Bromodomain and extra-terminal (BET) proteins belong to a class of proteins collectively called epigenetic "readers". BET bromodomains have emerged as promising drug targets for treatment of cancers, inflammatory diseases, and other medical conditions. GlaxoSmithKline scientists have successfully optimized a class of benzodiazepines as inhibitors of BET bromodomains, without any prior knowledge of identified molecular targets. It thus is possible to hit a target without aiming at it. The optimized lead compound I-BET762 is currently being evaluated in a phase I clinical trial for treatment of human cancer.