A consistency approach to evaluation of bridging studies and multi-regional trials.

Recently, global drug developments have attracted much attention from sponsors as well as regulatory authorities. The ICH E5 guideline defines a bridging study as a supplementary study conducted in the new region to provide pharmacodynamic or clinical data on efficacy, safety, dosage, and dose regimen to allow extrapolation of the foreign clinical data to the population of the new region. On the other hand, a multi-regional trial may incorporate subjects from many regions around the world under the same protocol so that after showing the overall efficacy of a drug in all global regions, we can simultaneously evaluate the possibility of applying the overall trial results to each region and consequently support drug registration in each region. In this paper, we develop a consistency approach for assessment of similarity between a bridging study conducted in a new region and studies conducted in the original region. A statistical criterion is also established to assess the consistency between the region of interest and overall results in a multi-regional trial. The method for sample size determination for the bridging study is also proposed. Numerical examples illustrate applications of the proposed approaches in different scenarios.