Chapter 22. Growth Hormone Secretagogues Ravi P. Nargund and Lex H. T. Van der Ploeg Merck Research Laboratories P.O. Box 2000 Rahway, NJ 07065 Introduction - In recent years, the growth hormone releasing peptides (GHRPs) and GHRP peptidomimetics have received considerable attention as potential alternatives to injectable GH replacement therapy (1, 2). These compounds can restore and enhance pulsatile GH release in humans (3). It is therefore anticipated that inducing physiologically relevant, pulsatile release of GH with GH-secretagogues (GHSs) may provide the beneficial effects of GH replacement therapy without the associated side effects that result from bolus GH administration. Furthermore, the GH-secretagogues may offer the potential advantages of oral dosing. Considerable progress has been made in identifying small molecule mimetics for the peptidyl secretagogues GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2;EGo=lO nM) (4, 5), GHRP-2 (D-Ala-DP-Nal-Ala-Trp-D-Phe-Lys-NH2; EC50=3 nM) (6), GHRP-1 (Ala-His-D-P-NalAla-Trp-D-Phe-Lys-NH2; EC50=6 nM ) (7) and hexarelin (His-D-2-methylTrpAla-Trp-D-Phe-Lys-NH2; EC50=l nM) (8). Their design is of significant interest since these ligands are receptor agonists. In 1993, a group at Merck disclosed benzolactam secretagogue 1 (L692,429; EC50=6O nM) (9, 10). Mechanism of action studies in vitro with cultured rat primary pituitary cells showed that its mode of action was identical to that of GHRP-6 and distinct from that of GHRH suggesting that its actions were mediated through the same putative GHRP receptor and not the GHRH receptor (11). In the clinic, 1 released GH after acute i.v. treatment in young and elderly subjects (12, 13). There were, like GHRP-6 (14), transient increases in cortisol and prolactin. The other measured hormones were in the normal range. Continous intravenous infusion of 1 to young healthy adults and healthy older subjects resulted in an upregulated GH secretory pattern that was pulsatile in nature (15). The discovery of 1 showed that it was possible to design smaller peptidomimetics for GHRPS. Furthermore, the clinical results with GHRP-6 and 1 validated the GHRP-mechanism for GH release as a viable alternative to GH replacement therapy. Encouraged by the these findings considerable effort has been spent to identify GH secretagogues that may have good oral bioavailability. To this end, significant progress has been made in the design of peptidomimetics for GHRP-6 within the past several years. Furthermore, breakthroughs have been attained in understanding their molecular basis and mechanisms of action. This is of interest since the GHRPs and peptidomimetics were discovered without knowledge of a molecular target or an endogenous counterpart This chapter will discuss developments in the design of new peptidomimetics of the GHRP pathway and in understanding their mechanism of action. ANNUAL REPORTS IN MEDICINAL C H E M I S T R Y 4 2
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Copyrlght 0 1997 by Academic b s b , Ine All righte of r s p m d u c t l o n in any form FeBewed 0065-7743/97 $25 00
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Benzolactams Significantly more potent analogs of 1 include 2 (L-692,585; EC50=3 nM) (16) and carboxamide 3 (EC50=3 nM) (17). Acute i.v. administration of 2 to beagles caused significant increases in GH levels at doses as low as 0.005 mg/kg (18). Once-daily i.v. administration of 0.01 and 0.10 mg/kg of 2 to beagles did not lead to desensitization of the GH response (18). Futhermore, there were transient increases in levels of insulin-like growth factor-1 (IGF-1). A sustained amplification of episodic GH release resulted after a 12-h infusion of 2 to guinea pigs (19). The oral bioavailabilityof 1 in dogs is less than 2%, which may be due its zwitterionic nature. Therefore, it is of interest that carboxamidea is orally active for releasing GH in beagles at 5.0 mg/kg (17). Urea-based replacements for the 2'4etrazole of 1 have been disclosed in the patent literature (20). Recently, a group from Novo Nordisk disclosed naphtholactam-based secretagogues in a pending patent application (21). The effect of these structural changes on oral bioavailability is yet to be reported.
1 -
R=H
-3
OH
-
Pevelopment of GHRP Analoas Considerable effort has been spent to identify analogs of GHRP-6 with improved metabolic stability. To this end, an analog of GHRP-6 that bears an aminomethylene substitution between DPhe5 and Lys6 (4; EC50=0.5 nM) displayed a twenty-fold increase in potency in an anesthetized rat model when compared with GHRP-6 (22). Compound 5 (G-7203; EC5p0.43 nM), a cyclic analog of the linear hexapeptide GHRP-2, was designed in an effort to understand the topographical requirements for the GH releasing activity of the GHRPs (23). McDowell and co-workers (23) showed that the D-2-Nal-Ala-Trp-D-Phe fragment adopts a compact conformation with nested hairpin turns initiated at D-Lys' and Ala3. Other cyclic GHRP-2 analogs that did not readily adopt this conformation were considerably less active suggesting that a precise arrangement of the three aromatic side-chains was crucial for GH releasing activity.
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H
CZOO HN
NHz
0:c.
-5
4
NHz
H
-6
-7
Extensive medicinal chemistry studies were carried out (23) around a tetrapeptide Tyr-D-Trp-D-Trp-Phe-NH2that was previously reported (24) to be weakly active for releasing GH. The D-Nal-Ala-Trp-D-Phetriaromatic core of GHRP-6 was converted to D-2Nal-D-2-Nal-Phe and an isonipecotic acid amino side-chain was utilized for the N-terminal histidine of GHRP-6 in the design of tetrapeptide secretagogue 6 (G-7039; EC50=0.18 nM) (23). Further optimization of 6 by removal of the Phe and Lys residues and optimization of the C-terminus provided a series of small molecule GH secretagogues exemplified by L (G-7502; EC50=10.6 nM). Compound Z was active in rats with an i.v. ED50 of 0.80 mg/kg. The biochemical properties and specificity towards other hormones of 6 and L were similar to GHRP-6. These results suggest that these new peptidomimetics exert their action also through the GHRP pathway. In 150-day old female rats 6 was significantly more effective for increasing body weight when it was administered by S.C. minipump 2X daily for 14 days as compared with the body weight gain after S.C. minipump infusion of 6 for 14 days at 100 pg per rat per day (25). In obese male ZDF rats serum fasting glucose levels over a 3 week period were considerably higher than those of lean controls when 5 100 pg per rat per day by twice daily S.C. injection (25). However, giving the secretagogue+rhlGF-1 somewhat attenuated the effects on serum glucose elevation suggesting that IGF-1 is an important factor in moderating the effects of GH secretagogues on serum glucose and in maximizing the anabolic potential of these agents.
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Tripeptides such as (AIB-D-Trp-D-homoPhe-OEt;EC50=3 nM; AIB = aminoisobutyric acid) and g (AIB-D-Trp-D-Trp-OEt; EC50=6 nM ) that are more potent than GHRP-6 (EC50=10nM) have been described (26).
B
9
a
Compound has been reported to be inactive for releasing GH in an infant rat model (27). Peptide analogs such as (EP 51319; AIB-D-2-methylTrp-D-2methylTrp-NH2) and 11 (EP 51216; GAB-D-2-methylTrp-D-2-methyITrp-D-2methylTrp-LysNH2; GAB = y-aminobutyric acid) elevated GH levels into the 160-200 ng/mL range in an infant rat assay (27-29). Both 10 and 11 are orally active in dogs and in man where they were reported to elevate GH levels without increasing cortisol (29). Related to 1 are compounds with benzylamine side chains, as exemplified in that are claimed in pending patent applications by the Novo Nordisk company (30).
u,
CamDhor-Based GH Secretaaoaues - Non-peptide camphorsulfonamide GH secretagogues were disclosed in 1996 (31). Structure-activity relationship studies around a weakly active screening lead (L-368,112; GHS EC50=300 antagonist nM), that came from the oxytocin (OT) receptor
a
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program (OT IC50=68 nM), led to the discovery of 14 (GHS E&0=90 nM; OT IC50=130nM). It is interesting that 14 is an agonist at the GHS-R and an antagonist at the OT receptor. Development of Soiropiperidine-based GH secretaaoaues (MK-06771--A new structural class of GH secretagogues that has good oral bioavailability was disclosed in 1995 (32). The design of this spiropiperidine class of GH secretagogues originated in a project to derivativize so-called privileged stuctures as a strategy to identify leads for receptor projects (33). The spiroindanylpiperidine was chosen for derivatization since it was present in sigma receptor ligands (34) and in the oxytocidGH secretagogue active (31,33, 34). From this type of approach, compounds (L-262,564; mixture of 4 diastereomers; EC50=50 nM) was designed. Secretagogue =was active i.v. in dogs at 0.10 mg/kg but not active after an oral dose of 5 mg/kg. Extensive medicinal chemistry studies around 15 led to the discovery of (L-163,191 (MK-0677); EC50=l.3 nM).which was orally active in beagles at doses as low as 0.0675 mg/kg and i.v. down to 0.025 mg/kg (32, 35). The oral bioavailabilityof 16 in dogs was determined to be over 60%. Like GHRP6 and 1,transient 'increases in cortisol were observed after an 1 mg/kg oral dose to beagles (19). In vitro =was mechanistically indistinguishablefrom GHRP-6 and 11321.
a a
15
16
x=o
IZ
X=CH2
18
MK-0677 is a long-acting GH secretagogue, since an oral dose of 1 mg/kg in beagles leads to a sustained elevation of GH for about 6 to 8 hours (35). Chronic once-daily oral administration of 0.50 or 1.0 mg/kg 16 to beagles leads to a marked desensitization of the GH response (36). Frequent sampling for GH on day 4 showed that the GH response was pulsatile in nature (1 36). Furthermore,there was a considerable increase in IGF-1 levels (-126%) that was also sustained throughout the experiment. Oral administration of 1.0 mg/kg &to dogs on alternate days did not result in desensitization of the GH response. The authors suggested that the desensitization observed on daily GHS administration results from the sustained IGF-1 elevation which may lead to IGF-1 mediated down regulation of GH secretion (36).
A 3-phenylpropyl-D-glycinederivative UL-l63,255; EC50=l.5 nM) has been reported to be active in releasing GH and in increasing IGF-1 levels
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in finisher pigs when it was administered for 72 hours at 360 ppm ad libitum in feed (37). These results suggest that GHSs may be useful as growth promotants in pigs. Of interest is a chronic study that investigated the anabolic and functional effects of l.2 when administered in a dog hind limb immobilization protocol (38). At week 15, an 43% increase in muscle strength in the immobilized limbs, as measured by isometric torque, was seen in treated group vs 16% in the control group (38). The results of this study suggest that GHSs may be of value in rehabilitation therapy. Other GHRP PeDtidomimetics - By analogy with oxytocin receptor antagonists (39), use of piperazine-based replacements for the spiropiperidine of provided analog U (EC5p6.3 nM) with comparable GH releasing activity in vitro (40). As discussed above 16 is a long-acting GHS. It is unclear at this time what type of pharmacodynamic profile will result in optimal efficacy and, therefore, it is of interest that spiroindane esters and acids are potent, orally active and characterized by a much shorter duration of action than l§ have been reported (41). GH responses following once-a-day administration to dogs for several days with these short-acting secretagogues do not result in the same extent of desensitization as observed with a long-acting compound like 16. As a result IGF-1 elevations are also less robust (41). In pending patent applications, a group from Pfizer has claimed tetrahydroquinoline-based and 4-heterocyclic piperidine-based GH secretagogues (42). A group from Eli Lilly has claimed structures that include their NK1 clinical candidate LY 303870 (43) as well as 2acylaminopropanamidederivatives as GH secretagogues (44). The biological activities and in vivo properties of these structurally distinct secretagogues is yet to be disclosed.
. .
ion. C h a r m i o n and C l m a- of the GH S e c r e t a w e Rec/GHS-Q - As discussed above the GHRPs and GHRP peptidomimetics were discovered without knowledge of their molecular target or endogenous counterpart. Aided by tools like [35S] MK-0677 (specific activity of 1000 1.3 nM) (45), the growth hormone CVmmol (16); GH release EC50 secretagogue receptor was identified in swine and rat anterior pituitary membranes (46). These binding sites exhibited the appropriate pharmacology in which the Kd and EC50 for GH release with diverse GH secretagogues had the predicted rank-order of potency. The binding of [35S]MK-0677 was inhibited by GTP-y-S suggesting that the GHS-R is most likely a G-protein coupled receptor (GPC-R) (46).
-
An expression cloning strategy was employed to isolate the first GHS-R cDNA from swine. The swine GHS-R clone was subsequently used to isolate human and rat GHS-R homologues (47). Determination of the nucleotide sequence of the full length human GHS-R mRNA (type la) showed that it encoded a GPC-R with seven transmembrane (TM) domains. The swine and human GHS-R encode a predicted protein of 366 amino acids, while the rat GHS-R encoded a 364 amino acid protein (47, 48). Human, rat and swine GHS-Rs are 94 % identical at the amino acid level and share several GPC-R features, including an ERY GPC-R signature sequence, Nlinked glycosylation sites and serine and threonine phosphorylation sites. A
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second GHS-R mRNA (type 1b) encoded a shorter protein (265 amino acids) with only five predicted transmembrane domains. A comparison of GPC-Rs showed that the human GHS-R is most closely related to the neurotensin receptor (-35% identity) and the thyrotropin releasing hormone receptor (-29% identity). The GHS-R receptor exhibited the predicted pharmacology based on competition with MK-0677, GHRP-2 and GHRP-6. Type 1b cDNA transfection in COS-7 cells failed to express an MK-0677 binding site, even though type 1b protein was expressed on the COS-7 cell surface.
. .
. .
GHS-R mRNA Fxpression in Rrain and Pi- In situ hybridizationstudies were carried out in rhesus brain (47), rat brain and pituitary (49) and GHS-R RNAse protection with human brain derived poly A+ RNA (48) to determine the sites of type l a and l b GHS-R expression. Specific diffuse signals could be detected in the anterior rat pituitary, while the posterior pituitary failed to show specific signals (51). Analysis of rat brain gave the most complete overview of the pattern of GHS-R expression, and was consistent with the data obtained in both rhesus and human brain. First, as predicted from MK0677 binding studies specific signals were detected in the arcuate nucleus, the ventral medial hypothalamus and the paraventricular nucleus (49). Interestingly, significant hybridizationcould be detected at several other brain regions including the dentate gyrus and CA2 and CA3 regions of the hippocampus and in dopaminergic neurons of the pars compacta of the substantia nigra and the ventral tegmental area. Other brain regions that showed GHS-R mRNA expression included the suprachiasmatic nuclei, preoptic nucleus, supraoptic nucleus, anterior hypothalamic area, the lateroanterior hypothalamic area (49) and tuberomammilary nuclei. Regions in the brain stem including the Edinger-Westphal, dorsal and median raphe nuclei also gave distinct hybridization signals (49). Finally, the latero dorsal tegmental area and the facial nerve revealed hybridization signals for GHS-R mRNA. Type l a and l b mRNA expression patterns were similar in the tissues examined. The role of GHS-R mRNA expression in other neurons in the hypothalamus, hippocampus and brain stem including, dopaminergic, serotonergic and NPY containing neurons (49-51) will require further investigation. Clinical Evaluation of GH Secretagoaues - The GHRPs are effective at releasing GH in healthy young and old human subjects and in numerous disease states (52). The GHRPs and peptidomimetics do show some degree of non-specificity since they also cause transient increases in cortisol and prolactin (14). An intact hypothalamic-pituitaryconnection is essential since GHSs dio not elicit a GH response in patients with a hypothalamic-pituitary disconnection (53). Co-administrationof GHRP-6 and GHRH to young adults produced a synergistic GH reponse (14). As discussed above, i.v. infusion of short-acting GHRP-6 or 1augments pulsatile GH secretion (3,13). Likewise, once daily oral administration of long-acting MK-0677 to healthy elderly subjects daily for two weeks provided a prolonged upregulation of the GH secretory pattern (54). In this study, a down regulation of the initial cortisol response was also observed and no significant difference in cortisol release were observed on day 14 when compared to the placebo group (54). Furthermore, there was an approximately 60% increase in serum IGF-1 levels (54) *
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Long term intranasal administration of hexarelin (60 pgkg, tid) to nonGH deficient short stature children enhanced growth velocity (55). MK-0677 treatment at 25 mg in short term diet-induced nitrogen wasting in healthy young men led to a sustained increase in serum GH, IGF-1 and IGFBP-3 levels (56). Treatment of catabolic conditions with MK-0677 may therefore prove beneficial. Eight-week treatment of obese individuals with once-daily 25 mg MK-0677 resulted in significant increases in basal metabolic rate and fatfree mass (57). But in contrast to GH studies, there were increases in body weight and body fat was unchanged. Longer term studies may be required to see the desired changes on body composition. TheraDeutic Potential - Growth hormone deficient children are candidates for treatment with GH secretagogues. Other conditions which potentially could be treated with GH secretagogues include a variety of catabolic conditions, including post-operative recovery, malnutrition from a variety of causes, and muscle wasting due to chronic exposure to corticosteroids, osteoporosis, Turner's syndrome and age-related deficiences in GH levels. Clinical studies are underway to evaluate the utility of secretagogues in several of these conditions. It is unknown whether they can overcome the GH resistance associated with catabolic states. Of considerable interest are potential clinical applications for GH secretagogues in reversing age-related loss in muscle strength and functional abilities. In this frail patient population GH secretagogues may show improved satey and tolerability since the GH profile is physiologicalin nature.
-
Within the past several years highly active GHRP peptidomimetics with short-acting and long-acting pharmacodynamic profiles have been identified. Furthermore, oral dosing is possible. The mechanisms by which pulsatile GH secretory pattern results from GH secretagogue treatment are being elucidated (11). GHRP-6 was shown to act directly on somatotrophs to cause GH release, to potentiate the actions of GH-stimulatory hormone, growth hormone-releasinghormone (GHRH; a hypothalamic peptide), and by being a functional antagonist of somatostatin, a hypothalamic peptide that inhibits GH release by several mechanisms (1). The relevance of this synergy with GHRH is exemplified by the loss of GHS sensitivity in hypothalamidpituitary-stalksectioned animals, which lack portal blood derived growth hormone-releasing hormone (GHRH) and which are no longer GHS responsive (58). The identificationof the GHS-R that is specifically expressed in the hypothalamus, pituitary and several other discrete brain regions, provides significant evidence for the presence of a third neuroendocrine pathway, in addition to GHRH and somatostatin, with a dominant mode of action in the control of pulsatile GH release. Furthermore, it highlights the specificity of the action of the GH secretagogues. It is anticipated that the identificationof the putative endogenous ligand of the GHS-R will shed further light on the normal physiological function of this receptor and its role in the control of pulsatile GH release. Finally, the small molecule GH secretagogues present important tools for evaluating their therapeutic potential in the clinic and in animal husbandry.
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References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.
12. 13. 14. 15. 16. 17 18.
R. G. Smith, S. -S.Pong, G. Hicke , T. Jacks, K. Cheng, R. Leonard, C. J. Cohen, J. P. Arena, C. H. Chang, J. Drisko, Wyvratt, M. Fisher, R. Nargund, and A. Patchett, Recent Progress in Hormone Research, &, 261, (1996). R. J. DeVita, M. J. Wyvratt, Drugs of the Future, 21,273, (1996). C. A. Jaffe, P. J. Ho, R. Demottfriberg, C. Y. Bowers, A. L. Barkan, Journal Of Clinical Endocrinology And Metabolism, Lz, 1641, (1993). C. Y. Bowers, F. A. Momany, G. A. Reynolds, A. Hong, Endocrind., 114,1537, (1984). F. A. Momany, C. Y. Bowers, G. A. Reynolds, A. Hong, K. Newlander, Endocrinol., 114, 1531, 1984). C. Y. In Molecular and Clinical Advances in Pituitary Disorders, Melmed, S., Ed.; Endocrine Research and Education: Los An eles, CA, 1993; pp. 153-157. C. Y. Bowers, J. Pediatr. Endocrinol., 6, 21,71993). A. Deghenghi, Life Sci., 1321 (1994). R. G. Smith, K. Cheng, W. R. Schoen, S. S.Pon , G. Hickey, T. Jacks, B. Butler, W. W. S. Chan, L. Y. P. Chaung, F. Judith, J. Taylor, h! J. Wyvratt, M. H. Fisher, Science, 1640, 1993). W. R. choen, J. M. Pisano,,K. Prendergast, M. J. Wyvratt, M. H. Fisher, K. Cheng, W. W. S. Chan, B. Butler, R. G. Smith, R. G. Ball, J. Med. Chem.,x, 897, (1994). K. Cheng, W. W.-S Chan, B. Butler, L. Wei, W. R. Schoen, M. J. Wyvratt, M. H. Fisher, R. G. Smith, Endocrinol., X g 2729, (1993). B. J. Gertz, J. S. Barrett, R. Eisenhandler, D. A.Krupa, ; Wittreich, J. A.; Seibold, J. R.; Schneider, S. H., J. Clin. Endocrinol. Metab., 1393, (1993). J.A. Aloi, B. J. Gertz, M. L. Hartman, Huhn, W.C.; S. S. Peuoli, J. M. Wittreich, D. A. Krupa, M. A. Thomer, J. Endocrinol. Metab., 943, (1994). C. Y. Bowers, G. A. Reynolds, D. Dutham, C. M. Barrera, S. S. Peuoli, M. O.Thomer, Endocrinol., Ze 975, (1990). I. M. Chapman, M. L. Hartman, S. S. Peuoli, M. 0. Thomer, J. Clin. Endocrinol. Metab., 2874, (1996). W. R. Schoen, D. Ok, R. J. DeVita, J. M. Pisano, P. Hodges, K. Cheng, W. W. -S.Chan, B. S. Butler, R. G. Smith, M. J. Wyvratt, Jr., M. H. Fisher, Bioorg. Med. Chem. Lett., 4 1117, (1994). R. J. DeVita, W. R. Schoen, M. H. Fisher, A. J. Frontier, J. M. Pisano, M. J. ratt, Jr., K. Cheng, W. W. -S.Chan, B. S. Butler, G. J. Hickey, T. M. Jacks, R. G. Smith, ioorg. Med. Chem. Lett., 4 2249, (1994). K. M. Faithall, A. Mynett, R. G. Smith, I. C. A. F. Robinson, J. Endocrinol., 417,
d
bowers,
L
n,
a
u,
Y
19.
y.gi5backs, G. J. Hickey, F. Judith, J. Taylor, H. Y. Chen, D..A. Kru a, W. P. Feeney, W. R. Schoen, D. Ok, M. H. Fisher, M. J. Wyvratt, Jr., R. G. Smith, J. '!ndocrinol., 399,
20.
k'.g!%ochis, M. J. Wyvratt, W. R. Schoen, US Patent 5,283,241. H. Thogersen, B S. Hansen, B. Peschke, T. K. Hansen, K. E. Andersen, PCT Patent Publication WO 96/05195. N. L. Johansen, B. S. Hansen, H. Klitgaard, M. Ankersen, In 10th International Congress of Endocrinol , San Francisco, CA, June 12-15, P1-586 (Abstract), (1996 . R. S. McDow~[K. A. Elias, M. S. Stanley, D.J . Burdick, J. P. Burner, . S. Chan, W. J.Fairbrother, R. G. Hammond, G. S. Ingle, N. E. Jacobsen, D. L. Mortensen, T. E. Rawson, W. B. Won, R. G. Clark, T. C. Somers, Proc. Natl. Acad. Sci. USA , 92, 11 165,
21. 22. 23.
24. 25.
26. 27. 28. 29.
30. 31. 32.
2
!,g~5klomany, C. Y. Bowers, G. A. Reynolds, A. Hong, K. Newlander, Endocrinol., 114, 1531, (1981). T. K. Somers, K. A. Elias, R. G. Clark, R. S. McDowell, M. S. Stanley, J. P. Bumier, T. E. Rawson, PCT Patent Publication WO 961151148. L. Yan , R. P. Na und,.G. Morriello, K. Barakat, Y. Pan, K. Prender ast, K. Cheng, Smith, A. A. Patchett, 210th American Chemical 8ociety Nabonal W.W.-d! Chan, R. Meetin Chica IL 1995, MEDl 01 1 (Abstract). R. Degien h i m vBoutrgnon, ' ' ' M. Luoni, R. Grilli, M. Guidi, V. Locatelli, 10th International Congress 03 Endocrinology. San Francisco, CA, June 12-15, 1996; P1-581 (Abstract). R. Deghenghi, In Growth Hormone Secretagogues, Bercu, B.B., Walker, R.F., Eds.; Springer-Vedag: New York, 1996; pp. 85-102. R. Deghenghi, F. Boutignon, M. Luoni, A. Rigamonti, S. G. Cella, F. Broglio, E. Arvat, E. Ghigo, V. Locatelli, 2nd International S mposium on Growth Hormone Secretagogues, Tampa, FL, Febwary 13-16, 1997; P9 (Aistract). L. Je er, B. Peschke, N. Johansen, M. Ankersen, PCT Patent Publication WO 96122997. R. P.% ar und, K. J. Barakat, K. Cheng, W. W. -S.Chan, B. S. Butler, R. G. Smith, A. A. Patchett, Iioorg. Med. Chem. Lett.,& 1265, (1996). A. A. Patchett, R. P. Nargund, J. R. Tata, M. -H. Chen, K. J. Barakat, D. B. R. Johnston, K. Cheng, W.W.4. Chan, B. Butler, G. Hickey, T. Jacks, K. Schleim, S.-S. Pong, L. Y. -P.
8.
Section N-Immunology,
33. 34.
35 * 36. 37.
38. 39.
40. 41. 42.
43.
44.
45.
48. 49.
50. 51.
52.
Hagmann, Ed.
Chaun , H. Y. Chen, E. Frazier, K. H. Leung, S.-H.L. Chiu, R. G. Smith, Proc. Nan. Acad. Sci. U#A,E, 7001, (1995). B. E. Evans, K. E. Rittle, M. G. Bock, R. M. DiPardo, R. M. Freidinger, W. L. Whitter, G. F. Lundell, D. F. Veber, P. S. Anderson, R. S. L. Chan , V. J. Lotti, D. J. Cerino, T. B. Chen, P. J. Kling, K. A. Kunkel, J. P. Springer, J. J. Hirshfidd, J. Med. Chem., 2235, (1988). M. S. Chambers, R. Baker, D. C. Billington, A. K. Knight, D. N. Middlemiss, E. H. F. Wong, J. Med. Chem.,& 2033, (1992). T. Jacks, R. Smith, F. Judith, K. Schleim, E. Frazier, H. Chen, D. Krupa, D. Hora, Jr., R. Nargund, A. Patchett, G. Hickey, Endocrinol., 5284, (1996). G. Hickey, T. Jacks, K. Schleim, E. Frazier, H. Chen, D. Krupa, W. Feeney, R. Nargund, A. Patchett, R. G. Smith, J. Endocrinol., (1997), in press. C. H. Chang, E. L.. Rickes, L. McGuire, E.,Frazier, H. Chen, K. Barakat, R. Nargund, A. Patchett, R. G. Smith, G. J. Hickey, Endocnnol., XZ, 4851,, (1996). T. Jacks, R. Lieber, K. D. Schleim, R. Mohler, M. Haven, W. Feene , D. Hora, G. Hickey, 10th International Congressof Endocrinology, _. San Francisco, CA, June 12-15, 1996; P1602 (Abstract). P. D. Williams, P. S. Anderson, R. G. Ball, M. G. Bock, L. A. Carroll, S.-H. L. Chiu, B. V. Clineschmidt, J. C. Culberson, J. M. Eh. B. E. Evans, S. L. Fitzpatrick, R. M. Freidinger, M. J. Kaufman, G. F. Lundell, J. S. Murphy, J. M. Paduc k, D. S. Perlow, D. J. Pettibone, S. M. Pitzenberger, K. L. Thompson, D. F. Veber,r. Med. Chem., 3.2 565,
994$s.
(K. l J. rakat, R. P. Nar und, K. J. Prendergast, K. Cheng, T. M. Jacks, K. Schleim, W.W.S. Chan, B. Butler, E. ? h e r , G. J. Hicke , R. G. Smith, A. A. Patchett, 212th American Chemical Society National Meeting, Orland%, FL, 1996, MEDlO71 (Abstract). J. R. Tata, Z. Lu, K. Cheng, L. Wei, W. W. -S. Chan, B. Butler, K. D. Schleim, T. M. Jacks, K. Leun , S. H. L.Chiu, G. Hickey, R. G. Smith, A. A. Patchett, Biorg. Med. Chem. Lett., accepte! for publicatron. P. A. Carpino, P. A. DaSilva Jardine, B. Lefker, J. A. Ragan, PCT Patent Publication WO 96J38471. P. A. Hipskind, J. J. Howbert, R. F. Burns, S. S. Y.,Cho, T. A. Crowell, M. M. Foreman, D. R.Gehlert, S. lyen r, K. W. Johnson, J. H. Krushinski, D. L. LI,K. L. Lobb, N. R. Mason, B. S. Muehl, J. A. Exon, L. A. Phebus, D. Regoli, R. M. Simmons, P. G. Threlkeld, D. C. Waters, B. D. Gitter, J. Med. Chem., 736, (1996). a) J. A. Dod , P. A. Hipskind, PCT Patent Publication WO 97/06803. b) J. A. Dodge, P. A. Hipskind, VCT Patent Publication WO 97/07117 D. C. Dean, R. P. Nargund, S.-S. Pong, L.-Y. Chaun , P. Griffin, D. G. Melillo, R. L. Ellsworth, L. H. T. Van der Ploeg, A. A. Patchett, R. Smith, J. Med. Chem., 1767,
a,
8.
s,
R.P. Nargund, A.A. Patchett and R.G. Smith.
46. 47.
Endocrinology and Metabolic Diseases
A.D. Howard, S.D. Feighner, D.F. Cully, J.P. Arena, P.A. Liberator, C.I. Rosenblum, M.J. Hamelin, D.L. Hreniuk, O.C. Palyha, J. Anderson, P.S. Paress, C. Diaz, M. Chou, K. Liu, K.K. McKee, S . 4 . Pong, L.-Y. Chaung, A. Elbrecht, M. Dashkevicz, R. Heavens, M. Rigby, D.J.S. Sirinathsinghl, D.C. Dean, D.G. Melillo, A.A. Patchett, R. Nargund, P.R. Gnffin, J.A. DeMartino, S.d. Gupta, J.M. Schaeffer, R.G. Smith, L.H.T. Van der Ploeg, 974, (1996). Science K. Kulju McKee, O.C. Palyha, S.D.Feighner, D.L. Hreniuk, C. Tan., M. Phillips, R.G. Smith, L.H.T. Van der Ploeg, A.D. Howard. Molecular Endocrinolo , In press (1997). X . 4 . Gum, H. Yu, O.C. Palyha, K. Kulju McKee, S.D. Feighner, D%ririnathsinghji, R.G. Smith, L.H.T. Van der Ploeg, A:D. Howard. Brain Res., In press (1997 . S. L. Dickson, 0 Doutrelant-Viltart, R.E.J. Dyball and G. Leng. J. ndocrinol, 323-
a
b
331 1997).
S.L. ickson, S.M. Luckman, Endocrinol., l38,771, (1997). For a comprehensive review on the clinical evaluation of GHRPs see:Z. Laron, Drugs,
595, (1995).
x,
57.
V. Popovic.; S. Damjanovic; D. Micic; M. Djurovic; M. Doknic; C. Doeguiz; Casanueva, J. Endocrinol., P96 (Abstract), (1995). I. M. Chapman, M. A. Bach, E. Van Cauter, M. Farmer, D. Krupa, A. M. Ta lor, L. M. Schilling, K. Y. Cole, E. H. Skiles, S. S. Peuoli, M. L. Hartman, J. D. Veldxuis, G. J. Gormley, M. 0. Thomer, J. Clin. Endocrinol. Metab., 4249, (1996). 2. Laron, J. Frenkel, R. Deghenghi, S. Anin, B. Klinger, A. Silbergeld, Clinical 631, (1995). Endocrinology, D. R. Clemmons, L. J. Plunkett, W. M. Polvino, Endo. and Metab., 4(Supplement A), 35 (Abstract), (1997). J. Svensson, L. Lonn, J. Jansson, [ Abstract] Endo. and Metab., 4 (Supplement A), 35,
58.
~.g~7kletcher, G. B. Thomas, J. 0. Willoughby, I. J. Clarke, Neuroendocrinol., 6Q, 76,
53. 54. 55.
56
u,
a
(1994).