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Biostatistics

Biostatistics. Dr. Larry Rubinstein, National Cancer Institute. Phase 0 Trial Statistics for PD Assay. Endpoints are PD assay, baseline (ideally, just before Tx) vs. post-Tx, in tumor tissue and in blood

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Biostatistics

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  1. Biostatistics Dr. Larry Rubinstein, National Cancer Institute

  2. Phase 0 Trial Statistics for PD Assay • Endpoints are PD assay, baseline (ideally, just before Tx) vs. post-Tx, in tumor tissue and in blood • Baseline measures: 1 pre-treatment tumor biopsy measurement and at least 3 pre-treatment blood measurements (ideally, taken over the baseline to post-Tx time span) per patient • 1 post-Tx measurement used as primary endpoint for tumor and blood (at same time post-Tx) • Declare significant Tx-related change, for an individual patient, for observed 2-fold change combined with 90% statistical confidence of a true difference (10% false positive rate) • For blood this is 1.8 x intra-pt pre-Tx SD • For tumor tissue this is 1.8 x inter-pt pre-Tx SD

  3. Minimal Phase 0 Trial Design • Accrue 3 patients to each of the dose levels • For either endpoint, tumor or blood, significant Tx-related response for a dose is defined as significant change for at least 2 patients out of the 3 • For a dose, if there is 80% likelihood of observing change at the patient level, there is 90% power to detect significant response for the dose level • There is an overall 6% false positive rate, for both endpoints combined, for a dose level with no biologic effect (because of the 10% false positive observed change at the patient level)

  4. Enhanced Phase 0 Trial Design • There may be a need to detect a lower rate of response per dose level—use a 2-stage design • Accrue 3-5 patients per dose level, allowing for the expansion of a cohort to 5 patients if the results are not definitive for the initial 3 • Declare significant change, for an individual patient, for an observed 2-fold change combined with 95% statistical confidence of a true difference • For tumor tissue this is 2.3 x inter-patient pre-Tx SD • For blood this is 2.3 x intra-pt pre-Tx SD

  5. Enhanced Phase 0 Trial Design Details • Accrue 3 patients to each dose level • If a significant change is observed for exactly 1 patient, for either endpoint, expand the dose to 5 patients • For either endpoint, significant Tx-related response for a dose, for cohort size 3 or 5, is defined as significant change for at least 2 pts • For a dose, if there is 60% likelihood of observing change at the patient level, there is 89% power to detect significant response for the dose level • There is an overall 4% false-positive rate, for both endpoints combined, for a dose level with no biologic effect (because of the 5% false- positive observed change at the patient level)

  6. The Next Speaker is:Dr. Holly Taylor

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