Abstract
The International Conference on Harmonisation E5 document entitled “Ethnic Factors in the Acceptability of Foreign Clinical Data” has been implemented in several countries. Although E5 has been considered feasible in assessing the acceptability of foreign clinical data, there have been some lingering challenges since its implementation. This article raises some issues regarding using E5 to predict whether a drug is likely to possess different efficacy and safety profiles in the new region, for example, whether ethnicity is an appropriate variable to define the various drug responses among individuals, whether there should be a hierarchical relationship between the assessment of pharmacokinetic/pharmacodynamic properties and the assessment of clinical properties, and whether E5 is suitable to deal with the ethnic-based differences in drug safety. Measures to improve the scientific merit of this assessment are suggested.