Structure-Activity Relationship Studies of Trisubstituted Isoxazoles as Selective Allosteric Ligands for the Retinoic-Acid-Receptor-Related Orphan Receptor gamma t.
Meijer, F.A., Saris, A.O.W.M., Doveston, R.G., Oerlemans, G.J.M., de Vries, R.M.J.M., Somsen, B.A., Unger, A., Klebl, B., Ottmann, C., Cossar, P.J., Brunsveld, L.(2021) J Med Chem 64: 9238-9258
- PubMed: 34008974 
- DOI: https://doi.org/10.1021/acs.jmedchem.1c00475
- Primary Citation of Related Structures:  
7NEC, 7NP5, 7NP6, 7NPC - PubMed Abstract: 
The inhibition of the nuclear receptor retinoic-acid-receptor-related orphan receptor γt (RORγt) is a promising strategy in the treatment of autoimmune diseases. RORγt features an allosteric binding site within its ligand-binding domain that provides an opportunity to overcome drawbacks associated with orthosteric modulators. Recently, trisubstituted isoxazoles were identified as a novel class of allosteric RORγt inverse agonists. This chemotype offers new opportunities for optimization into selective and efficacious allosteric drug-like molecules. Here, we explore the structure-activity relationship profile of the isoxazole series utilizing a combination of structure-based design, X-ray crystallography, and biochemical assays. The initial lead isoxazole ( FM26 ) was optimized, resulting in compounds with a ∼10-fold increase in potency (low nM), significant cellular activity, promising pharmacokinetic properties, and a good selectivity profile over the peroxisome-proliferated-activated receptor γ and the farnesoid X receptor. We envisage that this work will serve as a platform for the accelerated development of isoxazoles and other novel chemotypes for the effective allosteric targeting of RORγt.
Organizational Affiliation: 
Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Technische Universiteit Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.