e., one or more growth factor polypeptides, and preferably does so with high affinity. A binding unit preferably comprises at least one peptide or polypeptide, but other embodiments are possible as well, including organic small molecules, aptamers, and combinations of the same. While a binding unit preferably comprises a single polypeptide, it may comprise multiple polypeptides if a single polypeptide is not sufficient for binding a particular growth factor. When more than one binding unit or polypeptide segment is in a given binding construct, the binding units may be joined directly (i.e., through a covalent bond, e.g., a peptide, ester, or sulfhydryl bond, or non-covalently, e.g., hydrophobically) together via a linker. A binding construct may further include a heterologous peptide or other chemical moieties. Such additions are can modify binding construct properties such as stability, solubility, toxicity, serum half-life, immunogenicity, detectability, or other properties.
The term “high affinity” is used in a physiological context pertaining to the relative affinity of the binding construct for the growth factor ligand(s) in vivo in a mammal, such as a laboratory test animal, a domesticated farm or pet animal, or a human. The targeted growth factors of the invention, e.g., the VEGF/PDGF family members, have characteristic affinities for their receptors in vivo, typically measured in terms of sub-nanomolar dissociation constants (Kd). For the purposes of this invention, a binding construct can bind to its target growth factor(s) with a Kd less than or equal to 1000 times the Kd of the natural growth factor-receptor pair, while retaining the specificity of the natural pair. A binding unit that binds a growth factor with a Kd less than or equal to 10 times the Kd of the natural growth factor-receptor pair, while retaining the specificity of the natural pair, is considered high affinity. While high affinity is preferred, it is not a requirement. In a preferred embodiment, the affinity of the binding unit for the growth factor equals or exceeds the affinity of the natural receptor for the growth factor.
By binding activity is meant the ability to bind to a ligand, receptor, or binding construct, and does not require the retention of biological activity in so far as enzymatic activity or signaling is concerned. Binding may include either binding to a monomer or a dimer, homodimers or heterodimers, whether of receptors or ligands. Polypeptides for use according to the present invention can be used in the form of a protein dimer, particularly a disulfide-linked dimer. Mechanistic descriptions of binding constructs, e.g., as ligand traps, are not meant to be limiting. For example, a binding construct comprising a receptor extracellular domain fragment may function by forming inactive dimers with an endogenous receptor monomer.
In some embodiments, a binding construct comprises a first binding unit (e.g., a polypeptide) operatively associated with a second binding unit (e.g., a polypeptide), wherein each binding unit binds a growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, PDGF-D, D1701 VEGF, NZ2 VEGF, NZ7 VEGF, and fallotein. In some embodiments the first and second binding units act together to bind a single ligand molecule (wherein the ligand may comprise a monomer or dimer). In some embodiments, the binding units act independently, i.e., each polypeptide binds a separate ligand molecule. In some embodiments, the first and second binding units are capable of either acting together or acting independently to bind one or more ligand polypeptides. In some embodiments, a binding unit of a first binding construct is able to interact with a binding unit on a second binding construct, e.g., to form dimers between binding units.
In some embodiments, the binding construct comprises a first polypeptide operatively connected to a second polypeptide, wherein the first and second polypeptides each binds at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, and PDGF polypeptides; wherein the amino acid sequence of the first polypeptide differs from the amino acid sequence of the second polypeptide; and wherein the first and second polypeptides comprise members independently selected from the group consisting of:
(a) a polypeptide comprising an amino acid sequence at least 35% identical to the VEGFR-1 extracellular domain amino acid sequence comprising positions 27-758 of SEQ ID NO: 2;
(b) a fragment of (a) that binds VEGF-A, VEGF-B, or PDGF;
(c) a polypeptide comprising an amino acid sequence at least 35% identical to the VEGFR-2 extracellular domain amino acid sequence comprising positions 20-764 of SEQ ID NO: 4;
(d) a fragment of (c) that binds VEGF-A, VEGF-C, VEGF-E or VEGF-D;
(e) a polypeptide comprising an amino acid sequence at least 35% identical to the VEGFR-3 extracellular domain amino acid sequence comprising residues 24-775 of SEQ ID NO: 6;
(f) a fragment of (e) that binds VEGF-C or VEGF-D;
(g) a polypeptide comprising an amino acid sequence at least 35% identical to the neuropilin-1 extracellular domain amino acid sequence comprising residues 22-856 of SEQ ID NO: 113;
(h) a fragment of (g) that binds VEGF-A, VEGF-B, VEGF-C, VEGF-E, or PDGF;
(i) a polypeptide comprising an amino acid sequence at least 35% identical to the neuropilin-2 extracellular domain amino acid sequence comprising residues 21-864 of SEQ ID NO: 115;
(j) a fragment of (i) that binds VEGF-A, VEGF-C, or PDGF;
(k) a polypeptide comprising an amino acid sequence at least 35% identical to the platelet derived growth factor receptor alpha extracellular domain amino acid sequence comprising residues 24-524 of SEQ ID NO: 117;
(l) a fragment of (k) that binds PDGF-A, PDGF-B, or PDGF-C;
(m) a polypeptide comprising an amino acid sequence at least 35% identical to the platelet derived growth factor beta extracellular domain amino acid sequence comprising residues 33 to 531 of SEQ ID NO: 119;
(n) a fragment of (m) that binds PDGF-B or PDGF-D;
(o) a polypeptide comprising an antigen binding fragment of an antibody that binds to at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D;
(p) a polypeptide that binds at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PDGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D polypeptides, wherein the polypeptide is generated using phage display; and
(q) an organic molecule that mimics the binding properties of (a)-(p).
Preferably, the binding units of a binding construct are not exclusively polypeptides comprising (antibody) antigen binding fragments. In some embodiments, the binding construct comprises at least one non-antigen binding fragment comprising binding unit. In some embodiments, the binding construct comprises two or more receptor fragments. In some embodiments, the binding construct comprising at least one receptor fragment and at least one polypeptide comprising an antigen binding fragment.
In some embodiments, the binding units all comprise antigen binding fragments. Exemplary bispecific antibodies are provided in co-owned, concurrently (Mar. 5, 2004) filed U.S. Provisional Patent Application No. 60/550,511: “Multivalent Antibody Materials And Methods For VEGF/PDGF Family Of Growth Factors,” and related, co-filed International Patent Application No. PCT/US05/07742, both applications incorporated herein by reference it their entirety.
In some embodiments, one or more of the polypeptides of a binding construct is replaced with another type of molecule, e.g., a nucleic acid, that mimics the binding properties of any of the polypeptides described above in (a) through (p). Such nucleic acids include, for example, aptamers.
A. Binding Units
The growth factors that are the targets of the binding constructs of the invention exert their physiological effects in vivo by binding to the extracellular domains of growth factor receptors. Accordingly, growth factor receptors and fragments thereof constitute examples of binding units. Exemplary human nucleotide and amino acid sequences, for relevant ligands and receptors are set forth in the sequence listing as summarized below:







TABLE 1A







RECEPTOR SEQUENCES










RECEPTOR
SEQ ID NOS:







VEGFR-1
1 and 2



VEGFR-2
3 and 4



VEGFR-3 short
5 and 6



VEGFR-3 long
120 and 121



PDGFR-α
116 and 117



PDGFR-β
118 and 119



Neuropilin-1
112 and 113



Neuropilin-2
114 and 115

















TABLE 1B







RECEPTOR SEQUENCES










LIGAND
SEQ ID NOS:







VEGF-A
80 and 81



VEGF-A 232 isoform
90 and 91



VEGF-B isoform 1
94 and 95



VEGF-B isoform 2
96 and 97



VEGF-C
82 and 83



VEGF-D
86 and 87



VEGF-E (NZ7)
88 and 89



PlGF
84 and 85



D1701 VEGF
92 and 93



PDGF-A
98 and 99



PDGF-B
100 and 101



PDGF-C
102 and 103



PDGF-D
104 and 105










Other VEGF growth factors members include snake venom VEGFs (e.g., EMBL. AY033151, AY033152, and AY42981), various VEGF-E (orf virus VEGF homologs, some of which are presented in Table 1B) molecules including VEGF-E NZ2 [S67520], VEGF-E NZ7, VEGF-E D1701, VEGF-E Orf-11, and VEGF-E OV-IA82. [See generally, WO 00/25085.]
Members of the PDGF/VEGF family are characterized by a number of structural motifs including a conserved PDGF motif defined by the sequence: P—[PS]—C—V—X(3)-R—C-[GSTA]-G-C—C (SEQ ID NO: 111), where the brackets indicate a variable position that can be any one of the amino acids within the brackets. The number contained within the parentheses indicates the number of amino acids that separate the “V” and “R” residues. This conserved motif falls within a large domain of 70-150 amino acids defined in part by eight highly conserved cysteine residues that form inter- and intramolecular disulfide bonds. This domain forms a cysteine knot motif composed of two disulfide bonds which form a covalently linked ring structure between two adjacent β strands, and a third disulfide bond that penetrates the ring [see for example, FIG. 1 in Muller et al., Structure 5:1325-1338 (1997)], similar to that found in other cysteine knot growth factors, e.g., transforming growth factor-β (TGF-β). The amino acid sequence of all known PDGF/VEGF proteins, with the exception of VEGF-E, contains the PDGF domain. The PDGF/VEGF family proteins are predominantly secreted glycoproteins that form either disulfide-linked or non-covalently bound homo- or heterodimers whose subunits are arranged in an anti-parallel manner [Stacker and Achen, Growth Factors 17:1-11 (1999); Muller et al., Structure 5:1325-1338 (1997)]. Binding constructs of the invention include those that bind VEGF/PDGF growth factor monomers, homodimers, and heterodimers.
The VEGF subfamily is composed of members that share a VEGF homology domain (VHD) characterized by the sequence: C—X(22-24)-P—[PSR]—C—V—X(3)—R—C-[GSTA]-G—C—C—X(6)-C—X(32-41)-C. (SEQ ID: 110) The VHD domain, determined through analysis of the VEGF subfamily members, comprises the PDGF motif but is more specific. The VEGF subfamily of growth factors and receptors regulate the development and growth of the vascular endothelial system. VEGF family members include, but are not limited to VEGF-A, VEGF-B, VEGF-C, VEGF-D and PlGF [Li, X. and U. Eriksson, “Novel VEGF Family Members: VEGF-B, VEGF-C and VEGF-D,” Int. J. Biochem. Cell. Biol., 33(4):421-6 (2001))] Other VEGFs are bacterial or viral, the “VEGF-Es.” Other VEGFs are derived from snake venom, the “NZ” series. [See e.g., Komori, et al. Biochemistry, 38(36):11796-803 (1999); Gasmi, et al., Biochem Biophys Res Commun, 268(1):69-72 (2002); Gasmi, et al., J Biol Chem; 277(33):29992-8 (2002); de Azevedo, et al., J. Biol. Chem., 276: 39836-39842 (2001)].
At least seven cell surface receptors that interact with PDGF/VEGF family members have been identified. These include PDGFR-α [See e.g., GenBank Acc. No. NM006206; Swiss Prot No. P16234], PDGFR-β [See e.g., GenBank Acc. No. NM002609; Swiss Prot. No. P09619], VEGFR-1/Flt-1 (fms-like tyrosine kinase-1; hereinafter “R-1”) [GenBank Acc. No. X51602; De Vries, et al., Science 255:989-991 (1992)]; VEGFR-2/KDR/Flk-1 (kinase insert domain containing receptor/fetal liver kinase-1, hereinafter “R-2”) [GenBank Acc. Nos. X59397 (Flk-1) and L04947 (KDR); Terman, et al., Biochem. Biophys. Res. Comm. 187:1579-1586 (1992); Matthews, et al., Proc. Natl. Acad. Sci. USA 88:9026-9030 (1991)]; VEGFR-3/Flt4 (fms-like tyrosine kinase 4; hereinafter “R-3”) [U.S. Pat. No. 5,776,755 and GenBank Ace. No. X68203 and S66407; Pajusola et al., Oncogene 9:3545-3555 (1994); Hughes, et al., J. Mol. Evol. 52(2):77-79 (2001); Pajusola, et al., Oncogene 8(11):2931-37) (1993); Borg, et al., Oncogene 10(5):973-984 (1995), neuropilin-1 [Gen Bank Acc. No. NM003873], and neuropilin-2 [Gen Bank Acc. No. NM003872; SwissProt O60462]. The two PDGF receptors mediate signaling of PDGFs. Non-human VEGF and PDGF receptors may also be employed as part of the invention, e.g., chicken VEGFR-1 may be used alone or in hybrid form with human R-1 for improved expression.
VEGF121, VEGF165, VEGF-B, PlGF-1 and PlGF-2 bind VEGF-R1; VEGF121, VEGF145, VEGF165, (fully processed mature) VEGF-C, (fully processed mature) VEGF-D, VEGF-E, and NZ2 VEGF bind VEGF-R2; VEGF-C and VEGF-D bind VEGFR-3; VEGF165, VEGF-C, PlGF-2, and NZ2 VEGF bind neuropilin-1; and VEGF165 and VEGF-C binds neuropilin-2. [Neufeld, et al., FASEB. J. 13:9-22 (1999); Stacker and Achen, Growth Factors 17:1-11 (1999); Ortega, et al., Fron. Biosci. 4:141-152 (1999); Zachary, Intl. J. Biochem. Cell. Bio. 30:1169-1174 (1998); Petrova, et al., Exp. Cell. Res. 253:117-130 (1999); U.S. Pat. Appl. Pub. No. 20030113324]. Ligand, receptor interactions for the VEGFR subfamily are summarized in FIG. 1. PDGF-A, PDGF-B, and PDGF-C bind PDGFR-α. PDGF-B and PDGF-D bind PDGF-β.
Both the ligands and the receptors generally exist as dimers, including both homodimers and heterodimers. Such dimers can influence binding. For example, for the PDGFs, PDGF-AA binds PDGFR-α/α. PDGF-AB and PDGF-CC bind PDGFR-α/α and PDGFR-α/β. PDGFR-BB binds both of the homodimers and the heterodimeric PDGF receptor. PDGF-DD binds PDGF receptor heterodimers and beta receptor homodimers. [See, e.g., Pietras, et al., Cancer Cell, 3:439-443 (2003).] VEGF-A can heterodimerize with VEGF-B and PlGF. The VEGFs, PDGFs, and PlGFs, may exist as two or more isoforms, e.g., splice variants, and not all isoforms of a particular growth factor will share the same binding profile, or ability to dimerize with particular molecules. Certain isoforms of the same growth factor may also dimerize with each other. For example the 167 and 186 isoforms of VEGF-B can heterodimerize with each other.
Growth factor receptor tyrosine kinases generally comprise three principal domains: an extracellular domain, a transmembrane domain, and an intracellular domain. The extracellular domain binds ligands, the transmembrane domain anchors the receptor to a cell membrane, and the intracellular domain possesses one or more tyrosine kinase enzymatic domains and interacts with downstream signal transduction molecules. The vascular endothelial growth factor receptors (VEGFRs) and platelet derived growth factor receptors (PDGFRs) bind their ligand through their extracellular domains (ECDs), which are comprised of multiple immunoglobulin-like domains (Ig-domains). Ig-domains are identified herein using the designation “D#.” For example “D1” refers to the first Ig-domain of a particular receptor ECD. “D1-3” refers to a construct containing at least the first three Ig-domains, and intervening sequence between domains 1 and 2 and 2 and 3, of a particular construct. Table 2 defines the boundaries of the Ig-domains for VEGFR-1, VEGFR-2, and VEGFR-3 of the invention. These boundaries are significant as the boundaries chosen can be used to form constructs, and so can influence the binding properties of the resulting constructs. This relationship is discussed in Example 1.
The complete ECD of PDGFRs and VEGFRs is not required for ligand (growth factor) binding. The ECD of VEGFR-1 (R-1) and VEGFR-2 (R-2) consists of seven Ig-like domains and the ECD of VEGFR-3 (R-3) has six intact Ig-like domains—D5 of R-3 is cleaved post-translationally into disulfide linked subunits leaving VEGFR-3. Veikkola, T., et al., Cancer Res. 60:203-212 (2000). In general, receptor fragments of at least the first three Ig-domains for this family are sufficient to bind ligand. The PDGFRs have five Ig-domains.







TABLE 2







IMMUNOGLOBULIN-LIKE DOMAINS FOR


VEGFR-1, VEGFR-2 AND VEGFR-3














R-1
R-1
R-2
R-2
R-3
R-3



SEQ ID
SEQ ID
SEQ ID
SEQ ID
SEQ ID
SEQ ID



NO: 1
NO: 2
NO: 3
NO: 4
NO: 5
NO: 6



positions
positions
positions
positions
positions
positions

















D1
394-580
 49-111
145-316
 48-105
158-364
 47-115


D2
709-880
154-211
436-610
145-203
479-649
154-210


D3
 990-1192
248-315
724-931
241-310
761-961
248-314


D4
1303-1474
352-409
1039-1204
346-401
1070-1228
351-403


D5
1957-1864
450-539
1321-1600
440-533
1340-1633
441-538


D6
1966-2167
573-640
1699-1936
566-645
1739-1990
574-657


D7
2281-2452
678-735
2050-2221
683-740
2102-2275
695-752









In some embodiments, a binding unit of a binding construct comprises the ECD of a growth factor receptor. A binding unit may comprise at least one Ig-domain of a VEGFR as described in Table 2, to as many as seven. Ig-domain information for PDGFR-α and PDGFR-β is provided in Lokker, et al., J. Biol. Chem. 272: 33037-33044 (1997), which is incorporated by reference in its entirety. A binding unit may include sequence before the N-terminal most Ig-domain, may include sequence beyond the C-terminal most Ig-domain, and may include sequence between the Ig-domains as well. Binding units may also comprise variants, e.g., with one or more amino acid substitutions, additions, or deletions of an amino acid residue. Binding units also may comprise chimeras, e.g., combinations of Ig-domains from different receptors. In some embodiments, the first or second polypeptide comprises a receptor fragment comprising at least the first three Ig domains of a receptor tyrosine kinase.
The binding of a binding unit to a particular growth factor ligand refers to the ability to bind at least one natural isoform of at least one target growth factor, especially processed forms that are secreted from cells and circulate in vivo and/or bind heparin moieties. For example, “capable of binding VEGF-A” refers to the ability to bind at least one isoform of VEGF-A under physiological conditions. At least five human VEGF-A isoforms of 121, 145, 165, 189 or 206 amino acids in length (VEGF121-VEGF206), encoded by distinct mRNA splice variants, have been described, all of which are capable of stimulating mitogenesis in endothelial cells. [See generally, Ferrara, J. Mol. Med. 77:527-543 (1999).] Two VEGF-β isoforms generated by alternative mRNA splicing exist, VEGF-B186 and VEGF-B167, with the first isoform accounting for about 80% of the total VEGF-B transcripts [Li, X., et al., Growth Factor, 19:49-59 (2001); Grimmond, et al., Genome Res., 6:124-131 (1996); Olofsson, et al., J. Biol. Chem., 271:19310-19317 (1996).] Three isoforms of PlGF produced by alternative mRNA splicing have been described [Hauser, et al., Growth Factors 9:259-268 (1993); Maglione, et al., Oncogene 8:925-931 (1993)]. PDGF-A and PDGF-B can homodimerize or heterodimerize to produce three different isoforms: PDGF-AA, PDGF-AB, or PDGF-BB.
The term “identity”, as known in the art, refers to a relationship between the sequences of two or more polypeptide molecules or two or more nucleic acid molecules, as determined by comparing the sequences. In the art, “identity” also means the degree of sequence relatedness nucleic acid molecules or polypeptides sequences, as the case may be, as determined by the match between strings of two or more nucleotide or two or more amino acid sequences. “Identity” measures the percent of identical matches between the smaller of two or more sequences with gap alignments (if any) addressed by particular a mathematical model of computer program (i.e., “algorithms”). Appropriate algorithms for determining the percent identities of the invention include BLASTP and BLASTN, using the most common and accepted default parameters.
1. VEGFR-1-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a VEGFR-1 polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 2, wherein the fragment and the polypeptide binds one or more growth factors selected from the group consisting of VEGF-A, VEGF-B, and PlGF. The fragment minimally comprises enough of the VEGFR-1 sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:1 encoding a ligand binding fragment of VEGFR-1. Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the R-1 receptor. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more R-1 ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 1 under moderately or highly stringent conditions discussed herein.
Exemplary R1 fragments for use as binding unit polypeptides (or for use as a starting point for designing R-1 analogs) have an amino terminal residue selected from the group consisting of positions 1 to 129 of SEQ ID NO: 2, and a carboxy terminal residue selected from the group consisting of positions 229 to 758 of SEQ ID NO: 2, wherein the VEGFR-1 fragment binds at least one of VEGF-A, VEGF-B, and PlGF.
2. VEGFR-2-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a VEGFR-2 polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 4, wherein the fragment and the polypeptide binds one or more growth factors selected from the group consisting of VEGF-A, VEGF-C, VEGF-D, or VEGF-E. The fragment minimally comprises enough of the VEGFR-2 sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:3 encoding a ligand binding fragment of VEGFR-2. Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the R-2 receptor. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more R-2 ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 3 under moderately or highly stringent conditions discussed herein.
Exemplary R2 fragments for use as binding unit polypeptides (or for use as a starting point for designing R-2 analogs) have an amino terminal residue selected from the group consisting of positions 1 to 118 of SEQ ID NO: 4, and a carboxy terminal residue selected from the group consisting of positions 326 to 764 of SEQ ID NO: 4, wherein VEGFR-2 fragment binds at least one of VEGF-A, VEGF-C, VEGF-D, and VEGF-E. Exemplary R2 fragments for use as binding unit polypeptides (or for use as a starting point for designing R-2 analogs) may alternatively have an amino terminal residue selected from the group consisting of positions 1 to 192 of SEQ ID NO: 4, and a carboxy terminal residue selected from the group consisting of positions 393 to 764 of SEQ ID NO: 4, wherein the VEGFR-2 fragment binds at least one of VEGF-A, VEGF-C, VEGF-D, and VEGF-E. Exemplary R2 fragments for use as binding unit polypeptides (or for use as a starting point for designing R-2 analogs) may also have an amino terminal residue selected from the group consisting of positions 1 to 48 of SEQ ID NO: 4, and a carboxy terminal residue selected from the group consisting of positions 214 to 764 of SEQ ID NO: 4, wherein the VEGFR-2 fragment binds at least one of VEGF-A, VEGF-C, VEGF-D, and VEGF-E.
In some embodiments, a binding unit of the binding construct comprises a fragment of R-2, SEQ ID NO: 4, selected from the group consisting of positions 24-326 (SEQ ID NO: 8), 118-326 (SEQ ID NO: 20), positions 118-220 (SEQ ID NO: 22), positions 118-226 (SEQ ID NO: 24), and positions 118-232 (SEQ ID NO: 26). In some embodiments, a binding unit of the binding construct comprises a fragment of R-2, SEQ ID NO: 4, selected from the group consisting of positions 106-240, positions 112-234, positions 114-220, positions 115-220, positions 116-222, positions 117-220, positions 118-221, positions 118-222, positions 118-223, positions 118-224, and positions 118-228. In some embodiments, a binding unit of the binding construct comprises a fragment of R-2, SEQ ID NO: 4, selected from the group consisting of positions 48-203, and 145-310 and 48-310. Exemplary embodiments are also discussed in Example 1.
3. VEGFR-3-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a VEGFR-3 polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 6, where the fragment and the polypeptide binds one or more growth factors selected from the group consisting of VEGF-C and VEGF-D. The fragment minimally comprises enough of the VEGFR-3 sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the R-3 receptor.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:5 encoding a ligand binding fragment of VEGFR-3. Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more R-3 ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 5 under moderately or highly stringent conditions discussed herein.
Exemplary R-3 fragments for use as binding unit polypeptides (or for use as a starting point for designing R-3 analogs) have an amino terminal residue selected from the group consisting of positions 1 to 47 of SEQ ID NO: 6, and a carboxy terminal residue selected from the group consisting of positions 226 to 775 of SEQ ID NO: 6, wherein VEGFR-3 fragment binds at least one of VEGF-C and VEGF-D.
In some embodiments, a binding unit of the binding construct comprises a fragment of R-3, SEQ ID NO: 6, selected from the group consisting of positions 1-226 (SEQ ID NO: 38), positions 1-229 (SEQ ID NO: 36), and positions 1-329 (SEQ ID NO: 44). In some embodiments, a binding unit of the binding construct comprises a fragment of R-3, SEQ ID NO: 6, selected from the group consisting of positions 47-224, positions 47-225, positions 47-226, positions 47-227, positions 47-228, positions 47-229, positions 47-230, positions 47-231, positions 47-232, positions 47-236, positions 47-240, and positions 47-245. In some embodiments, a binding unit of the binding construct comprises a fragment of R-3, SEQ ID NO: 6, selected from the group consisting of positions 47-314, positions 47-210, and positions 47-247. Exemplary embodiments are also discussed in Example 1.
4. Neuropilin-1-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a neuropilin-1 polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 113, where the fragment and the polypeptide binds one or more growth factors selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-E, and PlGF. The fragment minimally comprises enough of the neuropilin-1 sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:112 encoding a ligand binding fragment of neuropilin-1. Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the neuropilin-1 receptor. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more neuropilin-1 ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 112 under moderately or highly stringent conditions discussed herein.
Exemplary neuropilin-1 fragments for use as binding unit polypeptides (or for use as a starting point for designing neuropilin-1 analogs) comprise a neuropilin-1 extracellular domain amino acid sequence comprising residues 22-856 of SEQ ID NO: 113, or a portion thereof; wherein the neuropilin-1 fragment and the binding unit bind at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-E, and PlGF.
5. Neuropilin-2-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a neuropilin-2 polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 115, wherein the fragment and the polypeptide binds one or more growth factors selected from the group consisting of VEGF-A, VEGF-C, and PlGF. The fragment minimally comprises enough of the neuropilin-2 sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:114 encoding a ligand binding fragment of neuropilin-2. Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the neuropilin-2 receptor. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more neuropilin-2 ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 114 under moderately or highly stringent conditions discussed herein.
Exemplary neuropilin-2 fragments for use as binding unit polypeptides comprising residues 21-864 of SEQ ID NO: 115, or a portion thereof; wherein the neuropilin-2 fragment and the binding unit bind at least one growth factor selected from the group consisting of VEGF-A, VEGF-C, and PlGF.
Further neuropilin-1 and -2 species, isoforms, soluble fragments, etc., are provided in WO03/029814, U.S. application Ser. Nos. 10/262,538, 10/669,176, and 60/505,607, which are incorporated by reference in their entireties.
6. PDGFR-Alpha-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a PDGFR-α polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 117, where the fragment and the polypeptide binds one or more growth factors selected from the group consisting of PDGF-A, PDGF-B, and PDGF-C. The fragment minimally comprises enough of the PDGFR-α sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the R-α receptor.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:116 encoding a ligand binding fragment of R-α Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more R-α ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 116 under moderately or highly stringent conditions discussed herein.
Exemplary R-α fragments for use as binding unit polypeptides (or for use as a starting point for designing R-α analogs) have an amino terminal residue selected from the group consisting of positions 1 to 123 of SEQ ID NO: 117, and a carboxy terminal residue selected from the group consisting of positions 313 to 524 of SEQ ID NO: 117, wherein the PDGFR-α fragment binds at least one of PDGF-A, PDGF-B, and PDGF-C.
7. PDGFR-Beta-Derived Binding Units
In some embodiments, a binding unit comprises a polypeptide similar or identical in amino acid sequence to a R-β polypeptide or fragment thereof, preferably from the same species as the targeted growth factor(s). Thus, for binding to human growth factors, a binding unit preferably comprises a polypeptide that comprises an amino acid similar or identical to a fragment of SEQ ID NO: 119, where the fragment and the polypeptide binds one or more growth factors selected from the group consisting of PDGF-B and PDGF-D. The fragment minimally comprises enough of the PDGFR-β sequence to bind the ligand, and may comprise the complete receptor. Extracellular domain fragments are preferred. Preferred polypeptides have an amino acid sequence at least 80% identical to a ligand binding fragment thereof. Fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. A genus of similar polypeptides can alternatively be defined by the ability of encoding polynucleotides to hybridize to the complement of a nucleotide sequence that corresponds to the cDNA sequence encoding the R-β receptor.
Preferred polypeptides may also be described as having an amino acid sequence encoded by a nucleic acid sequence at least 80% identical to a fragment of SEQ ID NO:118 encoding a ligand binding fragment of PDGFR-β. Nucleic acid fragments that are more similar, e.g., 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 100% are highly preferred. Fragments that are 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75% are also contemplated. For example, a preferred binding unit polypeptide comprises an amino acid sequence that binds one or more R-β ligands and that is encoded by a nucleotide sequence that hybridizes to the complement of SEQ ID NO: 118 under moderately or highly stringent conditions discussed herein.
Exemplary R-β fragments for use as binding unit polypeptides (or for use as a starting point for designing R-β analogs) have an amino terminal residue selected from the group consisting of positions 1 to 124 of SEQ ID NO: 119, and a carboxy terminal residue selected from the group consisting of positions 314 to 531 of SEQ ID NO: 119, wherein PDGFR-β fragment binds at least one of PDGF-B and PDGF-D.
8. Other Binding Units
Although a binding unit may comprise a polypeptide similar or identical to an extracellular domain fragment of a growth factor receptor tyrosine kinase, other binding units are contemplated as well. In some embodiments, the binding unit is generated using phage display. In some embodiments, the binding unit comprises an antibody. In some embodiments, a binding unit comprises a polypeptide comprising an antibody (antigen binding) fragment, e.g., a domain antibody. Binding units, as well as binding constructs, need not comprise a polypeptide. In some embodiments, the binding construct comprises nucleic acid, e.g., DNA or RNA, such as an aptamer. In some embodiments, the binding construct comprises polysaccharides.
Growth factor binding molecules that have been described in the literature may be used as binding units to construct binding constructs of the inventory including molecules taught by the following: Veikkola, T., et al., Cancer Res. 60:203-212 (2000); Davis-Smyth, T., et al., EMBO J., 15(18): 4919-27 (1996), U.S. Pat. Nos. 5,952,199; 6,100,071; 6,383,486; U.S. Pat. Appl. Nos. 20030092604; Niwa, et al., U.S. Pat. No. 6,348,333; Fairbrother, et al., Biochemistry, 37:17754-64 (1998); Starovasnik, M. et al., J. Mol. Biol., 293: 531-44 (1999); Wiesmann, C., et al., Cell, 91:695-704 (1997); Fuh, et al., J. Biol. Chem., 273(18): 11197-11204 (1998); Shinkai, A. et al., J. Biol. Chem., 273(47):31283-88 (1998); Lu, et al., J. Biol. Chem., 275(19): 14321-14330 (2000); Lu et al., J. Immunological Methods, 230:159-71 (1999); Lu, et al., J. Biol. Chem., 278(44): 43496-43507 (2003); Makkinen, T., et al., Nature Medicine, 7(2), 199-205 (2001); Alitalo, et al., WO 02/060950; Karpanen, T., et al., Cancer Research 61:1786-90 (2001); Liu, et al., U.S. Pat. Appl. Publ. No. 2003/0064053; Kubo, H., et al., Blood, 96(2): 546-553 (2000); Rosen, Hematol. Oncol. Clin. N. Am., 16:1173-1187 (2002); Kaplan, et al., Growth Factors, 14:243-256 (1997); Thomas, et al., U.S. Pat. No. 6,375,929; Kendall and Thomas, PNAS, U.S.A., 90:10705-10709 (1993); Kovesdi, U.S. Pat. Appl. Publ. No. 2003/0053989, Daly, et al., U.S. Pat. Appl. Publ. No.: 2004/0014667; and Lokker, et al., J. Biol. Chem. 272: 33037-33044 (1997). These and other documents cited in this application are incorporated in their entireties. Molecules that have not previously been tested for their ability to bind to a particular growth factor may tested according to the assays provided herein. For example, some of the above documents teach a R-2 fragment that binds VEGF-A. That same molecule may be tested for its ability to bind VEGF-C.
Except as otherwise noted, descriptions supplied for receptors, also apply to receptor fragments and such fragments incorporated into binding constructs as described herein.
The growth factor receptors, from which binding units may be derived, include splice variants and naturally-occurring allelic variations. Allelic variants are well known in the art, and represent alternative forms or a nucleic acid sequence that comprise substitution, deletion or addition of one or more nucleotides, but which do not result in any substantial functional alteration of the encoded polypeptide. Standard methods can readily be used to generate such polypeptides including site-directed mutagenesis of polynucleotides, or specific enzymatic cleavage and ligation. Similarly, use of peptidomimetic compounds or compounds in which one or more amino acid residues are replaced by a non-naturally-occurring amino acid or an amino acid analog that retain binding activity is contemplated. Preferably, where amino acid substitution is used, the substitution is conservative, i.e. an amino acid is replaced by one of similar size and with similar charge properties. As used herein, the term “conservative substitution” denotes the replacement of an amino acid residue by another, biologically similar residue. Examples of conservative substitutions include the substitution of one hydrophobic residue such as isoleucine, valine, leucine, alanine, cysteine, glycine, phenylalanine, proline, tryptophan, tyrosine, norleucine or methionine for another, or the substitution of one polar residue for another, such as the substitution of arginine for lysine, glutamic acid for aspartic acid, or glutamine for asparagine, and the like. Neutral hydrophilic amino acids that can be substituted for one another include asparagine, glutamine, serine and threonine. The term “conservative substitution” also includes the use of a substituted amino acid in place of an unsubstituted amino acid.
Alternatively, conservative amino acids can be grouped as described in Lehninger, (Biochemistry, Second Edition; Worth Publishers, Inc. NY:NY, pp. 71-77 (1975)) as set out in the following:
Non-polar (hydrophobic)

    
    
        A. Aliphatic: A, L, I, V, P,
        B. Aromatic: F, W,
        C. Sulfur-containing: M,
        D. Borderline: G.
    
    


Uncharged-polar

    
    
        A. Hydroxyl: S, T, Y,
        B. Amides: N, Q,
        C. Sulfhydryl: C,
        D. Borderline: G.
    
    


Positively Charged (Basic): K, R, H.
Negatively Charged (Acidic): D, E.
B. Linkers
While binding units may be directly attached to one another (via a peptide, disulfide or other type of covalent bond), the binding constructs of the present invention may further comprise a (one or more) linker that connects together two or more different binding units, e.g., a receptor fragments with another receptor fragment, or even a copy of itself. A linker may also link a binding unit to other substituents described herein. The linker is generally a heterologous protein polypeptide. In some embodiments, the linker comprises a peptide that links the binding units to form a single continuous peptide that can be expressed as a single molecule. Linkers may be chosen such that they are less likely to induce an allergic reaction. Polysaccharides or other moieties also may be used to link binding units to form a binding construct.
More than one linker may be used per binding construct. The linker may be selected for optimal conformational (steric) freedom between the various ligand binding units to allow them to interact with each other if desired, e.g., to form dimers, or to allow them to interact with ligand. The linker may be linear such that consecutive binding units are linked in series, or the linker may serve as a scaffold to which various binding units are attached, e.g., a branched linker. A linker may also have multiple branches, e.g., as disclosed in Tam, J. Immunol. Methods 196:17 (1996). Binding units may be attached to each other or to the linker scaffold via N-terminal amino groups, C-terminal carboxyl groups, side chains, chemically modified groups, side chains, or other means.
Linker peptides may be designed to have sequences that permit desired characteristics. For example, the use of glycyl residues allow for a relatively large degree of conformational freedom, whereas a proline would tend to have the opposite effect. Peptide linkers may be chosen so that they achieve particular secondary and tertiary structures, e.g., alpha helices, beta sheets or beta barrels. Quaternary structure can also be utilized to create linkers that join two binding units together non-covalently. For example, fusing a protein domain with a hydrophobic face to each binding unit may permit the joining of the two binding units via the interaction between the hydrophobic interaction of the two molecules. In some embodiments, the linker may provide for polar interactions. For example, a leucine zipper domain of the proto-oncoproteins Myc and Max, respectively, may be used. Luscher and Larsson, Ongogene 18:2955-2966 (1999). In some embodiments, the linker allows for the formation of a salt bridge or disulfide bond. Linkers may comprise non-naturally occurring amino acids, as well as naturally occurring amino acids that are not naturally incorporated into a polypeptide. In some embodiments, the linker comprises a coordination complex between a metal or other ion and various residues from the multiple peptides joined thereby.
Linear peptide linkers of at least one amino acid residue are contemplated. In some embodiments the linker has more than 10,000 residues. In some embodiments the linker has from 1-10,000 residues. In some embodiments, the linker has from 1-1000 residues. In some embodiments, the linker has from 1-100 residues. In some embodiments, the linker has from 1-50 residues. In some embodiments the linker has 1-10 residues. In some embodiments, the linear peptide linker comprises residues with relatively inert side chains. Peptide linker amino acid residues need not be linked entirely or at all via alpha-carboxy and alpha-amino groups. That is, peptides may be linked via side chain groups of various residues.
The linker may affect whether the polypeptide(s) to which it is fused to is able to dimerize to each other or to another polypeptide. The linker serves a number of functions. Native receptor monomers restrained to the roughly two-dimensional plane of the cell membrane enjoy a relatively high local concentration and in the availability of co-receptors (binding units), increasing the probability of finding a partner. Receptors free in solution lacking such advantages may be aided by a linker that increases the effective concentration of the monomers.
In some embodiments, a binding construct may comprise more than one type of linker. Suitable linkers may also comprise the chemical modifications discussed below.
C. Substituents And Other Chemical Modifications
The binding constructs of the invention may be chemically modified with various substituents. Such modifications preferably does not substantially reduce the growth factor binding affinities or specificities of the binding construct. Rather, the chemical modifications impart additional desirable characteristics as discussed herein. Chemical modifications may take a number of different forms such as heterologous peptides, polysaccarides, lipids, radioisotopes, non-standard amino acid resides and nucleic acids, metal chelates, and various toxins.
The receptor fragments, binding constructs, and other peptide molecules of the present invention may be fused to heterologous peptides to confer various properties, e.g., increased solubility, modulation of clearance, targeting to particular cell or tissue types. In some embodiments, the receptor fragment is linked to a Fc domain of IgG or other immunoglobulin. In some embodiments, a receptor fragment is fused to alkaline phosphatase (AP). Methods for making Fc or AP fusion constructs are found in WO 02/060950. By fusing the ligand binding domain of VEGFR-2 or VEGFR-3 (or other receptors) with protein domains that have specific properties (e.g. half life, bioavailability, interaction partners) it is possible to confer these properties to the VEGFR binding domains (e.g., the receptor binding domain could be engineered to have a specific tissue distribution or specific biological half life). In some embodiments, binding construct may include a co-receptor and a VEGFR fragment.
The particular heterologous polypeptide used in a particular construct can influence whether or not a growth factor receptor fragment will dimerize, which in turn may affect ligand binding. Fc fusion all may permit dimers, whereas AP fusions may permit monomers, cited, which along with Ig-domain boundary differences as possible reasons for different results obtained by different groups for receptor fragments binging to ligands. [Lu, et al., J. Biol. Chem. 275(19): 14321-14330 (2000).]
For substituents such as an Fc region of human IgG, the fusion can be fused directly to a binding construct or fused through an intervening sequence. For example, a human IgG hinge, CH2 and CH3 region may be fused at either the N-terminus or C-terminus of a binding construct to attach the Fc region. The resulting Fc-fusion construct enables purification via a Protein A affinity column (Pierce, Rockford, Ill.). Peptide and proteins fused to an Fc region can exhibit a substantially greater half-life in vivo than the unfused counterpart. A fusion to an Fc region allows for dimerization/multimerization of the fusion polypeptide. The Fc region may be a naturally occurring Fc region, or may be modified for superior characteristics, e.g., therapeutic qualities, circulation time, reduced aggregation.
Polypeptides can be modified, for instance, by glycosylation, amidation, carboxylation, or phosphorylation, or by the creation of acid addition salts, amides, esters, in particular C-terminal esters, and N-acyl derivatives. The proteins also can be modified to create peptide derivatives by forming covalent or noncovalent complexes with other moieties. Covalently bound complexes can be prepared by linking the chemical moieties to functional groups on the side chains of amino acids comprising the peptides, or at the N- or C-terminus.
Polypeptides can be conjugated to a reporter group, including, but not limited to a radiolabel, a fluorescent label, an enzyme (e.g., that catalyzes a calorimetric or fluorometric reaction), a substrate, a solid matrix, or a carrier (e.g., biotin or avidin). Examples of analogs are described in WO 98/28621 and in Olofsson, et al., Proc. Nat'l. Acad. Sci. USA, 95:11709-11714 (1998), U.S. Pat. Nos. 5,512,545, and 5,474,982; U.S. Patent Application Nos. 20020164687 and 20020164710.
Cysteinyl residues most commonly are reacted with haloacetates (and corresponding amines), such as chloroacetic acid or chloroacetamide, to give carboxymethyl or carbocyamidomethyl derivatives. Cysteinyl residues also are derivatized by reaction with bromotrifluoroacetone, α-bromo-β(5-imidozoyl)propionic acid, chloroacetyl phosphate, N-alkylmaleimides, 3-nitro-2-pyridyl disulfide, methyl 2-pyridyl disulfide, p-chloromercuribenzoate, 2-chloromercuri-4-nitrophenol, or chloro-7-nitrobenzo-2-oxa-1,3-diazole.
Histidyl residues are derivatized by reaction with diethylprocarbonate at pH 5.5-7.0 because this agent is relatively specific for the histidyl side chain. Para-bromophenacyl bromide also is useful; the reaction is preferably performed in 0.1M sodium cacodylate at pH 6.0.
Lysinyl and amino terminal residues are reacted with succinic or carboxylic acid anhydrides. Derivatization with these agents has the effect of reversing the charge of the lysinyl residues. Other suitable reagents for derivatizing α-amino-containing residues include imidoesters such as methyl picolinimidate; pyridoxal phosphate; pyridoxal; chloroborohydride; trinitrobenzenesulfonic acid; O-methylissurea; 2,4 pentanedione; and transaminase catalyzed reaction with glyoxylate.
Arginyl residues are modified by reaction with one or several conventional reagents, among them phenylglyoxal, 2,3-butanedione, 1,2-cyclohexanedione, and ninhydrin. Derivatization of arginine residues requires that the reaction be performed in alkaline conditions because of the high pK of the guanidine functional group. Furthermore, these reagents may react with the groups of lysine as well as the arginine epsilon-amino group.
The specific modification of tyrosyl residues per se has been studied extensively, with particular interest in introducing spectral labels into tyrosyl residues by reaction with aromatic diazonium compounds or tetranitromethane. Most commonly, N-acetylimidizol and tetranitromethane are used to form O-acetyl tyrosyl species and 3-nitro derivatives, respectively. Tyrosyl residues are iodinated using 125I or 131I to prepare labeled proteins for use in radioimmunoassay.
Carboxyl side groups (aspartyl or glutamyl) are selectively modified by reaction with carbodiimides (R1) such as 1-cyclohexyl-3-(2-morpholinyl-(4-ethyl) carbodiimide or 1-ethyl-3 (4 azonia 4,4-dimethylpentyl)carbodiimide. Furthermore, aspartyl and glutamyl residues are converted to asparaginyl and glutaminyl residues by reaction with ammonium ions.
Derivatization with bifunctional agents is useful for crosslinking the binding construct to water-insoluble support matrixes. Such derivation may also provide the linker that may connect adjacent binding elements in a binding construct, or a binding elements to a heterologous peptide, e.g., a Fc fragment. Commonly used crosslinking agents include, e.g., 1,1-bis(diazoacetyl)-2-phenylethane, glutaraldehyde, N-hydroxysuccinimide esters, for example, esters with 4-azidosalicylic acid, homo-bifunctional imidoesters, including disuccinimidyl esters such as 3,3′-dithiiobis(succinimidylpropionate), and bifunctional maleimides such as bis-N-maleimido-1,8-octane. Derivatizing agents such as methyl-3-[(p-azidophenyl) dithio] propioimidate yield photoactivatable intermediates that are capable of forming cross links in the presence of light. Alternatively, reactive water-insoluble matrices such as cyanogen bromide-activated carbohydrates and the reactive substrates described in U.S. Pat. Nos. 3,969,287; 3,691,016; 4,195,128; 4,247,642; 4,229,537; and 4,330,440, incorporated herein by reference, are employed for protein immobilization.
Glutaminyl and asparaginyl residues are frequently deamidated to the corresponding glutamyl and aspartyl residues. Alternatively, these residues are deamidated under mildly acidic conditions. Either form of these residues falls within the scope of this invention.
Other modifications include hydroxylation of proline and lysine, phosphorylation of hydroxyl groups of seryl or threonyl residues, methylation of the α-amino groups of lysine, arginine, and histidine side chains (T. E. Creighton, Proteins: Structure and Molecule Properties, W. H. Freeman & Co., San Francisco, pp. 79-86, 1983), acetylation of the N-terminal amine, and, in some instances, amidation of the C-terminal carboxyl groups. Such derivatives are chemically modified polypeptide compositions in which the binding construct polypeptide is linked to a polymer. The polymer selected is typically water soluble so that the protein to which it is attached does not precipitate in an aqueous environment, such as a physiological environment. The polymer selected is usually modified to have a single reactive group, such as an active ester for acylation or an aldehyde for alkylation, so that the degree of polymerization may be controlled as provided for in the present methods. The polymer may be of any molecular weight, and may be branched or unbranched. Included within the scope of the binding construct polypeptide polymers is a mixture of polymers. Preferably, for therapeutic use of the end-product preparation, the polymer will be pharmaceutically acceptable.
The polymers each may be of any molecular weight and may be branched or unbranched. The polymers each typically have an average molecular weight of between about 2 kDa to about 100 kDa (the term “about” indicating that in preparations of a water soluble polymer, some molecules will weigh more, some less, than the stated molecular weight). The average molecular weight of each polymer is between about 5 kDa and about 50 kDa, more preferably between about 12 kDa to about 40 kDa and most preferably between about 20 kDa to about 35 kDa.
Suitable water soluble polymers or mixtures thereof include, but are not limited to, N-linked or O-linked carbohydrates, sugars, phosphates, carbohydrates; sugars; phosphates; polyethylene glycol (PEG) (including the forms of PEG that have been used to derivatize proteins, including mono-(C1-C10) alkoxy- or aryloxy-polyethylene glycol); monomethoxy-polyethylene glycol; dextran (such as low molecular weight dextran, of, for example about 6 kD), cellulose; cellulose; other carbohydrate-based polymers, poly-(N-vinyl pyrrolidone)polyethylene glycol, propylene glycol homopolymers, a polypropylene oxide/ethylene oxide co-polymer, polyoxyethylated polyols (e.g., glycerol) and polyvinyl alcohol. Also encompassed by the present invention are bifunctional crosslinking molecules which may be used to prepare covalently attached multimers.
In general, chemical derivatization may be performed under any suitable condition used to react a protein with an activated polymer molecule. Methods for preparing chemical derivatives of polypeptides will generally comprise the steps of (a) reacting the polypeptide with the activated polymer molecule (such as a reactive ester or aldehyde derivative of the polymer molecule) under conditions whereby the binding construct becomes attached to one or more polymer molecules, and (b) obtaining the reaction product(s). The optimal reaction conditions will be determined based on known parameters and the desired result. For example, the larger the ratio of polymer molecules:protein, the greater the amount of attached polymer molecule. In one embodiment, the binding construct polypeptide derivative may have a single polymer molecule moiety at the amino terminus. (See, e.g., U.S. Pat. No. 5,234,784).
A particularly preferred water-soluble polymer for use herein is polyethylene glycol (PEG). As used herein, polyethylene glycol is meant to encompass any of the forms of PEG that can be used to derivatize other proteins, such as mono-(C1-C10) alkoxy- or aryloxy-polyethylene glycol. PEG is a linear or branched neutral polyether, available in a broad range of molecular weights, and is soluble in water and most organic solvents. PEG is effective at excluding other polymers or peptides when present in water, primarily through its high dynamic chain mobility and hydrophibic nature, thus creating a water shell or hydration sphere when attached to other proteins or polymer surfaces. PEG is nontoxic, non-immunogenic, and approved by the Food and Drug Administration for internal consumption.
Proteins or enzymes when conjugated to PEG have demonstrated bioactivity, non-antigenic properties, and decreased clearance rates when administered in animals. F. M. Veronese et al., Preparation and Properties of Monomethoxypoly(ethylene glycol)-modified Enzymes for Therapeutic Applications, in J. M. Harris ed., Poly(Ethylene Glycol) Chemistry—Biotechnical and Biomedical Applications, 127-36, 1992, incorporated herein by reference. These phenomena are due to the exclusion properties of PEG in preventing recognition by the immune system. In addition, PEG has been widely used in surface modification procedures to decrease protein adsorption and improve blood compatibility. S. W. Kim et al., Ann. N.Y. Acad. Sci. 516: 116-30 1987; Jacobs et al., Artif. Organs 12: 500-501, 1988; Park et al., J. Poly. Sci, Part A 29:1725-31, 1991, incorporated herein by reference. Hydrophobic polymer surfaces, such as polyurethanes and polystyrene can be modified by the grafting of PEG (MW 3,400) and employed as nonthrombogenic surfaces. Surface properties (contact angle) can be more consistent with hydrophilic surfaces, due to the hydrating effect of PEG. More importantly, protein (albumin and other plasma proteins) adsorption can be greatly reduced, resulting from the high chain motility, hydration sphere, and protein exclusion properties of PEG.
PEG (MW 3,400) was determined as an optimal size in surface immobilization studies, Park et al., J. Biomed. Mat. Res. 26:739-45, 1992, while PEG (MW 5,000) was most beneficial in decreasing protein antigenicity. (F. M. Veronese et al., In J. M. Harris, et al., Poly(Ethylene Glycol) Chemistry—Biotechnical and Biomedical Applications, 127-36.)
Methods for preparing pegylated binding construct polypeptides will generally comprise the steps of (a) reacting the polypeptide with polyethylene glycol (such as a reactive ester or aldehyde derivative of PEG) under conditions whereby the binding construct polypeptide becomes attached to one or more PEG groups, and (b) obtaining the reaction product(s). In general, the optimal reaction conditions for the acylation reactions will be determined based on known parameters and the desired result. For example, the larger the ratio of PEG:protein, the greater the percentage of poly-pegylated product. In some embodiments, the binding construct will have a single PEG moiety at the N-terminus. See U.S. Pat. No. 8,234,784, herein incorporated by reference.
Derivatized binding constructs disclosed herein may have additional activities, enhanced or reduced biological activity, or other characteristics, such as increased or decreased half-life, as compared to the non-derivatized molecules.
II. POLYNUCLEOTIDES ENCODING BINDING CONSTRUCTS AND EXPRESSION SYSTEMS
The invention comprises not only the binding constructs, binding units, and polypeptides described herein, but also nucleic acids encoding such molecules, vectors comprising such molecules, and host cells comprising such vectors. Method employing any of the constructs, units, polypeptides, nucleic acids, vectors, and hosts cells are all considered aspects of the invention.
A. Nucleic Acids of the Invention
This invention also includes nucleic acid molecules whose sequence encode the polypeptides, binding units, and binding constructs of the invention. Nucleic acid molecules include those molecules which comprise nucleotide sequences which hybridize under moderately or highly stringent conditions as defined herein with the fully complementary sequence of the nucleic acid molecule of receptor tyrosine kinases described in Table 1A, or of a molecule encoding a polypeptide, which polypeptide comprises the receptor tyrosine kinase amino acids sequences described in Table 1A, or of a nucleic acid fragment as defined herein, or of a nucleic acid fragment encoding a polypeptide as defined herein.
Hybridization probes may be prepared using the sequences provided herein to screen cDNA, genomic or synthetic DNA libraries for related sequences. Regions of the DNA and/or amino acid sequence that exhibit significant identity to known sequences are readily determined using sequence alignment algorithms as described herein, and those regions may be used to design probes for screening.
The term “highly stringent conditions” refers to those conditions that are designed to permit hybridization of DNA strands whose sequences are highly complementary, and to exclude hybridization of significantly mismatched DNAs. Hybridization stringency is principally determined by temperature, ionic strength, and the concentration of denaturing agents such as formamide. Examples of “highly stringent conditions” for hybridization and washing are 0.015 M sodium chloride, 0.0015 M sodium citrate at 65-68° C. or 0.015 M sodium chloride, 0.0015 M sodium citrate, and 50% formamide at 42° C. See Sambrook, Fritsch & Maniatis, Molecular Cloning: A Laboratory Manual, 2nd Ed., Cold Spring Harbor Laboratory, (Cold Spring Harbor, N.Y. 1989); and Anderson et al., Nucleic Acid Hybridization: a Practical approach, Ch. 4, IRL Press Limited (Oxford, England). Limited, Oxford, England. Other agents may be included in the hybridization and washing buffers for the purpose of reducing non-specific and/or background hybridization. Examples are 0.1% bovine serum albumin, 0.1% polyvinyl-pyrrolidone, 0.1% sodium pyrophosphate, 0.1% sodium dodecylsulfate (NaDodSO4 or SDS), ficoll, Denhardt's solution, sonicated salmon sperm DNA (or another non-complementary DNA), and dextran sulfate, although other suitable agents can also be used. The concentration and types of these additives can be changed without substantially affecting the stringency of the hybridization conditions. Hybridization experiments are usually carried out at pH 6.8-7.4, 6.8-7.4; however, at typical ionic strength conditions, the rate of hybridization is nearly independent of pH. See Anderson et al., Nucleic Acid Hybridization: a Practical Approach, Ch. 4, IRL Press Limited (Oxford, England).
Factors affecting the stability of a DNA duplex include base composition, length, and degree of base pair mismatch. Hybridization conditions can be adjusted by one skilled in the art in order to accommodate these variables and allow DNAs of different sequence relatedness to form hybrids. The melting temperature of a perfectly matched DNA duplex can be estimated by the following equation:

Tm(° C.)=81.5+16.6(log [Na+])+0.41(%G+C)−600/N−0.72(% formamide)

where N is the length of the duplex formed, [Na+] is the molar concentration of the sodium ion in the hybridization or washing solution, % G+C is the percentage of (guanine+cytosine) bases in the hybrid. For imperfectly matched hybrids, the melting temperature is reduced by approximately 1° C. for each 1% mismatch.
The term “moderately” stringent conditions“ ” refers to conditions under which a DNA duplex with a greater degree of base pair mismatching than could occur under “highly stringent conditions” is able to form. Examples of typical “moderately stringent conditions” are 0.015 M sodium chloride, 0.0015 M sodium citrate at 50-65° C. or 0.015 M sodium chloride, 0.0015 M sodium citrate, and 20% formamide at 37-50° C. By way of example, a “moderately stringent” condition of 50° C. in 0.015 M sodium ion will allow about a 21% mismatch.
It will be appreciated by those skilled in the art that there is no absolute distinction between “highly” and “moderately” stringent conditions. For example, at 0.015M sodium ion (no formamide), the melting temperature of perfectly matched long DNA is about 71° C. With a wash at 65° C. (at the same ionic strength), this would allow for approximately a 6% mismatch. To capture more distantly related sequences, one skilled in the art can simply lower the temperature or raise the ionic strength.
A good estimate of the melting temperature in 1M NaCl* for oligonucleotide probes up to about 20 nt is given by:

Tm=2° C. per A-T base pair+4° C. per G-C base pair

*The sodium ion concentration in 6× salt sodium citrate (SSC) is 1 M. See Suggs et al., Developmental Biology Using Purified Genes, p. 683, Brown and Fox (eds.) (1981).

High stringency washing conditions for oligonucleotides are usually at a temperature of 0-5° C. below the Tm of the oligonucleotide in 6×SSC, 0.1% SDS.
Differences in the nucleic acid sequence may result in conservative and/or non-conservative modifications of the amino acid sequence relative to the amino acid sequence. The invention is also directed to an isolated and/or purified DNA that corresponds to, or that hybridizes under stringent conditions with, any one of the foregoing DNA sequences.
B. Preparation of DNA Encoding Ligand, Receptor, and Binding Construct Polypeptides
A nucleic acid molecule encoding all or part of a polypeptide of the invention such as a binding construct or binding unit of the invention can be made in a variety of ways, including, without limitation, chemical synthesis, cDNA or genomic library screening, expression library screening, and/or PCR amplification of cDNA or genomic DNA. These methods and others useful for isolating such DNA are set forth, for example, by Sambrook, et al., “Molecular Cloning: A Laboratory Manual,” Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989), by Ausubel, et al., eds., “Current Protocols In Molecular Biology,” Current Protocols Press (1994), and by Berger and Kimmel, “Methods In Enzymology: Guide To Molecular Cloning Techniques,” vol. 152, Academic Press, Inc., San Diego, Calif. (1987). Preferred nucleic acid sequences are mammalian sequences, such as human, rat, and mouse.
Chemical synthesis of nucleic acid molecules can be accomplished using methods well known in the art, such as those set forth by Engels, et al., Angew. Chem. Intl. Ed., 28:716-734 (1989). These methods include, inter alia, the phosphotriester, phosphoramidite and H-phosphonate methods of nucleic acid synthesis. Nucleic acids larger than about 100 nucleotides in length can be synthesized as several fragments, each fragment being up to about 100 nucleotides in length. The fragments can then be ligated together, as described below, to form the full length nucleic acid of interest. A preferred method is polymer-supported synthesis using standard phosphoramidite chemistry.
C. Preparation of a Vector for Expression
The term “vector” refers to a nucleic acid molecule amplification, replication, and/or expression vehicle, often derived from or in the form of a plasmid or viral DNA or RNA system, where the plasmid or viral DNA or RNA is functional in a selected host cell, such as bacterial, yeast, plant, invertebrate, and/or mammalian host cells. The vector may remain independent of host cell genomic DNA or may integrate in whole or in part with the genomic DNA. The vector will contain all necessary elements so as to be functional in any host cell it is compatible with. Such elements are set forth below.
Nucleic acid encoding a polypeptide or fragment thereof has been isolated, it is preferably inserted into an amplification and/or expression vector in order to increase the copy number of the gene and/or to express the encoded polypeptide in a suitable host cell and/or to transform cells in a target organism (to express the polypeptide in vivo). Numerous commercially available vectors are suitable, though “custom made” vectors may be used as well. The vector is selected to be functional in a particular host cell or host tissue (i.e., for replication and/or expression). The polypeptide or fragment thereof may be amplified/expressed in prokaryotic and/or eukaryotic host cells, e.g., yeast, insect (baculovirus systems), plant, and mammalian cells. Selection of the host cell will depend at least in part on whether the polypeptide or fragment thereof is to be glycosylated. If so, yeast, insect, or mammalian host cells are preferable; yeast and mammalian cells will glycosylate the polypeptide if a glycosylation site is present on the amino acid sequence.
Typically, the vectors used in any of the host cells will contain 5′ flanking sequence and other regulatory elements such as an enhancer(s), a promoter, an origin of replication element, a transcriptional termination element, a complete intron sequence containing a donor and acceptor splice site, a signal peptide sequence, a ribosome binding site element, a polyadenylation sequence, a polylinker region for inserting the nucleic acid encoding the polypeptide to be expressed, and a selectable marker element. Optionally, the vector may contain a “tag” sequence, i.e., an oligonucleotide sequence located at the 5′ or 3′ end of the coding sequence that encodes polyHis (such as hexaHis) or another small immunogenic sequence. This tag will be expressed along with the protein, and can serve as an affinity tag for purification of the polypeptide from the host cell. Optionally, the tag can subsequently be removed from the purified polypeptide by various means such as using a selected peptidase.
The vector/expression construct may optionally contain elements such as a 5′ flanking sequence, an origin of replication, a transcription termination sequence, a selectable marker sequence, a ribosome binding site, a signal sequence, and one or more intron sequences. The 5′ flanking sequence may be homologous (i.e., from the same species and/or strain as the host cell), heterologous (i.e., from a species other than the host cell species or strain), hybrid (i.e., a combination of 5′ flanking sequences from more than one source), synthetic, or it may be the native polypeptide 5′ flanking sequence. As such, the source of the 5′ flanking sequence may be any unicellular prokaryotic or eukaryotic organism, any vertebrate or invertebrate organism, or any plant, provided that the 5′ flanking sequence is functional in, and can be activated by, the host cell machinery.
A transcription termination element is typically located 3′ to the end of the polypeptide coding sequence and serves to terminate transcription of the polypeptide. Usually, the transcription termination element in prokaryotic cells is a G-C rich fragment followed by a poly T sequence. Such elements can be cloned from a library, purchased commercially as part of a vector, and readily synthesized.
Selectable marker genes encode proteins necessary for the survival and growth of a host cell in a selective culture medium. Typical selectable marker genes encode proteins that (a) confer resistance to antibiotics or other toxins, e.g., ampicillin, tetracycline, or kanamycin for prokaryotic host cells, (b) complement auxotrophic deficiencies of the cell; or (c) supply critical nutrients not available from complex media.
A ribosome binding element, commonly called the Shine-Dalgarno sequence (prokaryotes) or the Kozak sequence (eukaryotes), is necessary for translation initiation of mRNA. The element is typically located 3′ to the promoter and 5′ to the coding sequence of the polypeptide to be synthesized. The Shine-Dalgarno sequence is varied but is typically a polypurine (i.e., having a high A-G content). Many Shine-Dalgarno sequences have been identified, each of which can be readily synthesized using methods set forth above.
All of the elements set forth above, as well as others useful in this invention, are well known to the skilled artisan and are described, for example, in Sambrook, et al., “Molecular Cloning: A Laboratory Manual,” Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989) and Berger, et al., eds., “Guide To Molecular Cloning Techniques,” Academic Press, Inc., San Diego, Calif. (1987].
For those embodiments of the invention where the recombinant polypeptide is to be secreted, a signal sequence is preferably included to direct secretion from the cell where it is synthesized. Typically, the polynucleotide encoding the signal sequence is positioned at the 5′ end of the coding region. Many signal sequences have been identified, and any of them that are functional in a target cell or species may be used in conjunction with the transgene.
In many cases, gene transcription is increased by the presence of one or more introns on the vector. The intron may be naturally-occurring, especially where the transgene is a full length or a fragment of a genomic DNA sequence. The intron may be homologous or heterologous to the transgene and/or to the transgenic mammal into which the gene will be inserted. The position of the intron with respect to the promoter and the transgene is important, as the intron must be transcribed to be effective. A preferred position for an intron is 3′ to the transcription start site, and 5′ to the polyA transcription termination sequence. For cDNA transgenes, an intron is placed on one side or the other (i.e., 5′ or 3′) of the transgene coding sequence. Any intron from any source, including any viral, prokaryotic and eukaryotic (plant or animal) organisms, may be used to express the polypeptide, provided that it is compatible with the host cell(s) into which it is inserted. Also included herein are synthetic introns. Optionally, more than one intron may be used in the vector.
Preferred vectors for recombinant expression are those that are compatible with bacterial, insect, and mammalian host cells. Such vectors include, inter alia, pCRII (Invitrogen Company, San Diego, Calif.), pBSII (Stratagene Company, La Jolla, Calif.), and pETL (BlueBacII; Invitrogen).
After the vector has been constructed and a nucleic acid has been inserted into the proper site of the vector, the completed vector may be inserted into a suitable host cell for amplification and/or polypeptide expression. Commonly used include: Prokaryotic cells such as gram negative or gram positive bacteria, i.e., any strain of E. coli, Bacillus, Streptomyces, Saccharomyces, Salmonella, and the like; eukaryotic cells such as CHO (Chinese hamster ovary) cells; human kidney 293 cells; COS-7 cells; insect cells such as Sf4, Sf5, Sf9, and Sf21 and High 5 (all from the Invitrogen Company, San Diego, Calif.); plant cells and various yeast cells such as Saccharomyces and Pichia. Any transformable or transfectable cell or cell line derived from any organism such as bacteria, yeast, fungi, monocot and dicot plants, plant cells, and animals are suitable.
Insertion (also referred to as “transformation” or “transfection”) of the vector into the selected host cell may be accomplished using such methods as calcium chloride, electroporation, microinjection, lipofection or the DEAE-dextran method. The method selected will in part be a function of the type of host cell to be used. These methods and other suitable methods are well known to the skilled artisan, and are set forth, for example, in Sambrook, et al., supra.
The host cells containing the vector (i.e., transformed or transfected) may be cultured using standard media well known to the skilled artisan. The media will usually contain all nutrients necessary for the growth and survival of the cells. Suitable media for culturing E. coli cells are for example, Luria Broth (LB) and/or Terrific Broth (TB). Suitable media for culturing eukaryotic cells are RPMI 1640, MEM, DMEM, all of which may be supplemented with serum and/or growth factors as required by the particular cell line being cultured. A suitable medium for insect cultures is Grace's medium supplemented with yeastolate, lactalbumin hydrolysate, and/or fetal calf serum as necessary.
Typically, an antibiotic or other compound useful for selective growth of the transformed cells only is added as a supplement to the media. The compound to be used will be dictated by the selectable marker element present on the plasmid with which the host cell was transformed. For example, where the selectable marker element is kanamycin resistance, the compound added to the culture medium will be kanamycin.
The amount of polypeptide produced in the host cell can be evaluated using standard methods known in the art. Such methods include, without limitation, Western blot analysis, SDS-polyacrylamide gel electrophoresis, non-denaturing gel electrophoresis, HPLC separation, immunoprecipitation, and/or binding assays.
D. Purification of Polypeptides
If the polypeptide has been designed to be secreted from the host cells, the majority of polypeptide will likely be found in the cell culture medium. If, however, the polypeptide is not secreted from the host cells, it will be present in the cytoplasm (for eukaryotic, gram positive bacteria, and insect host cells) or in the periplasm (for gram negative bacteria host cells).
For intracellular polypeptides, the host cells are first disrupted mechanically or osmotically to release the cytoplasmic contents into a buffered solution. The polypeptide is then isolated from this solution.
Purification of the polypeptide from solution can be accomplished using a variety of techniques. If the polypeptide has been synthesized such that it contains a tag such as hexahistidine or other small peptide at either its carboxyl or amino terminus, it may essentially be purified in a one-step process by passing the solution through an affinity column where the column matrix has a high affinity for the tag or for the polypeptide directly (i.e., a monoclonal antibody specifically recognizing the polypeptide). For example, polyhistidine binds with great affinity and specificity to nickel, thus an affinity column of nickel (such as the Qiagen nickel columns) can be used for purification of the His-tagged polypeptide. (See, for example, Ausubel, et al., eds., “Current Protocols In Molecular Biology,” Section 10.11.8, John Wiley & Sons, New York (1993)).
The strong affinity a ligand for its receptor permits affinity purification of binding constructs, and binding constructs using an affinity matrix comprising a complementary binding partner. Affinity chromatography may be employed, e.g., using either natural binding partners (e.g. a ligand when purifying a binding construct with affinity for the same) or antibodies generated using standard procedures (e.g., immunizing a mouse, rabbit or other animal with an appropriate polypeptide). The peptides of the present invention may be used to generate such antibodies. Known antibodies or antibodies to known growth factor receptors may be employed when they share an epitope with a targeted binding construct.
In addition, other well known procedures for purification can be used. Such procedures include, without limitation, ion exchange chromatography, molecular sieve chromatography, HPLC, native gel electrophoresis in combination with gel elution, and preparative isoelectric focusing (“Isoprime” machine/technique, Hoefer Scientific). In some cases, two or more of these techniques may be combined to achieve increased purity. Preferred methods for purification include polyhistidine tagging and ion exchange chromatography in combination with preparative isoelectric focusing.
Polypeptide found in the periplasmic space of the bacteria or the cytoplasm of eukaryotic cells, the contents of the periplasm or cytoplasm, including inclusion bodies (bacteria) if the processed polypeptide has formed such complexes, can be extracted from the host cell using any standard technique known to the skilled artisan. For example, the host cells can be lysed to release the contents of the periplasm by French press, homogenization, and/or sonication. The homogenate can then be centrifuged.
If the polypeptide has formed inclusion bodies in the periplasm, the inclusion bodies can often bind to the inner and/or outer cellular membranes and thus will be found primarily in the pellet material after centrifugation. The pellet material can then be treated with a chaotropic agent such as guanidine or urea to release, break apart, and solubilize the inclusion bodies. The solubilized polypeptide can then be analyzed using gel electrophoresis, immunoprecipitation or the like. If it is desired to isolate the polypeptide, isolation may be accomplished using standard methods such as those set forth below and in [Marston, et al., Meth. Enz., 182:264-275 (1990).]
III. ANTI-LIGAND AND ANTI-RECEPTOR THERAPEUTIC COMPOUNDS
Anti-ligand or anti-receptor therapies as discussed below include, but are not limited to antibody, aptamer, antisense and interference RNA techniques and therapies. The following description makes specific reference to the production, testing, and use of particular anti-VEGFR-2 antibodies. However, the methods described may also be readily adapted for the production of other antibodies of the present invention, e.g., anti-growth factor ligand antibodies as binding units of the binding constructs. Such antibody-type binding units may form one binding unit of a binding construct. In some embodiments a binding construct has at least one binding unit that comprising a receptor fragment and at least one binding unit that comprises an antigen binding fragment. Antibodies directed against growth factors and receptors may also be used in combination with the binding constructs of the invention. Exemplary antibodies may be found in the co-owned, concurrently (Mar. 5, 2004) filed U.S. Provisional Patent Application Nos. 60/550,511: “Multivalent Antibody Materials And Methods For VEGF/PDGF Family Of Growth Factors,” and related, co-filed International Patent Application No. PCT/US05/07742; and 60/550, 441: “Chimeric Anti-VEGF-D Antibodies And Humanized Anti-VEGF-D Antibodies And Methods Of Using Same,” and related, co-filed International Patent Application No. PCT/US05/07283; all applications are incorporated by reference in their entireties.
A. Therapeutic Anti-VEGFR-2 Selective VEGF-A Antagonist Antibodies
Antibodies can be used for purification for VEGFR-2 constructs as described above or therapeutically where inhibition of VEGF-A binding by VEGFR-2 is desired (e.g., to achieve anti-neoplastic effects).
Polyclonal or monoclonal therapeutic anti-VEGFR-2 antibodies useful in practicing this invention may be prepared in laboratory animals or by recombinant DNA techniques using the following methods. Polyclonal antibodies to the VEGFR-2 molecule or a fragment thereof containing the target amino acid sequence generally are raised in animals by multiple subcutaneous (sc) or intraperitoneal (ip) injections of the VEGFR-2 molecule in combination with an adjuvant such as Freund's adjuvant (complete or incomplete). To enhance immunogenicity, it may be useful to first conjugate the VEGFR-2 molecule or a fragment containing the target amino acid sequence of a protein that is immunogenic in the species to be immunized, e.g., keyhole limpet hemocyanin, serum albumin, bovine thyroglobulin, or soybean trypsin inhibitor using a bifunctional or derivatizing agent, for example, maleimidobenzoyl sulfosuccinimide ester (conjugation through cysteine residues), N-hydroxysuccinimide (through lysine residues), glutaraldehyde, succinic anhydride, SOCl, or R1N═C═NR, where R and R1 are different alkyl groups. Alternatively, VEGF-2-immunogenic conjugates can be produced recombinantly as fusion proteins.
Animals are immunized against the immunogenic VEGFR-2 conjugates or derivatives (such as a fragment containing the target amino acid sequence) by combining about 1 mg or about 1 microgram of conjugate (for rabbits or mice, respectively) with about 3 volumes of Freund's complete adjuvant and injecting the solution intradermally at multiple sites. Approximately 7 to 14 days later, animals are bled and the serum is assayed for anti-VEGFR-2 titer. Animals are boosted with antigen repeatedly until the titer plateaus. Preferably, the animal is boosted with the same VEGFR-2 molecule or fragment thereof as was used for the initial immunization, but conjugated to a different protein and/or through a different cross-linking agent. In addition, aggregating agents such as alum are used in the injections to enhance the immune response.
Monoclonal antibodies may be prepared by recovering spleen cells from immunized animals and immortalizing the cells in conventional fashion, e.g. by fusion with myeloma cells. The clones are then screened for those expressing the desired antibody. The monoclonal antibody preferably does not cross-react with other VEGFR family members.
Preparation of antibodies using recombinant DNA methods such as the phagemid display method, may be accomplished using commercially available kits, as for example, the Recombinant Phagemid Antibody System available from Pharmacia (Uppsala, Sweden), or the SurfZAPTM phage display system (Stratagene Inc., La Jolla, Calif.).
One may increase the population of anti-VEGFR-2 antibodies that selectively block VEGF-A binding by using a Ig-domain 3 or other fragment as the immunogen, but that is not necessary. After antibodies are generated, they may be tested to ascertain their specific affinities. Competition studies may be performed that show that the antibody competes for binding to VEGFR-2 with VEGF-A, but not with VEGF-C.
One method comprises incubating VEGFR-2 expressing cells with either labeled-VEGF-A alone, the antibody being tested alone, or with both the VEGF-A and the antibody. A label on the antibody may be employed in addition to that on VEGF-A or instead of that label. The antibody may also be detected using a labeled secondary antibody. The first two groups acting as controls allow one to confirm that both the antibody and the VEGF-A ligand (or optionally VEGF-E) are able to bind to the receptor in the absence of the other. Those cell samples treated with both VEGF-A (or VEGF-E) and an antibody, that reveal binding of the antibody, but not VEGF-A (or VEGF-E) indicate that the antibody should be further tested. As described below, stoichiometric analysis can be used to ascertain that the ligand and antibody are competing for the same molecule.
This further testing may comprise binding studies that reveal that both VEGF-C (or VEGF-D) and the antibody are able to bind the receptor simultaneously. This testing also is designed to determine whether VEGF-C and the antibody are simultaneously binding to a single VEGFR-2 molecule as opposed to binding of VEGF-C and the antibody binding to different VEGFR-2 molecules. Comparative quantitative binding studies may accordingly be used. The VEGFR-2 cells are counted in each sample. VEGFR-2 samples, having been counted, are incubated with either labeled VEGF-C alone or labeled (or unlabelled using a secondary antibody for detection) antibody alone. The degree of binding is measured, quantitated, using suitable imaging procedures, e.g., if radiolabel is employed using a phosphoimager. The average number of VEGFR-2 receptors per cell are calculated by dividing the amount of bound molecules by the total number of cells. Whether the receptors are saturated with molecules may be achieved by repeating the assay with increasing amounts of the labeled molecule(s). The binding assay is repeated again with both ligand and antibody. If the quantification reveals that the number of antibodies and ligands bound is greater than the total number of receptors, then the antibody has the desired characteristics.
The described protocols may also be modified and used to produce antibodies against binding constructs and other constructs of the inventions to aid in purification of such constructs.
Preferably, antibodies for administration to humans, although prepared in a laboratory animal such as a mouse, will be “humanized”, or chimeric, i.e. made to be compatible with the human immune system such that a human patient will not develop an immune response to the antibody. Even more preferably, human antibodies which can now be prepared using methods such as those described for example, in Lonberg, et al., Nature Genetics, 7:13-21 (1994) are preferred for therapeutic administration to patients. Fully human antibodies are highly preferred.
1. Humanization of Anti-VEGFR-2 Monoclonal Antibodies
Selective binding agents, including monoclonal antibodies, which selectively block VEGF-A without blocking VEGF-C (or VEGF-D) binding may be applied therapeutically. Following are protocols to improve the utility of anti-VEGFR-2 monoclonal antibodies as therapeutics in humans, by “humanizing” the monoclonal antibodies to improve their serum half-life and render them less immunogenic in human hosts (i.e., to prevent human antibody response to non-human anti-VEGFR-2 antibodies).
The principles of humanization have been described in the literature and are facilitated by the modular arrangement of antibody proteins. To minimize the possibility of binding complement, a humanized antibody of the IgG4 isotype is preferred.
For example, a level of humanization is achieved by generating chimeric antibodies comprising the variable domains of non-human antibody proteins of interest, such as the anti-VEGFR-2 monoclonal antibodies described herein, with the constant domains of human antibody molecules. (See, e.g., Morrison and Oi, Adv. Immunol., 44:65-92 (1989).) The variable domains of VEGFR-2 neutralizing anti-VEGFR-2 antibodies are cloned from the genomic DNA of a B-cell hybridoma or from cDNA generated from mRNA isolated from the hybridoma of interest. The V region gene fragments are linked to exons encoding human antibody constant domains, and the resultant construct is expressed in suitable mammalian host cells (e.g., myeloma or CHO cells).
To achieve an even greater levels of humanization, only those portions of the variable region gene fragments that encode antigen-binding complementarity determining regions (“CDR”) of the non-human monoclonal antibody genes are cloned into human antibody sequences. [See, e.g., Jones et al., Nature, 321:522-525 (1986); Riechmann et al., Nature, 332:323-327 (1988); Verhoeyen et al., Science, 239:1534-36 (1988); and Tempest et al., Bio/Technology, 9:266-71 (1991).] If necessary, the B-sheet framework of the human antibody surrounding the CDR3 regions also is modified to more closely mirror the three dimensional structure of the antigen-binding domain of the original monoclonal antibody. [(See Kettleborough et al., Protein Engin., 4:773-783 (1991); and Foote et al., J. Mol. Biol., 224:487-499 (1992).)]
In an alternative approach, the surface of a non-human monoclonal antibody of interest is humanized by altering selected surface residues of the non-human antibody, e.g., by site-directed mutagenesis, while retaining all of the interior and contacting residues of the non-human antibody. [See Padlan, Molecular Immunol., 28(4/5):489-98 (1991).]
The foregoing approaches are employed using VEGFR-2-neutralizing anti-VEGFR-2 monoclonal antibodies and the hybridomas that produce them to generate humanized VEGFR-2-neutralizing antibodies useful as therapeutics to treat or palliate conditions wherein VEGFR-2 expression is detrimental and/or activation by VEGF-A. One therapeutic target is selective promotion of lymphangiogenesis while minimizing promotion of angiogenesis.
2. Human VEGFR-2-Neutralizing Antibodies from Phage Display
Human VEGFR-2-neutralizing antibodies are generated by phage display techniques such as those described in Aujame et al., Human Antibodies, 8(4):155-168 (1997); Hoogenboom, TIBTECH, 15:62-70 (1997); and Rader et al., Curr. Opin. Biotechnol., 8:503-508 (1997), all of which are incorporated by reference. For example, antibody variable regions in the form of Fab fragments or linked single chain Fv fragments are fused to the amino terminus of filamentous phage minor coat protein pIII. Expression of the fusion protein and incorporation thereof into the mature phage coat results in phage particles that present an antibody on their surface and contain the genetic material encoding the antibody. A phage library comprising such constructs is expressed in bacteria, and the library is panned (screened) for VEGFR-2-specific phage-antibodies using labeled or immobilized VEGFR-2 as antigen-probe.
3. Human VEGFR-2-Neutralizing Antibodies from Transgenic Mice
Human VEGFR-2-neutralizing antibodies are generated in transgenic mice essentially as described in Bruggemann and Neuberger, Immunol. Today, 17(8):391-97 (1996) and Bruggemann and Taussig, Curr. Opin. Biotechnol., 8:455-58 (1997). Transgenic mice carrying human V-gene segments in germline configuration and that express these transgenes in their lymphoid tissue are immunized with an VEGFR-2 composition using conventional immunization protocols. Hybridomas are generated using B cells from the immunized mice using conventional protocols and screened to identify hybridomas secreting anti-VEGFR-2 human antibodies (e.g., as described above).
4. Bispecific Antibodies
Bispecific antibodies that specifically bind to VEGFR-2 and that specifically bind to other antigens relevant to pathology and/or treatment are produced, isolated, and tested using standard procedures that have been described in the literature. See, e.g., Pluckthun & Pack, Immunotechnology, 3:83-105 (1997); Carter et al., J. Hematotherapy, 4: 463-470 (1995); Renner & Pfreundschuh, Immunological Reviews, 1995, No. 145, pp. 179-209; Pfreundschuh U.S. Pat. No. 5,643,759; Segal et al., J. Hematotherapy, 4: 377-382 (1995); Segal et al., Immunobiology, 185: 390-402 (1992); and Bolhuis et al., Cancer Immunol. Immunother., 34: 1-8 (1991), all of which are incorporated herein by reference in their entireties. Bispecific antibodies that may be employed in combination with the binding constructs of the invention include those described in the co-owned, concurrently (Mar. 5, 2004) filed U.S. Provisional Patent Application No. 60/550,511: “Multivalent Antibody Materials And Methods For VEGF/PDGF Family Of Growth Factors,”.
For example, bispecific antibodies (bscAb) are produced by joining two single-chain Fv fragments via a glycine-serine linker using recombinant methods. The V light-chain (VL) and V heavy-chain (VH) domains of two antibodies of interest are isolated using standard PCR methods. The VL and VH cDNA's obtained from each hybridoma are then joined to form a single-chain fragment in a two-step fusion PCR. Bispecific fusion proteins are prepared in a similar manner. Bispecific single-chain antibodies and bispecific fusion proteins are antibody substances included within the scope of the present invention.
Antibody fragments that contain the antigen binding, or idiotype, of the molecule may be generated by known techniques. For example, such fragments include, but are not limited to, the F(ab′)2 fragment which may be produced by pepsin digestion of the antibody molecule; the Fab′ fragments which may be generated by reducing the disulfide bridges of the F(ab′)2 fragment, and the two Fab′ fragments which may be generated by treating the antibody molecule with papain and a reducing agent.
Chemically constructed bispecific antibodies may be prepared by chemically cross-linking heterologous Fab or F(ab′)2 fragments by means of chemicals such as heterobifunctional reagent succinimidyl-3-(2-pyridyldithiol)-propionate (SPDP, Pierce Chemicals, Rockford, Ill.). The Fab and F(ab′)2 fragments can be obtained from intact antibody by digesting it with papain or pepsin, respectively (Karpovsky et al., J. Exp. Med. 160:1686-701, 1984; Titus et al., J. Immunol., 138:4018-22, 1987).
5. Humanization of Known Anti-VEGFR-2 Antibodies
Existing anti-VEGF-2 antibodies may also be employed in the various methods and compositions of the present invention, and, if not already humanized, may be humanized as discussed herein. Known anti-VEGFR-2 antibodies may be tested for the ability to selectively block VEGF-A binding using the methods discussed herein. Known anti-VEGFR-2 antibodies (anti-KDR antibodies) are taught for example in Lu et al., J. Immunological Methods, 230:159-71 (1999); Lu, et al., J. Biol. Chem., 275(19): 14321-14330 (2000); and Lu, et al., J. Biol. Chem., 278(44): 43496-43507 (2003).
6. Domain Antibodies
A domain antibody comprises a functional binding unit of an antibody, and can correspond to the variable regions of either the heavy (VH) or light (VL) chains of antibodies. A domain antibody can have a molecular weight of approximately 13 kDa, or approximately one-tenth of a full antibody. Domain antibodies may be derived from full antibodies such as those described herein.
B. Anti-Receptor and Anti-Ligand Aptamers
Recent advances in the field of combinatorial sciences have identified short polymer sequences with high affinity and specificity to a given target. For example, SELEX technology has been used to identify DNA and RNA aptamers with binding properties that rival mammalian antibodies, the field of immunology has generated and isolated antibodies or antibody fragments which bind to a myriad of compounds and phage display has been utilized to discover new peptide sequences with very favorable binding properties. Based on the success of these molecular evolution techniques, it is certain that molecules can be created which bind to any target molecule. A loop structure is often involved with providing the desired binding attributes as in the case of: aptamers which often utilize hairpin loops created from short regions without complimentary base pairing, naturally derived antibodies that utilize combinatorial arrangement of looped hyper-variable regions and new phage display libraries utilizing cyclic peptides that have shown improved results when compared to linear peptide phage display results. Thus, sufficient evidence has been generated to suggest that high affinity ligands can be created and identified by combinatorial molecular evolution techniques. For the present invention, molecular evolution techniques can be used to isolate binding constructs specific for ligands described herein. For more on aptamers, See generally, Gold, L., Singer, B., He, Y. Y., Brody. E., “Aptamers As Therapeutic And Diagnostic Agents,” J. Biotechnol. 74:5-13 (2000). Relevant techniques for generating aptamers may be found in U.S. Pat. No. 6,699,843, which is incorporated by reference in its entirety.
In some embodiments, the aptamer may be generated by preparing a library of nucleic acids; contacting the library of nucleic acids with a growth factor, wherein nucleic acids having greater binding affinity for the growth factor (relative to other library nucleic acids) are selected and amplified to yield a mixture of nucleic acids enriched for nucleic acids with relatively higher affinity and specificity for binding to the growth factor. The processes may be repeated, and the selected nucleic acids mutated and rescreened, whereby a growth factor aptamer is be identified. Nucleic acids may be screened to select for molecules that bind to more than growth factor. Binding more than one growth factor can refer to binding more than one growth factor simultaneously or competitively. In some embodiments a binding construct will comprise at least one aptamer, wherein a first binding unit binds VEGF-A and a second binding unit binds VEGF-C. In some embodiments a binding construct will comprise at least one aptamer, wherein a first binding unit binds a VEGF growth factor subfamily member and a second binding unit binds a PDGF subfamily member.
C. Anti-Sense Molecules and Therapy
Another class of inhibitors that may be used in conjunction with the present invention is isolated antisense nucleic acid molecules that can hybridize to, or are complementary to, the nucleic acid molecule, nucleotide sequence, or fragments, analogs or derivatives thereof. An “antisense” nucleic acid comprises a nucleotide sequence that is complementary to a “sense” nucleic acid encoding a protein (e.g., complementary to the coding strand of a double-stranded cDNA molecule or complementary to an mRNA sequence). In specific embodiments, antisense nucleic acid molecules are provided that comprise a sequence complementary to at least about 10, 25, 50, 100, 250 or 500 nucleotides or an entire receptor or ligand coding strand, or to only a portion thereof. Nucleic acid molecules encoding fragments, homologs, derivatives and analogs of receptor or ligand or antisense nucleic acids complementary to a receptor or ligand nucleic acid sequence are additionally provided.
In one embodiment, an antisense nucleic acid molecule is antisense to a “coding region” of the coding strand of a nucleotide sequence encoding a receptor or ligand protein (or fragments or fragment combination thereof). The term “coding region” refers to the region of the nucleotide sequence comprising codons that are translated into amino acid residues. In another embodiment, the antisense nucleic acid molecule is antisense to a “conceding region” of the coding strand of a nucleotide sequence encoding the receptor or ligand protein. The term “conceding region” refers to 5′ and 3′ sequences that flank the coding region and that are not translated into amino acids (i.e., also referred to as 5′ and 3′ untranslated regions).
Given the coding strand sequences encoding the receptor or ligand protein disclosed herein, antisense nucleic acids of the invention can be designed according to the rules of Watson and Crick or Hoogsteen base pairing. The antisense nucleic acid molecule can be complementary to the entire coding region of a ligand or receptor mRNA, but more preferably is an oligonucleotide that is antisense to only a portion of the coding or noncoding region of receptor or ligand mRNA. For example, the antisense oligonucleotide can be complementary to the region surrounding the translation start site of receptor or ligand mRNA. An antisense oligonucleotide can be, for example, about 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 nucleotides in length. An antisense nucleic acid of the invention can be constructed using chemical synthesis or enzymatic ligation reactions using procedures known in the art. For example, an antisense nucleic acid (e.g., an antisense oligonucleotide) can be chemically synthesized using naturally-occurring nucleotides or variously modified nucleotides designed to increase the biological stability of the molecules or to increase the physical stability of the duplex formed between the antisense and sense nucleic acids (e.g., phosphorothioate derivatives and acridine substituted nucleotides can be used).
Examples of modified nucleotides that can be used to generate the antisense nucleic acid include: 5-fluorouracil, 5-bromouracil, 5-chlorouracil, 5-iodouracil, hypoxanthine, xanthine, 4-acetylcytosine, 5-(carboxyhydroxylmethyl) uracil, 5-carboxymethylaminomethyl-2-thiouridine, 5-carboxymethylaminomethyluracil, dihydrouracil, beta-D-galactosylqueosine, inosine, N6-isopentenyladenine, 1-methylguanine, 1-methylinosine, 2,2-dimethylguanine, 2-methyladenine, 2-methylguanine, 3-methylcytosine, 5-methylcytosine, N6-adenine, 7-methylguanine, 5-methylaminomethyluracil, 5-methoxyaminomethyl-2-thiouracil, beta-D-mannosylqueosine, 5′-methoxycarboxymethyluracil, 5-methoxyuracil, 2-methylthio-N6-isopentenyladenine, uracil-5-oxyacetic acid (v), wybutoxosine, pseudouracil, queosine, 2-thiocytosine, 5-methyl-2-thiouracil, 2-thiouracil, 4-thiouracil, 5-methyluracil, uracil-5-oxyacetic acid methylester, uracil-5-oxyacetic acid (v), 5-methyl-2-thiouracil, 3-(3-amino-3-N-2-carboxypropyl) uracil, (acp3)w, and 2,6-diaminopurine. Alternatively, the antisense nucleic acid can be produced biologically using an expression vector into which a nucleic acid has been subcloned in an antisense orientation (i.e., RNA transcribed from the inserted nucleic acid will be of an antisense orientation to a target nucleic acid of interest, described further in the following section).
The antisense nucleic acid molecules of the invention are typically administered to a subject or generated in situ such that they hybridize with or bind to cellular mRNA and/or genomic DNA encoding a receptor or ligand to thereby inhibit expression of the protein (e.g., by inhibiting transcription and/or translation). The hybridization can be by conventional nucleotide complementarity to form a stable duplex, or, for example, in the case of an antisense nucleic acid molecule that binds to DNA duplexes, through specific interactions in the major groove of the double helix. An example of a route of administration of antisense nucleic acid molecules of the invention includes direct injection at a tissue site. Alternatively, antisense nucleic acid molecules can be modified to target selected cells and then administered systemically. For example, for systemic administration, antisense molecules can be modified such that they specifically bind to receptors or antigens expressed on a selected cell surface (e.g., by linking the antisense nucleic acid molecules to peptides or antibodies that bind to cell surface receptors or antigens). The antisense nucleic acid molecules can also be delivered to cells using the vectors described herein. To achieve sufficient nucleic acid molecules, vector constructs in which the antisense nucleic acid molecule is placed under the control of a strong pol II or pol III promoter are preferred.
In yet another embodiment, the antisense nucleic acid molecule of the invention is an alpha-anomeric nucleic acid molecule. An alpha-anomeric nucleic acid molecule forms specific double-stranded hybrids with complementary RNA in which, contrary to the usual alpha-units, the strands run parallel to each other. See, e.g., Gaultier, et al., Nucl. Acids Res., 15:6625-6641 (1987). The antisense nucleic acid molecule can also comprise a 2′-o-methylribonucleotide (see, e.g., Inoue, et al. Nucl. Acids Res., 15:6131-6148 (1987)) or a chimeric RNA-DNA analogue (see, e.g., Inoue, et al., FEBS Lett., 215:327-330 (1987)).
Production and delivery of antisense molecules are facilitated by providing a vector comprising an anti-sense nucleotide sequence complementary to at least a part of the Receptor or ligand DNA sequence. According to a yet further aspect of the invention such a vector comprising an anti-sense sequence may be used to inhibit, or at least mitigate, Receptor or ligand expression. The use of a vector of this type to inhibit Receptor or ligand expression is favored in instances where Receptor or ligand expression is associated with a particular disease state.
D. Anti-Ligand or Anti-Receptor RNA Interference
Use of RNA Interference to inactivate or modulate receptor or ligand expression is also contemplated by this invention. RNA interference is described in U.S. Patent Appl. No. 2002-0162126, and Hannon, G., J. Nature, 11:418:244-51 (2002). “RNA interference,” “post-transcriptional gene silencing,” “quelling”—these terms have all been used to describe similar effects that result from the overexpression or misexpression of transgenes, or from the deliberate introduction of double-stranded RNA into cells (reviewed in Fire, A., Trends Genet. 15:358-363 (1999); Sharp, P. A., Genes Dev., 13:139-141 (1999); Hunter, C., Curr. Biol., 9:R440-R442 (1999); Baulcombe, D. C., Curr. Biol. 9:R599-R601 (1999); Vaucheret, et al. Plant J. 16:651-659 (1998), all incorporated by reference. RNA interference, commonly referred to as RNAi, offers a way of specifically and potently inactivating a cloned gene.
IV. THERAPEUTIC FORMULATIONS AND ADMINISTRATION
A. Therapeutic Formulations
Binding constructs, or polynucleotides encoding the same, can be used directly to practice materials and methods of the invention, but in preferred embodiments, the compounds are formulated with pharmaceutically acceptable diluents, adjuvants, excipients, or carriers. The phrase “pharmaceutically or pharmacologically acceptable” refers to molecular entities and compositions that do not produce adverse, allergic, or other untoward reactions when administered to an animal or a human, e.g., orally, topically, transdermally, parenterally, by inhalation spray, vaginally, rectally, or by intracranial injection. (The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intracisternal injection, or infusion techniques. Administration by intravenous, intradermal, intramusclar, intramammary, intraperitoneal, intrathecal, retrobulbar, intrapulmonary injection and/or surgical implantation at a particular site is contemplated as well.) Generally, this will also entail preparing compositions that are essentially free of pyrogens, as well as other impurities that could be harmful to humans or animals. The term “pharmaceutically acceptable carrier” includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutically active substances is well known in the art.
Therapeutic formulations of the compositions useful for practicing the invention such as polypeptides, polynucleotides, or antibodies may be prepared for storage by mixing the selected composition having the desired degree of purity with optional physiologically pharmaceutically-acceptable carriers, excipients, or stabilizers (Remington's Pharmaceutical Sciences, 18th edition, A. R. Gennaro, ed., Mack Publishing Company (1990)) in the form of a lyophilized cake or an aqueous solution. Pharmaceutical compositions may be produced by admixing with one or more suitable carriers or adjuvants such as water, mineral oil, polyethylene glycol, starch, talcum, lactose, thickeners, stabilizers, suspending agents, etc. Such compositions may be in the form of solutions, suspensions, tablets, capsules, creams, salves, ointments, or other conventional forms.
Acceptable carriers, excipients or stabilizers are nontoxic to recipients and are preferably inert at the dosages and concentrations employed, and include buffers such as phosphate, citrate, or other organic acids; antioxidants such as ascorbic acid; low molecular weight polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions such as sodium; and/or nonionic surfactants such as Tween, Pluronics or polyethylene glycol (PEG).
The composition to be used for in vivo administration should be sterile. This is readily accomplished by filtration through sterile filtration membranes, prior to or following lyophilization and reconstitution. Therapeutic compositions generally are placed into a container having a sterile access port, for example, an intravenous solution bag or vial having a stopper pierceable by a hypodermic injection needle. The route of administration of the composition is in accord with known methods, e.g. oral, injection or infusion by intravenous, intraperitoneal, intracerebral, intramuscular, intraocular, intraarterial, or intralesional routes, or by sustained release systems or implantation device. Where desired, the compositions may be administered continuously by infusion, bolus injection or by implantation device. The composition for parenteral administration ordinarily will be stored in lyophilized form or in solution.
The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases the form should be sterile and should be fluid to the extent that easy syringability exists. It should be stable under the conditions of manufacture and storage and should be preserved against the contaminating action of microorganisms, such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and vegetable oils. The proper fluidity can be maintained, for example, by the use of a coating, such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. The prevention of the action of microorganisms can be brought about by various antibacterial an antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminum monostearate and gelatin.
Suitable examples of sustained-release preparations include semipermeable polymer matrices in the form of shaped articles, e.g. films, or microcapsules. Sustained release matrices include polyesters, hydrogels, polylactides (U.S. Pat. No. 3,773,919, EP 58,481), copolymers of L-glutamic acid and gamma ethyl-L-glutamate (Sidman, et al., Biopolymers, 22: 547-556 (1983)), poly(2-hydroxyethyl-methacrylate) (Langer, et al., J. Biomed. Mater. Res., 15:167-277 (1981) and Langer, Chem. Tech., 12:98-105 (1982)), ethylene vinyl acetate (Langer, et al., supra) or poly-D(−)-3-hydroxybutyric acid (EP 133,988). Sustained-release compositions also may include liposomes, which can be prepared by any of several methods known in the art (e.g., DE 3,218,121; Epstein, et al., Proc. Natl. Acad. Sci. USA, 82:3688-3692 (1985); Hwang, et al., Proc. Natl. Acad. Sci. USA, 77:4030-4034 (1980); EP 52,322; EP 36,676; EP 88,046; EP 143,949).
An effective amount of the compositions to be employed therapeutically will depend, for example, upon the therapeutic objectives, the route of administration, and the condition of the patient. A therapist can titer the dosage and modify the route of administration to obtain the optimal therapeutic effect. A typical daily dosage may range from about 1 μg/kg to up to 100 mg/kg or more, depending on the factors mentioned above. Typically, a clinician will administer the composition until a dosage is reached that achieves the desired effect. The progress of this therapy is easily monitored by conventional assays designed to evaluate the particular disease state being treated.
B. Kits and Unit Doses
In related variations of the preceding embodiments, a binding construct may be packaged or formulated together with another binding construct or other therapeutic (e.g., a chemotherapy agent), e.g., in a kit or package or unit dose, to permit co-administration, but these two components are not in admixture. In some embodiments, the two components to the kit/unit dose are packaged with instructions for administering the two compounds to a human subject for treatment of one of the disorders and diseases described herein.
C. Polynucleotide-Based Therapies
The present invention also includes gene therapy materials and methods. Specifically, polypeptides and binding constructions of the invention can be produced at therapeutic levels in vivo by administration of a gene therapy contrast that enters cells and is expressed in vivo to produce the polypeptides or binding constructs. For example, in some embodiments, the vasculature of a cancer cell or cancer cells may be contacted with an expression construct capable of providing a therapeutic peptide or binding constructs of the present invention. Expression of the polypeptide or binding construct causes a therapeutic outcome, for example, inhibition of growth factors and receptors in the vasculature of a tumor, an inhibition of angiogenesis, an inhibition of lymphangiogenesis, an ablation, regression or other inhibition of tumor growth, an induction of apoptosis of the blood or lymphatic vasculature of the tumor or indeed the tumor cells themselves.
For these embodiments, an exemplary expression construct comprises a virus or engineered construct derived from a viral genome. Such vectors and constructs are considered aspect of the invention. The expression construct generally comprises a nucleic acid encoding the gene or binding construct, including any nucleic acid molecule described herein, to be expressed and also additional regulatory regions that will effect the expression of the gene in the cell to which it is administered. Such regulatory regions include for example promoters, enhancers, polyadenylation signals and the like.
DNA may be introduced into a cell using a variety of viral vectors. In such embodiments, expression constructs comprising viral vectors containing the genes of interest may be adenoviral (see, for example, U.S. Pat. No. 5,824,544; U.S. Pat. No. 5,707,618; U.S. Pat. No. 5,693,509; U.S. Pat. No. 5,670,488; U.S. Pat. No. 5,585,362, each incorporated herein by reference), retroviral (see, for example, U.S. Pat. No. 5,888,502; U.S. Pat. No. 5,830,725; U.S. Pat. No. 5,770,414; U.S. Pat. No. 5,686,278; U.S. Pat. No. 4,861,719, each incorporated herein by reference), adeno-associated viral (see, for example, U.S. Pat. No. 5,474,935; U.S. Pat. No. 5,139,941; U.S. Pat. No. 5,622,856; U.S. Pat. No. 5,658,776; U.S. Pat. No. 5,773,289; U.S. Pat. No. 5,789,390; U.S. Pat. No. 5,834,441; U.S. Pat. No. 5,863,541; U.S. Pat. No. 5,851,521; U.S. Pat. No. 5,252,479, each incorporated herein by reference), an adenoviral-adenoassociated viral hybrid (see, for example, U.S. Pat. No. 5,856,152 incorporated herein by reference) or a vaccinia viral or a herpesviral (see, for example, U.S. Pat. No. 5,879,934; U.S. Pat. No. 5,849,571; U.S. Pat. No. 5,830,727; U.S. Pat. No. 5,661,033; U.S. Pat. No. 5,328,688, each incorporated herein by reference) vector. Other vectors described herein may also be employed. Replication-deficient viral vectors are specifically contemplated.
In other embodiments, non-viral delivery is contemplated. These include calcium phosphate precipitation (Graham and Van Der Eb, Virology, 52:456-467 (1973); Chen and Okayama, Mol. Cell. Biol., 7:2745-2752, (1987); Rippe, et al., Mol. Cell. Biol., 10:689-695 (1990)), DEAE-dextran (Gopal, Mol. Cell. Biol., 5:1188-1190 (1985)), electroporation (Tur-Kaspa, et al., Mol. Cell. Biol., 6:716-718, (1986); Potter, et al., Proc. Nat. Acad. Sci. USA, 81:7161-7165, (1984)), direct microinjection (Harland and Weintraub, J. Cell Biol., 101:1094-1099 (1985)), DNA-loaded liposomes (Nicolau and Sene, Biochim. Biophys. Acta, 721:185-190 (1982); Fraley, et al., Proc. Natl. Acad. Sci. USA, 76:3348-3352 (1979); Felgner, Sci. Am., 276(6):102-6 (1997); Felgner, Hum. Gene Ther., 7(15):1791-3, (1996)), cell sonication (Fechheimer, et al., Proc. Natl. Acad. Sci. USA, 84:8463-8467 (1987)), gene bombardment using high velocity microprojectiles (Yang, et al., Proc. Natl. Acad. Sci. USA, 87:9568-9572 (1990)), and receptor-mediated transfection (Wu and Wu, J. Biol. Chem., 262:4429-4432 (1987); Wu and Wu, Biochemistry, 27:887-892 (1988); Wu and Wu, Adv. Drug Delivery Rev., 12:159-167 (1993)).
In a particular embodiment of the invention, the expression construct (or indeed the peptides discussed above) may be entrapped in a liposome. Liposomes are vesicular structures characterized by a phospholipid bilayer membrane and an inner aqueous medium. Multilamellar liposomes have multiple lipid layers separated by aqueous medium. They form spontaneously when phospholipids are suspended in an excess of aqueous solution. The lipid components undergo self-rearrangement before the formation of closed structures and entrap water and dissolved solutes between the lipid bilayers (Ghosh and Bachhawat, “In Liver Diseases, Targeted Diagnosis And Therapy Using Specific Receptors And Ligands,” Wu, G., Wu, C., ed., New York: Marcel Dekker, pp. 87-104 (1991)). The addition of DNA to cationic liposomes causes a topological transition from liposomes to optically birefringent liquid-crystalline condensed globules (Radler, et al., Science, 275(5301):810-4, (1997)). These DNA-lipid complexes are potential non-viral vectors for use in gene therapy and delivery.
Liposome-mediated nucleic acid delivery and expression of foreign DNA in vitro has been very successful. Also contemplated in the present invention are various commercial approaches involving “lipofection” technology. In certain embodiments of the invention, the liposome may be complexed with a hemagglutinating virus (HVJ). This has been shown to facilitate fusion with the cell membrane and promote cell entry of liposome-encapsulated DNA (Kaneda, et al., Science, 243:375-378 (1989)). In other embodiments, the liposome may be complexed or employed in conjunction with nuclear nonhistone chromosomal proteins (HMG-1) (Kato, et al., J. Biol. Chem., 266:3361-3364 (1991)). In yet further embodiments, the liposome may be complexed or employed in conjunction with both HVJ and HMG-1. In that such expression constructs have been successfully employed in transfer and expression of nucleic acid in vitro and in vivo, then they are applicable for the present invention.
Other vector delivery systems that can be employed to deliver a nucleic acid encoding a therapeutic gene into cells include receptor-mediated delivery vehicles. These take advantage of the selective uptake of macromolecules by receptor-mediated endocytosis in almost all eukaryotic cells. Because of the cell type-specific distribution of various receptors, the delivery can be highly specific (Wu and Wu (1993), supra).
Receptor-mediated gene targeting vehicles generally consist of two components: a cell receptor-specific ligand and a DNA-binding agent. Several ligands have been used for receptor-mediated gene transfer. The most extensively characterized ligands are asialoorosomucoid (ASOR) (Wu and Wu (1987), supra) and transferrin (Wagner, et al., Proc. Nat'l. Acad. Sci. USA, 87(9):3410-3414 (1990)). Recently, a synthetic neoglycoprotein, which recognizes the same receptor as ASOR, has been used as a gene delivery vehicle (Ferkol, et al., FASEB. J., 7:1081-1091 (1993); Perales, et al., Proc. Natl. Acad. Sci., USA 91:4086-4090 (1994)) and epidermal growth factor (EGF) has also been used to deliver genes to squamous carcinoma cells (Myers, EPO 0273085).
In other embodiments, the delivery vehicle may comprise a ligand and a liposome. For example, Nicolau, et al., Methods Enzymol., 149:157-176 (1987) employed lactosyl-ceramide, a galactose-terminal asialganglioside, incorporated into liposomes and observed an increase in the uptake of the insulin gene by hepatocytes. Thus, it is feasible that a nucleic acid encoding a therapeutic gene also may be specifically delivered into a particular cell type by any number of receptor-ligand systems with or without liposomes.
In another embodiment of the invention, the expression construct may simply consist of naked recombinant DNA or plasmids. Transfer of the construct may be performed by any of the methods mentioned above that physically or chemically permeabilize the cell membrane. This is applicable particularly for transfer in vitro, however, it may be applied for in vivo use as well. Dubensky, et al., Proc. Nat. Acad. Sci. USA, 81:7529-7533 (1984) successfully injected polyomavirus DNA in the form of CaPO4 precipitates into liver and spleen of adult and newborn mice demonstrating active viral replication and acute infection. Benvenisty and Neshif, Proc. Nat. Acad. Sci. USA, 83:9551-9555 (1986) also demonstrated that direct intraperitoneal injection of CaPO4 precipitated plasmids results in expression of the transfected genes.
Another embodiment of the invention for transferring a naked DNA expression construct into cells may involve particle bombardment. This method depends on the ability to accelerate DNA coated microprojectiles to a high velocity allowing them to pierce cell membranes and enter cells without killing them (Klein, et al., Nature, 327:70-73 (1987)). Several devices for accelerating small particles have been developed. One such device relies on a high voltage discharge to generate an electrical current, which in turn provides the motive force (Yang, et al., Proc. Natl. Acad. Sci. USA, 87:9568-9572 (1990)). The microprojectiles used have consisted of biologically inert substances such as tungsten or gold beads.
Those of skill in the art are well aware of how to apply gene delivery to in vivo and ex vivo situations. For viral vectors, one generally will prepare a viral vector stock. Depending on the kind of virus and the titer attainable, one will deliver 1×104, 1×105, 1×106, 1×107, 1×108, 1×109, 1×1010, 1×1011 or 1×1012 infectious particles to the patient. Similar figures may be extrapolated for liposomal or other non-viral formulations by comparing relative uptake efficiencies. Formulation as a pharmaceutically acceptable composition is discussed below.
Various routes are contemplated for various cell types. For practically any cell, tissue or organ type, systemic delivery is contemplated. In other embodiments, a variety of direct, local and regional approaches may be taken. For example, the cell, tissue or organ may be directly injected with the expression vector or protein.
Promoters for gene therapy for use in this invention include cytomegalovirus (CMV) promoter/enhancer, long terminal repeat (LTR) of retroviruses, keratin 14 promoter, and a myosin heavy chain promoter.
In a different embodiment, ex vivo gene therapy is contemplated. In an ex vivo embodiment, cells from the patient are removed and maintained outside the body for at least some period of time. During this period, a therapy is delivered, after which the cells are reintroduced into the patient; preferably, any tumor cells in the sample have been killed.
The techniques, procedures and methods outlined herein are applicable to any and all of the polypeptides and binding constructs of the present invention.
D. Chemotherapy and Other Combination Therapies
Any one of the binding constructs of the present invention when used in a method of treating a disease, e.g. a neoplastic condition such as a tumor, may be employed alone, or in combination with other agents. In some embodiments, more than one binding construct may be administered. In some embodiments, a binding construct may be administered together with a chemotherapeutic agent.
Certain cancers or patients may lend themselves to a treatment of combined binding construct and chemotherapeutic agent to achieve an additive or even a synergistic effect compared to the use of any one therapy alone. The chemotherapeutic agents may include, but are not limited to, platinum coordination compounds, topoisomerase inhibitors, antibiotics, antimitotic alkaloids and difluoronucleosides, as described in U.S. Pat. No. 6,630,124. The binding construct and chemotherapeutic agent need not be administered simultaneously, nor must they be administered by the same means.
In some embodiments, the chemotherapeutic agent is a platinum coordination compound. The term “platinum coordination compound” refers to any tumor cell growth inhibiting platinum coordination compound that provides the platinum in the form of an ion. Preferred platinum coordination compounds include, but are not limited to, cis-diamminediaquoplatinum (II)-ion; chloro(diethylenetriamine)-platinum(II) chloride; dichloro(ethylenediamine)-platinum(II), diammine(1,1-cyclobutanedicarboxylato) platinum(I) (carboplatin); spiroplatin; iproplatin; diammine(2-ethylmalonato)-platinum(II); ethylenediaminemalonatoplatinum(II); aqua(1,2-diaminodyclohexane)-sulfatoplatinum(II); (1,2-diaminocyclohexane)malonatoplatinum(II); (4-caroxyphthalato)(1,2-diaminocyclohexane)platinum(II); (1,2-diaminocyclohexane)-(isocitrato)platinum(II); (1,2-diaminocyclohexane)cis(pyruvato)platinum(II); (1,2-diaminocyclohexane)oxalatoplatinum(II); ormaplatin; and tetraplatin.
In some embodiments, cisplatin is the preferred platinum coordination compound employed in the compositions and methods of the present invention. Cisplatin is commercially available under the name PLATINOLTM from Bristol Myers-Squibb Corporation and is available as a powder for constitution with water, sterile saline or other suitable vehicle. Other platinum coordination compounds suitable for use in the present invention are known and are available commercially and/or can be prepared by conventional techniques. Cisplatin, or cis-dichlorodiammineplatinum II, has been used successfully for many years as a chemotherapeutic agent in the treatment of various human solid malignant tumors. More recently, other diamino-platinum complexes have also shown efficacy as chemotherapeutic agents in the treatment of various human solid malignant tumors. Such diamino-platinum complexes include, but are not limited to, spiroplatinum and carboplatinum. Although cisplatin and other diamino-platinum complexes have been widely used as chemotherapeutic agents in humans, they have had to be delivered at high dosage levels that can lead to toxicity problems such as kidney damage.
Preferably, when cisplatin is used in combination with the binding constructs of the present invention, the results obtained are synergistic. That is to say, the effectiveness of the combination therapy of a binding construct and the platinum coordination compound is synergistic, i.e., the effectiveness is greater than the effectiveness expected from the additive individual effects of each. Therefore, the dosage of the platinum coordination compound can be reduced and thus, the risk of the toxicity problems and other side effects is concomitantly reduced.
In some embodiments, the chemotherapeutic agent of the present invention is a topoisomerase inhibitor. Topoisomerases are enzymes that are capable of altering DNA topology in eukaryotic cells. They are critical for cellular functions and cell proliferation. Generally, there are two classes of topoisomerases in eukaryotic cells, type I and type II. Topoisomerase I is a monomeric enzyme of approximately 100,000 molecular weight. The enzyme binds to DNA and introduces a transient single-strand break, unwinds the double helix (or allows it to unwind), and subsequently reseals the break before dissociating from the DNA strand. Various topoisomerase inhibitors have recently shown clinical efficacy in the treatment of humans afflicted with ovarian, cancer, esophageal cancer or non-small cell lung carcinoma.
One especially preferred topoisomerase inhibitor of the present invention is camptothecin and camptothecin analogs. Camptothecin is a water-insoluble, cytotoxic alkaloid produced by Camptotheca accuminata trees indigenous to China and Nothapodytes foetida trees indigenous to India. Camptothecin exhibits tumor cell growth inhibiting activity against a number of tumor cells. Compounds of the camptothecin analog class are typically specific inhibitors of DNA topoisomerase I. By the term “inhibitor of topoisomerase” is meant any tumor cell growth inhibiting compound that is structurally related to camptothecin. Compounds of the camptothecin analog class include, but are not limited to, topotecan, irinotecan and 9-amino-camptothecin.
In addition to the foregoing topoisomerase inhibitors, such compounds also include, but are not limited to, any tumor cell growth inhibiting camptothecin analog claimed or described in: U.S. Pat. No. 5,004,758, issued on Apr. 2, 1991 and European Patent Application Number 88311366.4, published on Jun. 21, 1989 as Publication Number EP 0 321 122; U.S. Pat. No. 4,604,463, issued on Aug. 5, 1986 and European Patent Application Publication Number EP 0 137 145, published on Apr. 17, 1985; U.S. Pat. No. 4,473,692, issued on Sep. 25, 1984 and European Patent Application Publication Number EP 0 074 256, published on Mar. 16, 1983; U.S. Pat. No. 4,545,880, issued on Oct. 8, 1985 and European Patent Application Publication Number EP 0 074 256, published on Mar. 16, 1983; European Patent Application Publication Number EP 0 088 642, published on Sep. 14, 1983; Wani et al, J. Med. Chem., 29, 2358-2363 (1986); Nitta et al., Proc. 14th International Congr. Chemotherapy, Kyoto, 1985, Tokyo Press, Anticancer Section 1, p. 28-30, especially a compound called CPT-11. CPT-11 is a camptothecin analog with a 4-(piperidino)-piperidine side chain joined through a carbamate linkage at C-10 of 10-hydroxy-7-ethyl camptothecin. CPT-11 is currently undergoing human clinical trials and is also referred to as irinotecan; Wani et al, J. Med. Chem., 23, 554 (1980); Wani et. al., J. Med. Chem., 30, 1774 (1987); U.S. Pat. No. 4,342,776, issued on Aug. 3, 1982; U.S. patent application Ser. No. 581,916, filed on Sep. 13, 1990 and European Patent Application Publication Number EP 418 099, published on Mar. 20, 1991; U.S. Pat. No. 4,513,138, issued on Apr. 23, 1985 and European Patent Application Publication Number EP 0 074 770, published on Mar. 23, 1983; U.S. Pat. No. 4,399,276, issued on Aug. 16, 1983 and European Patent Application Publication Number 0 056 692, published on Jul. 28, 1982; the entire disclosure of each of which is hereby incorporated by reference. All of the above-listed compounds of the camptothecin analog class are available commercially and/or can be prepared by conventional techniques including those described in the above-listed references. The topoisomerase inhibitor may be selected from the group consisting of topotecan, irinotecan and 9-aminocamptothecin.
Preferably, when a topoisomerase inhibitor is used in combination with the binding constructs of the present invention, the results obtained are synergistic. That is, the effectiveness of the combination therapy of a binding construct and the topoisomerase inhibitor is synergistic, i.e., the effectiveness is greater than the effectiveness expected from the additive individual effects of each. Therefore, the dosage of the topoisomerase inhibitor can be reduced and thus, the risk of the toxicity problems and other side effects is concomitantly reduced.
The preparation of numerous compounds of the camptothecin analog class (including pharmaceutically acceptable salts, hydrates and solvates thereof) as well as the preparation of oral and parenteral pharmaceutical compositions comprising such a compounds of the camptothecin analog class and an inert, pharmaceutically acceptable carrier or diluent, is extensively described in U.S. Pat. No. 5,004,758, issued on Apr. 2, 1991 and European Patent Application Number 88311366.4, published on Jun. 21, 1989 as Publication Number EP 0 321 122, the teachings of which are incorporated herein by reference.
In still yet another embodiment of the present invention, the chemotherapeutic agent is an antibiotic compound. Suitable antibiotic include, but are not limited to, doxorubicin, mitomycin, bleomycin, daunorubicin and streptozocin.
Preferably, when an antibiotic is used in combination with the binding constructs of the present invention, the results obtained are synergistic. That is, the effectiveness of the combination therapy of a binding construct and the antibiotic compound is synergistic, i.e., the effectiveness is greater than the effectiveness expected from the additive individual effects of each. Therefore, the dosage of the antibiotic compound can be reduced and thus, the risk of the toxicity problems and other side effects is concomitantly reduced.
In some embodiments, the chemotherapeutic agent is an antimitotic alkaloid. In general, antimitotic alkaloids can be extracted from Cantharanthus roseus, and have been shown to be efficacious as anticancer chemotherapy agents. A great number of semi-synthetic derivatives have been studied both chemically and pharmacologically (see, O. Van Tellingen et al, Anticancer Research, 12, 1699-1716 (1992)). The antimitotic alkaloids of the present invention include, but are not limited to, vinblastine, vincristine, vindesine, Taxol and vinorelbine. The latter two antimitotic alkaloids are commercially available from Eli Lilly and Company, and Pierre Fabre Laboratories, respectively (see, U.S. Pat. No. 5,620,985). In a preferred aspect of the present invention, the antimitotic alkaloid is vinorelbine.
Preferably, when an antimitotic alkaloid is used in combination with the binding constructs of the present invention, the results obtained are synergistic. That is, the effectiveness of the combination therapy of a binding construct and an antimitotic alkaloids compound is synergistic, i.e., the effectiveness is greater than the effectiveness expected from the additive individual effects of each. Therefore, the dosage of the antimitotic alkaloid can be reduced and thus, the risk of the toxicity problems and other side effects is concomitantly reduced.
In another embodiment of the present invention, the chemotherapeutic agent is a difluoronucleoside. 2′-deoxy-2′,2′-difluoronucleosides are known in the art as having antiviral activity. Such compounds are disclosed and taught in U.S. Pat. Nos. 4,526,988 and 4,808,614. European Patent Application Publication 184,365 discloses that these same difluoronucleosides have oncolytic activity. Preferably, the 2′-deoxy-2′,2′-difluoronucleoside used in the compositions and methods of the present invention is 2′-deoxy-2′,2′-difluorocytidine hydrochloride, also known as gemcitabine hydrochloride. Gemcitabine is commercially available or can be synthesized in a multi-step process as disclosed and taught in U.S. Pat. Nos. 4,526,988, 4,808,614 and 5,223,608, the teachings of which are incorporated herein by reference.
Preferably, when a difluoronucleoside is used in combination with the binding constructs of the present invention, the results obtained are synergistic. That is, the effectiveness of the combination therapy of a binding construct and a difluoronucleoside compound is synergistic, i.e., the effectiveness is greater than the effectiveness expected from the additive individual effects of each. Therefore, the dosage of the difluoronucleoside can be reduced and thus, the risk of the toxicity problems and other side effects is concomitantly reduced.
E. Disease Targets
1. Neoplasms
Neoplasms treatable by the present invention include solid tumors, for example, carcinomas and sarcomas. Carcinomas include malignant neoplasms derived from epithelial cells which infiltrate, for example, invade, surrounding tissues and give rise to metastases. Adenocarcinomas are carcinomas derived from glandular tissue, or from tissues that form recognizable glandular structures. Another broad category of cancers includes sarcomas and fibrosarcomas, which are tumors whose cells are embedded in a fibrillar or homogeneous substance, such as embryonic connective tissue. The invention also provides methods of treatment of cancers of myeloid or lymphoid systems, including leukemias, lymphomas, and other cancers that typically are not present as a tumor mass, but are distributed in the vascular or lymphoreticular systems. Further contemplated are methods for treatment of adult and pediatric oncology, growth of solid tumors/malignancies, myxoid and round cell carcinoma, locally advanced tumors, cancer metastases, including lymphatic metastases. The cancers listed herein are not intended to be limiting. Both age (child and adult), sex (male and female), primary and secondary, pre- and post-metastatic, acute and chronic, benign and malignant, anatomical location cancer embodiments and variations are contemplated targets. Cancers are grouped by embryonic origin (e.g., carcinoma, lymphomas, and sarcomas), by organ or physiological system, and by miscellaneous grouping. Particular cancers may overlap in their classification, and their listing in one group does not exclude them from another.
Carcinomas that may targeted include adrenocortical, acinar, acinic cell, acinous, adenocystic, adenoid cystic, adenoid squamous cell, cancer adenomatosum, adenosquamous, adnexel, cancer of adrenal cortex, adrenocortical, aldosterone-producing, aldosterone-secreting, alveolar, alveolar cell, ameloblastic, ampullary, anaplastic cancer of thyroid gland, apocrine, basal cell, basal cell, alveolar, comedo basal cell, cystic basal cell, morphea-like basal cell, multicentric basal cell, nodulo-ulcerative basal cell, pigmented basal cell, sclerosing basal cell, superficial basal cell, basaloid, basosquamous cell, bile duct, extrahepatic bile duct, intrahepatic bile duct, bronchioalveolar, bronchiolar, bronchioloalveolar, bronchoalveolar, bronchoalveolar cell, bronchogenic, cerebriform, cholangiocelluarl, chorionic, choroids plexus, clear cell, cloacogenic anal, colloid, comedo, corpus, cancer of corpus uteri, cortisol-producing, cribriform, cylindrical, cylindrical cell, duct, ductal, ductal cancer of the prostate, ductal cancer in situ (DCIS), eccrine, embryonal, cancer en cuirasse, endometrial, cancer of endometrium, endometroid, epidermoid, cancer ex mixed tumor, cancer ex pleomorphic adenoma, exophytic, fibrolamellar, cancer fibro'sum, follicular cancer of thyroid gland, gastric, gelatinform, gelatinous, giant cell, giant cell cancer of thyroid gland, cancer gigantocellula're, glandular, granulose cell, hepatocellular, Hürthle cell, hypemephroid, infantile embryonal, islet cell carcinoma, inflammatory cancer of the breast, cancer in si'tu, intraductal, intraepidermal, intraepithelial, juvenile embryonal, Kulchitsky-cell, large cell, leptomeningeal, lobular, infiltrating lobular, invasive lobular, lobular cancer in situ (LCIS), lymphoepithelial, cancer medullare, medullary, medullary cancer of thyroid gland, medullary thyroid, melanotic, meningeal, Merkel cell, metatypical cell, micropapillary, cancer mol'le, mucinous, cancer muci'parum, cancer mucocellula're, mucoepidermoid, cancer muco'sum, mucous, nasopharyngeal, neuroendocrine cancer of the skin, noninfiltrating, non-small cell, non-small cell lung cancer (NSCLC), oat cell, cancer ossi'ficans, osteoid, Paget's, papillary, papillary cancer of thyroid gland, periampullary, preinvasive, prickle cell, primary intrasseous, renal cell, scar, schistosomal bladder, Schneiderian, scirrhous, sebaceous, signet-ring cell, cancer sim'plex, small cell, small cell lung cancer (SCLC), spindle cell, cancer spongio'sum, squamous, squamous cell, terminal duct, anaplastic thyroid, follicular thyroid, medullary thyroid, papillary thyroid, trabecular cancer of the skin, transitional cell, tubular, undifferentiated cancer of thyroid gland, uterine corpus, verrucous, villous, cancer villo'sum, yolk sac, squamous cell particularly of the head and neck, esophageal squamous cell, and oral cancers and carcinomas.
Sarcomas that may be targeted include adipose, alveolar soft part, ameloblastic, avian, botryoid, sarcoma botryoi'des, chicken, chloromatous, chondroblastic, clear cell sarcoma of kidney, embryonal, endometrial stromal, epithelioid, Ewing's, fascial, fibroblastic, fowl, giant cell, granulocytic, hemangioendothelial, Hodgkin's, idiopathic multiple pigmented hemorrhagic, immunoblastic sarcoma of B cells, immunoblastic sarcoma of T cells, Jensen's, Kaposi's, kupffer cell, leukocytic, lymphatic, melanotic, mixed cell, multiple, lymphangio, idiopathic hemorrhagic, multipotential primary sarcoma of bone, osteoblastic, osteogenic, parosteal, polymorphous, pseudo-kaposi, reticulum cell, reticulum cell sarcoma of the brain, rhabdomyosarcoma, rous, soft tissue, spindle cell, synovial, telangiectatic, sarcoma (osteosarcoma)/malignant fibrous histiocytoma of bone, and soft tissue sarcomas.
Lymphomas that may targeted include AIDS-related, non-Hodgkin's, Hodgkin's, T-cell, T-cell leukemia/lymphoma, African, B-cell, B-cell monocytoid, bovine malignant, Burkitt's, centrocytic, lymphoma cu'tis, diffuse, diffuse, large cell, diffuse, mixed small and large cell, diffuse, small cleaved cell, follicular, follicular center cell, follicular, mixed small cleaved and large cell, follicular, predominantly large cell, follicular, predominantly small cleaved cell, giant follicle, giant follicular, granulomatous, histiocytic, large cell, immunoblastic, large cleaved cell, large nocleaved cell, Lennert's, lymphoblastic, lymphocytic, intermediate; lymphocytic, intermediately differentiated, plasmacytoid; poorly differentiated lymphocytic, small lymphocytic, well differentiated lymphocytic, lymphoma of cattle; MALT, mantle cell, mantle zone, marginal zone, Mediterranean lymphoma mixed lymphocytic-histiocytic, nodular, plasmacytoid, pleomorphic, primary central nervous system, primary effusion, small b-cell, small cleaved cell, small concleaved cell, T-cell lymphomas; convoluted T-cell, cutaneous t-cell, small lymphocytic T-cell, undefined lymphoma, u-cell, undifferentiated, aids-related, central nervous system, cutaneous T-cell, effusion (body cavity based), thymic lymphoma, and cutaneous T cell lymphomas.
Leukemias and other blood cell malignancies that may be targeted include acute lymphoblastic, acute myeloid, lymphocytic, chronic myelogenous, hairy cell, lymphoblastic, myeloid, lymphocytic, myelogenous, leukemia, hairy cell, T-cell, monocytic, myeloblastic, granulocytic, gross, hand mirror-cell, basophilic, hemoblastic, histiocytic, leukopenic, Iymphatic, Schilling's, stem cell, myelomonocyic, prolyniphocytic, micromyeloblastic, megakaryoblastic, megakaryoctyic, rieder cell, bovine, aleukemic, mast cell, myelocytic, plamsa cell, subleukemic, multiple myeloma, nonlymphocytic, and chronic myelocytic leukemias.
Brain and central nervous system (CNS) cancers and tumors that may be targeted include astrocytomas (including cerebellar and cerebral), brain stem glioma, brain tumors, malignant gliomas, ependymoma, glioblastoma, medulloblastoma, supratentorial primitive neuroectodermal tumors, visual pathway and hypothalamic gliomas, primary central nervous system lymphoma, ependymoma, brain stem glioma, visual pathway and hypothalamic glioma, extracranial germ cell tumor, medulloblastoma, myelodysplastic syndromes, oligodendroglioma, myelodysplastic/myeloproliferative diseases, myelogenous leukemia, myeloid leukemia, multiple myeloma, myeloproliferative disorders, neuroblastoma, plasma cell neoplasm/multiple myeloma, central nervous system lymphoma, intrinsic brain tumors, astrocytic brain tumors, gliomas, and metastatic tumor cell invasion in the central nervous system.
Gastrointestinal cancers that may be targeted include extrahepatic bile duct cancer, colon cancer, colon and rectum cancer, colorectal cancer, gallbladder cancer, gastric (stomach) cancer, gastrointestinal carcinoid tumor, gastrointestinal carcinoid tumors, gastrointestinal stromal tumors, bladder cancers, islet cell carcinoma (endocrine pancreas), pancreatic cancer, islet cell pancreatic cancer, prostate cancer rectal cancer, salivary gland cancer, small intestine cancer, colon cancer, and polyps associated with colorectal neoplasia.
Bone cancers that may be targeted include osteosarcoma and malignant fibrous histiocytomas, bone marrow cancers, bone metastases, osteosarcoma/malignant fibrous histiocytoma of bone, and osteomas and osteosarcomas. Breast cancers that may be targeted include small cell carcinoma and ductal carcinoma.
Lung and respiratory cancers that may be targeted include bronchial adenomas/carcinoids, esophagus cancer esophageal cancer, esophageal cancer, hypopharyngeal cancer, laryngeal cancer, hypopharyngeal cancer, lung carcinoid tumor, non-small cell lung cancer, small cell lung cancer, small cell carcinoma of the lungs, mesothelioma, nasal cavity and paranasal sinus cancer, nasopharyngeal cancer, nasopbaryngeal cancer, oral cancer, oral cavity and lip cancer, oropharyngeal cancer; paranasal sinus and nasal cavity cancer, and pleuropulmonary blastoma.
Urinary tract and reproductive cancers that may be targeted include cervical cancer, endometrial cancer, ovarian epithelial cancer, extragonadal germ cell tumor, extracranial germ cell tumor, extragonadal germ cell tumor, ovarian germ cell tumor, gestational trophoblastic tumor, spleen, kidney cancer, ovarian cancer, ovarian epithelial cancer, ovarian germ cell tumor, ovarian low malignant potential tumor, penile cancer, renal cell cancer (including carcinomas), renal cell cancer, renal pelvis and ureter (transitional cell cancer), transitional cell cancer of the renal pelvis and ureter, gestational trophoblastic tumor, testicular cancer, ureter and renal pelvis, transitional cell cancer, urethral cancer, endometrial uterine cancer, uterine sarcoma, vaginal cancer, vulvar cancer, ovarian carcinoma, primary peritoneal epithelial neoplasms, cervical carcinoma, uterine cancer and solid tumors in the ovarian follicle), superficial bladder tumors, invasive transitional cell carcinoma of the bladder, and muscle-invasive bladder cancer.
Skin cancers and melanomas (as well as non-melanomas) that may be targeted include cutaneous t-cell lymphoma, intraocular melanoma, tumor progression of human skin keratinocytes, basal cell carcinoma, and squamous cell cancer. Liver cancers that may be targeted include extrahepatic bile duct cancer, and hepatocellular cancers. Eye cancers that may be targeted include intraocular melanoma, retinoblastoma, and intraocular melanoma Hormonal cancers that may be targeted include: parathyroid cancer, pineal and supratentorial primitive neuroectodermal tumors, pituitary tumor, thymoma and thymic carcinoma, thymoma, thymus cancer, thyroid cancer, cancer of the adrenal cortex, and ACTH-producing tumors.
Miscellaneous other cancers that may be targeted include advanced cancers, AIDS-related, anal cancer adrenal cortical, aplastic anemia, aniline, betel, buyo cheek, cerebriform, chimney-sweeps, clay pipe, colloid, contact, cystic, dendritic, cancer a deux, duct, dye workers, encephaloid, cancer en cuirasse, endometrial, endothelial, epithelial, glandular, cancer in situ, kang, kangri, latent, medullary, melanotic, mule-spinners', non-small cell lung, occult cancer, paraffin, pitch workers', scar, schistosomal bladder, scirrhous, lymph node, small cell lung, soft, soot, spindle cell, swamp, tar, and tubular cancers.
Miscellaneous other cancers that may be targeted also include carcinoid (gastrointestinal and bronchal) Castleman's disease chronic myeloproliferative disorders, clear cell sarcoma of tendon sheaths, Ewing's family of tumors, head and neck cancer, lip and oral cavity cancer, Waldenström's macroglobulinemia, metastatic squamous neck cancer with occult primary, multiple endocrine neoplasia syndrome, multiple myeloma/plasma cell neoplasm, Wilms' tumor, mycosis fungoides, pheochromocytoma, sezary syndrome, supratentorial primitive neuroectodermal tumors, unknown primary site, peritoneal effusion, malignant pleural effusion, trophoblastic neo-plasms, and hemangiopericytoma.
2. Other Disease Targets
Neoplasms are not the only diseases that may be targeted using the binding constructs of the invention. The binding constructs of the invention may also be used to treat such diseases as rheumatoid arthritis, edemas (and other types of plasma leakage), cancer associated disorders such as cancer-associated ascites formation, diabetes, and inflammatory diseases such as psoriasis. The binding constructs may be used as therapeutics for any disease associated with abnormally high levels of growth factor expression.
V. NON-EXCLUSIVE EXAMPLES OF THE INVENTION
The invention may be more readily understood by reference to the following examples, which are given to illustrate the invention and not in any way to limit its scope. These examples primarily make reference to binding constructs that bind particular growth factors of the VEGF subfamily, but they may also be adapted for use of binding constructs that bind other VEGF subfamily members, as well as for binding constructs that bind PDGF subfamily members. Similarly, binding constructs comprising other VEFGR receptor fragments, PDGFR receptor fragments, and neuropilin receptor fragments may also be employed in variations of these examples.
Example 1
VEGFR-2 and VEGFR-3 Fragments that Bind VEGF-A or VEGF-C
To determine the portion of a receptor's extracellular domain (ECD) that was sufficient for ligand binding, fragments of the ECDs of VEGFR-2 (R-2) and VEGFR-3 (R-3) were used to make various soluble constructs. The constructs included Fc domain human IgG fragments fused to the C-terminus of the receptor fragments. As indicated in Tables 3 and 4, some constructs were made using a heterologous (N-terminal) signal peptide derived from CD33.
Construction of Fragments and Plasmids
R-2 Constructs
To construct the VEGFR-2/IgG expression plasmid, the construct, R-2 A, comprising the first three Ig-domains (D1-3) of VEGFR-2 was amplified by PCR using primers 5′-GCGGATCCTTGCCTAGTGTTTCTCTTGATC-3′ (SEQ ID NO: 72), and 5′-CCAGTCACCTGCTCCGGATCTTCATGGACCCTGACAAATG-3′ (SEQ ID NO: 73), and cloned into the Signal pIgplus vector (Novagen, Madison, Wis.). The resulting plasmid was digested with BamHI and KpnI, treated with T4 polymerase and back-ligated. To assemble other VEGFR-2/IgG constructs, PCRs were performed using the D1-3 construct as the template, T7 forward primer and the following reverse primers:









5′-GCTGGATCTTGAACATAGACATAAATG-3′ (R-2 F),,
(SEQ ID NO: 59)



 


5′-CTAGGATCCCCTACAACGACAACTATG-3′ (R-2 B),,
(SEQ ID NO: 60)


 


5′-CTAGGATCCACATCATAAATCCTATAC-3′ (R-2 C),,
(SEQ ID NO: 61)


 


5′-GCATGGTCTCGGATCATGAGAAGACGGACTCAGAAC-3′ (R-2 D),,
(SEQ ID NO: 62)


 


5′-CTAGGATCCTTTTCTCCAACAGATAG-3′ (R-2 E);
(SEQ ID NO: 63)






    
    
        forward primer 5′-AGCGCTAGCGTTCAAGATTACAGATCTCC-3′ (SEQ ID NO: 64), and the following reverse primers:
    
    











5′-ATGTGTGAGGTTTTGCACAAG-3′ (R-2 G),,
(SEQ ID NO: 65)



 


5′-CTAGGATCCCCTACAACGACAACTATG-3′ (R-2 H),,
(SEQ ID NO: 66)


 


5′-CTAGGATCCACATCATAAATCCTATAC-3′ (R-2 I),,
(SEQ ID NO: 67)


 


5′-GCATGGTCTCGGATCATGAGAAGACGGACTCAGAAC-3′ (R-2 J),,
(SEQ ID NO: 68)


 


5′-CTAGGATCCTTTTCTCCAACAGATAG-3′ (R-2 K),,
(SEQ ID NO: 69)






    
    
        forward primer 5′-AGCGCTAGCTATAGGATTTATGATGTG-3′ (SEQ ID NO: 70), and reverse primer
    
    










(SEQ ID NO: 71)









5′-ATGTGTGAGGTTTTGCACAAG-3′(R-2 L),.







The PCR products were digested with NheI and BstYI (R-2 F and L constructs), NheI and BamHI (R-2 E, and H-K constructs), BamHI (R-2 linker B and C constructs), BamHI and BsaI (R-2 D construct), or NheI and BsmBI (R-2 G construct), and cloned into the Signal pIgplus vector. In order to repair frame-shifts in constructs containing nucleotide sequence coding for domain 1 of VEGFR-2, the vectors were cut with restriction enzyme NotI, blunted with Klenow enzyme, cut with EcoRV and back-ligated.
R-3 Constructs
A series of R-3 constructs with N-termini between Ig domains 2 and 3 of VEGFR-3 (R-3 C through F constructs) was created by PCR using the expression plasmid comprising the R-3 D1-3 transcript (e.g., the R-3 G construct, SEQ ID NO: 43) as template, T7 as forward primer and the following reverse primers:









5′-TCAGGATCCGCGAGCTCGTTGCCTG-3′,
(SEQ ID NO: 74)



 


5′-TACAGGATCCCCTGTGATGTGCACCAG-3′,
(SEQ ID NO: 75)


 


5′-TCAGGATCCGCGTGCACCAGGAAGG-3′,
(SEQ ID NO: 76)


and


 


5′-TCAGGATCCGCGAAGGGGTTGGAAAG-3′.
(SEQ ID NO: 77)






The Ig homology domain 1 was deleted from the D1-3 expression plasmid (R-3 G construct) by site-directed mutagenesis using primers
5′CCTTGAACATCACGGAGGAGTCACACGTCAGAGACTTTGA GCAGCCATTCATCAACAAGC-3′ (SEQ ID NO: 78) and
5′AGCTGCTGGTAGGGGAGAAGGATCCTGAACTGCACCGTGT GG-3′ (SEQ ID NO: 79), and excision of the BamH I fragment from the resulting plasmid. That procedure combined with the described truncation primers, for R-3 C through F constructs, allows for the production of the R-3 constructs (e.g., C, D, E, F, J, K, L, and M). The plasmid coding for domains 2 and 3 of VEGFR-3 (R-3 I) was made by transfer of the Sph I fragment from the original expression R-3 D1-3 plasmid into the plasmid encoding only domain 2 of VEGFR-3 (R-3 J). The sequence derived from a particular receptor is listed in Table 2. Expression was performed using standard calcium phosphate-mediated transfection into 293T cells.
The binding assays utilized minimal VEGF-A (SEQ ID NOS: 106 and 107) and VEGF-C (SEQ ID NOS: 108 and 109) fragments with 109 residues each (called VEGF-A 109 and VEGF-C 109). These constructs are not naturally occurring, but are effective for binding assays. Other growth factor constructs, either natural or artificial, may also be used for performing these assays.
Either Tritiated VEGF-A 109 or VEGF-C 109 was used in a given binding experiment. Ligand in solution was precipitated by mixing 175 μl of ligand solution with 100 μl binding mix at 4° C. overnight, with agitation. The ligand solution may be the supernatant of metabolically labeled 293T cells. The binding mixes used for the receptor binding analysis were as follows: for VEGFR-1 binding assays, the binding mix was phosphate buffered saline (PBS) containing 1.5% BSA, 0.06% Tween 20, 3 μg/ml heparin and 400 ng/ml VEGFR-1-Fc fusion protein (100 μl of this binding mix was added to 200 μl of ligand solution). For VEGFR-2 binding assays, the binding mix was 82% conditioned cell supernatant from 293T cells transiently expressing VEGFR-2-Fc fusion protein in mixture with 18% of a PBS solution that contained 5% BSA, 0.2% Tween 20, and 10 μg/ml heparin (250 μl of binding mix was added to 200 μl of ligand solution). For VEGFR-3 binding assays, the binding mix was 82% conditioned cell supernatant from 293T cells transiently expressing VEGFR-3-Fc fusion protein, 18% of PBS containing 5% BSA, 0.2% Tween 20, and 10 μg/ml heparin (250 μl of binding mix was added to 200 μl of ligand solution). To collect precipitated ligand, 50 μl of a 30% protein A sepharose (PAS, Pharmacia) slurry in PBS was added and incubated under agitation for at least 1.5 hr at 4° C. Standard buffer was added to each immunoprecipitation sample and boiled for 5 minutes at 95° C. during which the immunopreciptated proteins become dissociated from the protein A sepharose. After centrifugation, 10 μl of each sample was analyzed on 15% SDS-PAGE under reducing conditions. The gels were dried and exposed for either 12 hours on phosphorimager plates or 4 weeks on X-ray film.
Tables 3 and 4 identify constructs by name, a DNA and deduced amino acid sequence from the sequence listing, the portion of VEGFR-2 (SEQ ID NO: 4) or VEGFR-3 (SEQ ID NO: 6) amino acid sequence that was included in the constructs, whether the constructs expressed, and, if tested, whether constructs bound ligand. The table data is compiled from the PAGE gels shown in FIGS. 2 and 3. The asterisk adjacent to the “B*” indicates a “spill-over” from the adjacent lane, as the origin of the bands seen in the “B” lane. A failure to express under the particular experimental conditions used in this instance should not be interpreted as a failure to bind. The experiments can be repeated using different receptor fragments, binding constructs, ligands, or combinations thereof.







TABLE 3







VEGFR-2 CONSTRUCTS












Fc Fusion

SEQ ID

Binds
Binds


Constructs
SEQ ID NOS:
NO: 4
Expression
VEGF-A
VEGF-C





R-2 A
SEQ ID NOS:
 24-326
Yes
Yes
Yes


with CD33 Signal
7 and 8


Peptide


R-2 B
SEQ ID NOS:
 24-220
Yes
No
No


with CD33 Signal
9 and 10


Peptide


R-2 C
SEQ ID NOS:
 24-226
Yes
No
No


with CD33 Signal
11 and 12


Peptide


R-2 D
SEQ ID NOS:
 24-232
Yes
No
No


with CD33 Signal
13 and 14


Peptide


R-2 E
SEQ ID NOS:
 24-241
Yes
No
No


with CD33 Signal
15 and 16


Peptide


R-2 F
SEQ ID NOS:
 24-122
Yes
No
No


with CD33 Signal
17 and 18


Peptide


R-2 G
SEQ ID NOS:
118-326
Yes
Yes
Yes


with CD33 Signal
19 and 20


Peptide


R-2 H
SEQ ID NOS:
118-220
Yes
No
Yes


with CD33 Signal
21 and 22


Peptide


R-2 I
SEQ ID NOS:
118-226
Yes
No
Weak


with CD33 Signal
23 and 24


Peptide


R-2 J
SEQ ID NOS:
118-232
Yes
No
Very


with CD33 Signal
25 and 26



Weak


Peptide


R-2 K
SEQ ID NOS:
118-241
Yes
No
No


with CD33 Signal
27 and 28


Peptide


R-2 L
SEQ ID NOS:
220-326
Yes
No
No


with CD33 Signal
29 and 30


Peptide
















TABLE 4







VEGFR-3 CONSTRUCTS











Fc Fusion
Sequence ID
SEQ ID

Binds


Constructs
Nos.
NO: 6
Expression
VEGF-C





R-3 A with CD33
SEQ ID NOS:
138-329 
No
—


Signal Peptide
31 and 32


R-3 B with CD33
SEQ ID NOS:
138-226 
Yes
No


Signal Peptide
33 and 34


R-3 C
SEQ ID NOS:
1-229
Yes
Yes



35 and 36


R-3 D
SEQ ID NOS:
1-226
Yes
Yes



37 and 38


R-3 E
SEQ ID NOS:
1-223
No
—



39 and 40


R-3 F
SEQ ID NOS:
1-220
No
—



41 and 42


R-3 G
SEQ ID NOS:
1-329
Yes
Yes



43 and 44


R-3 H
SEQ ID NOS:
1-134
Yes
No



45 and 46


R-3 I
SEQ ID NOS:
1-39,
Yes
No



47 and 48
132-329


R-3 J
SEQ ID NOS:
1-39,
Yes
No



49 and 50
132-247


R-3 K
SEQ ID NOS:
1-39,
Yes
No



51 and 52
132-229


R-3 L
SEQ ID NOS:
1-39,
No
—



53 and 54
132-226


R-3 M
SEQ ID NOS:
1-39,
No
—



55 and 56
132-223


R-3 N
SEQ ID NOS:
1-40,
—
—



57 and 58
226-329









The results of these assays demonstrate that novel receptor fragments are capable of binding ligands that the receptor as a whole may bind. In addition to providing a clearer picture as to what regions of the ECD are necessary for ligand binding, the binding data identifies receptor fragments useful as therapeutics.
The present data show that the R-2H fragment of R-2 of approximately 100 residues and spanning D2 of R-2 is sufficient for VEGF-C binding. For R-3, a larger fragment is required for VEGF-C binding, e.g., the R-3 D construct in table 4, which spans D1-2 of R-3.
Three-dimensional modeling based on the structure of VEGFR-1 complexed with VEGF-A was used to predict that a groove in VEGF-C might accommodate the region between Ig-like domains 2 and 3 of VEGFR-3 (Flt4). WO 01/62942. The present data shows for the first time that sequence intermediate between the second and third Ig domains of R-3 is important for ligand binding.
For R-1 and R-2, the first Ig-domain has been described as inhibitory for VEGF-A binding. Lu, et al, J. Biol. Chem., 275(19): 14321-14330 (2000); Shinkai, A. et al., J. Biol. Chem., 273(47):31283-88 (1998). For VEGF-C binding, the present data show that the inhibitory role of the first Ig-domain appears to apply to R-2 fragments, but not R-3 fragments.
The data also provides novel information regarding R-2 fragments and VEGF-A binding. Conflicting reports exist for constructs comprising the second and third Ig-domains of R-2 and VEGF-A binding. Fuh, et al., J. Biol. Chem., 273(18): 11197-11204 (1998); Niwa, et al., U.S. Pat. No. 6,348,333; Shinkai, A. et al., J. Biol. Chem., 273(47):31283-88 (1998). Fuh reported that only domains 2 and 3 were needed. Niwa taught that only 1 and 2 were needed. Shinkai stressed the importance of domain 4 of R-2. The issue is further confused because different reports have defined the boundaries of the Ig-domains in different ways, i.e., different start and stop points, a practice that has been recognized as potentially affecting whether fragments bind ligands, and with what degree of affinity. Shinkai, A. et al., J. Biol. Chem., 273(47):31283-88 (1998).
Example 2
Ligand Binding Assays Involving Binding Constructs with More than One Binding Element
The assays as performed in Example 1 are repeated, substituting a binding construct with multiple binding units. For example, one employs a binding construct comprising a binding unit that binds VEGF-A and a binding unit that binds VEGF-C. One looks for the ability of such a binding construct to bind both VEGF-A and VEGF-C. This information may be obtained by using different radio- or other labels, e.g., fluorescent labels for fluorescence resonance energy transfer (FRET), on each type of ligand or use of labels on the binding construct and or ligands, to determine whether a given binding construct molecules are binding a molecule of VEGF-A and VEGF-C. Constructs that are shown to bind more than one growth factor ligand, as well as those described in Example 1 and elsewhere herein, have an indication for anti-neoplastic therapies where multiple growth factors contribute to neoplastic cell growth.
Example 3
Chimeric VEGFR Binding Constructs which Bind Multiple Ligands
As stated above, constructs that bind more than one growth factor ligand have an indication as anti-neoplastic therapies where multiple growth factors contribute to neoplastic cell growth. In order to determine the efficacy of a binding construct designed to bind more than one growth factor, two chimeric binding constructs were generated and their ability of each to bind to two growth factors was measured.
The binding constructs were designed as immunoblobulin fusion proteins as described above. To construct chimeric VEGF receptor/hIgG1Fc fusion proteins, the pIgPlus vector was used to build a construct comprising the first immunoglobulin-like domain of VEGFR-3 and the second and third Ig-like domains of VEGFR-2. The construct is designated R-3D1-R2D2+3/hIgG1Fc. To clone the R-3D1-R2D2+3/hIgG1Fc construct, PCR was performed with CMV forward primer (18782, 5′ TACTTGGCAGTACATCTACGTATTAGTCATCGC-3′) (SEQ ID NO: 122) and reverse primer v360 (5′-CGGAGATCTGTAGTCTTGCACGTACACGTAGGAGCTGGC-3′) (SEQ ID NO: 123) using plgPlus-hVEGFR-3D1-3-IgG1Fc as a template. The PCR-product was cut with SnaBI and BglII. The 718 bp D1-R2D2+3/hIgG1Fc insert was ligated into the SnaBI- and partially BglII-cut vector plgPlus-hVEGFR-2D1-3-IgG1Fc described above. The presence and sequence of the correct insert was confirmed by sequencing a representative isolated hVEGFR-3D1-R2D2+3/hIgG1Fc clone (clone #2). (SEQ ID NO: 124 and SEQ ID NO: 125).
In addition to the above chimeric construct, a chimeric VEGF receptor/hIgG1Fc fusion protein was constructed having the first Ig-like domain of VEGFR-3, the second Ig-like domain of VEGFR-2 and the third Ig-like domain of VEGFR-1. The construct is designated R-3D1-R2D2-R1D3/hIgG1Fc.
To clone the pIgPlus-hVEGFR-3D1-R2D2-R1D3/hIgG1Fc construct, PCR was performed using pIgPlus-hVEGFR-3D1-R2D2+3/hIgG1Fc as a template and the T7 forward and reverse primer v362 (5′-TACAATTGAGGACAAGCGTATGTCCACGAAGTAGTTTAACTGGACGAGGC GTGCTTATTTGCACATCATAAATCCTATACC-3′) (SEQ ID NO: 126). The PCR-product was cut with HindIII and MfeI/MunI. The 787 bp VEGFR-3D1-R2D2+3/hIgG1Fc insert was ligated into the HindIII- and partially MfeI-cut vector plgPlus-hVEGFR-1D1-3-IgG1Fc. The presence and sequence of the correct chimeric insert was confirmed by sequencing the a representative hVEGFR-3D1-R2D2-R1D3/hIgG1Fc clone (clone #6) (SEQ ID NO: 127 and SEQ ID NO: 128).
Expression of Chimeric VEGFR/hIgG1Fc Fusions:
For expression analysis, the two new chimeric VEGF receptors and control constructs expressing R-1D1-3/hIgG1Fc, R-2D1-3/hIgG1Fc, R-3D1-3/hIgG1Fc, mature VEGF-C and VEGF-A165 were transiently transfected into 293T cells using JetPEI (QBioGene/MP Biomedicals, Irvine, Calif.). Metabolic labeling with 35S-methionine and 35S-cysteine was carried out at 48 hours post-transfection and labeling maintained for 24 hours. The serum-free conditioned medium was then immunoprecipitated using Protein A sepharose and either: a) specific antiserum against human mature VEGF-C; b) goat polyclonal antibody against human VEGF-A (R&D systems, Minneapolis, Minn.); or, c) serum-free medium of 293T cells taken 48 to 72 hours post-transient transfection with VEGF receptor/hIgG1Fc proteins (control proteins, R-1D1-3, R-2D1-3, R-3D1-3; chimeric proteins, R-3D1-R2D2+3 and R-3D1-R2D2-R1D3).
The immunoprecipitated fractions were analyzed on 17% SDS-PAGE and the dried gels were exposed for 12 hours on phosphoimager plates or 36 hours on X-ray films. Expression analysis demonstrated that the chimeric receptor fusion proteins exhibited high expression levels in transfected 293 T cells.
Analysis of Binding Properties of Chimeric VEGF Receptor/hIgG1Fc Fusions:
Ligand binding analysis was performed as described for the VEGF-C/VEGF-A hybrid growth factors in Example 1. Briefly, the unlabeled conditioned medium of transiently transfected 293T cells expressing the chimeric VEGFR/IgG1Fc fusion proteins was used to precipitate the 35S metabolically labeled mature VEGF-C, full-length VEGF-C, and VEGF-A165. SDS-PAGE of ligands immunoprecipitated with chimeric and control VEGFR/IgFc showed that the R-3D1-R2D2-R1D3/Ig chimeric protein strongly bound both VEGF-A and VEGF-C, as predicted based on the VEGFR2 and R1 immunoglobulin domains. In one experiment, the chimeric construct R-3D1-R2D2+3/Ig exhibited binding to VEGF-C and not VEGF-A. A second experiment with the R-3D-R2D2+3 μg construct showed only weak binding to VEGF-A.
These results demonstrate that the ligand binding constructs generated herein are useful in developing compositions that bind multiple growth factors involved in numerous cell activities. These constructs provide promising therapy for diseases such as cancer and other proliferative diseases wherein multiple growth factors mediate the condition or disease state.
Example 4
Assay for Neutralization of Growth Factor Activity
The following protocol provides an assay to determine whether a binding construct neutralizes one or more PDGF/VEGF growth factors by preventing the growth factor(s) from stimulating phosphorylation of its receptor.
Cells such as NIH 3T3 cells are transformed or transfected with a cDNA encoding a PDGFR/VEGFR receptor, such as VEGFR-3, and cultured under conditions where the encoded receptor is expressed on the surface of the cells. Transfected cells are cultured with either 1) plain growth medium; 2) growth medium supplemented with 50 ng/ml of one or more ligands for the recombinant receptor, such as fully processed VEGF-C and/or VEGF-D, which are ligands for VEGFR-3; 3) growth medium supplemented with 50 ng/ml of growth factor that does not bind the recombinant receptor (e.g., VEGF-A in the case of VEGFR-3), to serve as a control; or any of (1), (2), or (3) that is first pre-incubated with varying concentrations of a binding construct to be tested.
After culturing with the culture mediums described above in the presence or absence of the binding construct, the cells are lysed, immunoprecipitated using anti-receptor (e.g., anti-VEGFR-3) antiserum, and analyzed by Western blotting using anti-phosphotyrosine antibodies. Cells stimulated with the appropriate growth factor ligand (VEGF-C/D) stimulate VEGFR-3 autophosphorylation, which is detected with the anti-phosphotyrosine antibodies. Binding constructs that reduce or eliminate the ligand-mediated stimulation of receptor phosphorylation (e.g., in a dose-dependent manner) are considered neutralizing binding constructs.
Example 5
EPO Chimera Survival/Proliferation Blocking Assay
A binding construct is tested for the ability to block the binding of the growth factor(s) to their receptors, using bioassays of receptor binding and cross-linking. These assays involve the use of Ba/F3 pre-B cells which have been transfected with plasmid constructs encoding chimeric receptors consisting of the extracellular domain of growth factor receptors and the cytoplasmic domain of the erythropoietin receptor (Stacker, S A. et al., J. Biol. Chem. 274:34884-34892, 1999; Achen, M G. et al., Eur. J. Biochem. 267:2505-2515, 2000). These cells are routinely passaged in interleukin-3 (IL-3) and will die in the absence of IL-3. However, if signaling is induced from the cytoplasmic domain of the chimeric receptors, these cells survive and proliferate in the absence of IL-3. Such signaling is induced by ligands which bind and cross-link the extracellular domains of the chimeric receptors. Therefore binding of a growth factor ligand to the extracellular domains of the chimeric receptors causes the cells to survive and proliferate in the absence of IL-3. Addition of binding constructs that block the binding of growth factor to the extracellular domains will cause cell death in the absence of IL-3. An alternative Ba/F3 cell line which expresses a chimeric receptor containing the extracellular domain of the Tie2 receptor (that does not bind VEGF family members) is not induced by the relevant growth factors to proliferate and is used, in the presence of IL-3, as a control to test for non-specific effects of potential inhibitors.
In an exemplary assay, a binding construct that can bind VEGF-A and VEGF-C is tested. Samples of purified VEGF-A and VEGF-C are incubated with varying amounts of the binding construct for one hour at 4° C. in PBS before dilution of the mixtures 1:10 with IL-3-deficient cell culture medium. Ba/F3 cell lines expressing receptor(s) capable of binding the growth factors are then incubated in the media for 48 hours at 37° C. To measure DNA synthesis in the cells, 1 μCi of 3H-thymidine is added and the cells are incubated for 4 hours prior to harvesting. Incorporated 3H-thymidine is measured using a cell harvester (Tomtec®) and beta counting. The ability of the binding construct to block growth factor-mediated cell growth and survival (as measured by DNA synthesis) is analyzed relative to the control Tie2 cell line in the presence of IL-3. Growth inhibition in the experimental group relative to the control group demonstrates that the binding construct blocks cell growth, presumably by blocking the binding and cross-linking of receptors by growth factor ligands at the cell surface.
Example 6
Effect of Binding Constructs on BCE Migration
Solutions containing growth factors pre-incubated alone or with varying concentrations of a binding construct are placed in wells made in collagen gel and used to stimulate the migration of bovine capillary endothelial (BCE) cells in the gel as follows. A further control comprising neither growth factor ligand nor binding construct may also be employed, as may a control with just binding construct. Binding constructs that cause a decrease in migration (relative to when growth factor alone is employed) have an indication as therapeutics to prevent or retard angiogenesis.
BCE cells (Folkman et al., Proc. Natl. Acad. Sci. (USA), 76:5217-5221 (1979)) are cultured as described in Pertovaara et al., J. Biol. Chem., 269:6271-74 (1994). These or other cells employed may be transformed with growth factor receptor if not already expressed. For testing of VEGF-A/VEGF-C binding constructs, cells would be transformed with both VEGFR-2 and/or VEGFR-3. The collagen gels are prepared by mixing type I collagen stock solution (5 mg/ml in 1 mM HCl) with an equal volume of 2×MEM and 2 volumes of MEM containing 10% newborn calf serum to give a final collagen concentration of 1.25 mg/ml. The tissue culture plates (5 cm diameter) are coated with about 1 mm thick layer of the solution, which is allowed to polymerize at 37° C. BCE cells were seeded on top of this layer. For the migration assays, the cells are allowed to attach inside a plastic ring (1 cm diameter) placed on top of the first collagen layer. After 30 minutes, the ring is removed and unattached cells are rinsed away. A second layer of collagen and a layer of growth medium (5% newborn calf serum (NCS)), solidified by 0.75% low melting point agar (FMC BioProducts, Rockland, Me.), are added. A well (3 mm diameter) is punched through all the layers on both sides of the cell spot at a distance of 4 mm, and the sample or control solutions are pipetted daily into the wells. Photomicrographs of the cells migrating out from the spot edge are taken after six days through an Olympus CK 2 inverted microscope equipped with phase-contrast optics. The migrating cells are counted after nuclear staining with the fluorescent dye bisbenzimide (1 mg/ml, Hoechst 33258, Sigma).
The number of cells migrating at different distances from the original area of attachment towards wells containing sample solutions are determined 6 days after addition of the media. The number of cells migrating out from the original ring of attachment is counted in five adjacent 0.5 mm×0.5 mm squares using a microscope ocular lens grid and 10× magnification with a fluorescence microscope. Cells migrating further than 0.5 mm are counted in a similar way by moving the grid in 0.5 mm steps. The experiments are carried out twice with similar results. Daily addition of 1 ng of FGF2 into the wells may be employed as a positive control for cell migration.
Example 7
Soluble VEGFR-1, VEGFR-2, and/or VEGFR-3 Containing Constructs Inhibitory Effect on VEGF-C Mediated Tumor Growth and Metastasis
To demonstrate the ability of polypeptides and binding constructs of the invention employed to inhibit tumor growth and/or metastasis, any accepted tumor model may be employed. Exemplary models include animals predisposed to developing various types of cancers, animals injected with tumors or tumor cells or tumor cell lines from the same or different species, including optionally cells transformed to recombinantly overexpress one or more growth factors such as VEGF-A, VEGF-B, VEGF-C, VEGF-D, or VEGF-E, or PDGF-A, or PDGF-B, or PDGF-C, or PDGF-D or PlGF. To provide a model for tumors in vivo in which multiple growth factors are detectable, it is possible to transform tumor cell lines with exogenous DNA to cause expression of multiple growth factors.
Polypeptide binding constructs may be administered directly, e.g., in protein form by i.v. transfusion or by implanted micropumps, or in nucleic acid form as part of a gene therapy regimen. Subjects are preferably grouped by sex, weight, age, and medical history to help minimize variations amongst subjects.
Efficacy is measured by a decrease in tumor, size (volume) and weight. One may also examine the nature of the effect on tumor size, spreads (metasteses) and number of tumors. For example, use of specific cell markers can be used to show the effect on angiogenesis relative to lymphangiogenesis, a VEGF-A binding construct expected to have a greater effect on the former, and a VEGF-C binding construct expected to have a greater effect on the latter. Animals may be looked at as a whole for survival time and changes in weight. Tumors and specimens are examined for evidence of angiogenesis, lymphangiogenesis, and/or necrosis.
SCID mice may be used as subjects for the ability of the soluble binding constructs of the present invention to inhibit or prevent the growth of tumors. The binding construct used in the therapy is generally chosen such that it binds to a growth factor ligand expressed by the tumor cell, especially growth factors that are overexpressed by the tumor cell relative to non-neoplastic cells in the subject. In the SCID model, tumor cells, e.g., MCF-7 cells, may be transfected with a virus encoding a particular growth factor under the control of a promoter or other expression control sequence that provides for overexpression of the growth factor as described in WO 02/060950. Alternatively, other cell lines may be employed, e.g., HT-1080, as described in U.S. Pat. No. 6,375,929. One may transfect the tumor cells with as may growth factor ligands as one desires to overexpress, or a tumor cell line may be chosen that already overexpresses one or more growth factor ligands of interest. One group of subjects is implanted with cells that have been mock-transfected, i.e., with a vector lacking a growth factor ligand insert.
Either before, concurrently with, or after the tumor implantation of the above-described cells, subjects are treated with a particular binding construct. There are a number of different ways of administering the construct. In vivo and/or ex vivo gene therapy may be employed. For example, cells may be transfected with a adenovirus, or other vector, that encodes the construct and implanted with the tumor cells expressing the growth factor(s), the cells transfected with the binding construct may be the same as those transformed with growth factor(s) (or already overexpressing the growth factor(s)). In some embodiments, an adenovirus that encodes that binding construct is injected in vivo, e.g., intravenously. In some embodiments, the binding construct itself (e.g., in protein form) is administered either systematically or locally, e.g., using a micropump. When testing the efficacy of a particular binding construct, at least one control is normally employed. For example, in the case of a vector-based therapy, a vector with an empty insert or LacZ is employed, or the insert may be a construct comprising a complete ECD of a growth factor receptor capable of binding the growth factor(s) of interest, such a control may employ more than one ECD construct if necessary (e.g., for binding multiple ligands if binding constructs with multiple ligand binding affinities are employed).
Exemplary Procedures
A. Preparation of Plasmid Expression Vectors, Transfection of Cells, and Testing of the Same
A cDNA encoding VEGF-A, VEGF-B, VEGF-C, VEGF-D, PlGF, PDGF-A, PDGF-B, PDGF-C, PDGF-D, or combinations thereof introduced into a pEBS7 plasmid (Peterson and Legerski, Gene, 107: 279-84, 1991). This same vector may be used for the expression of the soluble binding constructs.
The MCF-7S1 subclone of the human MCF-7 breast carcinoma cell line is transfected with the plasmid DNA by electroporation and stable cell pools are selected and cultured as previously described (Egeblad and Jaattela, Int. J. Cancer, 86: 617-25, 2000). The cells are metabolically labeled in methionine and cysteine free MEM (Gibco) supplemented with 100 μCi/ml [35S]-methionine and [35S]-cysteine (Redivue Pro-Mix, Amersham Pharmacia Biotech). The labeled growth factors are immunoprecipitated from the conditioned medium using antibodies against the expressed growth factor(s). The immunocomplexes and the binding complexes are precipitated using protein A sepharose (Amersham Pharmacia Biotech), washed twice in 0.5% BSA, 0.02% Tween 20 in PBS and once in PBS and analyzed in SDS-PAGE under reducing conditions.
B. Subject Preparation and Treatment
Cells (20,000/well) are plated in quadruplicate in 24-wells, trypsinized on replicate plates after 1, 4, 6, or 8 days and counted using a hemocytometer. Fresh medium is provided after 4 and 6 days. For the tumorgenesis assay, sub-confluent cultures are harvested by trypsination, washed twice and 107 cells in PBS are inoculated into the fat pads of the second (axillar) mammary gland of ovariectomized SCID mice, carrying subcutaneous 60-day slow-release pellets containing 0.72 mg 17β-estradiol (Innovative Research of America). The ovarectomy and implantation of the pellets are performed 4-8 days before tumor cell inoculation.
The cDNA coding for the binding construct(s) is subcloned into the pAdBglII plasmid and the adenoviruses produced as previously described (Laitinen et al., Hum. Gene Ther., 9: 1481-6, 1998). The binding construct(s) or LacZ control (Laitinen et al., Hum. Gene Ther., 9: 1481-6, 1998) adenoviruses, 109 pfu/mouse, are injected intravenously into the SCID mice 3 hours before the tumor cell inoculation.
C. Analysis of Treatment Efficacy
Tumor length and width are measured twice weekly in a blinded manner, and the tumor volume are calculated as the length×width×depth×0.5, assuming that the tumor is a hemi-ellipsoid and the depth is the same as the width (Benz et al., Breast Cancer Res. Treat., 24: 85-95, 1993).
The tumors are excised, fixed in 4% paraformaldehyde (pH 7.0) for 24 hours, and embedded in paraffin. Sections (7 μm) are immunostained with monoclonal antibodies against, for example, PECAM-1 (Pharmingen), VEGFR-1, VEGFR-2, VEGFR-3 (Kubo et al., Blood, 96: 546-553, 2000) or PCNA (Zymed Laboratories), PDGFR-α, PDGFR-β or polyclonal antibodies against LYVE-1 (Banerji et al., J Cell Biol, 144: 789-801, 1999), VEGF-C (Joukov et al., EMBO J., 16: 3898-911, 1997), laminin according to published protocols (Partanen et al., Cancer, 86: 2406-12, 1999), or any of the growth factors. The average of the number of the PECAM-1 positive vessels are determined from three areas (60× magnification) of the highest vascular density (vascular hot spots) in a section. All histological analyses are performed using blinded tumor samples.
Three weeks after injection of adenovirus constructs and/or protein therapy, four mice from each group are narcotized, the ventral skin is opened and a few microliters 3% Evan's blue dye (Sigma) in PBS is injected into the tumor. The drainage of the dye from the tumor is followed macroscopically.
Imagining and monitoring of blood and blood proteins to provide indication of the health of subjects and the extent of tumor vasculature may also be performed.
Example 8
Effects on Tumor Progression in Subjects Using a Combined Therapy of a Binding Construct and a Chemotherapeutic Agent
This study is carried out to test the efficacy of using the binding constructs of the invention in combination with other anti-cancer therapies and/or using multiple binding constructs of the invention. Such therapies include chemotherapy, radiation therapy, anti-sense therapy, RNA interference, and monoclonal antibodies directed to cancer targets. The combinatorial effect may be additive, but it is preferably synergistic in its anti-cancer effects, e.g., prevention, suppression, regression, and elimination of cancers, prolongation of life, and/or reduction in side-effects.
Subjects are divided into groups with one group receiving a chemotherapeutic agent, one group receiving a binding construct, and one group receiving both a chemotherapeutic agent and a binding construct at regular periodic intervals, e.g., daily, weekly or monthly. In human studies, the subjects are generally grouped by sex, weight, age, and medical history to help minimize variations among subjects. Ideally, the subjects have been diagnosed with the same type of cancer. In human or non-human subjects, progress can be followed by measuring tumor size, metastases, weight gain/loss, vascularization in tumors, and white blood cells counts.
Biopsies of tumors are taken at regular intervals both before and after beginning treatment. For example, biopsies are taken just prior to treatment, at one week, and then at one month intervals, thereafter, or whenever possible, e.g., as tumors are excised. One examines the biopsies for cell markers, and overall cell and tissue morphology to assess the effectiveness of the treatment. In addition, or in the alternative, imagining techniques may be employed.
For non-human animal studies, an additional placebo control may be employed. Animal studies, performed in accordance with NIH guidelines, also provide the advantage of the insertion of relatively uniform cancer cell population, and tumors that selectively overproduce the one or more growth factors targeted by the binding construct. Tumors may be excised and analyzed as described in any one of Examples 2-5.
Example 9
Animal Models to Demonstrate the Efficacy of Anti-VEGFR-2 Therapies for Treatment of Diseases by Inhibition of VEGF-A Mediated Effects While Preserving VEGF-C Binding
An acceptable animal model is used, e.g., mice or rats. In some embodiments, animals with tumors are treated with selective VEGF-A antagonist anti-VEGFR-2 antibodies or a control. At various time points, before, during, and after treatment, tumors are excised from the two groups. The tumors are then examined for VEGF-A and VEGF-C mediated characteristics to determine whether VEGF-A mediated characteristic have been diminished relative to VEGF-C mediated characteristics. These characteristics may be assessed using cell surface markers indicative of angiogenesis and markers indicative of lymphangiogenesis.
The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Because modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. The patents, patent application publications and other publications (e.g., Journal articles, and web/Internet materials) referenced herein are incorporated in their entirety.
Although the applicant(s) invented the full scope of the claims appended hereto, the claims are not intended to encompass within their scope the prior art work of others. Therefore, in the event that statutory prior art within the scope of a claim is brought to the attention of the applicants by a Patent Office or other entity or individual, the applicant(s) reserve the right to exercise amendment rights under applicable patent laws to redefine the subject matter of such a claim to specifically exclude such statutory prior art or obvious variations of statutory prior art from the scope of such a claim. Variations of the invention defined by such amended claims also are intended as aspects of the invention.

## Claims

1. A method of inhibiting endothelial cell proliferation comprising steps of:
(a) screening a mammal to identify a neoplastic disorder characterized by endothelial cell proliferation, and an elevated level of VEGF-C in serum or in a tissue sample from a tumor; and
(b) administering a composition to the mammal identified according to step (a) as having a neoplastic disorder characterized by endothelial cell proliferation and the elevated level of VEGF-C, wherein said composition comprises a fusion protein comprising a first binding unit polypeptide connected to a heterologous peptide, in an amount effective to inhibit endothelial or smooth muscle cell proliferation in said mammal, wherein the amino acid sequence of the first binding unit polypeptide consists of an amino acid sequence at least 95% identical to a VEGFR-3 fragment consisting of a portion of SEQ ID NO: 6,
wherein the amino-terminal amino acid of the VEGFR-3 fragment is selected from the group consisting of positions 1-47 of SEQ ID NO: 6,
wherein the carboxy-terminal residue of the VEGFR-3 fragment is selected from the group consisting of positions 211 to 247 of SEQ ID NO: 6, and
wherein the VEGFR-3 fragment and the purified fusion protein bind human VEGF-C.

2. A method of inhibiting endothelial cell proliferation in a mammal, comprising administering to a mammal a composition, said composition comprising a fusion protein comprising a first binding unit polypeptide connected to a heterologous peptide, in an amount effective to inhibit endothelial cell proliferation in the mammal, wherein the amino acid sequence of the first binding unit polypeptide consists of an amino acid sequence at least 95% identical to a VEGFR-3 fragment consisting of a portion of SEQ ID NO: 6,
wherein the amino-terminal amino acid of the VEGFR-3 fragment is selected from the group consisting of positions 1-47 of SEQ ID NO: 6,
wherein the carboxy-terminal residue of the VEGFR-3 fragment is selected from the group consisting of positions 211 to 247 of SEQ ID NO: 6, and
wherein the VEGFR-3 fragment and the purified fusion protein bind human VEGF-C.

3. The method of claim 1 or 2, wherein the heterologous peptide comprises an immunoglobulin constant domain fragment.

4. The method of claim 1 or 2, wherein the amino acid sequence that is at least 95% identical to the VEGFR-3 fragment is selected from the group consisting of SEQ ID NOS: 36 and 38.

5. The method of claim 1 or 2 wherein the fusion protein further comprises a signal peptide.

6. The method of claim 5, wherein the signal peptide directs secretion of the fusion protein from a cell that expresses the fusion protein.

7. The method of claim 1 or 2, wherein the VEGFR-3 fragment has an amino acid sequence selected from the group consisting of positions 1-226 and 1-229 of SEQ ID NO: 6.

8. The method of claim 1 or 2, wherein the fusion protein comprises an amino acid sequence of a VEGFR-3 fragment connected to a heterologous peptide, said VEGFR-3 fragment consisting of a portion of SEQ ID NO: 6,
wherein the amino-terminal residue of the VEGFR-3 fragment is selected from the group consisting of positions 1 to 47 of SEQ ID NO: 6,
wherein the carboxy-terminal residue of the VEGFR-3 fragment is selected from the group consisting of positions 211 to 247 of SEQ ID NO: 6, and wherein the VEGFR-3 fragment and the purified fusion protein bind human VEGF-C.

9. The method of claim 8, wherein the VEGFR-3 fragment has a carboxy-terminal amino acid selected from the group consisting of positions 226 and 229 of SEQ ID NO: 6.

10. The method of claim 1 or 2 wherein the composition comprises a binding construct comprising the fusion protein is operatively connected with a second binding unit that binds at least one growth factor selected from the group consisting of VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, PlGF, PDGF-A, PDGF-B, PDGF-C, and PDGF-D, wherein the second binding unit is selected from the group consisting of a polypeptide comprising a vascular endothelial growth factor receptor extracellular domain fragment, a platelet derived growth factor receptor extracellular domain fragment, and a polypeptide comprising an antigen binding fragment of an antibody that immunoreacts with the at least one of said growth factors.

11. The method of claim 10, further comprising a linker connecting the first and second binding units.

12. The method of claim 11, wherein the linker comprises a peptide that links the first and second polypeptides to form a single polypeptide.