01166nas a2200205   4500000000100000008004100001260001500042653002000057653002200077653002500099653002500124653002900149100002300178245006600201856007200267300001200339490000600351520058900357022001400946       2019                            d  c2019-06-0110aadaptive design10abiomarker studies10afalse discovery rate10amultiplicity problem10aphase II clinical trials1 aGail A. Van Norman00aPhase II Trials in Drug Development and Adaptive Trial Design  uhttps://www.sciencedirect.com/science/article/pii/S2452302X19300658  a428-4370 v43 aPhase II clinical studies represent a critical point in determining drug costs, and phase II is a poor predictor of drug success: >30% of drugs entering phase II studies fail to progress, and >58% of drugs go on to fail in phase III. Adaptive clinical trial design has been proposed as a way to reduce the costs of phase II testing by providing earlier determination of futility and prediction of phase III success, reducing overall phase II and III trial sizes, and shortening overall drug development time. This review examines issues in phase II testing and adaptive trial design.  a2452-302X