[Regulatory science for the proper evaluation of biomarkers (overview)]

New drug development (NDD) for intractable diseases such as cancer and Alzheimer's disease has been challenging in recent years because it is difficult to evaluate the therapeutic efficacy of new drugs and the response of individual patients. Thus biomarkers might be a useful tool to facilitate NDD because they can be used to evaluate accurately drug responses. Biomarkers include proteins, metabolites, and genetic targets; imaging data and can also be used in pre-clinical studies, clinical trials, and post-marketing surveillance. In pre-clinical studies, biomarkers are used as an index of the pharmacological and toxicological effects of a new drug, which may help to predict the clinical response. In clinical studies, biomarkers are widely used as an index of clinical efficacy and safety for dose-adjustment and for patient selection. In post-clinical studies, biomarkers may facilitate the evaluation of drug responses, as well as aid improvements in drug efficacy. Several points should be considered for biomarker-guided NDD. First, the clinical study design is very important and must be suitable to permit the use of the relevant biomarkers. The analytical methods should be carefully evaluated, and evidence should be provided regarding the physiological significance and relevance of the biomarker with regard to its intended use. Regulatory sciences are required to resolve these issues and bridge the gap between basic science and clinical studies that involve biomarkers.