Single-arm Phase II cancer survival trial designs.

The current practice for designing single-arm Phase II trials with time-to-event endpoints is limited to using either a maximum likelihood estimate test under the exponential model or a naive approach based on dichotomizing the event time at a landmark time point. A trial designed under the exponential model may not be reliable, and the naive approach is inefficient. The modified one-sample log-rank test statistic proposed in this article fills the void. In general, the proposed test can be used to design single-arm Phase II survival trials under any parametric survival distribution. Simulation results showed that it preserves type I error well and provides adequate power for Phase II cancer trial designs with time-to-event endpoints.