Objective

The BET (bromodomain and extra-terminal) family of BRDs are well studied with the discovery of potent and highly specific inhibitor and implications in several therapeutic areas. We used BRD4(1) in a comparative study of three different fluorescent assay technologies in high throughput screening (HTS). A diverse 7,000 compound set was screened in Fluorescence Lifetime (FLT), Fluorescence Polarization (FP) and Homogeneous Time-Resolved Fluorescence (HTRF®) to look at primary hit rates, compound overlap and hit confirmation rates. In addition a well annotated set of compounds with undesirable mechanism of inhibition (uMOI) was screened against BRD4(1) to compare the ability to discriminate true hits from artifact compounds. Hit rate and confirmation rate varied between the assays. Both unique and overlapping compounds were identified with all technologies. Discrimination of true hits from frequent hitters (uMOI) was significantly improved with FLT compared to FP.