Optimization of the Potency and Pharmacokinetic Properties of a Macrocyclic Ghrelin Receptor Agonist (Part I): Development of Ulimorelin (TZP-101) from Hit to Clinic
作者:Hamid R. Hoveyda、Eric Marsault、René Gagnon、Axel P. Mathieu、Martin Vézina、Annick Landry、Zhigang Wang、Kamel Benakli、Sylvie Beaubien、Carl Saint-Louis、Martin Brassard、Jean-François Pinault、Luc Ouellet、Shridhar Bhat、Mahesh Ramaseshan、Xiaowen Peng、Laurence Foucher、Sophie Beauchemin、Patrick Bhérer、Daniel F. Veber、Mark L. Peterson、Graeme L. Fraser
DOI:10.1021/jm2007062
日期:2011.12.22
High-throughput screening of Tranzyme Pharma's proprietary macrocycle library using the aequorin Ca2+-bioluminescence assay against the human ghrelin receptor (GRLN) led to the discovery of novel ago fists against this G-protein coupled receptor. Early hits such as 1 (K-i = 86 nM, EC50 = 134 nM) though potent in vitro displayed poor pharmacokinetic properties that required optimization. While such macrocycles are not fully rule-of-five compliant, principally due to their molecular weight and clogP, optimization of their pharmacokinetic properties proved feasible largely through conformational rigidification. Extensive SAR led to the identification of 2 (K-i = 16 nM, EC50 = 29 nM), also known as ulimorelin or TZP-101, which has progressed to phase III human clinical trials for the treatment of postoperative ileus. X-ray structure and detailed NMR studies indicated a rigid peptidomimetic portion in 2 that is best defined as a nonideal type-I' beta-turn. Compound 2 is 24% orally bioavailable in both rats and monkeys. Despite its potency, in vitro and in gastric emptying studies, 2 did not induce growth hormone (GH) release in rats, thus demarcating the GH versus GI pharmacology of GRLN.