[Biomarker exploration and its clinical use].

Biomarkers are useful tools as indicators/predictors of disease severity and drug responsiveness, and thus, are expected to make drug development more efficient and to accelerate proper use of approved drugs. Many academic achievements on biomarkers have been reported, but only several biomarkers are used in drug development and clinical settings. We first show our results on the pharmacogenomic analysis of the anti-cancer drug irinotecan and of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). UGT1A1*6 and *28 were significantly associated with altered pharmacokinetics of an irinotecan metabolite, SN-38, and with increased frequency of severe neutropenia. HLA* 58:01 and HLA-B*15:11/HLA-A*31:01 were associated with SJS/TEN by allopurinol and carbamazepine, respectively. Our papers have been cited in the package inserts of irinotecan and allopurinol. In addition to these genomic biomarkers, metabolomic biomarkers, which can reflect the disease phenotype and drug responsiveness, have been exploring for 12 major diseases in Japan, as a part of a multi-omics team with multi-national centers. In animal models of dilated cardiomyopathy and Alzheimer's disease, we found several changes in lipid metabolite levels in the diseased tissues. Moreover, two oxidized fatty acids were correlatively changed in the brain and plasma from Alzheimer's model mice before its onset, and thus, could be candidates for predictive biomarkers. Finally, we propose/discuss several key issues for academic researches on biomarker discovery and development, especially for newly coming researchers in the field of pharmaceutical sciences. We hope that this review would help novel biomarker identification and qualification in Japan.