The 8th Japan Bioanalysis Forum symposium.

The 8th Japan Bioanalysis Forum symposium, the Tower Hall Funabori, Tokyo, Japan, 8-9 February 2017 The 8th Japan Bioanalysis Forum (JBF) symposium was successfully held between 8 and 9 February 2017 at the Tower Hall Funabori, Tokyo, Japan. In total, 24 speakers from Japan, USA and Europe gave presentations regarding the immunogenicity of biopharmaceuticals, ICH S3A Q&A microsampling, ICH M10 bioanalytical method validation, large molecule analysis through LC-MS, auditing activities for bioanalysis and biomarker bioanalysis. Achievements regarding eight diverse themes were also shared by Japan Bioanalysis Forum discussion groups. Over 300 scientists from regulatory agencies, industry and academia actively took part in discussions during the symposium. This article provides the highlights of all the topics discussed in this symposium.

Potential Minor Haplotypes of CYP2D6 in the Japanese Population.

BACKGROUND: CYP2D6 is one of the most significant polymorphic genes of drugmetabolizing enzymes due to its association with different metabolic activities and the pharmacokinetics of CYP2D6 substrates. OBJECTIVE: The objective of this study was to explore for a novel haplotype of CYP2D6 in the Japanese population by using a large database of previous clinical studies. METHODS: We analyzed CYP2D6 genotype data from a total of 723 Japanese individuals for 8 loci (100C>T, 1758G>A, 1846G>A, 2573 insertion of C, 2850C>T, 2988G>A, 4125 insertion of 9bp, and 4180G>C) and gene deletion. Genotypes were determined by the designated alleles CYP2D6*2, *4, *5, *10, *14A, *14B, *18, *21, and *41. RESULTS: The frequencies of the common major haplotypes CYP2D6*1, *10, and *2 in the Japanese population were respectively 43.5%, 38.0%, and 11.3%. In 11 subjects, diplotypes of CYP2D6 were not identified and the genotypes at the 8 loci suggested that there were 2 minor haplotypes, one with only a variation at 4180G>C compared with the wild type CYP2D6*1 (Hap1, frequency: 0.4%) and one with only a variation at 100C>T (Hap2, frequency: 0.4%). The Hap1 haplotype is considered to have no effect on metabolic activity, while it is estimated that the Hap2 haplotype does have an effect on metabolic activity. By comparing with the allele nomenclature for CYP2D6, the Hap2 haplotype was considered to be a potentially novel haplotype involving 100C>T without 4180G>C. CONCLUSION: Using a large database of CYP2D6 genotypes in the Japanese population, we found a novel haplotype which involves 100C>T without 4180G>C. Although the haplotype will need to be confirmed by full sequencing, it may be a unique haplotype with an exception to the strong linkage disequilibrium between 100C>T and 4180G>C.

Correlation of Organic Cation/Carnitine Transporter 1 and Multidrug Resistance-Associated Protein 1 Transport Activities With Protein Expression Levels in Primary Cultured Human Tracheal, Bronchial, and Alveolar Epithelial Cells.

Understanding how transporters contribute to the distribution of inhaled drugs in the lung is important for the discovery and development of such drugs. Protein expression levels may be useful to predict and understand drug distribution. As previously reported, organic cation/carnitine transporter 1 (OCTN1) and multidrug resistance-associated protein 1 (MRP1) have higher levels of protein expression among transporters in primary cultured human lung cells. Nevertheless, it is unclear to what extent transport activity correlates with transporter protein expression. The purpose is to evaluate whether differences in OCTN1 and MRP1 protein expression govern the respective transport activity in primary cultured human lung cells. The model substrates of 4-[4-(dimethylamino) styryl]-N-methylpyridinium iodide (ASP(+)) and carboxy-dichlorofluorescein (CDF) for OCTN1 and MRP1, respectively, were used in the lung cells from five donors. Significant correlation was found between the kinetic parameter Vmax for ASP(+) and OCTN1 protein expression in plasma membrane of tracheal, bronchial, and alveolar cells (r(2) = 0.965, 0.834, and 0.877, respectively), and between the efflux of CDF and MRP1 protein expression in plasma membrane of tracheal, bronchial, and alveolar cells (r(2) = 0.800, 0.904, and 0.790, respectively). These findings suggest that OCTN1 and MRP1 protein concentrations are determinants for drug distribution in the lung.

Drug Transporter Protein Quantification of Immortalized Human Lung Cell Lines Derived from Tracheobronchial Epithelial Cells (Calu-3 and BEAS2-B), Bronchiolar-Alveolar Cells (NCI-H292 and NCI-H441), and Alveolar Type II-like Cells (A549) by Liquid Chromatography-Tandem Mass Spectrometry.

Understanding the mechanisms of drug transport in the human lung is an important issue in pulmonary drug discovery and development. For this purpose, there is an increasing interest in immortalized lung cell lines as alternatives to primary cultured lung cells. We recently reported the protein expression in human lung tissues and pulmonary epithelial cells in primary culture, (Sakamoto A, Matsumaru T, Yamamura N, Uchida Y, Tachikawa M, Ohtsuki S, Terasaki T. 2013. J Pharm Sci 102(9):3395-3406) whereas comprehensive quantification of protein expressions in immortalized lung cell lines is sparse. Therefore, the aim of the present study was to clarify the drug transporter protein expression of five commercially available immortalized lung cell lines derived from tracheobronchial cells (Calu-3 and BEAS2-B), bronchiolar-alveolar cells (NCI-H292 and NCI-H441), and alveolar type II cells (A549), by liquid chromatography-tandem mass spectrometry-based approaches. Among transporters detected, breast cancer-resistance protein in Calu-3, NCI-H292, NCI-H441, and A549 and OCTN2 in BEAS2-B showed the highest protein expression. Compared with data from our previous study,(Sakamoto A, Matsumaru T, Yamamura N, Uchida Y, Tachikawa M, Ohtsuki S, Terasaki T. 2013. J Pharm Sci 102(9):3395-3406) NCI-H441 was the most similar with primary lung cells from all regions in terms of protein expression of organic cation/carnitine transporter 1 (OCTN1). In conclusion, the protein expression profiles of transporters in five immortalized lung cell lines were determined, and these findings may contribute to a better understanding of drug transport in immortalized lung cell lines.

Quantitative expression of human drug transporter proteins in lung tissues: analysis of regional, gender, and interindividual differences by liquid chromatography-tandem mass spectrometry.

The purpose of the present study was to clarify the expression levels of transporter proteins in human lung tissue and to analyze regional and interindividual differences in primary cultured epithelial cells. Organic cation/carnitine tranporter 1 (OCTN1) protein expression was highest (2.08 ± 1.19 fmol/µg protein) in human lung tissue, followed by multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein expression (1.41 ± 0.41, 1.30 ± 1.29 fmol/µg protein, respectively). Interestingly, the same expression levels of OATP2B1 protein were demonstrated among the epithelial cells derived from all pulmonary regions for the first time. These results suggest that OCTN1 may be the best target transporter protein for pulmonary disease drug design, and OATP2B1 may be an alternative target. MRP1 protein expression was also high and mainly localized in bronchial and alveolar regions. Regarding interindividual differences, the MRP1 protein showed a significant 18-fold maximal difference in the bronchial region among five donors. Sixteen of the 18 transporters showed higher expression in female lungs than in male lungs, especially MRP8 showed a 7.32-fold maximal difference. In conclusion, the protein expression profiles of pulmonary drug transporters and regional, gender, and interindividual differences were clarified. These findings may provide significant insights for pulmonary disease drug design and indicate that administration by inhalation may be viable.

Absolute quantification and differential expression of drug transporters, cytochrome P450 enzymes, and UDP-glucuronosyltransferases in cultured primary human hepatocytes.

The levels of metabolizing enzymes and transporters expressed in hepatocytes are decisive factors for hepatobiliary disposition of most drugs. Induction via nuclear receptor activation can significantly alter those levels, with the coregulation of multiple enzymes and transporters occurring to different extents. Here, we report the use of a targeted liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method for concurrent quantification of multiple cytochrome P450 (P450), UDP-glucuronosyltransferase (UGT), and transporter proteins in cultured primary human hepatocytes. The effects of culture format (i.e., sandwich culture versus conventional culture) and of dexamethasone (DEX) media concentrations on mRNA, protein, and activity levels were determined for three donors, and protein expression was compared with that in liver. In general, P450 and UGT expression was lower in hepatocyte cultures than that in liver, and CYP2C9 was found to be the most abundant P450 isoform expressed in cultured hepatocytes. The sandwich culture format and 0.1 µM DEX in media retained the protein expression in the hepatocytes closest to the levels found in liver. However, higher in vitro expression was observed for drug transporters, especially for multidrug resistance protein 1 and breast cancer resistance protein. Direct protein quantification was applied successfully to study in vitro induction in sandwich cultured primary hepatocytes in a 24-well format using the prototypical inducers rifampicin, omeprazole, and phenobarbital. We conclude that targeted absolute LC-MS/MS quantification of drug-metabolizing enzymes and transporters can broaden the scope and significantly increase the impact of in vitro drug metabolism studies, such as induction, as an important supplement or future alternative to mRNA and activity data.

Reliability and robustness of simultaneous absolute quantification of drug transporters, cytochrome P450 enzymes, and Udp-glucuronosyltransferases in human liver tissue by multiplexed MRM/selected reaction monitoring mode tandem mass spectrometry with nano-liquid chromatography.

Mass spectrometry (MS)-based multiplexed multiple reaction monitoring quantification of proteins has recently evolved as a versatile tool for accurate, absolute quantification of proteins. The purpose of this study was to examine the validity of the present method with regard to standard bioanalytical criteria for drug transporters, cytochrome P450 (CYP) enzymes and uridine 5'-diphospho-glucuronosyltransferases (UGTs). Membrane preparations from human liver tissue were used for target protein quantification. As a result, the determination coefficients (r(2)) of all targets were greater than 0.986. In the absence of matrix, inaccuracy values (expressed as % deviation) were -8.1% to 20.3%, whereas imprecision values (expressed as % coefficient of variation) were within 15.9%. In the presence of matrix, which consisted of digested plasma membrane fraction for transporters and digested microsomal membrane fraction for CYP enzymes and UGTs, respectively, the inaccuracy was -15.3%-8.1%, and the imprecision were within 18.9%. Sufficient sample stability of membrane fraction was shown for three freeze-thaw cycles, 32 days at -20°C, and in processed samples for 7 days at 10°C. In conclusion, this study demonstrated, for the first time, that the MS-based assay with nano-liquid chromatography provides adequate reliability and robustness for the quantification of selected drug transporters, P450 enzymes and UGTs.

Renoprotective effects of telmisartan in the 5/6 nephrectomised rats.

The purpose of this study was to investigate the renoprotective effect of telmisartan on the advanced stages of nephropathy in rats with 5/6 nephrectomy (5/6 Nx). Telmisartan was orally administered for 12 weeks to rats that previously underwent 5/6 Nx or sham operations. After completion of the administration period, the degree of renal injury was examined histopathologically using indices of glomerulosclerosis and lesions of the renal tubule and interstitium. An immunohistochemical staining for transforming growth factor-beta (TGF-beta1) was also performed. The suppression of urinary protein was statistically significant in surviving animals dosed with telmisartan. The enalapril group's urinary protein was also significantly suppressed for these same parameters in surviving animals. Histopathologically, telmisartan significantly decreased the progression of glomerulosclerosis and the interstitial cell infiltration at all doses tested. As assessed by immunohistochemical staining the TGF-beta1 reactivity in the glomerular tissue tended to decrease in the telmisartan group when compared to the vehicle group. Thus, telmisartan ameliorates the progressive nephropathy in the remaining kidney after 5/6 Nx by non-haemodynamic as well as antihypertensive actions of the drug.

Comparison of toxicity and toxicokinetics/pharmacokinetics of an alpha 1L-adrenoceptor agonist in rats and rhesus monkeys.

We have investigated the toxicity of an alpha(1L)-adrenoceptor agonist, ESR 1150 CL, and compared the toxicokinetics and pharmacokinetics in rats and monkeys. In rats, this compound induced death with remarkable sacculated aneurysms of the aorta in groups given more than 3 mg/kg per day in a 4-week repeated oral administration study. On the other hand, these findings were not observed in monkeys during a 2-week repeated oral administration study at doses up to 30 mg/kg per day. Orally administered ESR 1150 CL raised blood pressure transiently and dose-dependently during the 4-week repeated study in rats, whereas no increase of blood pressure was observed during the 2-week oral toxicity study in monkeys. Contrary to our expectation, the exposure level of ESR 1150 CL in rats was not higher than that in monkeys in the toxicokinetic evaluation. Pharmacokinetic evaluation indicated good absorption of the compound, but the bioavailability was very low in both rats and monkeys. These findings suggest that the potent species difference in toxicity of ESR 1150 CL between rats and monkeys does not depend on differences of toxicokinetics/pharmacokinetics. Rather, we suggest that the reason is likely to be species difference in the biological susceptibility of the alpha(1L)-adrenoceptor subtypes between rats and monkeys, which would be closely related with the effect on blood pressure by alpha(1L)-adrenoceptor agonist.