Advances in genomic medicine and molecular biology have led to the development of early phase studies testing biologically rational therapies targeting aberrantly activated cellular pathways. Because many of these drugs have a wider therapeutic index than standard chemotherapeutic agents, these treatments may be more effective and less toxic than current strategies. However, to effectively integrate these targeted strategies, robust predictive biomarkers must be developed that will identify patients who will benefit from these approaches and rapidly match treatments to patients at diagnosis.