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Unformatted text preview: Phase II Clinical Trials: Design and Analysis Considerations Recall that the primary goal of a Phase II trial is usually to determine whether the inter- vention is promising enough to warrant a large-scale, expensive, randomized comparative study. By promising we mean that the intervention must have efficacy that is promising and toxicity that is low. We often look at pharmacokinetics and molecular markers as well. Sometimes if we dont have funding right away for molecular markers, we save tissue samples for future analysis. Phase II study designs The design reflects the primary scientific question: does this treatment have a strong enough efficacy to do a large-scale study with it? We are looking for potential big winners at this stage, not just very slight improvements. So we generally dont do a randomized comparison. Most Phase II studies use historical data for comparison. Some studies compare several possible regimens to decide which is best (e.g. PHII 70). Some studies randomize to a comparison group with standard treatment, like a small- scale Phase III study. The AIDS world calls these Phase 2.5 studies. RTOG 0246 is an example of a fairly straightforward Phase II trial. The treatment com- bination is complex, but there is only one regimen to be studied. Primary outcome: one-year overall survival rate. Other outcomes: major toxicities (Grade 4), proportion eligible for surgical salvage resection. They propose a sample size of 42. This allows for a 10% attrition to give the desired sample size for analysis of 38. How did they get this? Historical comparison: 60% survival at one year. What would be promising: 77.5% survival (a 50% reduction in the hazard). Desired Type I error: 0.05....
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This note was uploaded on 12/30/2010 for the course BST 252 taught by Professor Tsodikov during the Winter '06 term at UC Davis.
- Winter '06