Application of an adaptive design to a randomized phase II selection trial in gastric cancer: a report of the study design.

Randomized phase II selection trials seek to provide unbiased comparisons for the selection of the most promising treatment arm for evaluation in a future phase III trial. In this paper, we present an application of an adaptive design to a randomized phase II selection trial comparing three experimental treatments with a control arm in patients with advanced gastric cancer. The trial design continuously monitors multiple patient outcomes to protect future patients from treatments with unacceptably high toxicity and/or unacceptably low efficacy. We use a Bayesian approach to monitor the trial and carry out simulations to investigate operating characteristics of the trial design. The simulation study also evaluates the sensitivity of the design to the prior distribution by considering two alternative priors.