Two-stage design for phase II oncology trials with relaxed futility stopping.

Many oncology phase II trials are single arm studies designed to screen novel treatments based on efficacy outcome. Efficacy is often assessed as an ordinal variable based on a level of response of solid tumors with four categories: complete response, partial response, stable disease and progression. We describe a two-stage design for a single-arm phase II trial where the primary objective is to test the rate of tumor response defined as complete plus partial response, and the secondary objective is to estimate the rate of disease control defined as tumor response plus stable disease. Since the goal is to estimate the disease control rate, the trial is not stopped for futility after the first stage if the disease control rate is promising. The new design can be generated using easy-to-use software that is available at http://cancer.unc.edu/biostatistics/program/ivanova/.