Comment: Group Sequential Designs with Response-Adaptive Randomisation

Group sequential Phase III trial designs enable early stopping for positive or negative study outcomes. Response-adaptive randomisation can be included in such designs with the sampling ratio in each group of subjects determined by the current treatment effect estimate. We demonstrate the potential of adaptive randomisation to reduce the number of patients receiving the inferior treatment, even when there is a delay in observing each patient's response. We also observe that using a fixed but unequal sampling ratio may offer a simpler way to achieve the same objectives.