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Activity Number: 456 - Design and Analysis of Cancer Immunotherapy Trials with Complex Survival Patterns
Type: Topic Contributed
Date/Time: Wednesday, July 31, 2019 : 8:30 AM to 10:20 AM
Sponsor: Biopharmaceutical Section
Abstract #304269
Title: Robust Group Sequential Designs for Immunotherapy Trials
Author(s): Pranab Ghosh* and Cyrus Mehta
Companies: Cytel Inc. and Cytel
Keywords: immuno-oncology; Group Sequential; Harrington-Fleming; Survival; Late separation

Immunotherapy trials with time to event endpoints are characterized by late separation of the survival curves. In this setting the logrank test loses power because the hazard ratio under the alternative hypothesis is not constant over time. A robust alternative approach is to construct the test statistic as the maximum of three Harrington-Fleming statistics with weights representing early separation, no separation and late separation, respectively. Since survival is expected to be prolonged by the newer immunotherapy compounds a group sequential design with possible early stopping would reduce the expected study duration. We will present the statistical methodology for this approach and will examine its robustness to misspecification of the time of separation of the survival curves through systematic modelling of the delayed onset.

Authors who are presenting talks have a * after their name.

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