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Activity Number: 515
Type: Contributed
Date/Time: Wednesday, August 1, 2012 : 10:30 AM to 12:20 PM
Sponsor: Biopharmaceutical Section
Abstract - #304846
Title: Confidence Interval Estimation of the Response Rate in a Two-Stage Gehan Design
Author(s): Xiaoling Wu*+
Companies: Celgene Corporation
Address: 110 Allen Road, Basking Ridge, NJ, 07920, United States
Keywords: Two Stage ; truncated binomial ; confidence interval ; Oncology ; Response
Abstract:

Gehan's two stage design is commonly used when the response rate of the new agent under investigation is expected to be low, for instance no more than 20%. Such design rejects an ineffective treatment early when no success is observed among the first few patients. If at least one success is observed, the trial proceeds to the second stage. The exact or approximate lower and upper bounds of the associated response rate will therefore need adjustment. Since the number of response observed in the first stage follows a truncated binomial distribution. This work will apply methods developed by Atkinson and Brown (1985) and Tsai, Chi and Chen (2008), to construct confidence interval of response rate for Gehan's two stage design. These algorithms have been applied to Simon and Fleming's two-stage designs but not Gehan's approach. Interval estimation under various scenarios of a fictitious oncology phase 2 trial of Gehan design will be presented. My work will also search a threshold for the sample sizes of the second stage, above which the response rate's interval will be estimated with adequate precision. This threshold may result in more efficient two stage design than Genhan's.


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