title: Evaluation of a stable gonadotropin-releasing hormone analog in mice for the treatment of endocrine disorders and prostate cancer.
abstract: Gonadotropin-releasing hormone (GnRH) receptor agonists have wide clinical applications including the treatment of prostate cancer and endocrine disorders. However, such agonists are characterized by poor pharmacokinetic properties, often requiring repeated administration or special formulations. Therefore, the development of novel peptide analogs with enhanced in vivo stability could potentially provide therapeutic alternatives. The pharmacological evaluation of a bioactive peptide [Des-Gly¹⁰,Tyr⁵(OMe),D-Leu⁶,Aze-NHEt⁹]GnRH, analog 1, is presented herein and compared with leuprolide. Peptide stability was evaluated using mouse kidney membrane preparations, followed by a liquid chromatography-tandem mass spectrometry-based approach that afforded identification and quantification of its major metabolites. The analog was significantly more stable in vitro in comparison with leuprolide. In vitro and in vivo stability results correlated well, encouraging us to develop a clinically relevant pharmacokinetic mouse model, which facilitated efficacy measurements using testosterone as a biomarker. Analog 1, an agonist of the GnRH receptor with a binding affinity in the nanomolar range, caused testosterone release in mice that was acutely dose-dependent, an effect blocked by the GnRH receptor antagonist cetrorelix. Repeated dosing studies in mice demonstrated that analog 1 was well tolerated and had potency similar to that of leuprolide, based on plasma and testis testosterone reduction and histopathological findings. Analog 1 also shared with leuprolide similar significant antiproliferative activity on androgen-dependent prostate cancer (LNCaP) cells. On the basis of pharmacokinetic advantages, we expect that analog 1 or analogs based on this new design will be therapeutically advantageous for the treatment of cancer and endocrine disorders.
authors.affiliation: Division of Pharmacology-Pharmacotechnology, Biomedical Research Foundation, Academy of Athens, Athens, Greece. ctamvakop@bioacademy.gr
authors.forename: Theodora
authors.initials: T
authors.lastname: Katsila
authors.forename: Evangelos
authors.initials: E
authors.lastname: Balafas
authors.forename: George
authors.initials: G
authors.lastname: Liapakis
authors.forename: Patrizia
authors.initials: P
authors.lastname: Limonta
authors.forename: Marina
authors.initials: M
authors.lastname: Montagnani Marelli
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Gkountelias
authors.forename: Theodore
authors.initials: T
authors.lastname: Tselios
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Kostomitsopoulos
authors.forename: John
authors.initials: J
authors.lastname: Matsoukas
authors.forename: Constantin
authors.initials: C
authors.lastname: Tamvakopoulos
mesh_terms: D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000737:chemistry / Q000378:metabolism / Q000627:therapeutic use; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004700:Endocrine System Diseases / Q000188:drug therapy* / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000378:metabolism / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D011966:Receptors, LHRH / Q000378:metabolism; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone