Verification of pharmacogenomics-based algorithms to predict warfarin maintenance dose using registered data of Japanese patients.

PURPOSE: Large inter-individual differences in warfarin maintenance dose are mostly due to the effect of genetic polymorphisms in multiple genes, including vitamin K epoxide reductase complex 1 (VKORC1), cytochromes P450 2C9 (CYP2C9), and cytochrome P450 4F2 (CYP4F2). Thus, several algorithms for predicting the warfarin dose based on pharmacogenomics data with clinical characteristics have been proposed. Although these algorithms consider these genetic polymorphisms, the formulas have different coefficient values that are critical in this context. In this study, we assessed the mutual validity among these algorithms by specifically considering racial differences. METHODS: Clinical data including actual warfarin dose (AWD) of 125 Japanese patients from our previous study (Eur J Clin Pharmacol 65(11):1097-1103, 2009) were used as registered data that provided patient characteristics, including age, sex, height, weight, and concomitant medications, as well as the genotypes of CYP2C9 and VKORC1. Genotyping for CYP4F2*3 was performed by the PCR method. Five algorithms that included these factors were selected from peer-reviewed articles. The selection covered four populations, Japanese, Chinese, Caucasian, and African-American, and the International Warfarin Pharmacogenetics Consortium (IWPC). RESULTS: For each algorithm, we calculated individual warfarin doses for 125 subjects and statistically evaluated its performance. The algorithm from the IWPC had the statistically highest correlation with the AWD. Importantly, the calculated warfarin dose (CWD) using the algorithm from African-Americans was less correlated with the AWD as compared to those using the other algorithms. The integration of CYP4F2 data into the algorithm did not improve the prediction accuracy. CONCLUSION: The racial difference is a critical factor for warfarin dose predictions based on pharmacogenomics.

Analytical performance evaluation of the Elecsys® Cyclosporine and Elecsys® Tacrolimus assays on the cobas e411 analyzer.

BACKGROUND: Cyclosporine (CsA) and tacrolimus (TAC) are immunosuppressant drugs that are often used to treat autoimmune diseases and as transplantation therapy; therefore, their concentrations need to be monitored carefully. We herein evaluated the analytical performance of the Elecsys® Cyclosporine and Elecsys® Tacrolimus assay kits, which have been newly developed to measure CsA and TAC concentrations in the whole blood. METHODS: We used residual whole blood samples from autoimmune disease and transplantation patients who were being treated with CsA or TAC. CsA concentrations were measured using an affinity chrome-mediated immunoassay (ACMIA) and an electrochemiluminescence immunoassay (ECLIA). TAC concentrations were measured using a chemiluminescence immunoassay (CLIA) and ECLIA. We investigated assay precision, linearity, lower limit of quantitation (LOQ), stability of calibration, influence of interference substances and the hematocrit, correlation of ACMIA with ECLIA, and correlation of CLIA with ECLIA. RESULTS: Within-assay coefficients of variation were 1.8-3.6% (CsA: 94-1238 ng/mL) and 2.9-3.9% (TAC: 2.1-17.8 ng/mL), whereas day-to-day coefficients of variation ranged between 3.0-4.1% (CsA) and 2.8-3.9% (TAC). The limits of quantitation were defined as the concentration at which the CV was approximately 10%. Each lower LOQ obtained was 16 ng/mL (CsA), and 0.95 ng/mL (TAC). CsA and TAC calibrations were stable for at least 21 days. Neither the presence of conjugated bilirubin, unconjugated bilirubin, chyle, and rheumatoid factor nor the hematocrit affected these assays. A method comparison using a standardized major axis regression analysis of ACMIA and ECLIA was r=0.995, y=0.924x -1.175, n=200 (CsA), while that of CLIA and ECLIA was r=0.994, y=1.080x -0.197, n=200 (TAC). CONCLUSIONS: The analytical performances of the Elecsys® Cyclosporine and Elecsys®Tacrolimus assays were acceptable. Furthermore, CyA and TAC concentrations may be simultaneously measured using a single pretreatment which is of benefit if patients have to undertake conversion between these two drugs. Additionally, it benefits the workflow in the clinical laboratory. Thus, the Elecsys® Cyclosporine and Elecsys® Tacrolimus assays may be suitable for routine therapeutic drug monitoring.

Endogenous interleukin 18 regulates testicular germ cell apoptosis during endotoxemia.

Orchitis (testicular swelling) often occurs during systemic inflammatory conditions, such as sepsis. Interleukin 18 (IL18) is a proinflammatory cytokine and is an apoptotic mediator during endotoxemia, but the role of IL18 in response to inflammation in the testes was unclear. WT and IL18 knockout (KO) mice were injected lipopolysaccharide (LPS) to induce endotoxemia and examined 12 and 48  h after LPS administration to model the acute and recovery phases of endotoxemia. Caspase activation was assessed using immunohistochemistry. Protein and mRNA expression were examined by western blot and quantitative real-time RT-PCR respectively. During the acute phase of endotoxemia, apoptosis (as indicated by caspase-3 cleavage) was increased in WT mice but not in IL18 KO mice. The death receptor-mediated and mitochondrial-mediated apoptotic pathways were both activated in the WT mice but not in the KO mice. During the recovery phase of endotoxemia, apoptosis was observed in the IL18 KO mice but not in the WT mice. Activation of the death-receptor mediated apoptotic pathway could be seen in the IL18 KO mice but not the WT mice. These results suggested that endogenous IL18 induces germ cell apoptosis via death receptor mediated- and mitochondrial-mediated pathways during the acute phase of endotoxemia and suppresses germ cell apoptosis via death-receptor mediated pathways during recovery from endotoxemia. Taken together, IL18 could be a new therapeutic target to prevent orchitis during endotoxemia.