How Foreign Clinical Data Package can be Utilized to get a Speedy Approval of the New Drug—The Bridging Study Strategy—

Abstract

In a broad sense, ethnic factors represent the fundamental problems in the acceptability of foreign clinical data. The mainstays of the harmonized final document about ethnic factors in the acceptability of foreign clinical data include a complete clinical data package and a bridging study (for efficacy and/or for safety). A clinical data package that meets all of the regional regulatory requirements is defined as a complete clinical data package for submission and potential approval, irrespective of its geographic origin. The accept-ability of the foreign clinical data component of the complete data package depends upon whether it can be extrapolated to the population of the new region. Ethnic differences can be classified into intrinsic and extrinsic factors. In many cases extrinsic factors, such as medical practice and custom, might more influence the availability of foreign clinical data than intrinsic factors. To overcome the difficulties inherent in ethnic differences, the bridging study concept was created. A bridging study is defined as a study performed in the new region to provide pharmacodynamic or clinical data on efficacy, safety, dosage and dose regimen that will allow an extrapolation of the foreign clinical data to the population of the new region. When a bridging study is designed, it is important to consider first which clinical studies in the foreign clinical data package are intended to be bridged or extrapolated. Then, the counterpart study should be selected from among available foreign clinical studies as the foundation of the bridge. The bridging study should be performed in the new region by the same or similar design to the design of the counterpart study in terms of subjects included, the duration of study, endpoint(s), evaluation method of clinical effects, etc. A bridging study could be relatively small, but the results of the study should be comparable with those of the counterpart of foreign clinical studies in all respects. The Clinical Trials Advice Division of the Organization for Pharmaceutical Safety and Research has been dealing with consultations about bridging studies since February 1998. Since then, numbers of consultations in relation to bridging studies have steadily been increasing. However, employing bridging study strategy is not always possible for various reasons. It should be noticed that the bridging study is not the only way to utilize efficiently foreign clinical data to promote the new drug approval, although the bridging study strategy may be the best desirable way, when possible, in order to utilize extensively foreign clinical data package.