Discuss the type of "confirmatory evidence" that can support regulatory approval with a single adequate and well-controlled trial. Focus will be on developments since the 1998 FDA clinical “effectiveness” guidance, including the proposed revisions to the guidance. Emphasis will be on clinical pharmacology data as confirmatory evidence. Participants will have the opportunity to hear from experts and offer comments/suggestions during the panel discussion. The symposium should be of great interest to many stakeholders because the revised guidance is expected to have a broad impact on drug development and regulation.