[Personalized medicine in transplantation therapy].

Personalized medicine based on pharmacogenomics is being developed at the clinical stage. Various evidence is accumulating in transplantation therapy. Tacrolimus, a calcineurin inhibitor, is usually used for immunosuppressive therapy after transplantation. Tacrolimus is mainly metabolized by cytochrome P450 isozymes, CYP3A4 and CYP3A5, expressed in the intestine as well as in the liver. Recent studies of pharmacogenomics have reported that several single nucleotide polymorphisms (SNPs) of CYP3A5 are correlated with gene expression and enzyme activity. Phenotypes of CYP3A5 are typed as expressors (*1/*1 and *1/*3) or non-expressors (*3/*3) . In living-donor liver transplantation, CYP3A5 phenotypes could predict the blood concentration of tacrolimus. In particular, preoperative assessment of CYP3A5 genotypes in both recipients (intestine) and donors (graft liver) is required for predicting tacrolimus pharmacokinetics. In kidney transplantation, blood tacrolimus concentrations were significantly different between expressors and non-expressors. Genotyping and phenotyping of recipients were useful to predict blood tacrolimus levels in early phase of post-transplantation. Furthermore, phenotypes of CYP3A5 could predict the initial dose of tacrolimus. Combination therapy was performed after bone marrow transplantation to prevent complications. Genotyping and phenotyping of metabolic enzymes for combination dugs would be useful for predicting drug actions. In conclusion, phenotyping based on pharmacogenomics supports personalized medicine in transplantation therapy. In future, multiplex testing should be developed to support personalized medicine in various fields.