Are Phase 2 screening trials in oncology obsolete?

Phase 2 studies in Oncology are controversial because on the one hand they are substantially underpowered for making assessments of activity and on the other hand they are used as a screen to determine whether a Phase 3 trial is warranted. In this paper, we undertake a systematic assessment of the properties of a Phase 2 study in the context of a drug development program. We will show that, when considering only the efficiency of a clinical trials program, Phase 2 screening trials can substantially increase the efficiency with which drugs that provide clinical benefit are identified. However, if there are substantial costs in identifying drug candidates to test in clinical trials as there are today, then Phase 2 screening trials as a prelude to Phase 3 trials may reduce the efficiency of the drug development process as a whole. .