Structure-Based and Property-Driven Optimization of N-Aryl Imidazoles toward Potent and Selective Oral RORγt Inhibitors

Retinoic acid receptor-related orphan receptor gamma-t (RORγt) is considered to be the master transcription factor for the development of Th17 cells that produce proinflammatory cytokines such as IL-17A. Overproportionate Th17 cell abundance is associated with the pathogenesis of many inflammatory conditions including psoriasis. In a high-throughput fluorescence resonance energy transfer (FRET) screen, we identified compound 1 as a hit with promising lipophilic efficiency (LipE). Using structure-based drug design based on a number of X-ray cocrystal structures, we morphed this hit class into potent imidazoles, exemplified by compound 3 . To improve the poor absorption, distribution, metabolism, and excretion (ADME) properties of neutral imidazoles, we extended our ligands with carboxylic acid substituents toward a polar, water-rich area of the protein. This highly lipophilicity-efficient modification ultimately led to the discovery of compound 14, a potent and selective inhibitor of RORγt with good ADME properties and excellent in vivo pharmacokinetics. This compound showed good efficacy in an in vivo delayed-type hypersensitivity pharmacology model in rats.