Dynamic development paths for expanding a proof-of-concept study to explore dose range

In Phase II clinical development of a new drug, the two most important deliverables are proof of concept (PoC) and dose ranging. Traditionally, a PoC study is designed as the first Phase II clinical trial. In this PoC, there are two treatment groups-a high dose of the study medication, against the placebo control. After the concept is proven, the next Phase II study is a dose-ranging design with many test doses. This paper proposes a two-stage design with the first stage attempting to generate an early signal of efficacy. If successful, the second stage will adopt a "Go Fast" plan to expand the current study and add lower study doses of the test drug to explore the efficacy dose range. Otherwise, a "Go Slow" strategy is triggered, and the study will stop at a reduced sample size with high dose and placebo only.