The Fits and Starts of Targeted Cancer Drug Development

Despite the success of Gleevec, developing drugs that inhibit complex signaling pathways, while simultaneously trying to understand the biology around a drug's target, remains a challenge. Without biomarkers to help establish dosing and identify likely responding patients, clinical development of targeted cancer drugs will remain challenging. AstraZeneca's recent experience with Iressa bears this out. It's likely that single markers will not be sufficient to stratify patients by their tumor types; rather, patterns of gene and protein expression will be required. The technology to take these measurements is making its way from academia to industry, but the process is slow, and needs encouragement and better coordination between academia, regulators, and industry. Meanwhile, clinical trials themselves remain the best target validation tools. When all is said and done, efficacy is the best biomarker.