GnRH antagonists: a new generation of long acting analogues incorporating p-ureido-phenylalanines at positions 5 and 6

Article Article scientifique Article GnRH antagonists: a new generation of long acting analogues incorporating p-ureido-phenylalanines at positions 5 and 6 eng 2001 author Jiang G author Stalewski J author Galyean R author Dykert J author Schteingart C author Broqua Pierre 117612 author Aebi Alexandre 81887 author Aubert Michel 25310 author Semple G author Robson P author Akinsanya K author Haigh R author Riviere Philippe 519499 author Trojnar J author Junien JL author Rivier J E 453-467 10.1021/jm0003900 11462984 0022-2623 A series of antagonists of gonadotropin-releasing hormone (GnRH) of the general formula Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph/4Amf(P)-D4Aph/D4Amf(Q)-Leu-ILys-Pro-DAla-NH2 was synthesized, characterized, and screened for duration of inhibition of luteinizing hormone release in a castrated male rat assay. Selected analogues were tested in a reporter gene assay (IC50 and pA2) and an in vitro histamine release assay. P and Q contain urea/carbamoyl functionalities designed to increase potential intra- and intermolecular hydrogen bonding opportunities for structural stabilization and peptide/receptor interactions, respectively. These substitutions resulted in analogues with increased hydrophilicity and a lesser propensity to form gels in aqueous solution than azaline B [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Atz)-D4Aph(Atz)-Leu-ILys-Pro-DAla-NH2 with Atz = 3'-amino-1H-1',2',4'-triazol-5'-yl, 5], and in some cases they resulted in a significant increase in duration of action after subcutaneous (s.c.) administration. Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(L-hydroorotyl)-D4Aph(carbamoyl)-Leu-ILys-Pro-DAla-NH2 (acetate salt is FE200486) (31) and eight other congeners (20, 35, 37, 39, 41, 45-47) were identified that exhibited significantly longer duration of action than acyline [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Ac)-D4Aph(Ac)-Leu-ILys-Pro-DAla-NH2] (6) when administered subcutaneously in castrated male rats at a dose of 50 microg in 100 microL of phosphate buffer. No correlation was found between retention times on a C18 reverse phase column using a triethylammonium phosphate buffer at pH 7.0 (a measure of hydrophilicity) or affinity in an in vitro human GnRH report gene assay (pA2) and duration of action. FE200486 was selected for preclinical studies, and some of its properties were compared to those of other clinical candidates. In the intact rat, ganirelix, abarelix, azaline B, and FE200486 inhibited plasma testosterone for 1, 1, 14, and 57 days, respectively, at 2 mg/kg s.c. in 5% mannitol (injection volume = 20 microL). Based on the information that 31, 33, 35 and 37 were significantly shorter acting than acyline or azaline B after intravenous administration (100 microg/rat), we surmised that the very long duration of action of the related FE200486 (for example) was likely due to unique physicochemical properties such as solubility in aqueous milieu, comparatively low propensity to form gels, and ability to diffuse at high concentrations in a manner similar to that described for slow release formulations of peptides. Indeed, in rats injected s.c. with FE200486 (2 mg/kg), plasmatic concentrations of FE200486 remained above 5 ng/mL until day 41, and the time after which they dropped below 3 ng/mL and plasma LH levels started rising until full recovery was reached at day 84 with levels of FE200486 hovering around 1 ng/mL. Additionally, FE200486 was less potent at releasing histamine from isolated rat mast cells than any of the GnRH antagonists presently described in preclinical reports. Animals Cell Line Drug Evaluation, Preclinical Gels Genes, Reporter Gonadotropin-Releasing Hormone/antagonists & inhibitors Histamine Release/drug effects Humans Luteinizing Hormone/blood Male Mast Cells/metabolism Oligopeptides/chemical synthesis/chemistry/pharmacology Orchiectomy Phenylalanine/analogs & derivatives/chemical synthesis/chemistry/pharmacology Rats Rats, Sprague-Dawley Solubility Structure-Activity Relationship Testosterone/blood Urea/analogs & derivatives/chemical synthesis/chemistry/pharmacology Dewey 613 Dewey 618 58 Département de pédiatrie, gynécologie et obstétrique 223 64 Département de santé et médecine communautaires 22A false Journal of medicinal chemistry 44 3 178d2cac-78ec-41bd-9d90-8c636a64f9a4 Article (Published version) Restricted 453-467.pdf 158499 application/pdf restrictedAccess Faculté de médecine / Section de médecine clinique / Département de pédiatrie, gynécologie et obstétrique Faculté de médecine / Section de médecine clinique / Département de santé et médecine communautaires

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GnRH antagonists: a new generation of long acting analogues incorporating p-ureido-phenylalanines at positions 5 and 6	Journal of medicinal chemistry			2001	694	0

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Riviere, Philippe