Borrowing Information of a Surrogate Endpoint for Planning a Phase III Study

• Activity Number: 100 - Cross Trial Borrowing in Drug Development: The Promising Potentials
• Type: Topic Contributed
• Date/Time: Monday, August 8, 2022 : 8:30 AM to 10:20 AM
• Sponsor: Biopharmaceutical Section
• Author(s): Hui Quan* and Zhixing Xu and Gautier Paux and Meehyung Cho and Xun Chen
• Companies: Sanofi and Sanofi and Sanofi and Sanofi and Sanofi
• Keywords: Bivariate Bayesian analysis; posterior distribution; dynamic data borrowing; power prior; probability of success

Abstract

To design a phase III study with a final endpoint and calculate the required sample size for the desired probability of success, we need a good estimate of the treatment effect on the endpoint. It is prudent to fully utilize all available information including the historical and phase II information of the treatment as well as external data of the other treatments. It is not uncommon that a phase II study may use an intermediate biomarker as the primary endpoint and has no or limited data for the final endpoint. On the other hand, external information from the other studies for the other treatments on the biomarker and final endpoints may be available to establish a relationship between the treatment effects on the two endpoints. Through this relationship, making full use of the biomarker information may enhance the estimate of the treatment effect on the final endpoint. In this research, we propose a bivariate Bayesian analysis approach to comprehensively deal with the problem. A dynamic borrowing approach is considered to regulate the amount of historical data and biomarker information borrowing based on the level of consistency. A much simpler frequentist method is also discussed. Simulations are conducted to compare the performances of different approaches. An example is used to illustrate the applications of the methods.