PEPTIDOMIMETICS FOR IMAGING THE GHRELIN RECEPTOR

Abstract

The present invention concerns compositions comprising and methods of identification and use of imaging agents. The imaging agents comprise a growth hormone secretagogues having a conjugated fluoride. The imaging agents of the present invention may be used for detection, diagnosis and/or staging of prostate or other forms of cancer, and may also be used for cardiac disease.

Claims

1. A conjugate comprising a peptidomimetic of a growth hormone secretagogue (GHS) having a conjugated fluoride group.

2. The conjugate of claim 1, wherein the peptidomimetic includes one or more unnatural amino acid residues.

3. The conjugate of claim 1, wherein the peptidomimetic includes a lysine residue and the fluoride group is conjugated to the lysine residue.

4. The conjugate of claim 1-3, wherein the fluoride is non-radioactive or radioactive.

5. The conjugate of claim 1, wherein the peptidomimetic having the conjugated fluoride is selected from H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(4-FB)-NH.sub.2 and H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH.sub.2.

6. The conjugate of claim 1, wherein the peptidomimetic having the conjugated fluoride is selected from H-Inp-(D-2-Nal)2-Ser-Phe-Lys(2-FP)-NH.sub.2, H-Inp-(D-2-Nal)2-Phe-Ser-Lys(2-FP)-NH.sub.2, H-Inp-(D-2-Nal)2-Tyr-Lys(2-FP)-NH.sub.2 and H-Inp-(D-2-Nal)2-Ser-Lys(2-FP)-NH.sub.2.

7. A method of detecting ghrelin receptors at a target site of a subject, the method comprising: (a) providing a conjugate comprising a peptidomimetic of a growth hormone secretagogue (GHS) having a conjugated fluoride group; (b) administering a concentration of the conjugate of step (a) to the subject effective to detect the growth hormone receptors at the target site; (c) allowing the conjugate to accumulate at the target site within the subject; and (d) detecting the conjugate at the target site thereby detecting the ghrelin receptors at the target site.

8. The method of claim 7, wherein the peptidomimetic includes one or more unnatural amino acid residues.

9. The method of claim 7, wherein the peptidomimetic includes a lysine residue and the fluoride group is conjugated to the lysine residue.

10. The method of claim 7-9, wherein the fluoride group is non-radioactive or radioactive.

11. The method of claim 7, wherein the peptidomimetic having the conjugated fluoride group is selected from H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(4-FB)-NH.sub.2 and H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH.sub.2.

12. The method of claim 7, wherein the peptidomimetic having the conjugated fluoride is selected from H-Inp-(D-2-Nal)2-Ser-Phe-Lys(2-FP)-NH.sub.2, H-Inp-(D-2-Nal)2-Phe-Ser-Lys(2-FP)-NH.sub.2, H-Inp-(D-2-Nal)2-Tyr-Lys(2-FP)-NH.sub.2 and H-Inp-(D-2-Nal)2-Ser-Lys(2-FP)-NH.sub.2.

13. The method of claim 7-12, wherein the target site is a tumor or cardiac tissue.

14. The method of claim 7-13, wherein the detecting is performed with positron emission tomography (PET), PET-computed tomography (CT) hybrid or PET-magnetic resonance imaging (MRI) hybrid.

15. A method of assessing the malignancy of a tumor, the method comprising: (a) contacting the tumor with a conjugate as defined in claims 1-6, (b) detecting the expression of the conjugate in the tumor, (c) comparing the expression of step (b) with the expression of said conjugate in a control tissue, and (d) assessing the malignancy of the tumor based on the comparison.

16. The method of claim 15, wherein the detecting is performed with positron emission tomography (PET), PET-computed tomography (CT) hybrid or PET-magnetic resonance imaging (MRI) hybrid.

17. A use of the conjugate according to any one of claims 1-6 for imaging cancer cells and cardiac tissue.

18. A conjugate as defined in any one of claims 1-6 for use in imaging a ghrelin receptor.

19. A conjugate as defined in any one of claims 1-6 for use in imaging, diagnosing or staging cancer, and heart disease.

20. A pharmaceutical composition comprising a conjugate as defined in claims 1-6, and a pharmaceutically acceptable carrier.

21. A method of increasing the level of endogenous growth hormone in a subject comprising administering to the subject a pharmaceutically effective amount of the pharmaceutical composition of claim 20.

22. A method for treating a subject of a GHS-R1a receptor related disorder, the method comprising administering to the subject a pharmaceutically effective amount of the pharmaceutical composition of claim 20, wherein the disorder is selected from the group consisting of: cachexia in patient with cancer or chronic obstructive pulmonary disease, heart failure, and diabetes mellitus (including Type 1 and 2).

23. The method of claim 21 or claim 22, wherein the conjugate is selected from the group consisting of H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH.sub.2 and H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(2-FP)-NH.sub.2.

24. An isolated peptidimimetc, wherein said isolated peptidomimetic is selected from the group consisting of peptidomimetics included in Tables 1 and 2 which include a fluoride group.

25. An isolated peptidomimetic, wherein said isolated peptidomimetic comprises the amino acid sequence H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH.sub.2.

26. An isolated peptidomimetic, wherein said isolated peptidomimetic comprises the amino acid sequence H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(2-FP)-NH.sub.2.

27. An isolated peptidomimetic, wherein said isolated peptidomimetic comprises the amino acid sequence H-Inp-D-2-Nal-D-2-Nal-Tyr-Lys(2-FP)-NH.sub.2.

28. A compound comprising the amino acid sequence H-Inp-D-2-Nal-D-2-Nal-Xaa-Aaa(fluorine containing side-chain)-NH2, wherein Aaa is an amino acid having a side chain that readily allows the incorporation of a fluorine group and wherein Xaa is 0, 1, or 2 variable amino acid residues.

29. The compound of claim 28, wherein the variable amino acid Xaa is selected from the group consisting of 1-Nal, Tyr, Phe and Ser.

30. The compound of claim 28 or 29, wherein the Aaa is Lys.

31. A compound comprising a formula selected from the group of formulae consisting of: ##STR00002## ##STR00003##

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The following figures illustrate various aspects and preferred and alternative embodiments of the invention.

[0047] FIG. 1 (A) Chemical structure of prior art peptides of the original class of GHRPs. (B) Truncated ghrelin derivatives.

[0048] FIG. 2 A) DW-MRI in a 67-year-old male with PCa in the left mid-gland. Arrows show a restricted diffusion in the left peripheral zone of the prostate, (adapted from Seitz, M. et al., 2009), [38] B) 18F-fluorodeoxyglucose (FDG) PET/CT image of a 67-year-old man with PCa, with intense hypermetabolism in the right prostatic lobe apparent (adapted from Jadvar, H., 2011). [45]

[0049] FIG. 3 Scheme showing the synthesis of the [.sup.18F]MMF-01-115-H lead compound 5 by prosthetic group radiolabelling with [.sup.18F]SFB (4).

[0050] FIG. 4 Radio-chromatogram of the crude reaction mixture obtained by the radiolabelling of the precursor MMF-01-113-G with [.sup.18F]SFB.

[0051] FIG. 5 Scheme showing the synthesis of the precursor 4-(tert-butoxycarbonyl)-N,N,N-trimethylbenzenammonium triflate salt.

[0052] FIG. 6 Scheme showing the synthesis of .sup.18F-labelled [1-Nal.sup.4, Lys.sup.5(4-fluorobenzoic acid)]G-7039 (also referred to as MMF-01-115-H or H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH2).

[0053] FIG. 7 Scheme showing the synthesis of 4-nitrophenyl 2-bromopropionate.

[0054] FIG. 8 Scheme showing the synthesis of .sup.18F-labelled [Tyr.sup.4, Lys.sup.5(2-fluoropropionate)]G-7039 (also referred to as H-Inp-D-2-Nal-D-2-Nal-Tyr-Lys(2-FP)-NH2 or TL-MF-3-2FP (LCE No. 337).

[0055] FIG. 9 Radio-chromatogram of the [.sup.18F]SFB prosthetic group.

[0056] FIG. 10 Scheme of proposed radiolabelling of a brominated precursor to give the [.sup.18F]2-FP-G-7039 compound.

[0057] FIG. 11 Peptidomimetic chromatogram: LCE00210: H-Aib-His-D-2-Nal-D-Phe-Lys-NH2

[0058] FIG. 12 Peptidomimetic chromatogram LCE00211: H-Aib-His-D-2-Nal-D-Phe-Lys(4-FB)-NH2.

[0059] FIG. 13 Peptidomimetic chromatogram LCE00217: H-Aib-His-D-2-Nal-D-Phe-Lys(AEEA-4-FB)-NH2.

[0060] FIG. 14 Peptidomimetic chromatogram LCE00239: H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH2.

[0061] FIG. 15 Peptidomimetic chromatogram LCE00240: H-Ala-His-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2.

[0062] FIG. 16 (A) Peptidomimetic chromatogram LCE00243: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(4-FB)-NH2; (B) Peptidomimetic chromatogram LCE00244: H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys-NH2; (C) Peptidomimetic chromatogram LCE00245: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys-NH2.

[0063] FIG. 17 (A) Peptidomimetic chromatogram LCE00246: H-Inp-His-D-2-Nal-D-2-Thi-Lys(4-FB)-NH2; (B) Peptidomimetic chromatogram LCE00267: H-Aib-His-D-2-Nal-D-2-Thi-Lys(4-FB)-NH2; (C) Peptidomimetic chromatogram LCE00268: H-Inp-His-D-2-Nal-D-Phe-Lys(4-FB)-NH2.

[0064] FIG. 18 (A) Peptidomimetic chromatogram LCE00269: H-Inp-His-D-2-Nal-D-2-Nal-Lys(4-FB)-NH2; (B) Peptidomimetic chromatogram LCE00270: H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH2; (c) Peptidomimetic chromatogram LCE00272: H-His-D-Trp-Ala-Trp-D-Phe-Lys(4-FB)-NH2.

[0065] FIG. 19 (A) Peptidomimetic chromatogram LCE00281: H-His-D-Trp-Ala-Trp-D-Phe-Dpr(4-FB)-NH2; (B) Peptidomimetic chromatogram LCE00282: H-D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2; (C) Peptidomimetic chromatogram LCE00295: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(2-FP)-NH.sub.2.

[0066] FIG. 20 Peptidomimetic .sup.1H-NMR Spectrum LCE00210: H-Aib-His-D-2-Nal-D-Phe-Lys-NH.sub.2.

[0067] FIG. 21 Peptidomimetic .sup.1H-NMR Spectrum LCE00211: H-Aib-His-D-2-Nal-D-Phe-Lys(4-FB)-NH.sub.2.

[0068] FIG. 22 Peptidomimetic .sup.1H-NMR Spectrum LCE00217: H-Aib-His-D-2-Nal-D-Phe-Lys(4-FB-AEEA)-NH.sub.2.

[0069] FIG. 23 Peptidomimetic .sup.1H-NMR Spectrum LCE00239: H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH.sub.2.

[0070] FIG. 24 Peptidomimetic .sup.1H-NMR Spectrum LCE00240: H-Ala-His-D-2-Nal-Ala-Trp-D-Phe-Lys-NH.sub.2.

[0071] FIG. 25 Peptidomimetic .sup.1H-NMR Spectrum LCE00243: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(4-FB)-NH.sub.2.

[0072] FIG. 26 Peptidomimetic .sup.1H-NMR Spectrum LCE00244: H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys-NH.sub.2.

[0073] FIG. 27 Peptidomimetic .sup.1H-NMR Spectrum LCE00245: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys-NH.sub.2.

[0074] FIG. 28 Peptidomimetic .sup.1H-NMR Spectrum LCE00246: H-Inp-His-D-2-Nal-D-2-Thi-Lys(4-FB)-NH.sub.2.

[0075] FIG. 29 Peptidomimetic .sup.1H-NMR Spectrum LCE00267: H-Aib-His-D-2-Nal-D-2-Thi-Lys(4-FB)-NH.sub.2.

[0076] FIG. 30 Peptidomimetic .sup.1H-NMR Spectrum LCE00268: H-Inp-His-D-2-Nal-D-Phe-Lys(4-FB)-NH.sub.2.

[0077] FIG. 31 Peptidomimetic .sup.1H-NMR Spectrum LCE00269: H-Inp-His-D-2-Nal-D-2-Nal-Lys(4-FB)-NH.sub.2.

[0078] FIG. 32 Peptidomimetic .sup.1H-NMR Spectrum LCE00270: H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH.sub.2.

[0079] FIG. 33 Peptidomimetic .sup.1H-NMR Spectrum LCE00272: H-His-D-Trp-Ala-Trp-D-Phe-Lys(4-FB)-NH.sub.2.

[0080] FIG. 34 Peptidomimetic .sup.1H-NMR Spectrum LCE00281: H-His-D-Trp-Ala-Trp-D-Phe-Dpr(4-FB)-NH.sub.2.

[0081] FIG. 35 Peptidomimetic .sup.1H-NMR Spectrum LCE00282: H-D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH.sub.2.

[0082] FIG. 36 Peptidomimetic .sup.1H-NMR Spectrum LCE00295: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(2-FP)-NH.sub.2.

[0083] FIG. 37 Displacement curve for peptide standard ghrelin(1-28).

[0084] FIG. 38 Peptidomimetic displacement curve (A) LCE00210; (B) LCE00211.

[0085] FIG. 39 Peptidomimetic displacement curve (A) LCE00239; (B) LCE00240.

[0086] FIG. 40 Peptidomimetic displacement curve (A) LCE00243; (B) LCE00244.

[0087] FIG. 41 Peptidomimetic displacement curve (A) LCE00245; (B) LCE00246.

[0088] FIG. 42 Peptidomimetic displacement curve (A) LCE00267; (B) LCE00268.

[0089] FIG. 43 Peptidomimetic displacement curve (A) LCE00269; (B) LCE00270.

[0090] FIG. 44 Peptidomimetic displacement curve (A) LCE00272; (B) LCE00281.

[0091] FIG. 45 Peptidomimetic displacement curve LCE00282.

[0092] FIG. 46 (A): chemical structure of LCE00270; (B) chemical structure of LCE00295.

[0093] FIG. 47 Peptidomimetic displacement curve (A) TL-MF-5-2FP; (B) TL-MF-4-2FP.

[0094] FIG. 48 Peptidomimetic displacement curve (A) TL-MF-3-2FP; (B) TL-MF-2-2FP.

[0095] FIG. 49 Formula of (A) TL-MF-5-2FP and (B) TL-MF-4-2FP.

[0096] FIG. 50 Formula of (A) TL-MF-3-2FP and (B) TL-MF-2-2FP.

[0097] FIG. 51 Efficacy curves for agonist 1-Nal.sup.4, Lys.sup.5(4-FB)]G-7039 (referred to in Table 1 as compound MMF-01-115-H, LCE No. 270) and the control ligand ghrelin.

[0098] FIG. 52 Efficacy curves for agonist [Lys.sup.5(2-FP)]G-7039 (referred to in Table 1 as compound 2-FP-G-7039; LCE No. 295) and the control ligand ghrelin.

DESCRIPTION OF THE INVENTION

Definitions and Abbreviations

[0099] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Also, unless indicated otherwise, except within the claims, the use of or includes and and vice versa. Non-limiting terms are not to be construed as limiting unless expressly stated or the context clearly indicates otherwise (for example including, having and comprising typically indicate including without limitation). Singular forms including in the claims such as a, an and the include the plural reference unless expressly stated otherwise. In order to aid in the understanding and preparation of the within invention, the following illustrative, non-limiting, examples are provided. All publications cited are incorporated herein by reference.

[0100] The following standard one letter and three letter abbreviations for the amino acid residues in L forms which may be used throughout the specification: A, Alaalanine; R, ArgArginine; N, AsnAsparagine; D, AspAspartic acid; C, CysCysteine; Q, GlnGlutamine; E, GluGlutamic acid; G, GlyGlycine; H, HisHistidine; I, IleIsoleucine; L, LeuLeucine; K, LysLysine; M, MetMethionine; F, PhePhenyalanine; P, ProProline; S, SerSerine; T, ThrThreonine; W, TrpTryptophan; Y, TyrTyrosine; and V, ValValine.

D-Phe: D-Phenylalanine

D-2-Nal: D-2-Naphthylalanine

D-Ala: D-Alanine

[0101] Inp: Isonipecotic acid, i.e.:

##STR00001##

Aib: Aminoisobutyric acid.
1-Nal: 1-naphthylalanine.
4-FB: 4-fluorobenzoyl
2-FP: 2-fluoropropionyl

AEEA: Aminoethylethanolamine

[0102] EC.sub.50: half-maximal effective concentration
IC.sub.50: half-maximal inhibitory concentration

[18F]SFB: N-Succinimidyl-4-[18F]fluorobenzoate

[0103] [18F]NFP: 4-nitrophenyl 2-[18F]fluoropropionate
hot: the radioactive form of the compound
cold: the non-radioactive form of the compound
GHRPs: growth hormone releasing peptides
GH: growth hormone
GHS: growth hormone secretagogues

[0104] The term amino acid residue is known in the art. In general the abbreviations used herein for designating the amino acids and the protective groups are based on recommendations of the IUPAC-IUB Commission on Biochemical Nomenclature (see Biochemistry (1972) 11:1726-1732). In certain embodiments, the amino acids used in the application of this invention are those naturally occurring amino acids found in proteins, or the naturally occurring anabolic or catabolic products of such amino acids which contain amino and carboxyl groups. Particularly suitable amino acid side chains include side chains selected from those of the following amino acids: glycine, alanine, valine, cysteine, leucine, isoleucine, serine, threonine, methionine, glutamic acid, aspartic acid, glutamine, asparagine, lysine, arginine, proline, histidine, phenylalanine, tyrosine, and tryptophan. In certain embodiment, the amino acids used in the application of this invention include analogs, derivatives and congeners of any specific amino acid referred to herein, as well as C-terminal or N-terminal protected amino acid derivatives (e.g. modified with an N-terminal or C-terminal protecting group) as well as unnatural amino acids.

[0105] The term unnatural refers in this document to amino acids not naturally encoded or found in the genetic code of any organisms.

[0106] In this document the term non-coded amino acid or residue, refers to a natural amino acid that substitutes another natural amino acid in the wild type amino acid sequence of a peptide, including a natural amino acid that substitutes a natural amino acid in the peptide.

[0107] Subject or patient refers to a subject in need of treatment for a condition, disorder or disease, or in need of a diagnosis for a condition, disorder or disease.

[0108] Generic groups that allow both derivatisation with fluorine as well as convenient introduction of radiofluorine may be used. These groups are referred to as prosthetic groups.

[0109] Peptidomimetics are synthetic or artificial compounds based on, or derived from, peptides and proteins. Such peptidomimetics may have such attributes as having increased specificity and/or affinity for a receptor. Peptidomimetics of the present invention may be obtained by inserting an amino acid residue into a native or non-native GHS.

[0110] The peptides and peptidomimetics of the invention, can have a variety of lengths. A peptide or peptidomimetic of the invention can have, for example, a relatively short length of at least 4 residues, including 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 and so forth residues. A peptide or peptidomimetic of the invention also can be useful in the context of a significantly longer sequences.

[0111] A variety of peptidomimetics are known in the art including, for example, peptide-like molecules which contain a constrained amino acid, a non-peptide component that mimics peptide secondary structure, or an amide bond isostere. A peptidomimetic that contains a constrained, non-naturally occurring amino acid can include, for example, an -methylated amino acid; ,-dialkylglycine or -aminocycloalkane carboxylic acid; an N-C cyclized amino acid; an N-methylated amino acid; a - or -amino cycloalkane carboxylic acid; an ,-unsaturated amino acid; a ,-dimethyl or -methyl amino acid; a -substituted-2,3-methano amino acid; an N-C or C-C cyclized amino acid; a substituted proline or another amino acid mimetic; a cyclized amino acid such as Inp. A peptidomimetic which mimics peptide secondary structure can contain, for example, a nonpeptidic -turn mimic; -turn mimic; mimic of -sheet structure; or mimic of helical structure, each of which is well known in the art. A peptidomimetic also can be a peptide-like molecule which contains, for example, an amide bond isostere such as a retro-inverso modification; reduced amide bond; methylenethioether or methylenesulfoxide bond; methylene ether bond; ethylene bond; thioamide bond; trans-olefin or fluoroolefin bond; 1,5-disubstituted tetrazole ring; ketomethylene or fluoroketomethylene bond or another amide isostere. One skilled in the art understands that these and other peptidomimetics are encompassed within the meaning of the term peptidomimetic as used herein.

[0112] In one embodiment of the present invention, the peptides and peptidomimetics of the invention may be provided in isolated form. As used herein in reference to a peptide or peptidomimetic of the invention, the term isolated means a peptide or peptidomimetic that is in a form that is relatively free from material such as contaminating polypeptides, lipids, nucleic acids and other cellular material that normally is associated with the peptide or peptidomimetic in a cell or that is associated with the peptide or peptidomimetic in a library or in a crude preparation.

[0113] The compounds of the present invention may include a fluoro-containing prosthetic group, whereby the radioisotope fluorine-18 (F-18 or F18) is a part of the prosthetic group molecule allowing for attachment to the peptidomimetic. Non-limiting examples of prosthetic groups that may be used with the present invention may include 4-FB and 2-FP. Other prosthetic groups that readily allow for the incorporation of F-18 include click chemistry approaches to create a fluorinated triazole species, for example, through azide alkyne Huisgen cycloaddition or inverse electron demand Diels-Alder reaction. Alternatively, the addition of F-18 can be accomplished through the direct labelling of the peptide side-chain, through aliphatic or aromatic nucleophilic substitution.

[0114] Presented herein are imaging tools that may be used to investigate changes in the peptide hormone ghrelin and its receptor, GHS-R, in cancer cells and in cardiomyocytes as a possible marker of disease severity.

[0115] The present invention also provides a method of imaging a target site in a subject. The target site may be a tumor, preferably prostate cancer, and may be used to distinguish between malignant and benign tumors by targeting the ghrelin receptor, which is known to have a differential expression in benign and malignant tumors.

[0116] In one embodiment, a method of assessing or diagnosing the malignancy of a tumor may include: (a) contacting the tumor with a conjugate as defined in claims 1-6, (b) detecting the expression of the conjugate in the tumor, (c) comparing the expression of step (b) with the expression of said conjugate in a control tissue, and (d) assessing the malignancy of the tumor based on the comparison.

[0117] In another embodiment, a method of assessing or diagnosing the malignancy of a tumor may include administering to a subject a conjugate which contains a detectable label such as a fluoro-containing prosthetic group linked to a peptidomimetic of the present invention, and detecting the conjugate, thereby imaging the tumor in the subject. The image may then be compared to images of normal prostate tissue, or to images of benign prostate cancer, or to images of malignant prostate cancer. A diagnosis of the subject's image may then be made based on one or more of these comparisons. The present invention may also be used to diagnose heart disease, cardiac dysfunction. Examples of radionuclides useful as detectable labels include, but are not limited to, 4-FB, 2-FP and other prosthetic groups that allow for the incorporation of F-18.

[0118] Positron emission tomography (PET), including fluorine-18 PET, PET-computed tomography (CT) hybrid and PET-magnetic resonance imaging (MRI) hybrid imaging with the compounds of the present invention may enable oncologists to diagnose and stage cancer, and to enable cardiologists to predict LV dysfunction before it occurs through detection of early derangements in GHS-R, and to gauge the response to therapy.

[0119] In a further embodiment, the present invention provides a pharmaceutical composition comprising a conjugate of the present invention and a pharmaceutically acceptable carrier.

[0120] Such pharmaceutical compositions may be used for diagnostic purposes, preferably, for visualization of organs and tissues having a ghrelin receptor, preferably, for diagnosis of tumors, including distinguishing between benign and malignant tumors. Any suitable solid tumor may be encompassed by the invention, both primary tumors and metastasis, of tumors selected from, but not limited to, from melanoma, colon, breast, lung, prostate, brain or head and neck cancer. Preferably for diagnosis of prostate cancer, including distinguishing between benign and malignant prostate cancer. Such pharmaceutical compositions may also be used for diagnosis of heart disease or growth hormone (GH) deficiency.

[0121] The pharmaceutical compositions of the present invention may be used for administration to subjects in a biologically compatible form suitable for administration in vivo. By biologically compatible form suitable for administration in vivo is meant a form of the substance to be administered in which any toxic effects are outweighed by the therapeutic effects. Administration of a therapeutically active amount of the pharmaceutical compositions of the present invention, or an effective amount, is defined as an amount effective at dosages and for periods of time, necessary to achieve the desired result. A therapeutically effective amount of a substance may vary according to factors such as the disease state/health, age, sex, and weight of the recipient, and the inherent ability of the particular peptidomimetic to elicit a desired response. Dosage regimen may be adjusted to provide the optimum therapeutic response. For example, several divided doses may be administered daily or on at periodic intervals, and/or the dose may be proportionally reduced as indicated by the exigencies of the therapeutic situation. The amount of peptidomimetic for administration will depend on the nature of the peptidomimetic, the route of administration, time of administration and varied in accordance with individual subject responses. Suitable administration routes may be intramuscular injections, subcutaneous injections, intravenous injections or intraperitoneal injections, oral and intranasal administration. In a preferred embodiment, the administration route may be intravenous injection.

[0122] The pharmaceutical compositions may be provided in a kit that includes instructions or labels as to the use of the conjugate (i.e. imaging, diagnosis, etc. of ghrelin-receptors containing sites, such as tumors or cardiac tissue).

[0123] Such pharmaceutical compositions may be used to treat GH deficiency, stimulate GH secretion from the pituitary or increase appetite, attenuate cachexia in patient with cancer or chronic obstructive pulmonary disease. Such pharmaceutical compositions may also be used for suppressing ghrelin's orexigenic effects, treating obesity, regulating food intake, GI motility, gastric emptying or body weight, and treating ulcer or gastroparesis.

[0124] Such pharmaceutical compositions may also be used to treat a variety of disorders such as anorexia nervosa, heart failure, diabetes mellitus (including Type 1 and 2) or diabetes mellitus complications, constipation and Parkinson's disease. Such pharmaceutical compositions may also be used as a therapeutic agent to treat cancer (Vodnik M et al. Horm Metab Res 2016; 48: 1-15; Dimitrios Nikolopoulos et al., Regulatory Peptides 163 (2010) 7-17).

[0125] The peptidomimetics of the present invention have been found to have high affinity for GHS-R1a receptors as demonstrated by receptor-ligand binding assays described in Example 1, with IC.sub.50 nanomolar values in the single digits and even sub-nM values. As such, the peptidomimetics of the present invention listed in Table 1 (excluding GHRP-6, GHRP-1, GHRP-2 and G-7039) and Table 2, particularly TL-MF-4-2FP, TL-MF-3-2FP, 2-FP-G-7039 and MMF-01-113-G are GHS-R1a ligands.

[0126] As seen in Example 3 and illustrated in FIGS. 51 and 52, peptidomimetics of the present invention were also found to have low EC.sub.50 values and may serve as GHS-R1a agonists. As such, peptidomimetics of the present invention may be used for indications such as suppressing ghrelin's orexigenic effects, treating obesity, regulating food intake, GI motility, gastric emptying or body weight, and treating ulcer or gastroparesis, to treat a variety of disorders such as anorexia nervosa, heart failure, diabetes mellitus (including Type 1 and 2) or diabetes mellitus complications, constipation and Parkinson's disease.

[0127] . Examples of peptidomimetics that may be used as agonists include MMF-01-115-H and 2-FP-G-7039 both having an EC.sub.50 value below that of ghrelin (see FIGS. 51 and 52 respectively and Example 3).

[0128] As such, the present application includes methods of treating a disorder associated with GHS-R1a, including stimulation of growth hormone release, increase in appetite, gastric emptying, and cachexia, including cachexia in patients with cancer. The method may include administering to a person in need, an effective amount of a peptidomimetic of the present invention.

[0129] In order to aid in the understanding and preparation of the within invention, the following illustrative, non-limiting, examples are provided.

Example 1

[0130] Materials and Methods

[0131] All reagents were obtained from commercial suppliers and used without further purification. Reaction monitoring was carried out by TLC using 60F254 silica coated plastic plates (EMD Chemicals Inc.), with visualization under a UV lamp (254/365 nm). Melting points were recorded on a Mel-Temp 1101D digital melting point apparatus. Peptides were either synthesized manually or through the use of a Biotage Syro Wave automated peptide synthesizer. Peptide vessels were shaken using an IKA Vibrax VXR basic shaker with centrifugation performed on a Beckman Coulter Allegra X-30R or Fisher GS-6R centrifuge. In order to aid peptide dissolution, sonication of solutions was accomplished via a Bransonic 2510R-MTH or Fisher F5-14 ultrasonic cleaner. A Fisher 2052 Isotemp machine was used to heat up test tubes in the Kaiser Test. Peptides were cryodessicated using a Labconco FreeZone Freeze Dry System. UV traces were obtained with a Waters 2487 UV/Vis Dual A Absorbance Detector (170-900 nm) and low-resolution mass spectra with a Micromass Quattro Micro API mass spectrometer (ESI-LC-MS). Peptide purification was achieved through HPLC (MeCN+0.1% TFA, H.sub.2O+0.1% TFA solvent system). All peptides and small molecules obtained had a purity 95% as determined by HPLC or UPLC. A reverse-phase (RP) semi-preparative C-18 column (SunFireOBD, 19150 mm or AgilentZorbax 21.2150 mm) was used for preparative HPLC, whilst a C-18 RP column (SunFire 4.6150 mm or Agilent Zorbax, 4.6150 mm) was used for analytical HPLC. Accurate mass spectrometry (HRMS) was carried out on a Finnigan MAT 8400 Mass Spectrometer (EI) for small molecules and on a Bruker Daltonics Reflex IV Mass Spectrometer (ESI) for peptides. .sup.1H NMR and .sup.13C NMR spectroscopy were performed on a Mercury VX 400 machine at 400 and 100 MHz respectively. Chemical shifts are referenced to residual solvent, reported in ppm on a scale and all coupling constants quoted in hertz (Hz).

[0132] General Procedures

[0133] Manual Fmoc Solid-Phase Peptide Synthesis (Fmoc-SPPS)

[0134] Rink amide MBHA resin (192 mg, 0.1 mmol, 1.0 eq., 0.52 mmol g-1 loading) was vortexed in DCM (2.0 ml, 1 min.), allowed to swell (15 mins) and solvent removed. This was followed by addition of DMF (2.0 ml), vortexing (1 min.) and removal of solvent. Deprotection of the Fmoc group was then performed. A solution of 20% piperidine/DMF (1.5 ml, v/v) was added to the resin and the subsequent mixture vortexed (2 mins) and solvent removed. This was then repeated a second time with vortexing for 15 minutes. After solvent had been removed, the resin was washed of any unreacted by-products with DMF six times (2.0 ml, vortex 30 s). The desired amino acid or small molecule (Fmoc-AA1, 0.3 mmol, 3.0 eq.) and coupling reagent (HCTU, 0.12 g, 0.3 mmol, 3.0 eq.) were then dissolved in DMF (1.5 ml) and added to the deprotected resin. After vortexing (30 s), DIPEA (111 l, 0.6 mmol, 6.0 eq.) was added and the final mixture vortexed (1-2 hrs). The resin was then washed with DMF (2.0 ml, 30 s vortex) a final four times. The deprotection/coupling cycle was then repeated unless the final amino acid in the sequence had been added, in which case the peptide was washed with DCM five times (2.0 ml, 30 s vortex) and stored in a refrigerator. Removal of the N-terminal Fmoc-group was carried out in the same fashion as the deprotection cycle described previously, with resin washing occurring six times with DMF (2.0 ml, 30 s vortex) and four times with DCM (2.0 ml, 30 s vortex). Successful synthesis of the desired peptide was then ascertained via a microcleave prior to full cleavage of the peptide from the solid-support. This was carried out as follows: a solution of 95% TFA: 2.5% (iPr)3SiH: 2.5% H2O (300 l) was added to a small number of resin beads (<5 mg) and the subsequent mixture vortexed (3 hrs). The clear liquid was then treated with N.sub.2 until a small film formed. Analytical HPLC was then performed to determine whether the correct peptide had been synthesized. If the correct peptide had been obtained, a full cleavage was performed using a mixture of 95% TFA: 2.5% (iPr)3SiH: 2.5% H.sub.2O (2.0 ml) for 5-6 hrs. The subsequent solution was cooled in an ice-bath alongside .sup.tBme (40 ml). After 10 minutes, .sup.tBme (20 ml) was added to the peptide solution, leading to the formation of a white precipitate. The precipitate was cooled further (10 mins) and then centrifuged (7 mins). Decanting of the supernatant was followed by addition of a second aliquot of tBMe (20 ml), vortexing (30 s) and final centrifugation (7 mins). This delivered a white solid which was then freeze-dried (20 mins) to furnish crude peptide. Preparative HPLC was then used to purify the product peptide.

[0135] Deprotection of the Alloc Protecting Group

[0136] The resin-bound peptide was vortexed in DCM (4.5 ml, 30 s) and allowed to swell (10 mins). Deprotection was carried out under a blanket of N.sub.2. The swollen resin-bound peptide was stirred (5 mins) before addition of PhSiH.sub.3 (296 l, 2.4 mmol, 24.0 eq.). Further stirring (5 mins) ensued prior to treating with Pd(PPh.sub.3).sub.4 (120 mg, 0.01 mmol, 0.1 eq.). The reaction mixture changed colour from yellow to orange to brown to dark brown. After 5 minutes, the solution was vortexed (5 mins), solvent removed and the brown-coloured resin washed four times with DCM (2.0 ml, 30 s vortex). The procedure was then repeated ab initio, with final resin washing occurring in the following order: DCM, DMF, MeOH, DMF and DCM (all 2.0 ml, 30 s vortex).

[0137] Kaiser Test

[0138] The Kaiser test was used as a qualitative test to determine the success of amino acid coupling. A small number of resin beads (<5 mg) were taken and treated with Phenol: EtOH (200 l, 8:2 v/v), 0.001 M KCN(aq.): Pyridine (200 l, 2:98 v/v, 0.001 M aqueous KCN) and Ninhydrin in EtOH (200 l, 5% w/v) respectively. Tentagel resin (<5 mg) was used as a control in this test. Both test tubes were heated to 70 C. The presence of free amine was indicated by blue resin beads whilst yellow resin beads showed protected amine groups to be present.

[0139] Receptor-Ligand Binding Assay

[0140] Competitive binding assays were run at the Lawson Health Research Institute at St. Joseph's Health Care in London. These were carried out in triplicate using HEK293/GHS-R1a cells (prepared by our collaborator Becky McGirr) with [.sup.125I]ghrelin as a competitive radioligand. To begin with, a fresh solution of binding buffer (50 ml) was made up by adding HEPES (0.3 g, 25 mM), MgCl.sub.2 (0.051 g, 5 mM), CaCl.sub.2 (7.410.sup.3 g, 1 mM), EDTA (0.015 g, 2.5 mM) and BSA (0.2 g, 0.4%) to distilled H2O. The resultant solution was mixed over gentle heat. The pH was then adjusted to 7.4 and the solution filtered. Two miniature complete protease inhibitor tablets were then added and the final buffer solution kept on ice.

[0141] After the buffer had been made, assay tubes were labelled and kept on ice during the setup. To assay tubes 1-21, 25-27 and 28-30 was added binding buffer (200 l, 230 l and 300 l respectively). No buffer was added to tubes 22-24. An aliquot of frozen cells was thawed to room temperature, centrifuged (3000g, 10 mins, room temperature) and the subsequent cell pellet re-suspended in binding buffer (2 ml) and placed on ice. Cells (50 l) were then added to assay tubes 1-21 and 25-27. Cold peptide was then prepared. This was carried out by adding stock peptide (20 l) to binding buffer (180 l) to make a peptide solution of 10.sup.4M concentration. Binding buffer (180 l) was then added to assay tubes labelled 10.sup.5 to 10.sup.11. A series of dilutions was then made in order to acquire 10.sup.5 to 10.sup.11M concentrations. Cold peptide (30 l) was then added to the corresponding assay tubes in triplicate.

[0142] [.sup.125I]-ghrelin was then prepared by adding 10 l to binding buffer (3 ml) and vortexing the resultant solution. A second solution of [.sup.125I]-ghrelin (20 l) was added to an empty assay tube and counted on the gamma counter (using protocol 3). The volume of [.sup.125I]-ghrelin or binding buffer was adjusted as needed in order to get 15 000 cpm for every 20 l aliquot. [.sup.125I]-ghrelin (20 l) was then pipetted into assay tubes 1-27. All assay tubes were then vortexed, capped and immediately agitated (550 rpm, 20 mins, 37 C.). After 20 minutes, tubes 1-21 and 25-27 were spun in a large centrifuge (2800 rpm, 2 mins, 4 C.). The solution in all of the tubes was then transferred to Eppendorf tubes (0.5 ml), further binding buffer added (200 l), the solutions mixed by pipetting and transferred to 0.5 ml tubes. The tubes were then spun again (13 000g, 5 mins, 4 C.) and placed on ice. The supernatant was removed and the cell pellet rinsed with ice-cold Tris-HCl (200 l, 50 mM, pH 7.4) and the tubes mixed by inversion. Tubes were spun a final time (13,000g, 5 mins, 4 C.), cooled on ice and supernatant removed. The tubes were then placed in 1275 mm assay tubes and counted using a gamma counter (see protocol 3). The binding assay may be summarized as follows:

[0143] 1) Tubes 1-21: 200 l binding buffer, 50 l cells, 30 l cold peptide, 20 l [.sup.125I]-ghrelin.

[0144] 2) Tubes 22-24: 20 l [.sup.125I]-ghrelin.

[0145] 3) Tubes 25-27: 20 l [.sup.125I]-ghrelin, 50 l cells, 230 l binding buffer.

[0146] 4) Tubes 28-30: 300 l binding buffer.

[0147] Synthesis of Peptidomimetics

[0148] All peptides were synthesized by the same general procedure as described herein above unless otherwise noted.

LCE00210: H-Aib-His-D-2-Nal-D-Phe-Lys-NH.SUB.2 .(Ipamorelin)

[0149] The product was purified by preparative HPLC (5-80% MeCN+0.1% TFA). This furnished a white powder (20.5 mg, 19%): .sup.1H-NMR (400 MHz, CD3OD); D-2-Nal, D-Phe, His: 7.99 (s, 1H, ArH), 7.80-7.76 (m, 1H, ArH), 7.71 (d, J=8.6 Hz, 2H, ArH), 7.56 (s, 1H, ArH), 7.44-7.37 (m, 2H, ArH), 7.32-7.17 (m, 6H, ArH), 6.92 (s, 1H, His H), 4.58 (m, 3H, H), 3.30-3.21 (m, 1H, D-2-Nal H), 3.15-3.00 (m, 2H, H), 2.96-2.72 (m, 3H, H), Lys: 4.11 (dd, J=9.7, 4.2 Hz, 1H, H), 2.96-2.72 (m, 2H, H), 1.75-1.64 (m, 1H, H), 1.54-1.40 (m, 3H, H, 2H), 1.05-0.93 (m, 2H, H), Aib: 1.48 (s, 3H, CH3) 1.44 (s, 3H, CH3) ppm. ESI-LC-MS m/z 356.9 [M+2H]2+; HRMS (ESI-MS) calcd. for C38H50N9O5 [M+H]+ 712.3935, found 712.3959.

5.3.2 LCE00211: H-Aib-His-D-2-Nal-D-Phe-Lys(4-FB)-NH.SUB.2 .(4-FB-Ipamorelin)

[0150] Purification by preparative HPLC (20-70% MeCN+0.1% TFA) yielded a white powder (15.4 mg, 15%): .sup.1H-NMR (400 MHz, CD3OD); D-2-Nal, D-Phe, His, 4-FB: 7.91 (s, 1H, ArH), 7.85-7.77 (m, 3H, ArH, 2F-ArH), 7.70 (d, J=7.9 Hz, 2H, ArH), 7.54 (s, 1H, ArH), 7.45-7.40 (m, 2H, ArH), 7.29-7.19 (m, 6H, ArH), 7.14-7.07 (m, 2H, 2F-ArH), 6.93 (s, 1H, His H), 4.65-4.52 (m, 3H, H), 3.30-3.27 (m, 1H, H), 3.23 (d, J=4.0, 1H, H), 3.10 (dd, J=13.5, 7.8 Hz, 1H, H), 3.04-2.74 (m, 3H, H), Lys: 4.12 (dd, J=9.8, 4.2 Hz, 1H, H), 3.04-2.74 (m, 2H, H), 1.77-1.67 (m, 1H, H), 1.58-1.42 (m, 3H, H, 2H), 1.14-1.03 (m, 2H, H), Aib: 1.50 (s, 3H, CH3), 1.46 (s, 3H, CH3) ppm. ESI-LC-MS m/z 418.0 [M+2H]2+; HRMS (ESI-MS) calcd. for C45H53FN9O6 [M+H]+ 834.4103, found 834.4133.

5.3.3 H-Aib-His-D-2-Nal-D-Phe-Lys(4-FB-AEEA)-NH.SUB.2 .(4-FB-AEEA-Ipamorelin)

[0151] Peptide purification by preparative HPLC (20-60% MeCN+0.1% TFA) delivered an off-white powder (9.2 mg, 8%): .sup.1H-NMR (400 MHz, CD3OD); His, D-2-Nal, D-Phe, 4-FB: 7.93 (s, 1H, ArH), 7.86-7.77 (m, 3H, ArH, 2F-ArH), 7.71 (d, J=8.0 Hz, 2H, ArH), 7.55 (s, 1H, ArH), 7.46-7.41 (m, 2H, ArH), 7.31-7.18 (m, 6H, ArH), 7.17-7.10 (m, 2H, F-ArH), 6.94 (s, 1H, His H), 4.65-4.58 (m, 2H, H), 4.55 (t, J=7.5 Hz, 1H, H), 3.16-2.76 (m, 6H, H), Lys: 4.10 (dd, J=9.7, 4.2 Hz, 1H, H), 3.16-2.76 (m, 2H, H), 1.72-1.62 (m, 1H, H), 1.52-1.43 (m, 1H, H), 1.41-1.30 (m, 2H, H), 1.07-0.97 (m, 2H, H), AEEA linker: 3.93 (s, 2H, NHCOCH2O), 3.65-3.61 (m, 6H, CH2), 3.53 (t, J=5.6 Hz, 2H, CH2), Aib: 1.50 (s, 3H, CH3), 1.47 (s, 3H, CH3) ppm. ESI-LC-MS m/z 490.4 [M+2H] 2+; HRMS (ESI-MS) calcd. for C51H64FN10O9 [M+H]+, found.

5.3.4 H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH.SUB.2 .(GHRP-6)

[0152] Purification by preparative HPLC (15-80% MeCN+0.1% TFA) gave a white powder (19.7 mg, 14%): .sup.1H-NMR (400 MHz, CD3OD); His, D-Trp, Trp, D-Phe: 8.46 (s, 1H, His H), 7.54 (d, J=7.8 Hz, 1H, ArH), 7.46 (d, J=7.8 Hz, 1H, ArH), 7.28 (t, J=7.7 Hz, 2H, ArH), 7.23-7.13 (m, 4H, ArH), 7.12-6.92 (m, 8H, 7ArH, His H), 4.47 (t, J=7.4 Hz, 2H, Trp H), 4.35 (t, J=6.7 Hz, 1H, H), 4.28 (t, J=7.9 Hz, 1H, H), 3.22-3.14 (m, 3H, H), 3.14-3.02 (m, 3H, H), 2.83 (d, J=8.6 Hz, 2H, H), Lys: 4.03 (dd, J=10.3, 3.9 Hz, 1H, H), 2.75 (t, J=6.8 Hz, 2H, H), 1.76-1.63 (m, 1H, H), 1.51-1.39 (m, 3H, H, 2H), 0.97-0.88 (m, 2H, H), Ala: 3.91 (q, J=7.2 Hz, 1H, H), 0.86 (d, J=7.3 Hz, 3H CH3) ppm. ESI-LC-MS m/z 437.4 [M+2H]2+; HRMS (ESI-MS) calcd. for C46H57N12O6 [M+H]+ 873.4524 found 873.4531.

5.3.5 H-Ala-His-D-2-Nal-Ala-Trp-D-Phe-Lys-NH.SUB.2 .(GHRP-1)

[0153] The product was purified by preparative HPLC (15-80% MeCN+0.1% TFA). This yielded a white powder (26.4 mg, 19%): .sup.1H-NMR (400 MHz, CD3OD); His, D-2-Nal, Trp, D-Phe: 8.41 (s, 1H, His H), 7.81-7.71 (m, 3H, ArH), 7.65 (s, 1H, ArH), 7.49 (d, J=7.8 Hz, 1H, ArH), 7.46-7.40 (m, 2H, ArH), 7.35 (dd, J=8.4, 1.7 Hz, 1H, ArH), 7.31 (d, J=8.1 Hz, 1H, ArH), 7.24-7.13 (m, 3H, ArH), 7.10-7.04 (m, 4H, ArH), 7.00 (t, J=7.5 Hz, 1H, ArH), 6.89 (d, J=0.8 Hz, 1H, His H), 4.67-4.60 (m, 2H, H), 4.38 (t, J=7.4 Hz, 1H, H), 4.32 (t, J=7.7 Hz, 1H, H), 3.25-2.68 (m, 8H, H), Ala, Ala: 4.17-4.10 (m, 1H, H), 3.94 (q, J=7.0 Hz, 1H, H), 1.35 (d, J=7.1 Hz, 3H, CH3), 1.10-1.01 (m, 3H, CH3), Lys: 4.17-4.10 (m, 1H, H), 3.25-2.68 (m, 2H, H), 1.81-1.70 (m, 1H, H), 1.58-1.45 (3H, H, 2H), 1.10-1.01 (m, 2H, H), ppm. ESI-LC-MS m/z 478.5 [M+2H]2+; HRMS (ESI-MS) calcd. for C51H63N12O7 [M+H]+ 955.4943 found 955.4964.

5.3.6 H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(4-FB)-NH.SUB.2 .(4-FB-G-7039)

[0154] Preparative HPLC (35-80% MeCN+0.1% TFA) furnished the title compound as a white solid (5.90 mg, 6%): 1H-NMR (400 MHz, (CD3)2SO); 8.50 (d, J=8.2 Hz, 1H, NH), 8.45 (t, J=5.5 Hz, 1H, NH), 8.39 (s, 1H, NH), 8.15-8.09 (m, 2H, NH), 8.04 (d, J=8.4 Hz, 1H, NH), 7.86-7.82 (m, 2H, F-ArH), 7.82-7.76 (m, 2H, ArH), 7.75-7.66 (m, 4H, ArH), 7.58 (s, 1H, ArH), 7.48 (s, 1H, ArH), 7.45-7.38 (m, 4H, ArH), 7.31 (dd, J=8.5, 1.5 Hz, 1H, ArH), 7.28 (s, 1H, ArH), 7.26 (s, 1H, NH), 7.24-7.17 (m, 5H, ArH), 7.15-7.08 (m, 2H, ArH), 7.04 (s, 1H, NH), 4.66-4.60 (m, 1H, H), 4.60-4.53 (m, 2H, H), 4.20-4.14 (m, 1H, Lys-H), 3.25-3.14 (m, 2H, CH2), 3.13-3.02 (m, 3H, CH2), 2.98-2.91 (m, 1H, CH2), 2.90-2.83 (m, 1H, CH2), 2.81-2.56 (m, 5H, CH2), 2.30-2.22 (m, 1H, Inp-H), 1.75-1.65 (m, 1H, CH2), 1.62-1.55 (m, 1H, CH2), 1.54-1.43 (m, 6H, CH2), 1.38-1.19 (m, 2H, CH2), ppm. ESI-LC-MS m/z 452.5 [M+4HF]2+; HRMS (ESI-MS) calcd. for C54H59FN7O6 [M+H]+ 920.4511 found 920.4529.

5.3.7 H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys-NH.SUB.2 .(MMF-01-113-G)

[0155] Peptide purification by preparative HPLC (25-80% MeCN+0.1% TFA) delivered a white powder (24.9 mg, 23%): 1H-NMR (400 MHz, CD3OD); 8.12 (d, J=8.4 Hz, 1H, ArH), 7.84 (d, J=7.8 Hz, 1H, ArH), 7.78-7.72 (m, 2H, ArH), 7.68 (d, J=8.5 Hz, 3H, ArH), 7.62-7.46 (m, 5H, ArH), 7.43-7.35 (m, 5H, ArH), 7.30 (d, J=6.4 Hz, 1H, ArH), 7.27-7.21 (m, 2H, ArH), 7.02 (dd, J=8.4, 1.5 Hz, 1H, ArH), 4.69 (dd, J=9.4, 5.4 Hz, 1H, H), 4.65-4.55 (m, 2H, H), 4.32 (dd, J=9.4, 4.8 Hz, 1H, Lys-H), 3.65 (dd, J=14.4, 5.4 Hz, 1H, CH2), 3.20-3.10 (m, 2H, CH2), 3.05-2.94 (m, 3H, CH2), 2.92-2.80 (m, 5H, CH2), 2.76-2.62 (m, 2H, CH2), 2.30-2.23 (m, 1H, Inp-H), 1.92-1.81 (m, 1H, CH2), 1.75-1.29 (m, 9H, CH2), ppm. ESI-LC-MS m/z 424.8 [M+2H]2+; HRMS (ESI-MS) calcd. for C51H58N7O5 [M+H]+ 848.4499, found 848.4501.

5.3.8 H-Inp-D-2-Nal-D-2-Nal-Phe-Lys-NH.SUB.2 .(G-7039)

[0156] Purification of the peptide proceeded through preparative HPLC (25-80% MeCN+0.1% TFA). The title compound was obtained as a white powder (6.70 mg, 7%): .sup.1H-NMR (400 MHz, CD3OD); 7.80-7.76 (m, 1H, ArH), 7.74 (dd, J=6.1, 2.2 Hz, 2H, ArH), 7.70 (dd, J=8.5, 3.5 Hz, 3H, ArH), 7.56 (s, 1H, ArH), 7.50 (s, 1H, ArH), 7.46-7.35 (m, 4H, ArH), 7.26 (dd, J=8.5, 1.5 Hz, 1H, ArH), 7.20-7.10 (m, 6H, ArH), 4.66-4.56 (m, 2H, H), 4.50 (dd, J=9.3, 5.4 Hz, 1H, H), 4.30 (dd, J=9.5, 4.7 Hz, 1H, Lys-H), 3.20-2.80 (m, 10H, CH2), 2.78-2.64 (m, 2H, CH2), 2.33-2.24 (m, 1H, Inp-H), 1.92-1.82 (m, 1H, CH2), 1.74-1.65 (m, 1H, CH2), 1.64-1.44 (m, 5H, CH2), 1.44-1.24 (m, 3H, CH2), ppm. ESI-LC-MS m/z 399.8 [M+2H] 2+; HRMS (ESI-MS) calcd. for C47H56N7O5 [M+H]+ 798.4343 found 798.4339.

5.3.9 H-Inp-His-D-2-Nal-D-2-Thi-Lys(4-FB)-NH.SUB.2 .(Inp-Thi-4-FB-Ipamorelin)

[0157] The title peptide was prepared by automated peptide synthesis and purified by preparative HPLC (20-80% MeCN+0.1% TFA). This furnished a white powder (14.0 mg, 13%): .sup.1H-NMR (400 MHz, CD3OD); His, D-2-Nal, D-2-Thi, 4-FB: 8.23 (s, 1H, His H), 7.86-7.81 (m, 2H, F-ArH), 7.80-7.77 (m, 1H, ArH), 7.73 (dd, J=8.8, 3.3 Hz, 2H, ArH), 7.59 (s, 1H, ArH), 7.45-7.39 (m, 2H, ArH), 7.27 (dd, J=8.5, 1.6 Hz, 1H, ArH), 7.22 (dd, J=5.0, 1.2 Hz, 1H, Thi-ArH), 7.15-7.08 (m, 2H, F-ArH), 6.92 (s, 1H, His H), 6.91-6.85 (m, 2H, Thi-ArH), 4.61 (dd, J=10.3, 4.4 Hz, 1H, H), 4.53-4.47 (m, 2H, H), 4.22 (dd, J=9.8, 4.2 Hz, 1H, Lys-H), 3.39-3.29 (m, 6H, CH2), 3.26-3.22 (m, 1H, CH2), 3.01-2.80 (m, 5H, CH2), 2.53-2.44 (m, 1H, Inp-H), 1.87-1.50 (m, 8H, CH2), 1.35-1.22 (m, 2H, CH2), ppm. ESI-LC-MS m/z 433.8 [M+2H]2+; HRMS (ESI-MS) calcd. for C45H53FN9O6S [M+H]+ 866.3824 found 866.3850.

5.3.10 H-Aib-His-D-2-Nal-D-2-Thi-Lys(4-FB)-NH.SUB.2 .(Thi-4-FB-Ipamorelin)

[0158] The title peptide was synthesized by automated peptide synthesis and purified by preparative HPLC (20-80% MeCN+0.1% TFA). This furnished a white solid (4.20 mg, 4%): 1H-NMR (400 MHz, (CD3)2SO); 8.83 (s, 1H, ArH), 8.59 (d, J=8.1 Hz, 1H, NH), 8.42 (t, J=5.6 Hz, 1H, NH), 8.29 (d, J=9.3 Hz, 1H, NH), 8.20 (d, J=8.2 Hz, 1H, NH), 8.09 (d, J=8.9 Hz, 1H, NH), 7.99 (s, 2H, NH), 7.86-7.81 (m, 2H, F-ArH), 7.79-7.75 (m, 1H, ArH), 7.72 (dd, J=8.7, 3.7 Hz, 2H, ArH), 7.65 (s, 1H, ArH), 7.41-7.37 (m, 2H, ArH), 7.35-7.31 (m, 2H, ArH, NH), 7.26 (dd, J=4.8, 1.5 Hz, 1H, Thi-H), 7.22-7.16 (m, 2H, F-ArH), 7.05 (s, 2H, NH, ArH), 6.88-6.84 (m, 2H, Thi-H), 4.73-4.66 (m, 1H, H), 4.62-4.51 (m, 2H, H), 4.19-4.12 (m, 1H, Lys-H), 3.21-3.12 (m, 4H, 2H, 2H), 3.06-2.96 (m, 1H, H), 2.87-2.77 (m, 2H, H), 2.62-2.49 (m, 1H, H), 1.66-1.56 (m, 1H, Lys-H), 1.50-1.36 (m, 3H, Lys-H, 2H), 1.26 (s, 3H, CH3), 1.20-1.10 (m, 2H, H), 1.16 (s, 3H, CH3), ppm. ESI-LC-MS m/z 420.8 [M+2H]2+; HRMS (ESI-MS) calcd. for C43H51FN9O6S [M+H]+ 840.3667 found 840.3693.

5.3.11 H-Inp-His-D-2-Nal-D-Phe-Lys(4-FB)-NH.SUB.2 .(Inp-4-FB-Ipamorelin)

[0159] The title peptide was synthesized via automated peptide synthesis and purified by preparative HPLC (20-70% MeCN+0.1% TFA). The title compound was acquired as a white solid (6.30 mg, 6%): .sup.1H-NMR (400 MHz, (CD3)2SO); 8.79 (s, 1H, His H), 8.72 (s, 1H, NH), 8.44 (dd, J=10.8, 6.4 Hz, 2H, NH), 8.19 (d, J=7.8 Hz, 1H, NH), 8.17-8.10 (m, 2H, NH), 7.87-7.81 (m, 2H, F-ArH), 7.80-7.76 (m, 1H, ArH), 7.71 (d, J=7.9 Hz, 2H, ArH), 7.63 (s, 1H, ArH), 7.42-7.35 (m, 2H, ArH), 7.33-7.29 (m, 2H, NH), 7.22-7.18 (m, 6H, ArH), 7.17-7.11 (m, 2H, F-ArH), 7.06 (s, 1H, NH), 6.96 (s, 1H, His H), 4.64-4.56 (m, 1H, H), 4.55-4.44 (m, 2H, H), 4.15-4.07 (m, 1H, Lys-H), 3.19-3.07 (m, 5H, CH2), 2.94 (dd, J=13.6, 5.9 Hz, 1H, CH2), 2.87-2.67 (m, 5H, CH2), 2.58-2.48 (m, 1H, CH2), 2.38-2.29 (m, 1H, H), 1.67-1.34 (m, 8H, CH2), 1.15-1.00 (m, 2H, CH2), ppm. ESI-LC-MS m/z 430.9 [M+2H]2+; HRMS (ESI-MS) calcd. for C47H55FN9O6 [M+H]+ 860.4259 found 860.4284.

5.3.12 H-Inp-His-D-2-Nal-D-2-Nal-Lys(4-FB)-NH.SUB.2 .(MMF-01-140-H)

[0160] The title peptide was made by automated peptide synthesis and purified by preparative HPLC (20-80% MeCN+0.1% TFA). This delivered a white solid (11.3 mg, 10%): .sup.1H-NMR (400 MHz, (CD3)2SO); 8.77 (s, 1H, His H), 8.51 (d, J=7.5 Hz, 2H, NH), 8.36 (t, J=5.5 Hz, 1H, NH), 8.19-8.10 (m, 2H, NH), 8.05 (d, J=8.7 Hz, 1H, NH), 7.85-7.79 (m, 3H, 2F-ArH, ArH), 7.79-7.74 (m, 3H, ArH), 7.73 (s, 1H, ArH), 7.70 (s, 1H, ArH), 7.68 (d, J=2.4 Hz, 2H, ArH), 7.59 (s, 1H, ArH), 7.43-7.35 (m, 5H, ArH), 7.31-7.27 (m, 2H, NH), 7.20-7.13 (m, 2H, F-ArH), 7.05 (s, 1H, NH), 6.93 (s, 1H, His H), 4.67-4.60 (m, 2H, H), 4.52-4.44 (m, 1H, H), 4.16-4.08 (m, 1H, Lys-H), 3.17-2.93 (m, 7H, CH2), 2.88-2.66 (m, 4H, CH2), 2.53-2.47 (m, 1H, CH2), 2.34-2.25 (m, 1H, H), 1.63-1.34 (m, 6H, CH2), 1.32-1.23 (m, 2H, CH2), 1.07-0.95 (m, 2H, CH2), ppm. ESI-LC-MS m/z 455.9 [M+2H]2+; HRMS (ESI-MS) calcd. for C51H57FN9O6 [M+H]+ 910.4416 found 910.4400.

5.3.13 H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys(4-FB)-NH.SUB.2 .(MMF-01-115-H)

[0161] The product was purified by preparative HPLC (25-90% MeCN+0.1% TFA) which yielded a white powder (9.80 mg, 9%): .sup.1H-NMR (400 MHz, (CD3)2SO); 8.64 (d, J=8.3 Hz, 1H, NH), 8.46 (t, J=5.5 Hz, 1H, NH), 8.33 (s, 1H, NH), 8.25 (d, J=8.4 Hz, 1H, ArH), 8.13 (d, J=8.0 Hz, 1H, NH), 8.09 (d, J=7.5 Hz, 1H, NH), 8.03 (d, J=8.5 Hz, 1H, NH), 8.01-7.97 (m, 1H, NH), 7.89 (d, J=8.2 Hz, 1H, ArH), 7.86-7.80 (m, 2H, F-ArH), 7.79-7.72 (m, 3H, ArH), 7.71-7.66 (m, 2H, ArH), 7.58-7.50 (m, 4H, ArH), 7.44 (d, J=6.9 Hz, 1H, ArH), 7.42-7.34 (m, 5H, ArH), 7.31-7.25 (m, 2H, ArH), 7.21-7.15 (m, 3H, 2F-ArH, ArH), 7.07 (s, 1H, NH), 7.02 (d, J=8.4 Hz, 1H, ArH), 4.72-4.65 (m, 1H, H), 4.62-4.50 (m, 2H, H), 4.19 (dd, J=13.3, 8.4 Hz, 1H, Lys-H), 3.61 (dd, J=14.3, 3.9, 1H, CH2), 3.24-3.00 (m, 5H, CH2), 2.97-2.89 (m, 1H, CH2), 2.82-2.49 (m, 5H, CH2), 2.29-2.19 (m, 1H, Inp-H), 1.78-1.66 (m, 1H, CH2), 1.66-1.54 (m, 1H, CH2), 1.53-1.40 (m, 5H, CH2), 1.40-1.16 (m, 2H, CH2), ppm. ESI-LC-MS m/z 477.4 [M+4HF]2+; HRMS (ESI-MS) calcd. for C58H61FN7O6 [M+H]+ 970.4667 found 970.4693.

5.3.14 H-His-D-Trp-Ala-Trp-D-Phe-Lys(4-FB)-NH.SUB.2 .(4-FB-GHRP-6)

[0162] The product was purified by preparative HPLC (15-80% MeCN+0.1% TFA). This yielded a white powder (9.60 mg, 7%): .sup.1H-NMR (400 MHz, CD3OD); His, D-Trp, Trp, D-Phe, 4-FB: 8.50 (s, 1H, His H), 7.88-7.80 (m, 2H, F-ArH), 7.57 (d, J=7.9 Hz, 1H, ArH), 7.49 (d, J=7.8 Hz, 1H, ArH), 7.30 (t, J=8.2 Hz, 2H, ArH), 7.26-6.95 (m, 14H, 13ArH, His H), 4.53-4.46 (m, 2H, H), 4.37-4.30 (m, 2H, H), 3.26-3.04 (m, 6H, H), 2.87 (d, J=8.0 Hz, 2H, H), Lys: 4.04 (dd, J=10.2, 4.0 Hz, 1H, H), 3.26-3.04 (m, 2H, H), 1.81-1.70 (m, 1H, H), 1.58-1.43 (m, 3H, 2H, H), 1.06-0.97 (m, 2H, H), Ala: 3.94 (q, J=7.3 Hz, 1H, H), 0.87 (d, J=7.3 Hz, 3H, CH3) ppm. ESI-LC-MS m/z 498.4 [M+2H]2+; HRMS (ESI-MS) calcd. for C53H59FN12O7Na [M+Na]+1017.4511 found 1017.4522.

5.3.15 H-His-D-Trp-Ala-Trp-D-Phe-Dpr(4-FB)-NH.SUB.2 .(Dpr-4-FB-GHRP-6)

[0163] Preparative HPLC (25-70% MeCN+0.1% TFA) gave the title compound as a white solid (19.8 mg, 14%): .sup.1H-NMR (400 MHz, CD3OD); His, D-Trp, Trp, D-Phe, 4-FB: 8.58 (d, J=1.3 Hz, 1H, His H), 7.82-7.75 (m, 2H, F-ArH), 7.52 (d, J=7.9 Hz, 1H, ArH), 7.40 (d, J=7.9 Hz, 1H, ArH), 7.27 (dd, J=8.6, 1.5 Hz, 2H, ArH), 7.15-7.07 (m, 5H, ArH), 7.06-6.98 (m, 6H, ArH), 6.97-6.89 (m, 3H, 2ArH, His H), 4.54-4.45 (m, 1H, H), 4.44-4.30 (m, 3H, H), 3.22-2.98 (m, 6H, H), 2.93-2.74 (m, 2H, H), Dpr: 4.54-4.45 (m, 1H, H), 3.67 (dd, J=13.8, 5.6 Hz, 1H, H), 3.54 (dd, J=13.8, 7.8 Hz, 1H, H), Ala: 3.93 (q, J=7.3 Hz, 1H, H), 0.86 (d, J=7.3 Hz, 3H, CH3) ppm. ESI-LC-MS m/z 477.4 [M+2H]2+; HRMS (ESI-MS) calcd. for C50H54FN12O7 [M+H]+ 953.4223 found 953.4237.

5.3.16 H-D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH.SUB.2 .(GHRP-2)

[0164] Purification by preparative HPLC (25-70% MeCN+0.1% TFA) delivered the title peptide as a white powder (19.7 mg, 17%): .sup.1H-NMR (400 MHz, CD3OD); D-2-Nal, Trp, D-Phe: 7.76 (d, J=9.2 Hz, 2H, ArH), 7.73 (s, 1H, ArH), 7.65 (s, 1H, ArH), 7.51-7.47 (m, 1H, ArH), 7.44-7.37 (m, 2H, ArH), 7.35 (dd, J=8.4, 1.7 Hz, 1H, ArH), 7.25-7.14 (m, 4H, ArH), 7.09-7.01 (m, 4H, ArH), 7.00 (s, 1H, ArH), 4.77 (dd, J=10.9, 4.6 Hz, 1H, H), 4.49 (t, J=6.8 Hz, 1H, H), 4.36 (t, J=7.6 Hz, 1H, H), 3.11 (t, J=6.7 Hz, 2H, H), 3.07 (d, J=4.5 Hz, 1H, H), 2.88-2.70 (m, 3H, H), D-Ala, Ala: 4.23 (q, J=7.1 Hz, 1H, H), 3.79 (q, J=7.0 Hz, 1H, H), 1.27 (d, J=7.2 Hz, 3H, CH3), 1.00 (d, J=7.1 Hz, 3H, CH3), Lys: 4.16 (dd, J=10.3, 4.1 Hz, 1H, H), 2.88-2.70 (m, 2H, H), 1.82-1.72 (m, 1H, H), 1.56-1.43 (m, 3H, H, 2H), 1.07-0.96 (m, 2H, H), ppm. ESI-LC-MS m/z 409.9 [M+2H]2+; HRMS (ESI-MS) calcd. for C45H55N9O6Na [M+Na]+840.4204 found 840.4173.

5.3.17 H-Inp-D-2-Nal-D-2-Nal-Phe-Lys(FP)-NH.SUB.2 .(2-FP-G-7039)

[0165] The product was purified by preparative HPLC (30-80% MeCN+0.1% TFA). This yielded a white powder (mg, %): .sup.1H-NMR (400 MHz, CD3OD); 8.22-8.17 (m, 2H, amide NH), 8.11 (d, J=7.5 Hz, 2H, amide NH), 8.05 (dd, J=7.9, 2.0 Hz, 1H, amide NH), 7.79-7.66 (m, 6H, ArH), 7.58 (s, 1H, ArH), 7.48 (s, 1H, ArH), 7.44-7.34 (m, 4H, ArH), 7.28 (d, J=8.4 Hz, 1H, ArH), 7.16-7.06 (m, 6H, ArH), 4.96-4.90 (m, 0.5H, HC-F), 4.82-4.77 (m, 0.5H, HC-F), 4.68-4.56 (m, 2H, H), 4.55-4.48 (m, 1H, H), 4.28.4.21 (m, 1H, Lys-H), 3.22-3.13 (m, 4H, CH2), 3.12-2.64 (m, 8H, CH2), 2.34-2.26 (m, 1H, Inp-H), 1.89-1.78 (m, 1H, CH2), 1.76-1.64 (m, 1H, CH2), 1.60-1.23 (m, 11H, 8CH2, CH3), ppm.

[0166] Peptidomimetics have been designed based upon known growth hormone secretagogues, which consist of 5 or 6 unnatural amino acid residues. Analogues containing non-radioactive fluoride were prepared and evaluated in vitro for GHSR-1a affinity. Promising chemical entities were identified as MMF-01-115-H (LCE270) and 2-FP-G-7039 (LCE295) with IC50 values for the GHS-R1a of 68.8 nM and 12 nM respectively. These leads compounds are illustrated in FIG. 46. In addition, using ACD/Log P software, the lipophilicities of these compounds were computed and it was found that LCE00270 and LCE00295 had high Log P values of 8.760.88 and 5.190.88 respectively. However, given that these compounds may be used as imaging agents that may be administered to a subject by intravenous injection, oral biovailability (via oral administration) may not be a primary concern. These lead compounds may require further modification in order to adjust lipophilicity. Having chosen two lead compounds, the precursor of the first lead compound (MMF-01-113-G, LCE244) was radiolabelled using the [18F]SFB prosthetic group (4) by coupling it to the free lysine side-chain. The scheme of FIG. 3 shows the procedure used to radiolabel MMF-01-113-G with [18F]SFB. This synthetic pathway resulted in the formation of the radiolabelled version of the lead compound (MMF-03-67-H, 5) in a crude radiochemical yield of 35% by HPLC. The obtained reaction mixture is shown in FIG. 4, with the product eluting at 6.1 minutes, which is in agreement to the non-radioactive standard. Preparation of the prosthetic group 4 prior to coupling to the peptidomimetic proceeded in high yield and purity, as indicated in FIG. 5.

[0167] The synthesized compounds are listed in Table 1. Peptidomimetic chromatogram are illustrated in FIGS. 11-19, the .sup.1H-NMR spectra are illustrated in FIGS. 20-36 and the peptidomimetic displacement curves are illustrated in FIGS. 37-45.

[0168] The synthesis of the precursor for obtaining MMF-01-115-H is shown in FIG. 5, while the synthesis of MMF-01-115-H is shown in FIG. 6.

[0169] An additional radiolabelling strategy for the highest affinity compound (2-FP-G-7039, LCE295) is proposed in the scheme illustrated in FIG. 10, where a direct labelling approach is used.

TABLE-US-00001 TABLE 1 Synthesized Compounds Amino Acid IC.sub.50, HRMS HRMS LogP (calc.) Name Sequence nM (calculated) (found) LCE no. (ACD/Labs) Ipamorelin H-Aib-His-D-2-Nal- 483 712.3935 [M + H] 712.3959 210 1.72 0.85 D-Phe-Lys-NH.sub.2 4-FB- H-Aib-His-D-2-Nal- 170 834.4103 [M + H] 834.4133 211 3.97 0.89 Ipamorelin D-Phe-Lys(4-FB)- NH.sub.2 4-FB-AEEA- H-Aib-His-D-2-Nal- 474 / / 217 2.80 0.93 Ipamorelin D-Phe-Lys(4-FB- AEEA)-NH.sub.2 Inp-Thi-4-FB- H-Inp-His-D-2-Nal- 1170 866.3824 [M + H] 866.3850 246 3.60 0.89 Ipamorelin D-2-Thi-Lys(4-FB)- NH.sub.2 Thi-4-FB- H-Aib-His-D-2-Nal- 161 840.3667 [M + H] 840.3693 267 3.65 0.90 Ipamorelin D-2-Thi-Lys(4-FB)- NH.sub.2 Inp-4-FB- H-Inp-His-D-2-Nal- 688 860.4259 [M + H] 860.4284 268 3.92 0.89 Ipamorelin D-Phe-Lys(4-FB)- NH.sub.2 MMF-01-140-H H-Inp-His-D-2-Nal- 1920 910.4416 [M + H] 910.4400 269 5.15 0.89 D-2-Nal-Lys(4-FB)- NH.sub.2 GHRP-6 H-His-D-Trp-Ala- 73.1 873.4524 [M + H] 873.4531 239 1.51 0.88 Trp-D-Ple-Lys-NH.sub.2 4-FB-GHRP-6 H-His-D-Trp-Ala- 384 1017.4511 1017.4522 272 3.76 0.92 Trp-D-Phe-Lys(4- [M + H] FB)-NH.sub.2 Dpr-4-FB- H-His-D-Trp-Ala- 1060 953.4223 [M + H] 953.4237 281 3.86 0.93 GHRP-6 Trp-D-Phe-Dpr(4- FB)-NH.sub.2 GHRP-1 H-Ala-His-D-2-Nal- 181 955.4943 [M + H] 955.4964 240 2.60 0.90 Ala-Trp-D-Phe-Lys- NH.sub.2 GHRP-2 H-D-Ala-D-2-Nal- 449 840.4204 [M + H] 840.4173 282 3.41 0.86 Ala-Trp-D-Phe-Lys- NH.sub.2 G-7039 H-Inp-D-2-Nal-D-2- 5.21 798.4343 [M + H] 798.4339 245 5.28 0.82 Nal-Phe-Lys-NH.sub.2 4-FB-G-7039 H-Inp-D-2-Nal-D-2- 242 920.4511 [M + H] 920.4529 243 7.53 0.88 Nal-Phe-Lys(4-FB)- NH.sub.2 2-FP-G-7039 H-Inp-D-2-Nal-D-2- 12 / / 295 5.19 0.88 Nal-Phe-Lys(2-FP)- NH.sub.2 MMF-01-113-G H-Inp-D-2-Nal-D-2- 27.6 848.4499 [M + H] 848.4501 244 6.51 0.82 Nal-1-Nal-Lys-NH.sub.2 MMF-01-115-H H-Inp-D-2-Nal-D-2- 68.8 970.4667 [M + H] 970.4693 270 8.76 0.88 Nal-1-Nal-Lys(4-FB)- NH.sub.2 indicates data missing or illegible when filed

[0170] Literature Compounds:

[0171] 1. GHRP-6: H-His-D-Trp-Ala-Trp-D-Phe-Lys-NH.sub.2

[0172] 2. GHRP-1: H-Ala-His-D-2-Nal-Ala-Trp-D-Phe-Lys-NH.sub.2

[0173] 3. GHRP-2: H-D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH.sub.2

[0174] 4. G-7039: H-Inp-D-2-Nal-D-2-Nal-Phe-Lys-NH.sub.2

[0175] 5. (inip) bb nPA K: H-Inp-D-2-Nal-D-2-Nal-1-Nal-Lys-NH.sub.2

[0176] 6. Ipamorelin: H-Aib-His-D-2-Nal-D-Phe-Lys-NH.sub.2

Example 2

[0177] Using the compound G-7039 as a base, the novel conjugates of Table 2 were synthesized.

[0178] The synthesis of the precursor for obtaining TL-MF-3-2FP is shown in FIG. 7, while the synthesis of TL-MF-3-2FP is shown in FIG. 8.

[0179] Competitive binding assays were run on the compounds of Table 2 as described in Example 1. The results of the competitive binding are shown in FIGS. 47-48. The formulas of the compounds of Table 2 are illustrated in FIGS. 49 and 50.

TABLE-US-00002 TABLE 2 Synthesized Compounds Amino HRMS HRMS Acid IC.sub.50 (calculated) (found) LogP (calc.) Compound Sequence (nM) ([M + H].sup.+) ([M + H].sup.+) LCE no. (ACD/Labs) TL-MF-5- H-Inp-(D- 62.9 959.48 959.60 LCE00335 4.34 +/ 0.90 2FP 2-Nal).sub.2- Ser-Phe- Lys(2-FP)- NH.sub.2 TL-MF-4- H-Inp-(D- 4.35 959.48 959.60 LCE00336 4.34 +/ 0.90 2FP 2-Nal).sub.2- Phe-Ser- Lys(2-FP)- NH.sub.2 TL-MF-3- H-Inp-D-2- 0.283 888.44 888.32 LCE00337 4.46 +/ 0.88 2FP Nal-D-2- Nal-Tyr- Lys(2-FP)- NH.sub.2 TL-MF-2- H-Inp-(D- 60.3 812.41 812.41 LCE00338 2.77 +/ 0.87 2FP 2-Nal).sub.2- Ser-Lys(2- FP)-NH.sub.2

Example 3

[0180] Calcium Flux Assay

[0181] Another in vitro assay performed on the 4-fluorobenzoyl agonist [1-Nal.sup.4,Lys.sup.5(4-FB)]G-7039 and the [Lys.sup.5(2-FP)]G-7039 agonist was a calcium flux dose-response assay. This experiment allows the determination of the half-maximal effective concentration (EC.sub.50) for each agonist, a measure of the concentration of the agonist required to produce 50% of the maximum biological effect resulting from ghrelin receptor activation. In this particular case, the biological effect of the peptidomimetic [1-Nal.sup.4,Lys.sup.5(4-FB)]G-7039 and the peptidomimetic [Lys.sup.5(2-FP)]G-7039 is the release of intracellular calcium ions, a process which is detected by fluorescence using a FLIPRTETRA instrument. Endogenous ghrelin was used as a control in this assay, which was performed by EMD Millipore's GPCRProfiler service.

[0182] The calcium flux assay was carried out for both compounds [1-Nal.sup.4,Lys.sup.5(4-FB)]G-7039 (also referred to as 4-FBG-7039 in FIG. 51 and as compound MMF-01-115-H in Table 1) and in Lys.sup.5(2-FP)]G-7039 (also referred to as compound 2-FP-G-7039 in Table 1) by the EMD Millipore GPCRProfiler service. Samples of both compounds were dissolved in DMSO (1 ml) at a concentration of 250 M and solubility tested in the recommended buffer (Hanks balanced salt solution: 1.26 mM CaCl.sub.2, 0.493 mM MgCl.sub.2.6H.sub.2O, 0.407 mM MgSO.sub.4.7H.sub.2O, 5.33 mM KCl, 0.441 mM KH.sub.2PO.sub.4, 4.17 mM NaHCO.sub.3, 137.9 mM NaCl, 0.338 mM Na.sub.2HPO4, 5.56 mM D-Glucose with 20 mM HEPES, pH=7.4 and final concentration of 1.2% DMSO). If the compound remained soluble 15 minutes after addition, samples were shipped to the EMD Millipore Corporation (15 Research Park Drive, St. Charles, Mo. 63304, USA). The assay service calculated EC.sub.50 values for both peptidomimetics as well as the ghrelin control in terms of intracellular Ca.sup.2+ release. Human recombinant ghrelin receptor calcium-optimized stable cell lines (chem-1 cells) were loaded with a fluorescent calcium dye (Fluo-8 NW from ABD Bioquest 21080) and calcium flux detected in response to the agonists by a Molecular Devices FLIPR.sup.TETRA instrument. The agonist assay was performed for a total of 180 seconds. Each assay and assay concentration was performed in duplicate. The data acquired is presented in FIG. 51 ([1-Nal.sup.4,Lys.sup.5(4-FB)]G-7039) and FIG. 52 (Lys.sup.5(2-FP)]G-7039).

[0183] The control ligand ghrelin was found to have a high in vitro potency (EC.sub.50=1.6 nM), which is expected for the endogenous ligand of the GHS-R1a. The EC.sub.50 value of [1-Nal.sup.4,Lys.sup.5(4-FB)]G-7039 was found to be 1.1 nM. This demonstrates that the presence of the 4-fluorobenzoyl group still results in a low nanomolar efficacy. This is in spite of the slight increase in the IC.sub.50 value compared to the compound [1-Nal.sup.4]G-7039 (IC.sub.50=69 nM vs 28 nM respectively). The high in vitro potency acquired for [1-Nal.sup.4,Lys.sup.5(4-FB)]G-7039 indicates that it is a potent ghrelin receptor agonist.

[0184] The EC.sub.50 value for Lys.sup.5(2-FP)]G-7039 was found to be 20 pM or 0.02 nM, which is an exceptionally high efficacy for this peptidomimetic agonist. This is an unexpected improvement in efficacy as compared to the reported half-maximal efficacy of the parent compound G-7039 (EC.sub.50=0.18 nM) (Elias, K., et al., Endocrinology 1995, 136, 5694-5699) despite the different mode of potency determination (Ca.sup.2+ release for [Lys.sup.5(2-FP)]G-7039 but GH release for G-7039).

[0185] Advantages

[0186] The peptidomimetics of the present invention are different from existing technology in that it attempts to distinguish between malignant and benign tumours by targeting the ghrelin receptor, which is known to have a differential expression in benign and malignant tumours compare to, for example, normal prostetic tissue. This is an issue prevalent with imaging modalities in current clinical use (18F- and 11C-PET CT, PET/CT, MRI and mpMRI). There are currently no clinical imaging agents targeting specific receptors for prostate cancer imaging. In addition, the use of peptidomimetics represents superior targeting, stability and pharmacokinetic properties compared to peptide-based approaches.

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[0240] Through the embodiments that are illustrated and described, the currently contemplated best mode of making and using the invention is described. Without further elaboration, it is believed that one of ordinary skill in the art can, based on the description presented herein, utilize the present invention to the full extent. Future applications claiming priority to this application may or may not include the following claims, and may include claims broader, narrower, or entirely different from the following claims.