The Plan of Enrichment Designs for Dealing with High Placebo Response

• Activity Number: 234
• Type: Contributed
• Date/Time: Monday, August 4, 2014 : 2:00 PM to 3:50 PM
• Sponsor: Biopharmaceutical Section
• Author(s): Xiangmin Zhang*+ and Yeh-Fong Chen
• Companies: University of Iowa and FDA
• Keywords: Placebo Response ; Clinical Trials ; Enrichment Design ; Power ; Sample Size

Abstract

For dealing with high placebo response, especially in psychiatric clinical trials, different enrichment designs, such as the Sequential Parallel Design (SPD), Two-way Enriched Design (TED) and Sequential Enriched Design (SED) have been proposed and implemented recently. Nevertheless, depending on the historical trial information and the trial sponsors' resources, the detailed design elements need to be used for determining which design to adopt. To assist in making a right decision, we perform thorough evaluation for selecting those required design elements in terms of power optimization and sample size planning. Special cases, like the impact of power by assuming different treatment effects observed in different stages and different response rates to drug and placebo, are also considered.