This is the program for the 2010 Joint Statistical Meetings in Vancouver, British Columbia.

Abstract Details

Activity Number: 345
Type: Contributed
Date/Time: Tuesday, August 3, 2010 : 10:30 AM to 12:20 PM
Sponsor: Biopharmaceutical Section
Abstract - #307648
Title: Random Delayed Effects and the Power of the Unweighted Log-Rank Test in Survival Trials
Author(s): Jonathan Siegel*+
Companies: Bristol-Myers Squibb
Address: 5 Research Parkway, Wallingford, CT, 06492,
Keywords: Survival Analysis ; Non-Proportional Hazards ; Delayed Effect ; Random Delay ; Log-Rank Test

Clinical survival trials traditionally assume piece-wise constant hazards with fixed change points. Novel classes of immunotherapy cancer treatments have biological mechanisms of action suggesting a variable delayed effect. This paper focuses on the effects of random delay on the power of the unweighted log-rank test. It proposes a random time-to-repair approach, analogous to system-component failure bivariate interaction mixture models, in which drug effect delay is modeled as a Poisson signal whose onset reduces the hazard. The model is shown to be more powerful for finite observation periods than a two-compartment fixed delayed-effect model with the same true mean delay. The effects of random delay on power vis-a-vis constant hazards, fixed delay, and Weibull models are simulated. Problems of delayed effects in survival trial design and in regulatory use are discussed.

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