BET inhibitors is a class of small molecule drugs that reversibly bind the bromodomains of Bromodomain and Extra-Terminal motif (BET) proteins BRD2, BRD3, BRD4, and BRDT. These BET inhibitors prevent protein-protein interaction between BET proteins and acetylated histones and transcription factors. Dysregulated bromodomains of BET proteins are frequently found in cancer showing aberrant chromatin remodeling and gene expression.