Bromodomain and exoterminal motif (BET) inhibitors are a class of small-molecule drugs that reversibly bind to the bromodomain and exoterminal motif BET proteins BRD2, BRD3, BRD4, and the bromodomains of BRDT. These BET inhibitors are drugs that prevent protein-protein interactions between BET proteins and acetylated histones and transcription factors. Deregulated bromodomains of BET proteins are frequently found in cancer and display aberrant chromatin remodeling and gene expression.