Through the rapid acceleration of our understanding of the underlying genetic and molecular underpinnings of malignancy, in the past 5 years there has been an explosion in the development and approval of highly effective targeted therapies and immunotherapies in oncology, several with contemporaneous approvals of companion diagnostics. In 2014, of the 41 new molecular entities approved by the US Food and Drug Administration (FDA) Center for Drug Evaluation and Research, 9 were for oncologic indications, and 5 of these were designated as breakthrough therapies.1 In addition, there are now 22 in vitro diagnostics approved by the FDA Center for Diagnostic and Radiologic Health as companion diagnostics for various targeted therapies in oncology.2