Discovery of Benzo[cd]indol-2(1H)-ones and Pyrrolo[4,3,2-de]quinolin-2(1H)-ones as Bromodomain and Extra-Terminal Domain (BET) Inhibitors with Selectivity for the First Bromodomain with Potential High Efficiency against Acute Gouty Arthritis.

The bromodomain and extra-terminal domain (BET) family of proteins are readers which specifically recognize histone-acetylated lysine residues. Each BET bromodomain protein contains two highly homologous domains: the first bromodomain (BD1) and the second bromodomain (BD2). Pan-BET bromodomain inhibition is a potential therapy for various cancers and immune-inflammatory diseases, but only few reported inhibitors show selectivity within the BET family. Herein, we identified a series of benzo[cd]indol-2(1H)-ones and pyrrolo[4,3,2-de]quinolin-2(1H)-ones with good selectivity for BET BD1. Through structure-based optimization, highly active and selective compounds are ultimately obtained. The representative compounds are the first reported inhibitors with selectivity more than 100-fold for BRD4(1) over BRD4(2). Among them, we further show that 68 (LT052) mediates BRD4/NF-κB/NLRP3 signaling inflammatory pathways with comparable protein expression and significantly improves symptoms of gout arthritis in a rat model. Therefore, selective pharmacological modulation of individual bromodomains could represent a strategy for the treatment of acute gouty arthritis.