Practical issues and observations on the use of foreign clinical data in drug development.

The International Conference on Harmonization (ICH) has recently developed the ICH guidelines, which are the common guidelines for regulatory requirements in the ICH regions, i.e., European Union, Japan, and the United States of America. The guidelines have been successively implemented in the ICH regions, and the people involved in drug evaluation in the pharmaceutical industry, such as statisticians and pharmaceutical scientists, have referred to the guidelines during their daily work. Probably one of the most influential ICH guidelines on the drug development process in the ICH regions, especially in Japan, is the ICH-E5 guideline, which is encouraging the pharmaceutical industry to use the mountain of foreign clinical data for the registration of a new drug. In this article, we review the issues concerning the ICH-E5 guideline discussed so far, and discuss some practical issues in applying the guideline, especially the design of the study conducted in a new region. This is called a "bridging study." In addition, we introduce some statistical approaches for evaluating the acceptability of foreign clinical data.