The increasing number of negative trials in cancer treatment has prompted a systematic re-evaluation of target-based drugs. It is our impression that the sensitivity of current clinical trial methodology is inadequate to demonstrate the effectiveness of target-based drugs, in terms of tumor shrinkage, delay in progression, or improved survival. Enrichment of sensitive populations, based on the data from translational studies, is essential for a better understanding of the role of novel therapies in cancer. Translational and clinical studies are key to the identification and maximization of benefit of target-based therapy