Weighted evidence approach of bridging study

Area of Science:

• Pharmacometrics
• Clinical Trial Design
• Regulatory Science

Background:

• The International Council for Harmonisation (ICH) E5 Guidance provides a framework for evaluating ethnic factors in medicine efficacy and using bridging studies to extrapolate foreign clinical data.
• Conventional noninferiority criteria for bridging studies are often impractical, particularly in specifying the required treatment effect in a new region.

Purpose of the Study:

• To propose a novel statistical approach for evaluating the overall treatment effect by combining data from original and bridging clinical trials.
• To develop a method that addresses the challenges of prespecifying weights in Bayesian approaches for bridging studies.
• To establish criteria for regional drug approval based on the strength of evidence from bridging studies.

Main Methods:

• A Bayesian approach is extended to combine weighted treatment effects from original and bridging regions.
• The maximum allowable weight for the bridging region estimate is determined as a measure of the treatment effect's strength.
• Sample size requirements are derived, and simulations are conducted to evaluate Type I error rates and statistical power.

Main Results:

• The proposed method allows for the evaluation of regional approval by comparing estimated weights against predefined limits or through benefit-risk assessments.
• Simulation results demonstrate the performance of the proposed methods in terms of Type I error and power.
• The study provides a practical example illustrating the application of the developed procedures.

Conclusions:

• The presented approach offers a flexible and statistically sound method for assessing medicine efficacy in new regions using bridging studies.
• This framework can facilitate the registration of medicines by providing a more robust evaluation of treatment effects, considering regional data.
• The methodology aids in determining the strength of evidence required from bridging studies for regional regulatory approval.