CA2420765A1 - Anti-angiogenic peptides - Google Patents

Abstract

The invention relates to anti-angiogenic peptides derived from fibrinogen; pharmaceutical compositions comprising said peptides; nucleic acids encoding said peptides and methods to treat animals, preferably humans, suffering fro m diseases which would benefit from the inhibition of angiogenesis.

Description

ANTI-ANGIOGENIC PEPTIDES
The invention relates to the anti-angiogenic effects of peptides derived from fibrinogen.
Angiogenesis, the development of new blood vessels from an existing vascular bed, is a complex multistep process that involves the degradation of components of the extracellular matrix and then the migration, proliferation and differentiation of endothelial cells to form tubules and eventually new vessels. Angiogenesis is important in normal physiological processes including, by example and not by way of limitation, embryo implantation; embryogenesis and development; and wound healing. Excessive angiogenesis is also involved in pathological conditions such as tumour cell growth and non-cancerous conditions such as neovascular glaucoma, rheumatoid arthritis, psoriasis and diabetic retinopathy.
The vascular endothelium is normally quiescent. However, upon activation endothelial cells proliferate and migrate to form microtubules which will ultimately form a capillary bed to supply blood to developing tissues and, of course, a growing tumour. A number of growth factors have been identified which promote/activate endothelial cells to undergo angiogenesis. These include, by example and not by way of limitation; vascular endothelial growth factor (VEGF); transforming growth factor (TGFb); acidic and basic fibroblast growth factor (aFGF and bFGF); and platelet derived growth factor (PDGF) (1,2).
VEGF is a an endothelial cell-specific growth factor which has a very specific site of action, namely the promotion of endothelial cell proliferation, migration and differentiation. VEGF is a dimeric complex comprising two identical 23 1cD
polypeptides. The monomeric form of VEGF can exist as four distinct polypeptides of different molecular weight, each being derived from an alternatively spliced mRNA. Of the four monomeric forms, two exist as membrane bound VEGF and two are soluble. VEGF is expressed by a wide variety of cell/tissue types including CONFIRMATION COPY

embryonal tissues; proliferating lceratinocytes; macrophages; tumour cells.
Studies (2) have shown VEGF is highly expressed in many tumour cell-lines including glioma and AIDS-associated Kaposi's sarcoma. VEGF activity is mediated through VEGF specific receptors expressed by endothelial cells and tumour cells.
Indeed, VEGF receptors axe up-regulated in endothelial cells which infiltrate tumours thereby promoting tumour cell growth.
bFGF is a growth factor which functions to stimulate the proliferation of fibroblasts and endothelial cells. bFGF is a single polypeptide chain with a molecular weight of 16.SKd. Several molecular forms of bFGF have been discovered which differ in the length at their amino terminal region. However the biological function of the various molecular forms appears to be the same. bFGF is produced by the pituitary gland and is encoded by a single gene located on human chromosome 4.
A number of endogenous inhibitors of angiogenesis have been discovered, examples of which are angiostatin and endostatin, which are formed by the proteolytic cleavage of plasminogen and collagen XVIII respectively. Both of these factors have been shown to suppress the activity of pro-angiogenic growth factors such as vascular VEGF and bFGF. Both also suppress endothelial cell responses to VEGF and bFGF
in vitro, and reduce the vascularisation and growth of experimental tumours in animal models.
Fibrinogen, the soluble circulating precursor of fibrin, is a dimeric molecule containing pairs of non-identical chains, (ie the a-,(3- and y-chains). These are aa~ranged as three discrete domains, the two outer D-domains and the central E
-domain (4). Fibrinogen can be digested either by plasmin or thrombin.
The first step in plasmin cleavage of fibrinogen is the cleavage of the a chain C-terminal domain. Plasmin then cleaves the two D domains from the one E domain (consisting of the NH2 terminal regions of the a-,(3- and y-chains held together by disulphide bonds) and numerous smaller fragments including a small peptide, betal-42 (amino terminal of the (3- chain) (5). Thrombin, on the other hand, produces a fibrin monomer and two copies of fibrinopeptides A and B (4). Fibrinogen has been shown to accumulate around leaky blood vessels in solid tumours(5), Fibrinogen has also been shown to polymerise at host-tumour interface to form fibrin networks that promote tumour angiogenesis by supporting the adhesion, migration, proliferation and differentiation of endothelial cells (7).
The fibrin E-fragment (FnE-fragment), produced by the proteolytic cleavage of fibrin, stimulates angiogenesis in the chorioallantoic membrane assay (8).
Furthermore, the amount of this protein present in invasive breast carcinomas positively correlates with the degree of tumour vascularity (5).
A potent, new inhibitor of angiogenesis, which is a 50 lcDa proteolytic fragment of fibrinogen, fibrinogen E, is disclosed in our co-pending application, PCT/GBO1/02079, which is incorporated by reference. We have now identified a domain within the fibrinogen E fragment which has the same anti-angiogenic activity as the very much laxger fibrinogen E fragment. The domain is located at the amino terminus of the a chain and is referred to as al-24. A peptide derived from the domain has anti-angiogenic activity. We have also identified modified ocl-24 peptides which retain the anti-angiogenic activity of the unmodified al-24 peptide.
According to a first aspect of the invention there is provided a polypeptide comprising an amino acid sequence selected from the group consisting of:
i) a peptide of the sequence:
ADSXEXXFLAEGGGVXXPXVVEXH
wherein X is any amino acid residue;
ii) a peptide as represented in (i) wherein amino acid residue X is selected from the following group: alanine, valine, leucine, isoleucine, proline; and iii) a peptide represented in (i) or (ii) which has anti-angiogenic activity.

Reference to anti-angiogenic activity is determined by assays hereindisclosed.
For example, the polypeptides of the invention are tested by ifZ vitro assays which include the inhibition of endothelial cell mediated tubule formation, inhibition of endothelial cell migration, inhibition of VEGF and bFGF induced endothelial cell proliferation and endothelial cell cytotoxicity assays. Polypeptides can also be tested ih vivo using marine tumour models as hereindisclosed.
In a preferred embodiment of the invention said polypeptide comprises an amino acid sequence selected from the following group:
ADSGEGDFLAEGGGVRGPRVVERH
ADSGEGDFLAEGGGVRGPRVVEXH
ADSGEGDFLAEGGGVRGPXVVERH
ADSGEGDFLAEGGGVRXPRVVERH
ADSGEGDFLAEGGGVXGPRVVERH
ADSGEGXFLAEGGGVRGPRVVERH
ADSGEXDFLAEGGGVRGPRVVERH
ADSXEGDFLAEGGGVRGPRVVERH
ADSXEXDFLAEGGGVRXPRVVERH
ADSGEGXFLAEGGGVRGPXVVERH
In a further preferred embodiment of the invention said peptide comprises an amino acid sequence wherein X is alanine.
In a yet further preferred embodiment of the invention said polypeptide comprises the amino acid sequence:
ADSGEGDFLAEGGGVRGPRVVERH
Reference to a,1-24 peptide is reference to a peptide which has the sequence:
ADSGEGDFLAEGGGVRGPRVVERH, or active peptides derived from this sequence which have been modified by, addition, deletion, or substitution of at least one amino acid residue.
In a preferred embodiment of the invention said polypeptide is at least 24 amino acid residues in length. Preferably said peptide consists of the amino acid sequence ADSGEGDFLAEGGGVRGPRVVERH,orfragmentthereof.
Reference to fragment is reference to a peptide derived from the al-24 peptide which retains anti-angiogenic activity. Such fragments may be 3 amino acids in length;
preferably said fragments are 4, 5, 6, 7, 8, 9, 10, 1 l, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 or 23 amino acid residues in length.
It will be apparent to one skilled in the art that modification to the amino acid sequence of polypeptides comprising al-24 could enhance the binding and/or stability of the polypeptide with respect to its target sequence. In addition, modification of the polypeptide may also increase the in vivo stability of the polypeptide thereby reducing the effective amount of polypeptide necessary to inhibit angiogenesis. This would advantageously reduce undesirable side effects which may result in vivo. Modifications include, by example and not by way of limitation, acetylation and amidation.
In a preferred embodiment of the invention said polypeptide comprising the al-sequence is acetylated. Preferably said acetylation is to the amino terminus of said polypeptide. More preferably still the amino terminal alanine amino acid of the al-24 peptide is acetylated.
In a further preferred embodiment of the invention said polypeptide comprising the al-24 sequence is amidated. Preferably said amidation is to the carboxyl-terminus of said polypeptide. More preferably still the carboxy-terminal histidine amino acid is amidated.

In a fuxther preferred embodiment of the invention the oc 1-24 peptide, or fragment thereof, is modified by both acetylation and amidation. Preferably said acetylation is to the amino-terminal alanine amino acid of the al-24 peptide and said amidation is to the carboxyl-terminal histidine of the al-24 peptide.
It will be apparent to one skilled in the art that fragments of the al-24 peptide as herein disclosed, are susceptible to modifications such as acetylation axzd/or amidation.
Alternatively or preferably, said modification includes the use of modified amino acids in the production of recombinant or synthetic forms of polypeptides comprising al-24 peptide.
It will be apparent to one skilled in the art that modified amino acids include, by way of example and not by way of limitation, 4-hydroxyproline, 5-hydroxylysine, N6-acetyllysine, N6-methyllysine, N6,N6-dimethyllysine, N6,N6,N6-trimethyllysine, cyclohexyalanine, D-amino acids, ornithine. Other modifications include amino acids with a C2, C3 or C~ allcyl R group optionally substituted by l, 2 or 3 substituents selected from halo ( eg F, Br, I), hydroxy or C1-C4 alkoxy.
In a further preferred embodiment of the invention there is provided a polypeptide according to the invention which polypeptide comprises at least one modified amino acid wherein X denotes the position of said modified amino acid.
The incorporation of modified amino acids may confer advantageous properties on polypeptides comprising al-24. For example, the incorporation of modified amino acids may increase the affinity of the polypeptide for its binding site, or the modified amino acids may confer increased ih vivo stability on the polypeptide thus allowing a decrease in the effective amount of therapeutic polypeptide administered to a patient.

It will also be apparent to one skilled in the art that fragments of ocl-24 that retain anti-angiogenic activity could be recovered by fractionation of the intact polypeptide using, far example, proteolytic enzymes. Alternatively, fragments could be synthesised de novo and also modified by, for example, cyclisation.
Cyclisation is known in the art, (see Scott et al Chem Biol (2001), 8:801-815; Gellerman et al J.
Peptide Res (2001), 57: 277-291; Dutta et al J. Peptide Res (2000), 8: 398-412;
Ngolca and Gross J Amer Soc Mass Spec (1999), 10:360-363.
In a preferred embodiment of the invention the polypeptides according to the invention are modified by cyclisation.
According to a further aspect of the invention there is provided a nucleic acid molecule comprising DNA sequences selected from:
i) the DNA sequence as represented in Figure Sa;
ii) the DNA sequence as represented in Figure Sa which has been modified by addition, deletion, or substitution of at least one nucleotide base within at least one codon to encode a modified peptide according to the invention;
iii) DNA sequences which hybridise to the sequences presented in Figure 6 which encode a peptide having anti-angiogenic activity; and iv) DNA sequences which are degenerate as a result of the genetic code to the DNA sequences defined in (i), (ii) or (iii).
In a preferred embodiment of the invention there is provided an isolated nucleic acid molecule which anneals under stringent hybridisation conditions to the sequences described in (i), (ii), (iii) and (iv) above.
Stringent hybridisation/washing conditions are well known in the art. For example, nucleic acid hybrids that are stable after washing in O.IxSSC,0.1% SDS at 60°C. It is well known in the art that optimal hybridisation conditions can be calculated if the sequence of the nucleic acid is laiown. Typically, hybridisation conditions uses 4 - 6 x SSPE (20x SSPE contains 175.3g NaCI, 88.2g NaH~,P04 H20 and 7.4g EDTA

dissolved to 1 litre and the pH adjusted to 7.4); 5-lOx Denhardts solution (50x Denhardts solution contains Sg Ficoll (Type 400, Pharmacia), 5~
polyvinylpyrrolidone abd Sg bovine serum albumen; 100~g-l.Omglml sonicated salmon/herring DNA; 0.1-1.0% sodium dodecyl sulphate; optionally 40-60%
deionised formamide. Hybridisation temperature will vary depending on the GC
content of the nucleic acid target sequence but will typically be between 42°- 65° C.
According to a further aspect the invention there is provided a pharmaceutical composition comprising a al-24 peptide, or part thereof, When administered, the pharmaceutical compositions of the present invention are administered in pharmaceutically acceptable preparations. Such preparations may routinely contain pharmaceutically acceptable concentrations of salt, buffering agents, preservatives, compatible carriers, supplementary immune potentiating agents such as adjuvants and cytokines and optionally other therapeutic agents, such as chemotherapeutic agents.
The pharmaceutical compositions of the invention can be administered by any conventional route, including injection or by gradual infusion over time. The administration may, for example, be oral, intravenous, intraperitoneal, intramuscular, intracavity, subcutaneous, or transdermal.
The compositions of the invention are administered in effective amounts. An "effective amount" is that amount of a composition that alone, or together with further doses, produces the desired response. In the case of treating a particular disease, such as cancer, the desired response is inhibiting the progression of the disease. This may involve slowing the progression of the disease temporarily, although more preferably, it involves halting the progression of the disease permanently. This can be monitored by routine methods.

Such amounts will depend, of course, on the particular condition being treated, the severity of the condition, the individual patient parameters including age, physical condition, size and weight, the duration of the treatment, the nature of concurrent therapy (if my), the specific route of administration and like factors within the knowledge and expertise of the health practitioner. These factors are well lmown to those of ordinary skill in the art and can be addressed with no more than routine experimentation.
The pharmaceutical compositions used in the foregoing methods of treatment preferably are sterile and contain an effective amount of al-24 peptide or nucleic acid encoding a1-24 peptide for producing the desired response in a unit of weight or volume suitable for administration to a patient.
The doses of al-24 peptide or nucleic acid encoding al-24 peptide administered to a subject can be chosen in accordance with different parameters, in particular in accordance with the mode of administration used and the state of the subject.
Other factors include the desired period of treatment. In the event that a response in a subject is insufficient at the initial doses applied, higher doses (or effectively higher doses by a different, more localized delivery route) may be employed to the extent that patient tolerance permits.
When administered, the therapeutic preparations of the invention are applied in therapeutically-acceptable amounts and in pharmaceutically-acceptable compositions.
The term "pharmaceutically acceptable" means a non-toxic material that does not interfere with the effectiveness of the biological activity of the active ingredients.
Such preparations may routinely contain salts, buffering agents, preservatives, compatible carriers, and optionally other therapeutic agents. When used in medicine, the salts should be pharmaceutically acceptable, but non-pharmaceutically acceptable salts may conveniently be used to prepare pharmaceutically-acceptable salts thereof and are not excluded from the scope of the invention.

al-24 peptide compositions may be combined, if desired, with a pharmaceutically-acceptable carrier. The term "pharmaceutically-acceptable carrier" as used herein means one or more compatible solid or liquid fillers, diluents or encapsulating substances which are suitable for administration into a human. The term "caiTier"
denotes an organic or inorganic ingredient, natural or synthetic, with which the active ingredient is combined to facilitate the application.
The pharmaceutical compositions may contain suitable buffering agents, including:
acetic acid in a salt; citric acid in a salt; boric acid in a salt; and phosphoric acid in a salt.
The pharmaceutical compositions also may contain, optionally, suitable preservatives, such as: benzallconimn chloride; chlorobutanol; parabens and thimerosal.
The pharmaceutical compositions may conveniently be presented in unit dosage form and may be prepared by any of the methods well-known in the art of pharmacy.
All methods include the step of bringing the active agent into association with a carrier which constitutes one or more accessory ingredients. In general, the compositions are prepared by uniformly and intimately bringing the active compound into association with a liquid carrier, a finely divided solid carrier, or both, and then, if necessary, shaping the product.
Compositions suitable for oral administration may be presented as discrete units, such as capsules, tablets, lozenges, each containing a predetermined amount of the active compound. Other compositions include suspensions in aqueous liquids or non-aqueous liquids such as a syrup, elixir or an emulsion.
Compositions suitable for parenteral administration conveniently comprise a sterile aqueous or non-aqueous preparation of al-24 peptides or nucleic acids, which is preferably isotonic with the blood of the recipient. This preparation may be formulated according to known methods using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation also may be a sterile injectable solution or suspension in a non-toxic paxenterally-acceptable diluent or solvent, for example, as a solution in 1,3-butane diol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono-or di-glycerides. In addition, fatty acids such as oleic acid may be used in the preparation of injectables.
Carrier formulation suitable for oral, subcutaneous, intravenous, intramuscular, etc.
administrations can be found in Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton, PA.
In a preferred embodiment of the invention said pharmaceutical composition modulates angiogenesis. Preferably said modulation is the inhibition of angiogenesis.
Preferably said inhibition relates to endothelial cell stimulated angiogenesis.
Alternatively, or preferably, said inhibition is the inhibition of macrophage and/or tumour cell stimulated angiogenesis.
In a further preferred embodiment of the invention said inhibition is mediated by the inhibition of pro-angiogenic factors. Ideally these are either intracellular or cell surface receptors.
More preferably still, said inhibition is mediated via inhibition of the activity of pro-angiogenic growth factors. Ideally said growth factors are selected from:
VEGF, bFGF; aFGF; TGF(3; PDGF.

According to a yet further aspect of the invention there is provided the use of a polypeptide comprising al-24 peptides, or part thereof, in the manufacture of a medicament for use in the treatment of cancer.
Polypeptides which comprise al-24 peptides can be manufactured by in vitro peptide synthesis using standard peptide synthesis techniques. Alternatively, or preferably, polypeptides can be manufactured by recombinant techniques which are well known in the art.
According to a further aspect of the invention there is provided a vector, wherein said vector includes a nucleic acid molecule which encodes for polypeptides which comprise ccl-24 peptides.
Alternatively, vectors) which include nucleic acid encoding polypeptides which comprise a,1-24 peptides can be adapted for recombinant expression.
In a preferred embodiment of the invention said vector is an expression vector adapted for prokaryotic or eukaiyotic cell expression. Preferably said eulcaryotic vector is adapted for gene therapy.
Typically said adaptation includes, by example and not by way of limitation, the provision of transcription control sequences (promoter sequences) which mediate cell/tissue specific expression. These promoter sequences may be cell/tissue specific, inducible or constitutive.
Promoter is an art recognised term and, for the sake of clarity, includes the following features which axe provided by example only, and not by way of limitation.
Enhancer elements are cis acting nucleic acid sequences often found 5' to the transcription initiation site of a gene (enhancers can also be found 3' to a gene sequence or even located in intronic sequences and is therefore position independent).
Enhancers function to increase the rate of transcription of the gene to which the enhancer is linlced. Enhancer activity is responsive to tf°afzs acting transcription factors (polypeptides) which have been shown to bind specifically to enhancer elements. The binding/activity of transcription factors (please see Eulcaryotic Transcription Factors, by David S Latchman, Academic Press Ltd, San Diego) is responsive to a number of environmental cues which include, by example and not by way of limitation, intermediary metabolites or environmental effectors.
Promoter elements also include so called TATA box and RNA polymerase initiation selection (RIS) sequences which function to select a site of transcription initiation.
These sequences also bind polypeptides which function, inter alia, to facilitate transcription initiation selection by RNA polymerase.
Adaptations also include the provision of selectable markers and autonomous replication sequences which both facilitate the maintenance of said vector in either the eukaryotic cell or prokaryotic host. Vectors which axe maintained autonomously axe referred to as episomal vectors.
Adaptations which facilitate the expression of vector encoded genes include the provision of transcription termination/polyadenylation sequences. This also includes the provision of internal ribosome entry sites (IRES) which function to maximise expression of vector encoded genes arranged in bicistronic or mufti-cistronic expression cassettes.
These adaptations axe well known in the art. There is a significant amount of published literature with respect to expression vector construction and recombinant DNA techniques in general. Please see, Sambrook et al (1989) Molecular Cloning: A
Laboratory Manual, Cold Spring Harbour Laboratory, Cold Spring Harbour, NY and references therein; Maxston, F (1987) DNA Cloning Techniques: A Practical Approach Vol III IRL Press, Oxford UK; DNA Cloning: F M Ausubel et al, Current Protocols in Molecular Biology, John Wiley & Sons, Inc.(1994).

In a yet further preferred embodiment of the invention there is provided a gene therapy vector comprising the nucleic acid according to the invention.
It will be apparent to one skilled in the art that the delivery of gene therapy vectors either to endothelial cells or tumour cells target the production of polypeptides comprising al-24 peptides to the vicinity of the tumour thereby augmenting the anti-angiogenic effect ofpolypeptides comprising al-24.
According to a yet further aspect of the invention there is provided a cell transformed/transfected with the nucleic acid according to the invention.
Ideally said nucleic acid is the vector according to the invention.
According to a further aspect of the invention there is provided a method for the production of polypeptides comprising al-24 including:
r) providing a cell according to the invention;
ii) providing conditions conducive to the manufacture of polypeptides comprising al-24; and iii) purifying said polypeptides from a cell, or a cells culture environment.
According to yet still a further aspect of the invention there is provided a non-human, transgenic animal characterised in that said animal incorporates a nucleic acid molecule encoding a polypeptide comprising al-24 into its genome.
It will be apparent to one skilled in the art that the provision of non-human transgenic animals genetically modified by the provision of a transgene(s) encoding polypeptides which comprise al-24 is an alternative source of active polypeptide. It is well known in the art that transgenic animals can be used to make various therapeutic polypeptides.
In a preferred embodiment of the invention said transgene is of human origin.

In a further aspect of the invention there is provided a method to treat an animal which would benefit from inhibition of angiogenesis comprising:
i) administering an effective amount of an agent comprising a,1-24 to an animal to be treated;
ii). monitoring the effects of said agent on the inhibition of angiogenesis.
In a preferred method of the invention said treatment is the inhibition of tumour development.
In an alternative method of treatment, polypeptides comprising al-24 are additionally conjugated, associated or crosslinked to an agent which augments the anti-angiogenic effect of the polypeptide.
Typically the agent could be a cytotoxic agent, another anti-angiogenic agent, a prodrug activating enzyme, a chemotherapeutic agent, a pro-coagulant agent or immunomodulatory factor.
Examples of these are well known in the art, for example, and not by way of limitation cytotoxins, such as ricin A-chain or diphtheria toxin; antagonists of the key pro-angiogenic factors in tumours (eg VEGF, bFGF, TNF alpha, PDGF) would include neutralising antibodies or receptors for these factors, or tyrosine lcinase inhibitors for their receptors (eg. SU5416 for the VEGF receptor, Flk-1/KDR);
prodrug activating enzymes such as, human simplex virus-thymidine kinase HSV-TIC, which activates the prodrug, ganciclovir when it is then admininistered systemically; chemotherapeutic agents, such as neocarzinostatin; cisplatin;
carboplatin; cyclosphosphamide; melphalan; carmusline; methotrexate; 5-fluorouracil; cytarabine; mercaptopurine; daunorubicin; doxorubicin;
epirubicin;
vinblastine; vincristine; dactinomycin; mitomycin C; taxol; L-asparaginase; G-CSF;
an enediyne such as chalicheamicin or esperamicin; chlorambucil; ARA-C;
vindesine; bleomycin; and etoposide.

In addition, or alternatively, the cell surface domain of human tissue factor (this truncated form of tissue factor (tTF) could also be associated with al-24.
Truncated TF has limited anti-endothelial activity when free in the circulation, but becomes an effective and selective thrombogen (ie it causes extensive thrombosis and coagulation in blood vessels) when targeted to the surface of tumor endothelial cells.
An example of an immunomodulatory factor is the Fc effector domain of human IgGl. This binds natural killer (NK) cells and also the Clq protein that initiates the complement cascade. NK cells and complement then activate a powerful cytolytic response against the targeted endothelial cells.
It Will be apparent that the above combinations of al-24 and therapeutic agents will also have benefit with respect to the treatment of other conditions/diseases which are dependent on angiogenesis. For example, neovascular glaucoma, rheumatoid arthritis, psoriasis and diabetic retinopathy.
In a yet further alternative method of treatment, said gene therapy vector includes, and therefore said nucleic acid encoding a polypeptide comprising al-24 is provided with, nucleic acid encoding an agent which augments the anti-angiogenic effect of al-24.
According to a yet further aspect of the invention there is provided an imaging agent comprising ocl-24.
It will be apparent to the skilled artisan that polypeptides comprising al-24 can be used to target imaging agents to, for example, tumours, to identify developing tumours or to monitor the effects of treatments to inhibit tumour growth. It will also be apparent that the combined therapeutic compositions which comprise both al-and a further anti-angiogenic agent may be further associated with an imaging agent to monitor the distribution of the combined therapeutic composition and/or to monitor the efficacy of said combined composition.
Methods used to detect imaging agents are well known in the art and include, by example and not by way of limitation, positron emission tomographic detection of FI8 and C11 compounds.
An embodiment of the invention will now be described, by example only, and with reference to the following figures:
Figure 1 represents the nucleic acid and amino acid sequences of the a-(3-~y-polypeptides of fibrinogen E;
Figure 2 represents a comparison of the effects of Fibrinogen E-fragment (panel A) 1 S and Fibrin E-fragment (panel B) on tubule formation by HuDMECs in vitro.
Mean (~SEM) area covered by tubule formation in the absence (empty bars) or presence (coloured bars) of VEGF or bFGF. Each test condition was carried out in three replicate wells, with total area measured in three randomly selected fields of view per well (n=9).*p<0.005 with respect to the relevant control group;
Figure 3 represents a schematic diagram showing the difference in structure between the anti-angiogenic Fibrinogen E-fragment (A) and the pro-angiogenic Fibrin E-fragment (B). The only difference is the presence (Fibrinogen E-fragment) or absence (Fibrin E-fragment) of the 16 amino acid Fibrinopeptide A;
Figure 4 represents the effects of al-24 (~-bend) on tubule formation in the absence or presence of VEGF or bFGF by SVEC4-10 cells in vitro. Upper Panel (A):
Tubule formation in the GF-reduced Matrigel assay (x40 objective) in the absence of exogenous factors (control) (I), or the presence of 100nM al-24 (II), lOng/ml VEGF
(III) or lOng/ml VEGF + 100nM al-24. Lower panel (B): mean (~SEM) area of tubule formation in the absence of (empty bars) or presence (grey bars) of VEGF or bFGF. n=9, *p<0.03 wit respect to relevant control group;
Figure SA is the nucleic acid sequence encoding the a1-24 peptide; Figure SB
represents the linear amino acid sequence of the a 1-24 peptide and the amino acid sequence of various modified a-1-24 peptides;
Figure 6 illustrates the ih vivo effect of unmodified al-24 peptide on tumour growth in mice. The effect of daily injections (i.p.) of 25ug/kg al-24 peptide in PBS
or PBS
alone (control) on growth of CT26 tumours in Balb/c mice, (data from 2 separate experiments);
Figure 7 represents a comparison of the anti-angiogenic activity of an arginine 23 to alanine substitution (R23A); a 1-24 control peptide and a truncated a 1-24 (amino acids 17-24;
Figure 8 represents the anti-angiogenic activity of an alanine substituted a 1-peptide (G4A, G6A,G17A);
Figure 9 represents the anti-angiogenic activity of an alanine substituted a 1-peptide ( D7A and R19) and (R16A);
Figure 10 represents the anti-angiogenic activity of terminal modification (acetylation and amidation) to the a 1-24 peptide. The effect of terminal modification (TMa) on the inhibitory effect of alphal-24 peptide on tubule formation by HuDMECs (with or without 10 ng/ml VEGF) ih vitro; and Figure 11 represents the effect of a wider range of concentrations of al-24 peptide on tubule formation by HuDMECs (in the presence or absence of 10 ng/ml VEGF) ih vitro.

Materials and Metlzods Adult human dermal microvascular endothelial cells (HuDMECs) were obtained commercially (TCS Biologicals, Buckinghamshire, United Kingdom) and cultured in microvascular endothelial cell growth medium (EGM). This medium contains heparin (lOng/ml), hydrocortisone, human epidermal growth factor (lOnglml), human fibrablast growth factor (lOng/ml) (such endothelial growth factors are necessary fox routine passaging of HuDMECs in culture) and dibutyryl cyclic AMP. This was supplemented with 5°lo heat-inactivated FCS, SO~,g/ml gentamicin and SOnglml amphotericin B (TGS Biologicals, United Kingdom). Murine endothelial cells (SVEC
4-10) were obtained from the ATCC and cultured in DMEM + 10%FCS. Cells were grown at 37°C in a 100% humidified incubator with a gas phase of 5% C02 and routinely screened for Mycoplasma. Prior to their use in the assays indicated below, HuDMECs were grown to 80% confluency, incubated in DMEM + 1 %FCS for 2h, then harvested with 0.05% trypsin solution, washed twice and resuspended to the cell density required for each assay (see below).
Proteins and peptides.
Human fibrinogen (Fgn) E-fragment was purchased from Diagnostica Stago, Asnieres, France. This was produced by plasmin cleavage of fibrinogen and purified by electrophoresis, immuno-electrophoresis, ion exchange and gel filtration.
To generate human Fibrin (Fn) E-fragment, Fgn E-fragment was digested with human thrombin (Sigma-Aldrich Co, Dorset, United Kingdom), as previously described (10). To control for the possible effects of trace amounts of thrombin in the Fn E-fragment preparation on our assays, the same amount of thrombin (0.5 Ufml) was added to control media used in experiments using Fn E-fragment. HPLC-purified FpA was obtained commercially from Bachem Ltd., Saffron Walden, United Kingdom. This peptides was included in the study as this peptide is cleaved from Fgn E-fragment in the production of FnE and will be present in the assays in trace amounts. The beta-bend (al-24) was generated by standard peptide synthesis methods using FMOC amino acids and a synthesis machine. The purity of the peptide was checleed by mass spectroscopy.
Tubule formation assay.
24 well plates were coated with 30~1/well of growth factor-reduced (GF-reduced) Matrigel (Becton Dickinson Labware, Bedford, MA). Endothelial cells plated on this matrix migrate and differentiate into tubules within 6h of plating as described previously (14). HuDMECs or SVEC 4-10 cells were seeded at a density of 4x104 cells/ml and incubated for 6h in 500,1 of either DMEM + 1%FCS alone (control), or this medium + lOng/ml VEGF or bFGF in the presence or absence of fibrinogen E-fragment, fibrin E-fragment, FpA or a,1-24. Assessment of tubule formation involved fixing the cell preparation in 70% ethanol at 4°C for 15 minutes, rinsing in PBS and staining with haematoxylin and eosin. Three random fields of view in 3 replicate wells for each test condition were visualised under low power (x40 magnification), and colour images captured using a Fuji digital camera linlced to a Pentium III computer (containing a frame grabber board). Tubule formation was assessed by counting the number of tubule branches and the total area covered by tubules in each field of view using image analysis software supplied by Scion Image.
Mi~ratioh assay The Boyden chamber technique was adapted from (13) and used to evaluate HuDMEC migration across a porous membrane towards a concentration gradient of either VEGF (lOng/ml) or bFGF (lOng/ml). The Neuro Probe 48 well microchemotaxis chamber (Neuro Probe Inc, Cabin John, MD) was used with 8~m pore size polycarbonate membranes (Neuro Probe Inc, Cabin John, MD) coated with 100~.g/ml collagen type IV. lOng/ml VEGF or bFGF alone or with various concentrations of fibrinogen E-fragment, fibrin E-fragment, FpA or al-24 were dissolved in DMEM + 1%FCS and placed in the lower wells. The collagen-coated membrane was then placed over this and 50,1 of 25x104 HuDMECs/ml (in DMEM

containing 1%FCS) added to the upper chamber. The chambers were then incubated at 37°C for 4.5h. The chamber was then dismantled, the membrane removed and non-migrated cells scraped off the upper surface. Migrated cells on the lower surface were fixed with methanol, stained with Hema 'Gurr' rapid staining lcit (Merclc, Leics, United Kingdom) and counted using a light microscope (x 160 magnification) in random fields per well. Each test condition was carried out in 3-6 replicate wells and each experiment repeated 3 times.
Proliferation assay The MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay was used as previously described (12) to assess HuDMEC proliferation induced by VEGF or bFGF in the absence or presence of fibrinogen E-fragment, fibrin E-fragment, FpA or al-24. HuDMEC were seeded at 3x103 cells/100q,1 in DMEM +
1 %FCS + 1 Ong/ml VEGF or bFGF in test solution into 96 well microtitre plate for 4.5 and 6h. At these time points, a quarter volume of MTT solution (2mg MTT/ml PBS) was added to each well and each plate was incubated for 4h at 37°C
resulting in an insoluble purple formazan product. The medium was aspirated and the precipitates dissolved in 100,1 DMSO buffered at pH 10.5. The absorbance was then read at 540nm on a Dynex ELISA plate reader.
Cytotoxicity Assay HuDMECs were seeded at a density of 1-2x105 cells per well in a 24 well-plate in the absence or presence of fibrinogen E-fragment, fibrin E-fragment, FpA or al-24.
After 6h, both live (following removal by trypsinisation) and dead (floating) cells were harvested and cell viability of all cells present assessed using propidium iodide staining of 5000 cells in each of triplicate samples per treatment using a FACScan (Becton Dickinson) equipped with a blue laser excitation of lSmW at 488nm. The data was collected and analysed using Cell Quest software (Becton Dickinson).

In vivo Efficacy of al-24 peptides Experiments were performed on six-week-old Balb/C mice weighing 15g, obtained from Sheffield Field Laboratories. All experiments were approved by the Home Office Project Licence Number PPL50/1414.
Tumouf~ Cell Cultu~~e The CT26 cell line was maintained by in vitro passage in Dulbecco's Minimal Eagles Medium containing 10% foetal calf serum, and 1 % penicillin and streptomycin and maintained at 37°C in humidified atmosphere of 5% C02 in air. The cell line was routinely checlced to ensure freedom from mycoplasma (Mycoplasma rapid detection system, Gena-Probe Incorporated, U.S.A.).
Subcutaneous Tumouf~ hrZplautatiou Animals were anaesthetised with an intraperitoneal injection of diazepam (O.Smg/ml, Dumex Ltd.) and hypnorm (fentanyl citrate 0.0315mg/ml and fluanisone lmg/ml, Janssen Pharmaceutical Ltd.) in the ratio of 1:1 at a volume of O.lml/200g body weight, with supplementation as required to maintain adequate anaesthesia.
Naive Balb/c mice were immunised s.c into the right flank, following removal of the fur.
Tumour cells were injected at a concentration of 3x105 viable CT26 cells per animal suspended in 100u1 serum free medium. Animals were then allowed to recover.
Tumour growth and animal weights were monitored daily.
Admiuistratioft of Peptide al-24 Tumour growth was measured daily and when the majority of animals in the cohort had tumour volumes of >100mm3 but <350mm3 animals were divided into experimental and control groups. This occurred between 14 and 18 days following implantation of the tumour cell suspension. Animals then received an intraperitoneal (ip) injection of either active drug (peptide al-24 100mM; 100,1) or vehicle (phophate buffered saline, 100.1). Daily injections continued until the tumour growth in the control animals reached the maximum burden allowed by Home Office legislation.
Assessment of tumour,~rowth Tumour volumes were assessed by calliper measurements of the perpendicular diameters and volumes estimated using the equation:-Volume = (a2 x b)/2 where a is the smaller and b the larger diameter Animals were weighed on a daily basis and the general well being monitored.
Statistical AualVSis.
All experiments were performed at least three times and data analysed using the Mann-Whitney U test, a non-parametric test that does not assume a Gaussian distribution in the data being analysed. P<0.05 was taken as significant.
Endothelial cells were seen to elongate and begin to form tubules on GF-reduced Matrigel in the absence of exogenous stimuli, although it should be noted that a residual level of growth factors is present in this matrix. This assay is therefore used as a model of differentiation one of the major steps in the angiogenesis pathway. The subsequent tubule formation is measured as area covered by tubules although the number of branches yields a similar graphical pattern (data not shown). This differentiation process was significantly (p<0.001) enhanced upon the addition of either VEGF (lOng/ml) or bFGF (lOng/ml) to the culture medium within this assay system. Addition of the ocl-24 ((3-bend) to this system significantly (p<0.03) reduced tubule formation both in the absence and presence of growth factors as shown in Figure 4.
From the results shown in Figure 4 we would conclude that the peptide al-24 contains the active site of the fibrinogen E-fragment. A 24 amino acid peptide is liltely to have greater therapeutic utility than the more complicated, polypeptide structure of fibrinogen E-fragment, as the latter has to be made by cleavage of fibrinogen derived from blood. By contrast, the al-24 is a smaller peptide that can be made synthetically or by recombinant techniques. It may also be possible for this to be used as part of gene therapy protocol for the treatment of cancer or other angiogenesis-dependent diseases. We then determined the in vivo efficacy of the al-24 peptide.
In T~ivo Efficacy of Peptide al-24 Exa~znle 1 Experimental animals (n=6) were treated daily with ip al-24 and control animals (n=7) with ip vehicle. The starting tumour volumes were similar in both groups of animals (experimental vs control, 23530 vs 19828 mm3). Tumours in the control group continued to grow at a steady rate over the 14 day period reaching a final tumour volume of 2245371 mm3. In contrast tumours the experimental animals had a similar rate of growth until day 4, when growth was reduced. At day 7 tumours then continued to grow at a similar rate to the controls but with a reduced volume.
By day 10 tumour growth again stabilised until day 14, with a final tumour volume of 1341 ~
145 mm3 (p<0.001 ).
Exa~rzple 2 Experimental animals (n=7) were treated daily with ip al-24 and control animals (n=7) with ip vehicle. The starting tumour volumes were similar in both groups of animals (experimental vs control, 33839 vs 30065 mm3). Tumours in the control group continued to grow steadily over the 12 day period reaching a final tumour volume of 3072255 mm3. In contrast, tumours in the experimental animals had a similar rate of growth to the controls until day 7, when growth stabilised until animals were killed at day 12 with a final tumour volume of 2029504 mm3 (p<0.001).
This data, see Figure 6, therefore demonstrates the potential of peptide al-24 as an in vivo anti-angiogenic agent. Furthermore, peptide variants of al-24 show similar inhibitory activity to unmodified al-24, see Figures 7-9. Also, modification of al-24 by acetylation and amidation does not affect the anti-angiogenic effect.
References 1. Folkman J Angiogenesis in cancer, vascular, rheumatoid and other disease.
Nature Medicine, l: 27-31, 1995.
2. Leek R, Harris AL, and Lewis CE Cytokine networks in solid human tumours: regulation of angiogenesis. J. Leuk. Biol., 56: 423-35, 1994.
3. Cao Y Endogenous angiogenesis inhibitors: angiostatin, endostatin, and other proteolytic fragments. Prog Mol Subcell Biol., 20:161-76, 1998.
4. Doolittle R Fibrinogen and Fibrin. Scientific American, 245: 92-101, 1981.
5. Costantini V, Zacharski LR, Memoli VA, Kisiel W, Kudrylc BJ, and Rousseau SM Fibrinogen deposition without thrombin generation in primacy human breast cancer tissue. Cancer Res., 51:349-53, 1991.
6. Dvorak HF, Nagy JA, Feng D, Brown LF, and Dvoralc AM Vascular permeability factor/vascular endothelial growth factor and the significance of microvascular hyperpermeability in angiogenesis. Curr Top Microbiol Immunol, 237:97-132, 1999.

7. Thompson WD, Wnag JEH, Wilson SJ, and Ganesalingham N Angiogenesis and fibrin degradation in human breast cancer. Angiogenesis: Molecular Biology, Clinical Aspects, 245-251, 1994.
8. Thompson WD, Smith EB, Stirk CM, Marshall FI, Stout AJ, and Kocchar A
Angiogenic activity of fibrin degradation products is located in fibrin fragment E.
J.Pathol,16~: 47-53, 1992.
9. Malinda KM, Ponce L, Kleinman HK, Shaclcelton LM, and Millis AJ Gp38k, a protein synthesized by vascular smooth muscle cells, stimulates directional migration of human umbilical vein endothelial cells. Exp Cell Res 250:168-73, 1999.
10. Shen J, Ham RG, Karmiol S Expression of adhesion molecules in cultured human pulmonary microvascular endothelial cells. Microvasc Res., 50:360-72, 1995.

11. Liu J, Kolath J, Anderson J, Kolar C, Lawson TA, Talmadge J, and Gmeiner WH Positive interaction between 5-FU and FdUMP[10] in the inhibition of human colorectal tumour cell proliferation. Antisense Nucleic Acid Drug Dev., 9(5):481-6, 1999.

12. Dejano E, Languino LR, Polentarutti N, Balconi G, Ryclcewaert JJ, Larrieu MJ, Donati MB, Mantovani A, and Marguerie G Interaction between fibrinogen and cultured endothelial cells. J.CIin.Invest., 75: 11-18, 1985.

13. Bootle-Wilbraham CA, Tazzyman S, Marshall JM, Lewis CE. Fibrinogen E-fragment inhibits the migration and tubule formation of human dermal microvascular endothelial cells ih vitro. Cancer Research (2000) 60: 4719-4724 14. Marsh HC, Meinwald YC, Lee S, Martinelli RA, Scheraga HA. Mechanism of action of thrombin on fibrinogen: NMR evidence for a beta-bend at or near fibrinogen A alpha Gly(PS)-Gly(P4). Biochemistry (1985) 24: 2806-2812.

Claims (40)

1. A polypeptide comprising an amino acid sequence selected from the group consisting of:
i) a peptide of the sequence:
ADSXEXXFLAEGGGVXXPXVVEXH
wherein X is any amino acid residue;
ii) a peptide as represented in (i) wherein amino acid residue X is selected from the following group: alanine, valine , leucine, isoleucine, proline; and iii) a peptide represented in (i) or (ii) which has anti-angiogenic activity.

2. A polypeptide according to Claim 1 wherein said polypeptide comprises an amino acid sequence selected from the following group:
ADSGEGDFLAEGGGVRGPRVVERH
ADSGEGDFLAEGGGVRGPRVVEXH
ADSGEGDFLAEGGGVRGPXVVERH
ADSGEGDFLAEGGGVRXPRVVERH
ADSGEGDFLAEGGGVXGPRVVERH
ADSGEGXFLAEGGGVRGPRVVERH
ADSGEXDFLAEGGGVRGPRVVERH
ADSXEGDFLAEGGGVRGPRVVERH
ADSXEXDFLAEGGGVRXPRVVERH
ADSGEGXFLAEGGGVRGPXVVERH

3. A polypeptide according to Claim 1 or 2 wherein X is alanine.

4. A polypeptide according to Claim 1 or 2 wherein said polypeptide comprises the sequence:
ADSGEGDFLAEGGGVRGPRVVERH.

5. A polypeptide according to any of Claims 1-4 wherein the polypeptide is at least 24 amino acid residues in length.

6. A polypeptide according to any of Claims 1-4 wherein the polypeptide is an active fragment of the 24 amino acid polypeptide

7. A polypeptide according to Claim 5 wherein the polypeptide consists of the amino acid sequence ADSGEGDFLAEGGGVRGPRVVERH.

8. A polypeptide according to any of Claims 1-7 wherein the polypeptide is acetylated.

9. A polypeptide according to Claim 8 wherein said acetylation is to the amino terminus of said polypeptide.

10. A polypeptide according to Claim 9 wherein the amino terminal alanine amino acid of the .alpha.1-24 peptide is acetylated.

11. A polypeptide according to any of Claims 1-7 wherein said polypeptide is amidated.

12. A polypeptide according to Claim 11 wherein said amidation is to the carboxyl terminus of said polypeptide.

13. A polypeptide according to Claim 12 wherein the carboxyl-terminal histidine amino acid of the .alpha.1-24 peptide is amidated.

14. A polypeptide according to any of Claims 8-13 wherein said polypeptide is modified by both acetylation and amidation.

15. A polypeptide according to Claim 14 wherein said acetylation is to the amino-terminal alanine amino acid of the .alpha.1-24 peptide and said amidation is to the carboxyl-terminal histidine of the .alpha.1-24 peptide.

16. A polypeptide according to any of Claims 1-15 wherein said polypeptides are modified by cyclisation.

17. A nucleic acid molecule comprising DNA sequences selected from the following group:
i) the DNA sequence as represented in Figure 6;
ii) the DNA sequence as represented in Figure 6 which has been modified by addition, deletion or substitution of at least one nucleotide base within at least one codon to encode a peptide according to any of Claims 1-6;
iii) DNA sequences which hybridise to the sequence presented in Figure 6 which encode a peptide having anti-angiogenic activity; and iv) DNA sequences which are degenerate as a result of the genetic code to the DNA sequences defined in (i), (ii) or (iii).

18. A nucleic acid molecule according to Claim 17 wherein said nucleic acid molecule anneals under stringent hybridisation conditions.

19. A nucleic acid molecule according to Claim 18 wherein stringent hybridisation conditions comprise: 4 - 6 x SSPE; 5-10 x Denhardts solution; 100µg-1.0mg/ml sonicated salmon/herring DNA; 0.1-1.0% sodium dodecyl sulphate; 40-60%
deionised formamide; and a temperature of between 42°- 65° C.

20. A pharmaceutical composition comprising at least one .alpha.1-24 peptide, or part thereof,

21. A pharmaceutical composition according to Claim 20 which consists of at least one .alpha.1-24 peptide as represented by the amino acid sequences represented in Figure 5B.

22. A pharmaceutical composition comprising at least one .alpha.1-24 polypeptide and further including at least one chemotherapeutic agent.

23. A pharmaceutical composition according to Claim 22 wherein said agent is selected from the group consisting of: neocarzinostatin; cisplatin;
carboplatin;
cyclosphosphamide; melphalan; carmusline; methotrexate; 5-fluorouracil;
cytarabine;
mercaptopurine; daunorubicin; doxorubicin; epirubicin; vinblastine;
vincristine;
dactinomycin; mitomycin C; taxol; L-asparaginase; G-CSF; an enediyne such as chalicheamicin or esperamicin; chlorambucil; ARA-C; vindesine; bleomycin; and etoposide.

24. The use of a polypeptide comprising the .alpha.1-24 peptide, or part thereof, in the manufacture of a medicament for use in the treatment of cancer.

25. A vector which includes a nucleic acid molecule which encodes for polypeptides which comprise the .alpha.1-24 peptide, or part thereof.

26. A vector according to Claim 25 wherein said vector is a prokaryotic expression vector.

27. A vector according to Claim 25 wherein said vector is a eukaryotic expression vector.

28. A vector according to Claim 27 wherein said vector is a gene therapy vector.

29. A vector according to Claim 28 wherein said gene therapy vector is a viral based vector selected from the following viruses: adenovirus; adeno-associated virus;
herpesvirus; lentivirus; vacciniavirus; baculovirus.

30. A cell which has been transformed or transfected with the nucleic acid according to any of Claims 17-19 or the vector according to any of Claims 25-29.

31. A method for the production of polypeptides comprising .alpha.1-24 including:
i) providing a cell according to Claim 30;
ii) providing conditions conducive to the manufacture of polypeptides comprising .alpha.1-24; and iii) purifying said polypeptides from a cell, or a cells culture environment.

32. A non-human, transgenic animal characterised in that said animal incorporates a nucleic acid molecule encoding a polypeptide comprising .alpha.1-24 into its genome.

33. A non-human, transgenic animal according to Claim 32 wherein the transgene is of human origin.

34. A method to treat an animal which would benefit from inhibition of angiogenesis comprising:
i) administering an effective amount of an agent comprising .alpha.1-24 to an animal to be treated;
ii). monitoring the effects of said agent on the inhibition of angiogenesis.

35. A method to treat an animal which would benefit from inhibition of angiogenesis comprising:
i) administering an effective amount of a pharmaceutical composition according to Claim 20 or 21 to an animal to be treated;
ii). monitoring the effects of said composition on the inhibition of angiogenesis.

36. A method according to Claim 34 or 35 wherein polypeptides comprising ocl-24 peptides are conjugated, associated or crosslinked to a chemotherapeutic agent.

37. A method to treat an animal which would benefit from inhibition of angiogenesis comprising:
i) administering an effective amount of the nucleic acid according to any of Claims 17-19 or the vector according to Claim 28 or 29; and ii) monitoring the effects of transfection of the nucleic acid in (i) on the inhibition of angiogenesis.

38. A method according to any of Claims 34-37 wherein said treatment is the inhibition of tumour angiogenesis.

39. A method according to any of Claims 34-38 wherein said animal is human.

40. An imaging agent which comprises an .alpha.1-24 polypeptide conjugated, coupled, associated or crosslinked to a detectable label.