The goal of drug development is to expeditiously bring safe, effective medications to the patients who need them most. In parallel with the traditional phases of drug testing (1, 2, and 3), drug manufacturers must choose the patient populations and the indications for which drugs will first be studied. Historically, novel agents ordinarily have been introduced in patients with advanced disease states. If these trials were positive, approval was sought, whereas subsequent studies defined the role of the drug in less severe or earlier forms of the disease, in important subgroups, and even as chemoprevention. Recent trials in cardiovascular and cancer medicine, however, have challenged this approach; many novel drugs now seek to establish safety and efficacy in early disease settings.