Reducing the average number of patients needed in a phase II trial through novel design

Abstract Phase II represents a very important part of the drug development process. It is important that genuinely effective treatments have a high chance of succeeding whilst treatments that will fail at phase III are screened out. Because of the high number of treatments available for testing and limited resources and patients available, it is increasingly of interest to apply novel designs to improve the efficiency of phase II trials. This paper shall argue that phase II presents the most promising area for applying novel designs and will review some recent developments in three classes of novel design: group-sequential designs, multi-arm designs, and enrichment designs. All three types of design considerably improve the efficiency of phase II trials on average and also ensure that patients are more likely to be treated with the best available treatment for them. Although the designs have drawbacks, the considerable advantages mean that these designs will become increasingly important in phase II.