Discovery of aryl-substituted indole and indoline derivatives as RORγt agonists

A series of aryl-substituted indole and indoline derivatives were discovered as novel RORγt agonists by a scaffold-based hybridization of the reported RORγt agonists 1 and 2. SAR studies on the core structures, the RHS hydrophilic side chains and the LHS hydrophobic aryl groups of a hybrid compound 3 led to the identification of potent RORγt agonists with improved drug-like properties. Compound 14 represented a high potency lead with an EC₅₀ of 20.8 ± 1.5 nM, the (S)-enantiomer (EC₅₀ = 16.1 ± 4.5 nM) of which was 17 times more potent than the (R) counterpart (EC₅₀ = 286 ± 30.4 nM) in RORγ dual FRET assay. The cell-based GAL4 reporter gene assay also suggested 14 as the most active compound which exhibited an EC₅₀ of 247 ± 33.1 nM and a maximum activation percentage of 133%. Moreover, 14 showed high metabolic stability (t_1/2 = 113 min) in mouse liver microsome and had improved aqueous solubility at pH 7.4 compared to the parent compounds. Furthermore, 14 was found to be orally bioavailable and demonstrated excellent in vivo pharmacokinetics in mice. Present studies indicate that 14 deserves further investigation in tumor animal models as a potential candidate of RORγt agonist for cancer immunotherapy.