The nuclear hormone receptor retinoic acid receptor-related orphan C2 (RORC2, also known as RORγt) is a promising target for the treatment of autoimmune diseases. A small molecule, inverse agonist of the receptor is anticipated to reduce production of IL-17, a key proinflammatory cytokine. Through a high-throughput screening approach, we identified a molecule displaying promising binding affinity for RORC2, inhibition of IL-17 production in Th17 cells, and selectivity against the related RORA and RORB receptor isoforms. Lead optimization to improve the potency and metabolic stability of this hit focused on two key design strategies, namely, iterative optimization driven by increasing lipophilic efficiency and structure-guided conformational restriction to achieve optimal ground state energetics and maximize receptor residence time. This approach successfully identified 3-cyano-N-(3-(1-isobutyrylpiperidin-4-yl)-1-methyl-4-(trifluoromethyl)-1H-pyrrolo[2,3-b]pyridin-5-yl)benzamide as a potent and selective RORC2 inverse agonist, demonstrating good metabolic stability, oral bioavailability, and the ability to reduce IL-17 levels and skin inflammation in a preclinical in vivo animal model upon oral administration.

Background: Cholangiocarcinoma cells over-express oestrogen receptor-beta, which displays anti-proliferative and pro-apoptotic effects.Aim: To evaluate the effects of a newly developed and highly selective oestrogen receptor-beta agonist (KB9520) on experimental intrahepatic cholangiocarcinoma.Methods: In vitro, the effects of KB9520 on apoptosis and proliferation of HuH-28 cells, HuH-28 cells with selective oestrogen receptor-beta silencing (by small interfering RNA), HepG2 cells (oestrogen receptor-alpha and oestrogen receptor-beta negative) and HepER3 cells (HepG2 cells transformed to stably express oestrogen receptor-alpha) were evaluated. In vivo, the effects of KB9520 on experimental intrahepatic cholangiocarcinoma, induced by thioacetamide administration were tested.Results: In vitro, KB9520 induced apoptosis and inhibited proliferation of HuH-28 cells. KB9520 effects were absent in cells lacking oestrogen receptor-alpha and beta (HepG2) and in cells expressing only oestrogen receptor-alpha (HepER3); its pro-apoptotic effect was impaired in cells where oestrogen receptor-beta expression was decreased by specific small interfering RNA. In vivo, KB9520 inhibited experimental intrahepatic cholangiocarcinoma development in thioacetamide-treated rats and promoted tumour regression in rats where tumour was already established. In treated animals, tumour areas showed reduced proliferation but increased apoptosis.Conclusions: KB9520 induced apoptosis in cholangiocarcinoma by selectively acting on oestrogen receptor-beta, suggesting that oestrogen receptor-beta selective agonists may be a novel and effective therapeutic option for the medical treatment of intrahepatic cholangiocarcinoma. (C) 2011 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.