Failures of Phase III programs after successful Phase II programs is probably the worst outcome of a clinical development program, as it failed in the most costly way. Nevertheless, these failures occur not infrequently. In psychiatry, highly publicized Phase II success stories ended in discontinuations of development programs, such as the NK1-antagonist program in depression several years ago. More recently, other examples have emerged. Some skip the Phase II process altogether with designs, which are supposed to provide “pivotal” data for regulatory purposes in large Phase III-like studies, which are just labeled as Phase II. These failures do not come out of the blue. Sometimes it is important to go back to basics and consider the purpose of Phase II trials.
What is the purpose of a Phase II trial?
The purpose of Phase II trials, besides gaining insights into the safety of a compound, is broadly exploratory, i.e. to generate data, which help with the design of the pivotal Phase III program. In a therapeutic area, a reasonably performed Phase II study can provide insights into clinical and biological patient characteristics, which match the properties of the drug under study. With an increased interest in personalized medicine, these boundaries between patient populations have to be understood in order to be successful. This approach is in direct contradiction to the urge to generate a “pivotal” Phase II outcome. Continue reading