CA2073696A1 - Cyclic peptides containing arg-gly-asp flanked by proline - Google Patents

Abstract

A small cyclic peptide is provided having high affinity for the platelet GP IIbIIIa receptor, which peptide is represented by formula .alpha. where R1 and R4 are from 0 to 4 amino acids, R3 is from 1 to 4 amino acids; R2 is -CH2CO- or from 1 to 4 amino acids; Xaa8 may be Met, Phe, nLeu, Ile, Asp, Lys, Arg and Gln; and Z is a linking group, either disulfide, thioether or amide, but preferably disulfide. Preferred cyclic peptides exhibiting high inhibition potency in a platelet aggregation assay are represented by formula .beta. where Xaa2, Xaa3 and Xaa4 may be any amino acid but preferably are Arg, Ile and Pro, respectively.
Xaa8 is preferably Met, Phe or nLeu; Xaa10 when present, is preferably Ala; and Xaa11, when present, is preferably Ala or Asp. These compounds may be effectively employed in a pharmaceutical composition containing a pharmaceutically acceptable excipient for reducing platelet aggregation in a mammal. The pharmaceutical composition is especially useful in treating a mammal having an increased propensity for thrombus formation, and may be used in combination with an anticoagulant or thrombolytic agent.

Description

W~ 91/11458 ~ i 6 PCr/US91/00564 Cyclic Peptides Containing Arg~ly-Asp Flanked by Proline Field of the Invention The present invention relates generally to inhibitors of platelet aggregation, and more specifically to cyclic peptides capable of preventing binding of fibrinogen or other ligands to the platelet glycoprotein llbllla receptor (GP llbllla). The invention also relates to therapeutic applications of the cyclic peptide inhibitors in diseases for which blocking of platelet aggregation and intracellular adhesion is mediated by GP llbllla.
Background of the Inverltion Platelets are particles found in mammalian whole blood which participate in the process of thrombus formation and blood coagulation. A membrane bound glycoprotein, commonly known as GP llbllla (Phillips et al., (1988) Blood, 71, 831-843), is present in platelets and can, under certain circumstances, be exposed on the exterior surface of platelets.
Glycoprotein llbllla is a non-covalent, calcium ion dependent heterodimer complex comprised of alpha and beta subunits (Jennings, et al., J. Biol. Chem. (1982) 257, 10458). This complex is known to contribute to normal platelet function through interactions with proteins containing the sequence Arg-Gly-Asp such as fibrinogen. The interaction of GP llbllla with fibrinogen is stimulated by certain factors released or exposed when a blood vessel is injured. Multiple factors, including a variety of physiological stimuli and soluble mediators, initiate platelet - activation via several pathways tRink and Hallam (1984) Trends in Biochemical Sciences, 71~719;KrollandSchafer(1989)Blood,74, 1181-1195;andColmanandWalsh,(1987) - Hemostasis and Thrombosis: Basic Principles and Clinical Practice, pp. 594-60~, J.W.
Lippincott, Philadelphia). These pathways converge in a common final step which consists of 2; acUvation of the GP llbllla receptor on the platelet surface followed by binding of the receptor to fibrinogen culminating in aggregation and thrombus formation. By virtue of these interactions GP llbllla is an important component of the platelet aggregation system. Thus, inhibition of the interaction of GP llbllla with Arg-Gly-Asp containing ligands such as fibrinogen is a useful means of modulating thrombus formation.
Many common human disorders are characteristically associated with a hyperthrombotic state leading to intravascular thrombi and emboli. Since the hypothrombotic state is mediated by platelet aggregation and adhesion, inhibition represents a good target for therapeutic intervention (Stein et al. (1989) J. Am. Cell. Cardiol., 14, 813). These disorders are a major cause of medical morbidity, leading to infarction, stroke and phlebitis and of 3~ mortality from stroke and pulmonary and cardiac emboli. Patients with atherosclerosis are predisposed to arterial thromboembolic phenomena for a variety of reasons. Atherosclerotic plaques form niduses for platelet plugs and thrombii that lead to vascular narrowing and occlusion, resulting in myocardial and cerebral ischemic disease. This may happen spontaneously or following procedures such as angioplasty or endarterectomy. Thrombii that : '' . ' , , ': , '., , ~, . , ' : , 4~8 ~ 9~ 2 PCT/US91/00564 -break off and are released into the circulation may cause infarction of other organs, especially the brain, extremities, heart and kidneys.
In addition to being involved in arterial thrombosis, platelets may also play a role in . venous thrombosis. A large percentage of such pa;ients have no antecedent risk factors and develop venous thrombophlebitis and sùbsequent pulmonary emboli without a known cause.
Other patients who form venous thrombi have underlying diseases that are known to . predispose them to these syndromes. Some of these patients may have genetic or aquired deficiencies of factors that normally prevent hypercoagulability, such as antithrombin-3.
Others have mechanical obstructions to venous flow, such as tumor masses, that may lead to low flow states and thrombosis. Patients with malignancy often have a high incidence c thrombotic phenomena for unclear reasons. Antithrombotic therapy in these situations employing currently available agents may be dangerous and is often ineffective.
Patients whose blood flows over artificial surfaces, such as prosthetic synthetic cardiac valves or through extracorporeal perfusion devices, are also at risk for the development of platelet plugs, thrombii and emboli. It is standard practice that patients with artificial cardiac valves be treated chronically with anti-coagulation agents. However, in all instances, platelet activation and emboli formation may still occur despite adequate anticoagulation treatment.
Thus a large category of patients, including those with atherosclerosis, coronary artery disease, artificial heart valves, cancer, and a history of stroke, phlebitis, or pulmonary emboli, are candidates for limited or chronic antithrombobc therapy. The number of available therapeutic agents is limited and these, for the most part, act by inhibiting or reducing levels of circulating clotting fac~ors. These agents are frequently not effective against the patient's underlying hematologic problem, which often concerns an increased propensity for plat- let - 25 aggregation and adhesion. They also cause the patient to be susceptible to abnormal bleeding.
: Available antiplatelet agents, such as aspirin, inhibit only part of the platelet activation process and are therefore often inadequate for therapy.
Background Prior Art Inhibition of fibrinogen binding to the GP llbllla complex has been shown to be an effective antithrombotic treatment in animals (H. K. Gold, et al., ;,irculation (1988) 77, 670-6~7; T. Yasuda, et al., J. Clin. InvesL (1 988) 81,1284-1291; B. S. Coller, et al., Blood (1 986) 68, 783-786). A number of synthetic peptides, have been disclosed as inhibitors of fibrinogen binding to platelets all of which contain the Arg-Gly-Asp sequence. See US Patent 4,683,291;
EP 0 319 506 A2; Plow et al., Proc. NatL Acad. Sci. USA (1985) 82,8057-8061; Ruggeri et al., Proc Natl. Acad. Sci. USA (1986) 83, 5708-5712; Haverstick et al., Blood (1985) 66,946-952;
Plow et al., Blood (1987) 70,110-115; and references cited in the above publications.
Other proteins such as fibronectin contain the Arg-Gly-Asp sequence of amino acids.
Large polypeptide fragments of fibronectin have been shown to have activity for cell attachment to various surfaces which has been disclosed in US Patents 4,517,686; 4,589,881;

2 ~ i7 ~ 6 ~ ~
~v~) 91/11458 3 Pcr/lJS9l/00564 and 4,661,111. These large polypeptides contain the amino acid sequence Arg-Gly-Asp-Ser in - the interior portion of the polypeptide chain. Short peptides derived from the large polypeptides were also found to promote cell attachment to various substrates when bound on the substrate. Alternatively, the same short peptides were found to inhibit cell attachment to the 5 same substrates when dissolved or suspended in the medium surrounding the substrate. This activity has been disclosed in US Patents 4,578,079 and 4,614,517. The short peptides were defined as Q-Arg-Gly-Asp-AA1 -B

10 wherein Q is hydrogen or an amino acid; M1 is serine, threonine, or cysteine; and B is hydroxy or an amino acid.
Venoms from various pit vipers have been found to contain proteins that contain the Arg-Gly-Asp sequence and inhibit platelet aggregation. These venoms have been described and characterized by Huang et al., J. Biol. Chem., (1987) 262,16157-16136; Huang et al. (1989) 15 Biochemistry, 28, 661 -666; Gan et al. (1988) J. Biol. Chem., 263,19827-19832; Chao et al.
(1989) Proc. Natl. Acad. Sci. USA, 86,8050-8054; Shebuski et al., J. Biol. Chem., (1989) 264:
21550-21556; and Friedman et al., published European Application 338 634/A2. The final authors disclose relatively large (ca. 5,000 to ca. 7,000 dalton) platelet aggregation inhibitors isolated from venoms represented by the general formula X-Cys-R-R-R-Arg-Gly-Asp-R-R-R-R-R-Cys-Y

where X is hydrogen or at least one amino acid and Y is hydroxyl or at least one amino acid.
These authors report that a platelet aggregation inhibitor encompassed by the above 25 structural formula isolated from Echis carinatus loses its inhibitory activity in a platelet aggregation assay upon treatment with 80 mM dithiothreitol. Thus, the authors conclude one or more intrachain disulfide bonds are necessary for activity.
Small (1,000 - 2,000 dalton) synthetic cyclic peptides containing the Arg-Gly-Asp sequence capable of inhibiting cell attachment to fibronectin and vitronectin have also been 30 described by Pierschbacher et al. in WO 89/05150. These authors describe two cyclic peptides capable of inhibiting cell adhesion represented by the formula Gly-Pfn-Gly-Glu-Arg-Gly-Asp-Lys-Arg-Cys-Ala S ~S
and Gly-Arg-Gly-Asp-Ser-Pro-Asp-Gly HN CO

- : . . . . , . - ~: ,. . , : .

WO 91/1]458 c~ ) 4 PCT/US91/00564 -where Pen is penicillamine. No information is provided by these authors on the effectiveness of these small cyclic peptides in inhibiting platelet aggregation.
From the forgoing, it will be appreciated that a need exists for an inhibitor that would prevent binding of Arg-Gly-Asp containing proteins such as fibrinogen (and/or related ligands ;~ 5 such as fibronectin, vitronectin and von Willebrands factor) with the platelet GP llbllla receptor.
. Such an inhibitor would antagonize the final common pathway of platelet aggregation and act as a potent antithrombotic. Ideally, the inhibitor should be small in size to minimize antigenicity, simple to construct and exhibit high inhibition potency in a platelet aggregation assay.
Summary of the Invention These and other needs are achieved by providing a small cyclic peptide having a high affinity and specificity for the platelet GP llbllla receptor represented by Formula I
Rl -R2-Arg-Gly-Asp-Xaa8-Pro-R3-R4 , I z r where Rl and R4 are from O to 4 amino acids; R3 is from 1 to 4 amino acids; R2 is -CH2CO-or from 1 to 4 amino acids; Xaag may be Met, Phe, nLeu, lle, Asp, Lys, Arg and Gln; and Z is a linking group, either disulfide, thioether or amide, but preferably disulfide.A preferred embodiment of the instant invention having surprisingly high affinity for - 20 the GP llbllla receptor may be represented by Formula 11 ~I R~-Rs-Xaa2-Xaa3-Xaa4-Arg-Gly-Asp-Xaa8-Pro-Xaa~O-Xaal1-Xaa12-Cys-R4 ., I I
z where each of Xaa2, Xaa3, Xaa4, Xaa10, Xaall, Xaal2 are amino acids or are absent, but 25 preferably at least Xaa2, Xaa3 and Xaa4 are present. In this embodiment Rs is -CH2CO- or Cys; Z is thioether or disulfide; and R1, R4, and Xaa8 are as defined above.
The most preferred cyclic peptides of this invention, exhibiting especially high inhibition potency in a platelet aggregation assay are represented by Formula 111 Cys-Xaa2-Xaa3-Xaa4-Arg-Gly-Asp-Xaa8-Pro-Xaa10-Xaa"-Xaa~2-Cys where Xaa2, Xaa3 and Xaa4 may be any amino acid but preferably are Arg, lle and Pro, respectively. Xaag is preferably Met, Phe or nLeu; Xaa1o when present is preferably Ala; and Xaa1 1 when present is preferably Ala or Asp.
Representative preferred compounds according to this invention are conveniently selected from the following list:

. . .
: . , . : " ,,,, ~
- , , ... - ~ ~

, 91/11458 ~ i s i~ g ~ PC'r/US91/00564 Cys1 -Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp-Arg-Cys13;
. Cys1-Ala-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp-Arg-Cys13; : ~ .
: Cysl-Arg-Ala-Pro-Arg-Gly-Asp-Met-Pro-Asp Asp-Arg-Cysl3;
Cysl-Arg-lle-Ala-Arg-Gly-Asp-Met-Pro-Asp-Asp-Arg-Cysl3; -Cysl-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp-Arg-Cys13;
Cysl-Arg-lle-Pro~Arg-Gly-Asp-Met-Pro-Asp-Ala-Arg-Cysl3;
Cysl -Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp-Ala-Cysl3;
Cysl-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Ala-Arg-Cysl3;
Cysl-Arg-lle-Pro-Arg-Gly-Asp-Phe-Pro-Ala-Asp-Arg-Cysl3;
Cysl-Arg-lle-Pro-Arg-Gly-Asp-Leu-Pro-Ala-Asp-Arg-Cysl3;
Cysl-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp-Tyr-Cysl3;
.' Cysl-Arg-lle-Pro-Arg-Gly-Asp-nLeu-Pro-Ala-Asp-Arg-Cysl3;
' Cys~-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp-Cys~2;
. Cysl-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Cysll; and Cysl-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Cys10 where each Cysl-Cysl3, Cys1-Cys12, Cys1-Cysll, and Cysl-Cysl is linked through a disulfide.
In an alternative embodiment of the invention preferred compounds contain from 7 to about 16 amino acids and preferably from 10 to 13 amino acids in a ring bridged through the 2~ disulfide of cystine, and containing Pro residues flanking of the Arg-Gly-Asp sequence.
Given their high affinity for the platelet GP llbllla receptor, these compounds may be effectively employed in a pharmaceutical composition containing a pharmaceutically acceptable excipient for reducing platelet aggregation in a mammal. This pharmaceutical composition is especially useful in treating a mammal having an increased propensity for 25 thrombus formation, such as those which are post angioplasty, and may be used in combination with an anticoagulant or thrombolytic agent.
Delailed Description of the Invention The small cyclic peptides represented by Formulae I - lll above are composed of L
amino acids unless othenNise specified. Standard abbreviations are used for the amino acids 30 as provided below:
Abbreviation Anir~o acid Ala alanine Arg arginine ,, Asp aspartic acid Cys cysteine Gly glycine Ib isoleucine Leu leucine nLeu norleucine .. , , , ; : : . ~

WO91/11458 ~ 3~ 6 PCI`/US91/00~64 ~-Lys Iysine Met methionine - Phe phenylalanine p~O proline Tyr tyrosine Val valine The abbreviation Xaa represents an unspecified naturally ocurring L-amino acids.The small cyclic peptides of this invention are useful as inhibitors of plateletaggregation. Without intending to be limited to any particular theory or mechanism of action, it is believed these compounds exhibit this effect by acting as competitive inhibitors of the platelet GP llbllla receptor. By competing for the GP llbllla receptor, these small cyclic peptides prevent ~he binding, in a concentration dependent manner, of indigenous binding proteins such as fibrinogen, fibronectin, vitronectin, von Willebrands factor, as well as other Arg-Gly-Asp containing proteins. Thus, these compounds act as antagonists of the final common pathway of platelet aggregation and therefore are useful as antithrombotics. Mammals exposed to medical procedures such as angioplasty and thrombolytic therapy are particularly susceptable . ~ to thrombus formation. By preventing or modulating formation of platelet plugs, emboli, and thrombii, these compounds possess useful therapeutic properties.
The cyclic peptides of this invention are also useful in either inhibiting or promoting cell adhesion. Members of the integrin class of adhesion receptors are capable of recognizing the Arg-Gly-Asp sequence and therefore the instant cyclic peptides can effectively block cell attachment or adhesion.
The compounds of the present invention are preferably used to inhibit thrombus formaUon following angioplasty, or may be used in combination with thrombolytic agents such as tissue plasminogen activator and its derivatives (US patents 4,752,603; 4,766,075;
4,m,043; EP 199,574; EP 0238,304; EP 228,862; EP 297,860; PCT W089/04368; PCT
WO89/00197), streptokinase and its derivatives, or urokinase and its derivatives to prevent arterial reocclusion following thrombolytic therapy. When used in combination with the above thrombolytic agents, the compounds of the present invention may be administered prior to, simultaneously with, or subsequent to the antithrombolytic agent. Mammals exposed to renal dialysis, blood oxygenation, cardiac catheterization and similar medical procedures as well as mammals fitted with certain prosthetic devices are also susceptibl~ to thromboembolic disorders. Physiologic conditions, with or without known cause may also lead to thromboembolic disorders. Thus, the compounds described herein are useful in treating thromboembolic disorders in mammals. The compounds described herein may also be used as ad!uncts to anticoagulant therapy, for example in combination with aspirin, heparin or warfarin and other anticoagulant agents. The application of the compounds described herein for these and related disorders will be apparent to those skilled in the art.

?

'~

::
~'" 91/11458 7 2 ~ 7 3 ~ 9 6 PcrIUS91/00564 Preparation r~f the Peptides The small cyclic peptides represented by Formulae I - lll may be prepared by known methods, either recombinant or chemical.
To produce a linear peptide capable of cyclization using recombinant DNA
5 methodology, an oligonucleotide encoding the peptide is synthesized using standard phosphoramidate, phosphotriester or phosphonate methods (see e.g., Adams et al. (1983) J.
. Amer. Chem. Soc., 105, 661; Froehler et al. (1983) Jetrahedron Lett., 24, 3171; German Offenlegungsshrift2644432; Froehler et al., European Pub. No.219342, published 22 April 1987). A second oligonucleotide complementary to the first oligonucleotide sequence is also 10 synthesized either chemically or enzymatically and the h~o oligonucleotides are hybridized under standard conditions to generate a double stranded DNA molecule. A detailed discussion of hybridization procedures for oligonucleotides may be found in Sambrook et al., Molecular : Cloning: A Laboratory Manual, Coldspring Harbor Laboratory Press, New York, 1989. The oligonucleotide may be directly cloned into a plasmid expression vector such as pNH8a 15 (Stratagene, La Jolla, CA). The vector is first linearized using a restriction endonuclease such as Hind lll, and the ends are filled in blunted with DNA polymerase l large fragment (Klenow). The oligonucleotide is then blunt-ligated into the vector using the enzyme T4 ligase under appropriate conditions (Sagaramellar and Khorana (1972) J. Mol. Biol., 72, 427; Ferretti -and Sagaramellar (1981) Nuc. Acids. Res., 9, 3695). The vector containing the oligonucleotide insert is transformed as described in Sambrook, supra, into a particular strain of E. coli host cells engineered to 'accept' the foreign plasmid, and to produce the polypeptide encoded by the oligonucleotide. Exemplary host cell strains appropriate for plasmid pNH8a are E. coli D1210HP and D121û (Stratagene, La Jolla, CA). Transfected host cells producing the polypeptide in significant quantity are Iysed and the polypeptide purified employing appropriate - 2~ purification procedures.
The preferred synthetic method for the small cyclic peptides of the instant invention is by chemical synthesis. According to this preferred method, the small linear peptides are first synthesized with a commercially available automated peptide synthesizer (e.g., Milligen-Biosearch 9500 automated peptide synthesizer) or by manual solid phase synthesis (see e.g., 30 Merrifield, J. Am. Chem. Soc. (1964) 85,2149 or Houghten, Proc. Natl. Acad. Sci.(1985) 82, 5132). When solid phase synthesis is employed peptide synthesis is initiated at the C-terminus of the putative peptide by coupling an appropriately protected amino acid to any suitable resin (see e.g., U.S. Patent Nos.4,244,946; 4,305,872; and 4,316,891). Solid phase synthesis is then carried out as described in the above references and as provided in Vale et al., Science (1981) 35 213,1394-1397 and Marke et al., J. Am. Chem. Soc. (1981) 103, 3178.
However the linear peptide is synthesized, it is isolated and may be further purified using, for example, chromatographic methods such as high performance liquid chromatography (HPLC). The linear peptide then is cyclized to compounds of Formulae I - lll using standard i , . ~ .

:. : ,; . . ~' , ~:
., : ~ ; .

WO 91/11458 ~ 8 PCr/US91/00~
chemical methods well known in the art. Which cyclization procedure is employed will depend on the type of bond to be formed. Exernplary cyclization procedures are set forth below.
Cyclic Disulfide For example, the linear peptide may be cyclized by dissolution in water at pH 7.5 to 8 followed 5 by exposure of the solution to air until disulfide formation is complete. Alternatively, chemical oxidants may be used such as 12 or potassium ferricyanide.
Cyclic lllioethers Cyclic thioethers are prepared by coupling bromoacetic acid to the amino terminus of the peptide on the resin and following removal of the peptide from the resin cyclization under dilute 10 conditions is afforded by adjusting the pH to between 5 and 9.5.
Cyclic Arnides Cyclic amides can be prepared by using side chain protecting groups which can be removed independently of the other side chain protecting groups as well as the link to the resin. In the case of Fmoc chemistry such groups as allyl esters or allyl carbamates would suffice and in :~ 15 the case of Boc chemistry the Fmoc or fluorenylmethyl esters would allow such differential protection. Upon removal of these groups amide bond formation is achieved with standard . coupling procedures. Then the cyclized peptide can be deprotected and removed from the resin.
It is believed that for the preferred compounds containing from about 10 to about 13 20 amino acids in the cyclic portion of the peptide, there are no significant conformational differences among peptides cyclized through a disulfide, thioether, amide or other analogous bridging groups. Thus, it is contemplated that equivalent peptides may be prepared by - substituting amino acid analogues or other bifunctional ligands at the bridging positions (i.e., R2 and R3 of Formula 1). Exemplary equivalent bridging pairs would include Cys-pen, or pen-pen, 2~ where pen is penicillamine. Alternative exemplary bridging pairs would include amino acids having free a amino and carboxyl groups or pairs containing free side chain amino and carboxyl groups. Examples of the latter would include basic residues such as D/L ornithine or D/L Iysine and acidic residues such as D/L Glu or D/L Asp. It is also contemplated that Rl and R4 of Formula I can be blocking groups. Specifically, Rl may be acyl, either aryl or alkyl 30 and R4 may be an amine or substituted amine.
The compounds described in this invention may be isolated as such or converted to salts of various inorganic and organic acids and bases. Such salts are within the scope of this invention. Examples of such salts include ammonium, metal salts like sodium, potassium, calcium and magnesium; salts with organic bases like dicyclohexylamine, N-methyl-D-3~ glucamine and the like; and salts with amino acids like arginine or Iysine. Salts with inorganicand organic acids may be likewise prepared, for example, using hydrochloric, hydrobro mic, sulfuric, phosphoric, trifluoroacetic, m0thanesulfonic, malic, maleic, fumaric and the iike. Non-toxic and physiologically compatible salts are particularly useful although other less desireable salts may have use in the processes of isolation and purification.

..

2~7~
V'-) 91/11458 PCI/US91/00564 .. 9 A number of methods are useful for the preparation of the salts described above and are known to those skilled in the art. For example, reaction of the free acid or free base form of a compound selected from Formulae I - lll with one or more molar equivalents of the desired acid or base in a solvent or solvent mixture in which the salt is insoluble; or in a solvent like 5 water after which the solvent is removed by evaporation, distillation or freeze drying.
. ~ Alternatively, the free acid or base form of the product may be passed over an ion exchange resin to form the desired salt or one salt form of the product may be converted to another using the same general process.
GP ilbll4 Fibrinogen ELISA and Platelet Aggregation Assays The eYaluation of inhibitors of the fibrinogen - platelet interaction is guided by in vitro ; receptor binding assays and in vitro platelet aggregation inhibition assays.
In vitro biological activity of the compounds of Formulae I - lll were monitored using a modified fibrinogen - GP llbllla ELISA based on the method of Nachman and Leung (J. Clin.
Invest. (1982) 69,263-269) which measures the inhibition of fibrinogen binding to purified human platelet GP llbllla receptor. Human fibrinogen was prepared by the method of Lipinska, et al. J.
Lab. Clin. Med. (1974) 84,509-516. Platelet GP llbllla was prepared by the method of Fitzgerald, etal. (AnaL Biochem. (1985) 151,169-177).
Microtiter plates were coated with fibrinogen (10 Ilg/ml) and then blocked with TACTS buffer containing 0.5% bovine serum albumin tBSA). (TACTS buffer contains 20mM
Tris.HCI, pH 7.5,0.02% sodium azide,2 mM calcium chloride, û.05% Tween 20,150 mM sodium chloride.) The plate was washed with phosphate buffered saline (PBS) containing 0.01%
Tween 20 and the sample to be determined was added, followed by addition of solubilized GP
llbllla receptor (40 ~lg/ml) in TACTS, 0.5% BSA. After a one-hour incubation, the plate was washed and 1 ~lg/ml of murine anti GP Illa monoclonal antibody AP3 (P. J. Newman et al.
Blood (1985) 65,227-232) was added. After a one-hour incubation and another wash, a goat anti-mouse IgG conjugated to horseradish peroxidase was added. A final wash was performed and developing reagent buffer (0.67 mg/ml o-phenylenediamine dihydrochloride, 0.02% hydrogen peroxide, 0.22 mM citrate, 50 mM phosphate, pH 5.0) were added and the mixture was incubated until color developed. The reaction was stopped with 1 N sulfuric acid and the absorbance at 492 nm was recorded. :
In addition to the ~P llbllla ELISA assay, platelet aggregation assays may be performed in human platelet rich plasma (PRP). Fifty milliliters of whole human blood (9 parts) is drawn on 3.8% sodium citrate (1 part) from a donor who has not taken aspirin or related medications for at least two weeks. The blood is centrifuged at 160 x 9 for 10 min at 22 C
and then allowed to stand for 5 min after which the PRP is decanted. Platelet poor plasma (PPP) is isolated from the remaining blood after centrifugation at 2000 x g for 25 min. The platelet count Baker 9000 hematology analyzer of the PRP was diluted to ca. 300000 per microliter with PPP.

. . ~ . . .

, ...

:,, ~... . ~ .
'' . .. .

WO 91/11458 ~n ~ PCI'/US91/00 A 225 IlL aliquot of PRP plus 25 ~lL of either a dilution of the test sample or a control tPBS) is incubated for 5 min in a Chrono-log Whole Blood Aggregometer at 25 C. An aggregating agent (collagen, 1 ~,lg/ml; U46619, 100 ng/ml; or ADP, 8 ~M) is added and the platelet aggregation was measured by recording the change in light transmittance. Inhibition of platelet aggregation was measured at the maximum aggregation response.
Results of the receptor binding and platelet inhibition assays for many of the cyclic peptides synthesized as described above are set forth in Tables 1 and 2 of Example 25. The first compound in Table 1 represents a linear peptide containing Arg-Gly-Asp which binds to platelet GP llbllla. This compound was selected as the reference or standard compound to which the other cyclic peptides provided in Tables 1 and 2 were compared. The ratio value provided in the first column adjacent each peptide entry is the ratio of the binding affinity for that compound verses the standard. A ratio value greater than 1 represents a compound which binds GP llbllla with a lower affinity than the reference compound, while a ratio value lower than 1 represents a compound that has a higher affinity than the reference compound.
Generally, compounds having a ratio greater than 1 were not considered sufficiently potent to be considered candidates for a platelet aggregation inhibition assay. Therefore, generally, - ~ preferred compounds of the instant invention have a ratio value less than 1.
The ICso values in the platelet aggregation assay (column 2, Table 1) are considere~
a more accurate measure of a compounds utility as an anUthrombotic. Generally, to be considered suitable as an antithrombotic, a compound should be at least about 5 times more potent in the platelet aggregation assay than the reference or standard compound. Thus, preferred compounds of the instant invention have an ICso in platelet aggregation inhibition assays of less than about 15 ~LM, while most preferred compounds have an ICso of less than 5 ,uM, and very most preferred compounds have an ICso of less than about 1 ~LM.
:: 25 Accordingly, preferred compounds of the instant invention may be represented by Formulae I -- Ill or are cyclic peptides containing from 7 to about 16 amino acids in a ring containing the sequence Arg-Gly-Asp flanked on both sides by at least one proline. As used herein, flanked means immediately adjacent or within about 3 residues of the Arg-Gly-Asp sequence.
; Other apparently similar compounds described in the prior art as effective cell adhesion inhibitors have so far proved to be relatively impotent as platelet aggregation inhibitors. For example, the cyclic peptide Gly-Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys-Ala, Pen-Cys disulfide described by Piershbacher et al., J. Biol. Chem. (1987) 262, 17294-17298 exhibited a binding ratio of 7 (i.e., about 7 times lower affinity for platelet GP llbllla than the reference compound) with an ICso in the platelet aggregation inhibition assay of ~300 IlM.In view of the foregoing discoveries, an alternative preferred method for reducing platelet aggregation in a mammal is to administer to the mammal a pharmaceutically effective amount of a cyclic peptide having from about 7 to about 16 amino acids in the cycle, the cycle containing the sequence Arg-Gly-Asp and at least one proline, where the cyclic peptide exhibits an ICso in a platelet aggregation inhibition assay of less than about 15 IlM.

. .

.

;, ;. . . .
,~
.... .

~369~
V'') 91/11458 ll PCl`/US91/00564 The most preferred compounds for use in the above described method comprises thecompounds represented by Formulae I - Ill.
Dosage Formulat~ons In the management of thromboembolic disorders the compounds of this invention may 5 be utilized in compositions such as tablets, capsules or elixers for oral administration, suppositories for rectal administration, sterile solutions or suspensions for injectable administration, and the like. Animals in need of treatment using compounds of this invention can be administered dosages that will provide optimal efficacy. The dose and method of adminstration will vary from animal to animal and be dependent upon such factors as weight, 10 diet, concurrent medication and other factors which those skilled in the medical arts will recognize.
Dosage formulations of the cyclic polypeptides of the present invention are prepared for storage or administration by mixing the the cyclic polypeptide having the desired degree of purity with physiologically acceptable carriers, excipients, or stabilizers. Such materials are 15 non-toxic to the recipients at the dosages and concentrations employed, and include bufiers such as phosphate, citrate, acetate and other organic acid salts; antioxidants such as ascorbic acid; low molecular weight (less than about ten residues) peptides such as polyarginine, proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidinone; amino acids such as glycine, glutamic acid, aspartic acid, or 20 arginine; monosaccharides, disaccharides, and other carbohydrates including cellulose or its derivatives, glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sobitol; counterions such as sodium and/or nonionic surfactants such as Tween, Pluronics or polyethyleneglycol.
Dosage formulations of the cyclic polypeptides of the present invention to be used for 25 therapeutic administration must be sterile. Sterility is readily accomplished by filtration through sterile filtration membranes such as 0.2 micron membranes. Cyclic polypeptide formulations ordinarily will be stored in Iyophilized form or as an aqueous solution. The pH of the cyclic polypeptide preparations typically will be between 3 and 11, more preferably from 5 to 9 and most preferably from 7 and 8. It will be understood that use of certain of the 30 foregoing excipients, carriers, or stabilizers will result in the formation of cyclic polypeptide salts. While the preferred route of administration is by hypodermic injection needle, other methods of administration are also anticipated such as suppositories, aerosols, oral dosage formulations and topical formulations such as ointments, drops and dermal patches.
Therapeutic cyclic polypeptide formulations generally are placed into a container . 35 having a sterile access port, for example, an intravenous solution bag or vial having a stopper pierceable by hypodermic injection needle.
Therapeutically effective dosages may be determined by either in vitro or in viwmethods. One method of evaluating therapeutically effective dosages is illustrated in Table I
where the cyclic polypeptide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp-Arg-Cys, Cys1 .

. . , . ,.. . . ; , . -., .. - ; , -, ~ . , ,,, ;.. , ~ :

: . - . - ., , .i-. - . . ~ ~ . , i , ,, "
. , ~ .
.... : . :

WO 91/114~8 ~ 12 PCI/US91/00564.
Cys~3 disulfide was determined to have a 50% inhibitory concentration (ICso) of 18 nM using the method of Example 21 (a ratio of 0.5 to Gly-Arg-Gly-Asp-Val) when inhibiting fibrinogen binding to the GP llbllla platelet receptor. Similarly, in a platelet aggregation assay in Example 22 using the same cyclic peptide, the ICs0 was found to be 8 ,~M as shown in Table 1. Based 5 upon such in vitro assay techniques, a therapeutically effective dosage range may be determined. For each particular cyclic polypeptide of the present invention, individual determinations may be made to determine the optimal dosage required. The range of therapeutically effective dosages will naturally be influenced by the route of administration.
For injection by hypodermic needle it may be assumed the dosage is delivered into the body's lû fluids. For other routes of administration, the absorption efficiency must be individually determined for each cyclic polypeptide by methods well known in pharmacology.
The range of therapeutic dosages may range ~rom about 0.001 nM to about 1.0 mM, more preferably from about 0.1 nM to about 100 ~M, and most preferably trom about 1.0 nM
to about 50 ~,lM.
A typical formulation of compounds of Formulae I - lll as pharmaceutical compositions contain from about 0.5 to 500 mg of a compound or mixture of compounds as either the free acid or base form or as a pharmaceutically acceptable salt. These compounds or mixtures . are then compounded with a physiologically acceptable vehicle, carrier, excipient, binder, preseNative, stabilizer, or flavor, etc., as called for by accepted pharmaceutical practice.
20 The amount of active ingredient in these compositions is such that a suitable dosage in the range indicated is obtained.
Typical adjuvants which may be incorporated into tablets, capsules and the like are a binder such as acacia, corn starch or gelatin; an excipient such as microcNstalline cellulose; a disintegrating agent like corn stàrch or alginic acid; a lubricant such as magnesium stearate; a 2~ sweetening agent such as sucrose or lactose; a flavoring agent such as peppermint, wintergreen or cherry. When the dosage form is a capsule, in addition to the above materials it - may also contain a liquid carrier such as a fatty oil. Other materials of various types may be used as coatings or as modifiers of the physical form of the dosage unit. A syrup or elixer may contain the active compound, a sweetener such as sucrose, preservatives like propyl 30 paraben, a coloring agent and a flavoring agent such as cherry. Sterile compositions for injecUon can be formulated according to conventional pharmaceutical practice. For example, dissolution or suspension of the active compound in a vehicle such as water or naturally occuring vegatable oil like sesame, peanut, or cottonseed oil or a synthetic fatty vehicle like ethyl oleate or the like may be desired. Buffers, preseNatives, antioxidants and the like can 35 be incorporated according to accepted pharmaceutical practice.
Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and illustrative examples, make and utilize the present invention to the fullest extent. The following working examples therefore specifically point out preferred , ~ . . . ...................... , . ~ ... , . . . ~ .

. ~: , . . : .

.. . ..

91/114~8 13 2 ~ PC~/USgl/0056~
~; embodiments of the present invention, and are not to be construed as limiting in any way of .. the remainder of the disclosure.
Examples - In the following Examples, amino acids are described by the standard three letter amino acid code when refering to intermediates and final products. The linear peptides and intermediates described herein are prepared by the solid phase method of peptide synthesis (R.
Merrifield, J. Am. Chem Soc. 1964,85,2149 and M. Bodansky, ~Principles of Peptide Synthesis." Springer-Verlag,1984). Abbreviations used are as follows:
Flourenylmethyloxycarbonyl (Fmoc); 2,2,5,7,8-pentamethylchroman-6-sulfonyl (Pmc); trityl (Trt); benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (BOP);
trifluoroacetic acid (TFA); dimethylacetamide (DMA); and dimethylformamide (DMF).
Peptides were assembled using a Milligen-Biosearch 9500 automated peptide synthesizer. Protected amino acids were obtained from from Milligen-Biosearch as the pentafluorophenyl esters or dihydrooxobenzotriazine esters (threonine and serine) except for Fmoc-Arg(Pmc) which was obtained from Calbiochem. Side chain protection was Asp (t-butyl ester), Cys (Trt), and Arg (Pmc).
:~ Example1 ~
Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-As~As~Arg-Cys. . -The peptide was assembled on 1.5 g (0.145 mmol) of Fmoc-Cyc(Trt) PepSyn KA
resin (Milligen-Biosearch). The coupling protocols were those recommended by Milligen-Biosearch with the exception of Arg which was coupled using BOP and that DMA was used instead of DMF as solvent. After chain assembly the N-terminal Fmoc group was removed using 20% piperidine in DMA. The peptide resin was then washed with dichloromethane followed by methanol and then dried under vacuum. The peptide was then deprotected and removed from the resin by stirring the peptide-resin in 20 ml of a mixture of TFA (95):
; triethylsilane (2.5): anisole (2.0): water (0.5) for 1 hr at room temperature. The mixture was then filtered and the resin washed with TFA. The filtrate and washings were concentrated under vacuum. The isolated residue was triturated with ether then filtered. The recovered peptide was taken up in 10% acetic acid in water and Iyophilized. The crude linear peptide (230 mg) was purified by HPLC. The peptide was dissolved in 0.1% TFA in water, loaded onto a 2.5 ~m x 50 cm C-18 reversed phase column (15 micron, 300A) and eluted with a shallow gradient of increasing acetonitrile. The elution conditions consisted of a 0% to 40% acetonitrile (containing 0.1% TFA) gradient at 0.5% min-l. The aqueous phase was 0.1% TFA in water.
Product containing fractions were then Iyophilized to afford the pure title peptide. FAB mass ; 35 spectrum: Calc. M ~ H =1533.7; found 1533.9.
Example 2 Cys-Arg-lle-Pro-Arg-Gly-Asp Met-Pro-Asp-As~Arg-Cys, Cys1 . Cys13 disulfide.
. The purified linear peptide (85 mg) was dissolved in 200 ml of water and the pH
adjusted to 8.5 with ammonium hydroxide. The resulbng solubon was stirred for 2 days at .

. . . .. : ,:....... . . .

n ;~!. J
Wo 91/11458 7 ~ 14 PCI`/US91/0056~--room temperature. When the linear peptide was completely oxidized, as determined by HPLC
the solution was acidified to pH 3 with TFA loaded directly onto a reverse phasechromatography column and purified as described in Example 1. The product containing fractions were Iyophilized to afford the pure title compound. FAB mass spectrum: Calc. M + H
5= 1531.7; found 1531.8. HPLC tR = 30 min. Following the procedures in Examples 1 and 2 the compounds of Examples 3 - 21 were prepared.
Example 3 Cys-Arg-Arg-Ala-Arg-Gly-Asp-Asp-Leu-Asp-Asp-Tyr-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1555.6; found 1555.7. HPLC tR = 30 min.
10Example 4 Cys-~ Pro-Arg-Gly-Asp-Met-Pro-Asp-As~Arg-Cys, Cys1 - Cys13 disulfide.
-. FAB mass spectrum: Calc. M + H = 1446.6; found 1446.6. HPLC tR = 32 min.
Example 5 Cys-Arg-Ala-Pr~Arg-Gly-As~Met-Pro-Asp-Asp-Arg-Cys, Cys1 . Cys13 disulfide.
15FAB mass spectrum: Calc. M + H = 1489.6; found 1489.6. HPLC tR = 25 min.
Example 6 Cys-Arg-ll~Ala-Arg-Gly-As~Met-Pro-Asp-Asp-Arg-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Galc. M + H = 1505.6; tound 1505.6. HPLC tR = 29 min.
Example 7 20Cys-Arg-lle-Pro-Arg-Gly Asp Ala-Pro-As~Asp-Arg-Cys, Cys1 - Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1471.7; found 1471.7. HPLC tR = 27 min.
- Example 8 Cys-Arg-ll~Pr~Arg-Gly-Asp-Met-Ala-Asp-Asp-Arg-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H= 1505.7; found 1505.7. HPLC tR = 29 min.
25Example 9 Cys-Arg-lle-Pro-Arg-Gly-As~Met-Pro-Ala-As~Arg-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1487.7; found 1487.7. HPLCtR=30 min.
Example 10 Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Ala-Arg-Cys, Cys1 - Cys13 disulfide.
30FAB mass spectrum: Calc. M + H = 1487.7; found 1487.7. HPLCtR=31 min.
Example 11 Cys-Arg-lle-Pr~Arg-Gly Asp-Met-Pro-Asp-Asp-Ala-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1446.6; found 1446.6. HPLCtR=32 min.
Example 12 35Cys-Arg-lle-Pr~Arg-Gly-As~Met-Pr~Cys, Cys1 Cys10 disuifide.
FAB mass spectrum: Calc. M + H = 1145.5; found 1145.5. HPLCtR= 33 min.
Exarnple 13 Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Ala-Arg-Cys, Cysl - Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1443.7; found 1444Ø HPLCtR=31 min.

2~7 ~69 ~
V~''` 91/11458 15 PCI`/US91/00564 Exa nple 14 . Cys-Arg-ll~Pro-Arg-Gly-Asp-Phe-Pro-Ala-Asp-Arg~Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M ~ H = 1503.7; found 1504Ø HPLC tR = 34 min.
Example 15 Cys-Arg-lle-Pro-Arg-Gly-Asp Leu-Pro-Ala-As~Arg-Cys, Cysl Cys13 disulfide.
- FAB mass spectrum: Calc. M + H = 1469.7; found 1470Ø HPLC tR = 32 min.
. Example 16 .. Cys-Arg-lle-Pro-Arg-Gly-As~Met-Pro-Ala-As~Tyr-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1494.6; found 1495Ø HPLC tR = 31 min.
Example 17 Cys-Arg-lle-Pr~Arg-Gly-As~nLeu-Pro-Ala-As~Arg-Cys, Cysl Cys13 disulfide.
: FAB mass spectrum: Calc. M + H = 1469.7; found 1469.8. HPLC tR = 34 min.
Example 18 Cys-Arg-lle-Pro-Lys-Gly-Asp Met-Pro-Asp Asp-Arg-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1503.7; found 1503.8. HPLC tR = 30 min. -. Example 19 Cys-Arg-lle-Pro-Lys-Gly-As~Met-Pro-Ala-Asp-Arg-Cys, Cys1 Cys13 disulfide.
FAB mass spectrum: Calc. M + H = 1459.7; found 1460.4. HPLC tR = 30 min.
Example 20 Cys Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp-Cys, Cys1 - Cys12 disulfide.
FAB mass spectrum: Calc. M + H = 1331.6; found 1331.5. HPLC tR = 32 min.
Example 21 - BrCH2CO-Arg lle Pro Arg Gly Asp Met-Pro As~Asp Arg-Cys.
.~ The title compound is prepared using the procedure in Example 1 except that 2~ bromoacetic acid is used in place of S-trityl N-Fmoc cysteine pentafluorophenyl ester.
Example 22 CO-Ar9-lle-PrO-Ar9-GIY-ASP-Met-PrO-ASP-ASP-Ar9-CYS

The compound prepared in Example 21 is dissolved in deionized water (lmg/ml) and the pH of the solution is adjusted to 8.0 - 8.5 with ammonium hydroxide. After stirring for 4 hr at ambient temperature the reaction solution is acidified to pH 3.0 - 3.5 with trifluoroacetic acid and then Iyophilized. The resulting crude product is purified by HPLC using the conditions described in Example 1. The desired title compound elutes after 32 minutes. FAB mass spectrum: calc.1469.7; obs.1470.7 (M+1). In the Gp llbllla binding assay of Example 23 the title compound exhibits a ratio of 0.27 against the control compound (see note 1 of Table 1).

,. . . , , , .............................. .. : . - .
- . . . . . . . .
~ , : ' . - :
., , ., ~ . . .

WO 91/1 1458 e~ l 6 Pcr/us9 1/00~6 Example 23 Inhibrtion of Irrunobilked fibrinogen binding to GP llbllla Microtiter plates are coated with fibrinogen (10 ~,lg/ml) and then blocked with TACTS buffer containing 0.5% BSA. (TACTS buffer contains 20mM Tris.HCI, pH 7.5, 5 0.02% sodium azide, 2 mM calcium chloride, O.û5% Tween 20, l 50 mM sodium chloride.) The plate is washed with phosphate buffered saline containing 0.0l% Tween 20 and a dilution of the sample to be determined was added, followed by addition of solubilized llbllla receptor (40 g/ml) in TACTS, 0.5% BSA. After one-hour incubation, the plate is washed and mL ~e monoclonal anti-platelet antibody AP3 tl llg/ml) added. After one-hour incubation and another wash, goat anti-mouse IgG conjugated to horseradish peroxidase is added. A final wash is performed and developing reagent buffer (0.67 mg/ml o-phenylenediamine dihydrochloride, 0.02% hydrogen peroxide, 0.22 mM citrate, 50 mM phosphate, pH 5.0) is added and then incubated until color develops. The reaction is stopped with l N sulfuric acid and the absorbance at 492 nm is recorded. The procedure is repeated at several dilutions of the test l5 sample and the concentration of test sample which inhibits 50% of the binding of GPllbllla receptor to fibrinogen ICso is determined, using a four parameter fit (Marquardt, J. Soc.
Indust. Appl. Math. (l963) ll: 43l-44l) which is the ICso. The ratio of the IC50 of the test sample to that of the control compound (Gly-Arg-Gly-Asp-Val) is then determined and reported in Table 1. The smaller the ratio in Table 1, the more potently the test compound 2~) inhibits immobilized fibrinogen binding to GP llbllla.
Example 24 Inhibition of platelet aggregation.
Fifty milliliters of whole human blood (9 parts) is drawn on 3.8% sodium citrate (l part) from a donor who has not taken aspirin or related medications for at least two weeks.
The blood is centrifuged at l 6û x 9 for l O min at 22 C and then allowed to stand for 5 min after which the PRP is decanted. Platelet poor plasma (PPP) is isolated from the remaining blood after centrifugation at 2000 x 9 for 25 min. The platelet count of the PRP was diluted to ca. 300000 per microliter with PPP.
- A 225 uL aliquot of PRP plus 25 uL of either a dilution of the test sample or a control 30 (PBS) is incubated for 5 min in a Chrono-log Whole Blood Aggregometer at 25 C. Adenosine diphosphate (ADP, 8 IlM) is added and the platelet aggregation recorded. The lCso value represents the concentration of test compound needed to inhibit the maximum aggregation response to 50% of its normal value. The results of this test are recorded in Table l.
In view of the efficacy of these cyclic polypeptides as inhibitors of fibrinogen binding to GP llbllla, and the feasibility as demonstrated herein of producing these cyclic polypeptides, the present invention may have application in the treatment of a large group of disorders associated with, or characterized by, a hyperthrombotic state. Representative of such disorders are genetic or aquired deficiencies of factors which normally prevent a hyperthrombotic state; medical procedures such as angioplasty and thrombolytic therapy;

~, ;, . , ~

:: . . . ~ ... . . .:

1 91/11458 17 2 Q 7 ~ ~ 9 ~ Pcr/us9l/oo564 mechanical obstructions to blood flow, such as tumor masses, prosthetic synthetic cardiac valves, and extracorporeal perfusion devices; atherosclerosis; and coronary artery disease.

~ Results of GP llalllb - Fibrinogen ELISA and Platelet Aggregation Assays -:

Inhibition of Immobilized Fibrinogen Binding to GP llblll~ and Inhibition of Platelet Aogregation GP llbllla- Fibrinogen ELISA
Peptide ICso Ratiol ICso(uM) Platelet Aggregaticn Gly-Arg-Gly-Asp-Val l 75 Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp- 0 5 8 Arg-Cys, Cys1 Cys13 disulfide Cys-Arg-Arg-Ala-Arg-Gly-Asp-Asp-Leu-Asp- 5.2 300 Asf~Tyr-Cys, Cys1 Cys13 disulfide Cys-Ala-lle-Pro-Arg-Gly-Asp Me~-Pro-Asp-Asp 0.43 9 Arg-Cys, Cys1 Cysl3 disulfide Cys-Arg-Ala-Pro-Arg-Gly-Asp-Met-Pro-Asp- 0.54 13 Asp-Arg-Cys, Cys1 Cys13 disulfide Cys-Arg-lle-Ala-Arg-Gly-Asp-Met-Pro-Asp-Asp- 0 28 3 Arg-Cys, Cys1 Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Ala-Pro-Asp-Asp- l.0 4 3 Arg-Cys, Cys1 Cysl3 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Ala-Asp-Asp- l 5 39 Arg-Cys, Cys1 Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Mel-Pro-Ala-Asp- 01 l 0.5 Arg-Cys, Cys1 Cysl3 disulfide . - : . . . . . ~ .

. ' " ' ~ ' : ~;

. .

WO 91/11458 C~ 9Q 18 PCr/US~l/00564 Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Ala- 0.16 3 Arg-Cys, Cysl - Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp- 0.23 9 Ala-Cys, Cys1 - Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Cys, Cysl 0.21 4.3 - Cys10 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Ala- O.û4 û.5 Arg-Cys, Cysl Cys13 disulfide ::-Cys-Arg-lle-Pro-Arg-Gly-Asp-Phe-Pro-Ala-Asp- û.3 1.0 Arg-Cys, Cysl Cysl3 disulfide ' Cys-Arg-lle-Pro-Arg-Gly-Asp-Leu-Pro-Ala-Asp- 0.2 1.3 Arg-Cys, Cy51 Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp- 0.35 3.7 Tyr-Cys, Cysl Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-nLeu-Pro-Ala-Asp- 0.1 1.9 Arg-Cys, Cysl Cysl3 disulfide .'~
Cys-Arg-lle-Pro-Lys-Gly-Asp-Met-Pro-Asp-Asp- 46.4 , Arg-Cys, Cys1 . Cysl3 disulfide .
Cys-Arg-lle-Pro-Lys-Gly-Asp-Met-Pro-Ala-Asp- 0.5 Arg-Cys, Cys1 Cysl3 disulfide -: .
Cys-Arg-lle-Pro-Arg-Gly-Asp-Me~-Pro-Ala-Asp 0.13 0.8 Cys, Cysl Cys12 disulfide 1. Ratio of lCso of test compound to IC50 of Gly-Arg-Gly-Asp-Val. The IC~o of Gly-Arg-Gly-Asp-Val is typically about 4ûnM. Errors can range to about + 50%.

... ~: .
., ~ ' .

~ ~ 91/11458 2 ~ ~ 3 6 n ~ Pcrlussl/oo56~
Table 2 Inhibition of FibrinoQen Bindin~to GP llbllla bv Cyclic Peptides.1 GP llbllla- Fibrinogen ELISA

Peptide IC50 Ratio2 Cys-lle-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp- 0.8 Arg-Cys, Cys1 - Cys1 2 disulfide .
Cys-Pro-Arg-Gly-Asp-Met-Pro-Asp-Asp-Arg- 1.1 Cys, Cys1 - Cys1 1 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-Pro-Ala- 0.13 Cys, Cys1 - Cys11 disulfide Cys-!le-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp- û.8 Arg-Cys, Cys1 - Cys12 disulfide Cys-Pro-Arg-Gly-Asp-Met-Pro-Ala-Asp-Arg- 0.4 Cys, Cys1 - Cys11 disulfide Cys-Arg-Gly-Asp-Met-Pro-Ala-Asp-Arg-Cys, 4 Cys1 - Cys10 disulfide Cys-Arg-Gly-Asp-Met-Pro-Cys, Cys1 - Cys7 disulfide . Cys-Lys-Arg-Ala-Arg-Gly-Asp-Asp-Met-Asp- 4.6 Asp-Tyr-Cys, Cys1 -Cysl3 disulfide Cys-lle-Pro-Arg-Gly-Asp-Met-Pro-Cys, Cys1- 0.8 Cys9 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Pro-Met-Ala- 7 Asp-Arg-Cys, Cys1 - Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-lle-Pro-Ala-Asp- 16 Arg-Cys, Cys1 - Cys13 disulfide . . .
. : . , .. , ,, - . . .

, .

WO91/1~458 1~`' 20 PCI/US91/0~564 `

Cys-Arg-lle-Pro-Arg-Gly-Asp-Gln-Pro-Ala- 0.8 Asp-Arg-Cys, Cysl Çysl3 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Ser-Pro-Ala- 12 Asp-Arg-Cys, Cysl - Cysl3 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Met-(D-Pro)- 25 Ala-Asp-Arg-Cys, Cysl - Cysl3 disulfide Cys-Arg-lle-Pro-Ala-Gly-Asp-Met-Pro-Ala- 149 Asp-Arg-Cys, Cysl - Cysl3 disulfide Cys-Arg-lle-Pro-Arg-Ala-Asp-Met-Pro-Ala- 0.9 Asp-Arg-Cys, Cys1 . Cysl3 disulfide Cys-Arg-lle-Pro-Arg-Gly-Ala-Met-Pro-Ala- >lO000 Asp-Arg-Cys, Cysl - Cysl3 disulfide Cys-Arg-lle-Pro-Arg-Gly-Glu-Met-Pro-Ala- >lO000 Asp-Arg-Cys, Cys1 - Cys13 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Arg-Pro-Ala- 05 Asp-Arg-Cys, Cys1 Cysl3 disulfide Cys-Arg-lle-Pro-Arg-Gly-Asp-Lys-Pro-Ala- 1.3 Asp-Arg-Cys, Cys1 - Cysl3 disulfide Cys-lle-Pro-Arg-Gly-Asp-Met-Pro-(D-Ala)- 0.6 Asp-Arg-Cys, Cys1 - Cys12 disulfide Cys-lle-Pro-Arg-Gly-Asp-Met-Pro-Gly-Asp- 0.4 Arg-Cys, Cys1 - Cys12 disulfide Cys-lle-Pro-Arg-Gly-Asp-Met-Pro-Ser-Asp- 0.4 Arg-Cys, Cys1 - Cys12 disulfide Cys-lle-Pro-Arg-Gly-Asp-Met-Pro-Val-Asp- 05 Arg-Cys, Cys1 - Cys12 disulfide . .
. - . . . . .

. . ~ , , VO 91/11458 '? 9~ ~ 21 PCl`/US91/00564 1. The compounds in this Table were prepared following the procedures of Examples 1 and 2.
- 2. See Note 1 of Table 1 ~, ..... .
While the invention has necessarily been described in conjunction with preferred: 5 embodiments, one of ordinary skill, after reading the foregoing specification, will be able to effect various changes, substitutions of equivalents, and alterations to the subject matter set forth herein, without departing from the spirit and scope thereof. Hence, the invention can be practiced in ways other than those specifically described herein. It is therefore intended that the protection granted by Letters Patent hereon be limited only by the appended claims and 10 equivalents thereof.
. .

.
'~ .

.
.. . . . ..

.. - , . , . :. . , ~ ~ .

Claims (25)

What is claimed is:

1. A compound represented by the formula wherein R1 and R4 are independently selected from 0 to 4 amino acids;
R3 is independently selected from 1 to 4 amino acids;
R2 is -CH2CO- or from 1 to 4 amino acids;
Xaa8 is selected from Met, Phe, nLeu, Leu, lle, Asp, Lys, Arg and Gln;
Z is a linking group selected from disulfide, thioether and amide bond; and pharmaceutically acceptable salts thereof.

2. The compound of Claim 1 wherein R2 is -Rs-Xaa2-Xaa3-Xaa4 provided thal R5 is bonded to R1 and Z;
R3 is -Xaalo-Xaall-Xaal2-Cys- provided that Cys is bonded to R4 and Z;
where each Xaa2, Xaa3, Xaa4, Xaa10, Xaa11 and Xaa12 is independently selected from amino acids and null; and R5 is Cys or -CH2CO-.

3. The compound of Claim 2 wherein each Xaa2, Xaa3 and Xaa4 is an amino acid.

4. The compound of Claim 3 wherein R5 is Cys and Z is disulfide.

5. The compound of Claim 4 wherein R1 and R4 are null.

6. The compound of Claim 5 wherein Xaa3 is selected from Met, Phe and nLeu.

7. The compound of Claim 6 wherein Xaa4 is Pro.

8. The compound of Claim 7 wherein Xaa10 is Ala.

9. The compound of Claim 8 wherein Xaa11 is selected from Ala and Asp.

10. The compound of Claim 9 wherein Xaa2 is Arg and Xaa3 is lle.

11. The compound of Claim 1 selected from the group:
;
;
;
;
;
;
;
;
;
;
;
;

;
; and where each Cys1-Cys13, Cys1-Cys12, Cys1-Cys11, and Cys1-Cys10 is linked through a disulfide.

12. The compound of Claim 11 selected from the group ;
; and , where each Cys1-Cys13, and Cys1-Cys12 is linked through a disulfide.

13. A peptide comprising from 7 to about 16 amino acids in a ring bridged through the disulfide of cystine, the ring containing the sequence Arg-Gly-Asp flanked by Proline.

14. A pharmaceutical composition comprising a pharmaceutically acceptable excipient and the compound of Claim 1.

15. A method of inhibiting platelet aggregation which method comprises administering a platelet aggregation inhibiting amount of a compound of Claim 1 .

16. A method for reducing platelet aggregation in a mammal, comprising administering to the mammal a pharmaceutically effective amount of a cyclic peptide having from about 7 to about 16 amino acids in the cycle, the cycle further containing the sequence Arg-Gly-Asp and at least one proline, the cyclic peptide exhibiting an IC50 in a platelet aggregation inhibition assay of less than about 15µM.

17. A method for reducing platelet aggregation in a mammal, comprising administering a pharmaceutically effective amount of the composition of matter as defined by Claim 1 to said mammal.

18. The method of Claim 17, further comprising administering said composition of matter to said mammal in admixture with a pharmaceutically acceptable carrier.

19. A method for treating a mammal who has an increased propensity for thrombus formation, comprising administering a pharmaceutiacally effective amount of the composition of matter as defined by Claim 1 to said mammal.

20. A composition of matter for reducing platelet aggregation in a mammal, comprising the composition of matter as defined by Claim 1.

21. A composition of matter for treating a mammal who has an increased propensity for thrombus formation, comprising the composition of matter as defined by Claim 1.

22. A composition of matter for inhibiting fibrinogen binding to platelets in a mammal, comprising the composition of matter as defined by Claim 1.

23. A method for treating a mammal who has an increased propensity for thrombus formation, comprising administering a pharmaceutically effective amount of the composition of matter as defined by Claim 1 in combination with a thrombolytic agent.

24. A method for treating a mammal who has an increased propensity for thrombus formation, comprising administering a pharmaceutically effective amount of the composition of matter as defined by Claim 1 in combination with an anticoagulant.

25. A method for treating a mammal who has an increased propensity for thrombus formation, comprising administering a pharmaceutically effective amount of the composition of matter as defined by Claim 1 following angioplasty.