Phenylquinoxalinone CFTR activator as potential prosecretory therapy for constipation

• Published in: Translational research : the journal of laboratory and clinical medicine 2017-04, Vol.182, p.14-26.e4
• Main Authors: Cil, Onur, Phuan, Puay-Wah, Son, Jung-Ho, Zhu, Jie S., Ku, Colton K., Tabib, Niloufar Akhavan, Teuthorn, Andrew P., Ferrera, Loretta, Zachos, Nicholas C., Lin, Ruxian, Galietta, Luis J.V., Donowitz, Mark, Kurth, Mark J., Verkman, Alan S.
• Format: Article
• Language: English
• Subjects: Acute Disease; Animals; Body Fluids - drug effects; Body Fluids - metabolism; Cell Line; Chronic Disease; Constipation - drug therapy; Constipation - genetics; Constipation - pathology; Cystic Fibrosis Transmembrane Conductance Regulator - metabolism; Disease Models, Animal; Duodenum - drug effects; Duodenum - metabolism; Female; Gastric Acid - metabolism; Humans; Jejunum - drug effects; Jejunum - metabolism; Lubiprostone - pharmacology; Mice; Microsomes, Liver - drug effects; Microsomes, Liver - metabolism; Patch-Clamp Techniques; Peptides - pharmacology; Quinoxalines - chemical synthesis; Quinoxalines - chemistry; Quinoxalines - pharmacology; Quinoxalines - therapeutic use; Rats; Scopolamine - pharmacology; Structure-Activity Relationship
• ISSN: 1931-5244; 1878-1810
• DOI: 10.1016/j.trsl.2016.10.003

Constipation is a common condition for which current treatments can have limited efficacy. By high-throughput screening, we recently identified a phenylquinoxalinone activator of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel that stimulated intestinal fluid secretion and normalized stool output in a mouse model of opioid-induced constipation. Here, we report phenylquinoxalinone structure-activity analysis, mechanism of action, animal efficacy data in acute and chronic models of constipation, and functional data in ex vivo primary cultured human enterocytes. Structure-activity analysis was done on 175 phenylquinoxalinone analogs, including 15 synthesized compounds. The most potent compound, CFTRact-J027, activated CFTR with EC50 ∼ 200 nM, with patch-clamp analysis showing a linear CFTR current-voltage relationship with direct CFTR activation. CFTRact-J027 corrected reduced stool output and hydration in a mouse model of acute constipation produced by scopolamine and in a chronically constipated mouse strain (C3H/HeJ). Direct comparison with the approved prosecretory drugs lubiprostone and linaclotide showed substantially greater intestinal fluid secretion with CFTRact-J027, as well as greater efficacy in a constipation model. As evidence to support efficacy in human constipation, CFTRact-J027 increased transepithelial fluid transport in enteroids generated from normal human small intestine. Also, CFTRact-J027 was rapidly metabolized in vitro in human hepatic microsomes, suggesting minimal systemic exposure upon oral administration. These data establish structure-activity and mechanistic data for phenylquinoxalinone CFTR activators, and support their potential efficacy in human constipation.