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Activity Number: 248 - Statistical Issues Specific the Therapeutic Areas- 2
Type: Contributed
Date/Time: Monday, July 30, 2018 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract #329783 Presentation
Title: Sample Size Determination Under Non-Proportional Hazards
Author(s): Zhaowei Hua* and Miao Yang and Saran Vardhanabhuti
Companies: Takeda Pharmaceuticals International Co. and Oregon State University and Takeda Pharmaceuticals
Keywords: non-proportional hazards; sample size; time-to-event endpoint; logrank test; cancer immunotherapy; power analysis

The proportional hazards assumption rarely holds in clinical trials of cancer immunotherapy. Specifically, delayed separation of the Kaplan-Meier survival curves and long-term survival have been observed. Routine practice in designing a randomized controlled two-arm clinical trial with a time-to-event endpoint assumes proportional hazards. If this assumption is violated, traditional methods could inaccurately estimate statistical power and study duration. This article addresses how to determine the sample size in the presence of nonproportional hazards (NPH) due to delayed separation, diminishing effects, etc. Simulations were performed to illustrate the relationship between power and the number of patients/events for different types of nonproportional hazards. Novel efficient algorithms are proposed to optimize the selection of a cost-effective sample size.

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

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