SOMATOSTATIN-ANALOGOUS CYCLIC PEPTIDES WITH INHIBITORY ACTIVITY ON GROWTH HORMONE

Abstract: Cyclic peptides of general formula (I), wherein the groups are as described in the disclosure, having inhibitory activity on growth hormone. The peptides of formula (I) have also anticancer activity.

Description: SOMATOSTATIN-ANALOGOUS CYCLIC PEPTIDES WITH INHIBITORY ACTIVITY ON GROWTH HORMONE The present invention relateε to cyclic peptides which are homologues of somatostatin and have inhibitory activity on growth hormone. BACKGROUND OF THE INVENTION Somatostatin, or somatotropin-release inhibition factor, is a neuropeptide inhibiting the releaεe of the growth hormone (somatotropin) . A number of somatostatin synthetic analogues are known, which are used in human and animal therapies. In particular, octreotide has been known for some time, which is a somatostatin synthetic analogue used in therapy for the treatment of syndromes due to gastroenteral-pancreatic endocrine tumours, acromegaly as well as in the post-surgery treatment after pancreas surgery. Octreotide is also indicated as an agent inhibiting gastric secretion. This compound is described in U.S. 4.395.403 (in Sandoz name) and has the formula: D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-NHCH(CH 2 OH)CHOHCH3 The octapeptide described above lies within a general formula of monocyclic polypeptideε, comprising an hexapeptide residue containing a phenylalanine residue, optionally substituted at the 1- position of the aromatic ring, a cysteine residue at the 2- position, a D-trypthophan residue optionally substituted at the 4- position of the indole ring, a lysine residue at the 5- position, optionally N-alkylated at the position e, an amino acid residue at the 6- position and a cysteine residue at the 7- position, the two sulfur atoms of the 2 and 7 cysteine residues are linked together and an amino acid residue at the 8- position. Another somatostatin synthetic analogue, known under the name of Lanreotide, has been recently used in therapy. This compound has formula: D-j3Nal-Cys-Tyr-D-Trp-Lys-Val-Cys-ThrNH2. SUMMARY OF THE INVENTION Now it has been found that compounds of formula (I) A-pys-B-D-Trp-Lys-C-gys-R wherein A is D-2AlkTrp, D-βNal, D-Phe; B iε Tyr, Phe; C is Val, Thr; R is ThrNH 2 ; 2AlkTrpNH 2 with the proviso that when A iε D-βNal, B is not Tyr, C is not Val and R is not ThrNH 2 and the pharmaceutically acceptable salts of these peptides have activity inhibiting the release of the growth hormone and therefore are useful as active principles in human and animal medicine. The present invention is based on the most surpriεing finding that the change of some structural characteristicε, which had been defined esεential in U.S. 4,395,403, not only keepε the somatostatin-like activity, but also shows further advantages in terms of specificity (see for example the expreεεion of receptor sub-types in pituitary adenomas (G.M. Miller et al. J.C.E.M. 80, 1386, 1995) and in bronchial carcinoid tumors (H. Lefabre et al. J.C.E.M. 80, 1423, 1995). DETAILED DISCLOSURE OF THE INVENTION The abbreviations for the residues of amino acidε therein uεed are in agreement with the εtandard nomenclature for the peptideε, therefore, in the formula (I) reported above: Cys = cysteine; D-Trp = D-trypthophan; Lyε = L-lyεine; D-AlkTrp = D-2-alkyltryptophan; D-β-Nal = D-β-naphthylalanine; D-Phe = D-phenylalanine; Tyr = L-tyroεine; Phe = L-phenylalanine; Val = L-valine; Thr = L-threonine; ThrNH 2 = L-threonine amide Alk TrpNH 2 = L-2-alkyltryptophan amide. According to the preεent invention, for alkyl at position 2- of the tryptophan reεidue it iε intended lower alkyl, comprising from 1 to 3 carbon atoms. Exampleε of lower alkyl are methyl, ethyl, propyl, isopropyl. Among them, the methyl group is most preferred, and the abbreviation MeTrp is used to indicate 2-methyltryptophan. All the three letter-abbreviations of the amino acids preceded by a "D" indicate the D-configuration of the amino acidic residue. Preferred compounds according to the present invention are: D-MeTrp-Cys-Tyr-D-Trp-Lyε-Val-Cys-ThrNH 2 (Sequence Id no. 1); D-βNal-Cys-Tyr-D-Trp-Lys-Val-Cys-MeTrpNH 2 (Sequence Id no. 2 ) ; D-MeTrp-Cγs-Phe-D-Trp-Lys-Thr-Cys-MeTrpNH 2 (Sequence Id no. 3); D-Phe-Cys-Tyr-D-Trp-Lys-Cys-MeTrpNH (Sequence Id no. 4) wherein MeTrp is 2-methyltrγptophan. The compound: D-MeTrp-Cγs-Phe-D-Trp-Lyε-Thr-Cys-MeTrpNH 2 (Sequence Id no. 3) , wherein MeTrp is 2-methyltryptophan, is most preferred. The polypeptide compoundε according to the present invention can be syntheεized according to the uεual methodε of peptide chemistry, both solid-phase and solution, or by means of the clasεical methods known in the art. The solid-phase synthesis starts from C- terminal end of peptide. A suitable starting material can be prepared, for example attaching the required protected alpha-a ino acid to a chloromethylated resin, a hydroxymethylated resin, a benzhydrylamine resin (BHA), or to a para-methγlbenzhγdrylamine resin (p-Me- BHA). Aε example, a chloromethylated resin is sold with the Trade Mark BIOBEADS (R) SX 1 by BioRad Laboratories, Richmond, California. The preparation of the hydroxymethyl reεin is described by Bodansky et al., Chem. Ind. (London) 38, 15997, (1966). The BHA resin is deεcribed by Pietta and Marshall, Chem. Comm., 650 (1970) and iε commercially available by Peninεula Laboratories Inc., Belmont, California. After the starting attachment, the protecting group of the alpha-amino acid can be removed by means of different acid reagents, comprising trifluoroacetic acid (TFA) or hydrochloric acid (HCl) dissolved in organic solvents at room temperature. After the removal of the protecting group of the alpha-amino acid, the remaining protected amino acids can be coupled step by step in the desired order. Each protected amino acid can generally be reacted in excesε of about three timeε uεing a εuitable carboxyl activating group, εuch as dicyclohexylcarbodiimide (DCC) or diiεopropylcarbodi- imide (DIC) diεsolved, for example, in methylene chloride (CH 2 C1 2 ) or dimethylformamide (DMF) and their mixtures. After the desired amino acidic sequence has been completed, the desired peptide can be cleaved from the supporting resin by treatment with a reagent such as hydrogen fluoride (HF), which not only cleaves the peptide from the resin, but also the more common protecting groups of the lateral chains. When a chloromethylated resin or a hydroxymethylated resin iε uεed, the treatment with HF leadε to the formation of the acid peptide in free form. When a BHA or p-Me-BHA reεin is used, the treatment with HF directly leadε to the formation of the amide peptide in free form. The above discussed solid-phase procedure is known in the art and was described by Atherton and Sheppard, Solid Phase Peptide Synthesiε (IRL Preεε, Oxford, 1989). Some methods in εolution, which can be uεed to synthesize the peptide moieties of the present invention are detailed in Bodanεky et al., Peptide Synthesiε, 2 nά - edition, John Wiley & Sons, New York, N.Y. 1976 and in Jones, The Chemical Synthesis of Peptideε, (Clarendon Preεε, Oxford, 1994). Theεe compoundε can be administered to animals and humanε at an effective doεe which can be eaεily determined by the expert in the field and which can vary according to the specie, age, sex and weight of the treated subject. For example, in humans, when intravenouεly adminiεtered, the preferred doεe fallε in the range from about 0.1 μg to 10 μg of total peptide per kg of body weight. When orally adminiεtered, typically higher amountε are neceεsary. For example, in humans for the oral administration, the doεage level is typically from about 30 μg to about 1000 μg of polypeptide per kg of body weight. The exact level can be eaεily determined empirically baεed on the above diεcloεure. Compositions comprising as active ingredient the organic and inorganic addition salts of the above described polypeptides and their combinations, optionally, in admixture with a vehicle, diluent, matrix or delayed release coating, are also comprised in the scope of the present invention. The delayed release pharmaceutical forms, comprising bioerodible matrixes suitable for subcutaneous implant, are particularly interesting. Examples of these matrices are described in WO9222600 and W09512629. The biological activity of the peptides according to the present invention has been evaluated in vitro and in vivo. The study of the binding of the peptideε on so atoεtatin receptorε haε been carried out according to the displacement method which consistε in replacing from the receptors the radioligand (11-Tyr radioiodinated somatostatin 14-) before electrophoretic analysis on a denaturant polyacrylaminde gel (Prevoεt et al. European J . Cancer , 11 , 1589-1592 , 1993 ) . The biological activity waε teεted on rat and human cell lineε, namely a GH 3 rat cell line established starting from a pituitary tumor with two 70 and 57 kDa receptors; MCF7 human cell line establiεhed starting from a pleural effusion of a breast carcinoma with two main 57 and 42kDa receptorε and human cell line establiεhed εtarting from a εmall cell carcinoma of the lung with a 57 kDa receptor. The test waε effected on the following compoundε of the present invention listed below: D-MeTrp-Cys-Tyr-D-Trp-Lys-Val-Cys-ThrNH ; (b) D-βNal-Cys-Tyr-D-Trp-Lys-Val-Cyε-MeTrpNH; (c) D-MeTrp-Cys-Phe-D-Trp-Lyε-Thr-Cyε-MeTrpNH,; (d) -—— 1 * • D-Phe-Cys-Tyr-D-Trp-Lys-Cyε-MeTrpNH ; (e) wherein MeTrp is 2-methyltryptophan, respectively indicated with the letters b, c, d, e. Aε a compariεon, the known peptides Lanreotide (W.A. Murphy et al. Life Sci. 40, 2515, 1987), Antarelix (R. Deghenghi et al., Biomed. & Pharmacother. 47, 107, 1993) and somatostatin-14 were used. The pharmacological study of the displacement of the bond between radiolabelled somatoεtatin and the receptor by the tested peptides showed that the 70 kDa complex corresponds to the 1 or 4 εub-type receptorε, the 57 kDa complex corresponds to the sub-type 2 and the 42 kDa complex correεponds to the sub-type 3 or 5. The teεted peptideε were εuspended in 0,1% acetic acid at the final concentration of lOmM and stored at 4°C. Testε were carried out at a 10 -6 M concentration. Auto-radiographies in electrophoresis have shown that the 70 kDa complex is suppreεsed only by somatoεtatin-14, whereas the 57 kDa complex is displaced by the peptides according to the invention, by Lanreotide, but not by Antarelix. The 42 kDa complex is suppreεsed by the peptides c, d, e of the invention, which thus prove an action εpecificity. Tests with decreasing concentrations, 10 " ^, 10 " ^, 10 -8 M, have shown that the compounds according to the present invention are particularly active compared with the known compounds and somatostatin. The compounds according to the present invention have inhibitory activity on the release of growth hormone, therefore they are useful as active principles for the preparation of a medicament for the treatment of the diseases characterized by an unbalance of the growth hormone. In particular they are useful for the treatment of endocrine tumorε, acromegaly and in the conditionε in which the known somatostatin analogues are uεed. According to another aspect, the present invention provides cyclic peptides of formula (I) εhown above aε a εupport for a radioactive marker, for example or ^-^-Indium or ^^ Technetium uεeful aε diagnoεtic agentε for tumorε characterized by the preεence of εomatostatin receptors. SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: (A) NAME: DEGHENGHI Romano (B) STREET: Cheseaux Desεuε Bl (C) CITY: St. Cergue (E) COUNTRY: Switzerland (F) POSTAL CODE (ZIP): 1264 (ii) TITLE OF INVENTION: SOMATOSTATIN-ANALOGOUS CYCLIC PEPTIDES WITH INHIBITORY ACTIVITY ON GROWTH HORMONE (iii) NUMBER OF SEQUENCES: 4 (iv) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: Patentin Release #1.0, Version #1.30 (EPO) (vi) PRIOR APPLICATION DATA: (A) APPLICATION NUMBER: IT MI95A001670 (B) FILING DATE: 28-JUL-1995 (2) INFORMATION FOR SEQ ID NO: 1: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: circular (ii) MOLECULE TYPE: peptide (ix) FEATURE: (A) NAME/KEY: Disulfide-bond (B) LOCATION: 2..7 (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION:1 (D) OTHER INFORMATION: /product= "OTHER" /note= "Trp is D-2-Methyl-Trp" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION: (D) OTHER INFORMATION: /product= "OTHER" /note= "Trp is D-Trp" (ix) FEATURE: (A) NAME/KEY: Peptide (B) LOCATIONS (D) OTHER INFORMATION: /product= "OTHER" /note= "Thr is Thr-NH2" (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1: Trp Cyε Tyr Trp Lyε Val Cys Thr 1 5 (2) INFORMATION FOR SEQ ID NO: 2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: circular (ii) MOLECULE TYPE: peptide (ix) FEATURE: (A) NAME/KEY: Disulfide-bond (B) LOCATIONS..7 (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION:1 (D) OTHER INFORMATION: /product= "OTHER" /note= "Ala is D-betaNal" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATIONS (D) OTHER INFORMATION: /product= "OTHER" /note= "Trp is D-Trp" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION: 8 (D) OTHER INFORMATION: /product= "OTHER" /note= "Trp is 2-Methyl-Trp-NH2" (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 2: Ala cys Tyr Trp Lys Val Cys Trp (2) INFORMATION FOR SEQ ID NO: 3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 8 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: circular (ii) MOLECULE TYPE: peptide (ix) FEATURE: (A) NAME/KEY: Disulfide-bond (B) LOCATIONS..7 (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION:1 (D) OTHER INFORMATION:/product= "OTHER" /note= "Trp is D-2-Methyl-Trp" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATIONS (D) OTHER INFORMATION:/product= "OTHER" /note= "Trp is D-Trp" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATIONS (D) OTHER INFORMATION: /product= "OTHER" /note= "Trp is 2-Methyl-Trp-NH2" (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 3: Trp Cys Phe Trp Lys Thr Cys Trp 1 5 (2) INFORMATION FOR SEQ ID NO: 4: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 7 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: circular (ii) MOLECULE TYPE: peptide (ix) FEATURE: (A) NAME/KEY: Disulfide-bond (B) LOCATIONS..6 (ix) FEATURE: (A) NAME/KEY: Modified-εite (B) LOCATION:1 (D) OTHER INFORMATION: /product= "OTHER" /note= "Phe is D-Phe" (ix) FEATURE: (A) NAME/KEY: Modified-εite (B) LOCATIONS (D) OTHER INFORMATION:/product= "OTHER" /note= "Trp is D-Trp" (ix) FEATURE: (A) NAME/KEY: Modified-site (B) LOCATION:7 (D) OTHER INFORMATION:/product= "OTHER" /note= "Trp is 2-Methyl-Trp-NH2" (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 4: Phe Cys Tyr Trp Lys Cys Trp 1 5

Claims: CLAIMS 1. Compoundε of formula (I ) A-Cyε-B-D-Trp-Lyε-C-Cyε-R wherein A is D-AlkTrp, D-βNal,D-Phe; B is Tyr, Phe; C iε Val, Thr; R iε ThrNH 2 ; AlkTrpNH 2 with the proviεo that when A is D-βNal, B is not Tyr, C is not Val and R is not Thr NH 2 and the pharmaceutically acceptable εalts of said compoundε. 2. Compound according to claim 1, selected from the group consisting of: D-MeTrp-Cys-Tyr-D-Trp-Lys-Val-Cys-ThrNH 2 (Sequence Id no. 1); D-βNal-ςyε-Tyr-D-Trp-Lyε-Val-Cyε-MeTrpNH 7 (Sequence Id no. 2 ) ; D-MeTrp-Cyε-Phe-D-Trp-Lyε-Thr-Cy8-MeTrpNH 2 (Sequence Id no. 3); D_Phe-Cys-Tyr-D-Trp-Lys-Cys-MeTrpNH 2 (Sequence Id no. 4); wherein MeTrp is 2-methyltryptophane . 3. The use of the compounds of claims 1-2 for the preparation of a medicament with inhibitory activity on the growth hormone . 4. The use of the compounds of claimε 1-2 for the preparation of a medicament with antitumor activity. 5. Pharmaceutical compoεitions containing a therapeutically effective amount of a compound of claims 1-2 as active ingredient in admixture with carrierε and/or pharmaceutically acceptable excipients. 6. Compounds of claims 1-2 as ligands for a radioactive marker. 7. The use of the compounds of claim 6 for the prepa¬ ration of a diagnostic agent for the detection of tumors.

Inventors: DEGHENGHI ROMANO, DEGHENGHI, ROMANO
Applicants: DEGHENGHI ROMANO, DEGHENGHI, ROMANO
Application year: 1996
Main classification: C07K14
IPC codes: A61K31, A61K38, A61K51, A61P5, A61P35, C07K14