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Rare Cancer Trial Design — SCE Medical Oncology MCQ

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HardClinical Trials & StatisticsRare Cancer Trial DesignSCE Medical Oncology

A Simon two-stage, single-arm phase II study of a targeted agent in a molecularly defined rare sarcoma plans 12 patients in stage 1 and expansion to 35 only if at least two responses occur. No responses are observed in the first 12 evaluable patients. What is the correct action?

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Correct answer: C — Stop for futility as prespecified; continuing to 35 would defeat the design’s type-I and type-II error control

Explanation lettering: B = shown as A · A = shown as B · E = shown as C · C = shown as D · D = shown as E

E is correct. A Simon two-stage design limits exposure to an inactive agent while preserving prespecified operating characteristics. Failure to reach the stage-1 response boundary means the trial stops for futility. Continuing anyway or switching endpoint after seeing the data invalidates the planned false-positive and false-negative control. Zero responses do not justify phase III expansion. A single-arm design may be defensible in an ultra-rare, molecularly homogeneous setting with a robust historical response benchmark, but the benchmark, endpoint and stopping rules must be justified before recruitment.

Reference: NCI phase II oncology trial-design consensus: https://pmc.ncbi.nlm.nih.gov/articles/PMC2840069/