A regulatory view of adaptive trial design.

Developing a new medicine is an expensive and time-consuming process. Researchers are interested in applying better designs to expedite the approval of potential medicinal products. Adaptive designs, which allow for some types of prospectively planned mid-study change, can improve the efficiency of a trial and maximize the chance of success. Possible design adaptations of clinical trials include sample size re-estimation, change in primary endpoint, interim dropping of treatment arms, change in statistical hypothesis, and change in the primary analysis. In this article, the regulatory considerations of the methodological issues with respect to adaptive design are discussed. Several examples of design adaptation that the Center for Drug Evaluation has encountered during the past 3 years are presented.