Current landscape of personalized medicine adoption and implementation in Southeast Asia.

BMC Med Genomics. 2018 Oct 26;11(1):94

Authors: Chong HY, Allotey PA, Chaiyakunapruk N

Abstract
BACKGROUND: The emergence of personalized medicine (PM) has raised some tensions in healthcare systems. PM is expensive and health budgets are constrained - efficient healthcare delivery is therefore critical. Notwithstanding the cost, many countries have started to adopt this novel technology, including resource-limited Southeast Asia (SEA) countries. This study aimed to describe the status of PM adoption in SEA, highlight the challenges and to propose strategies for future development.
METHODS: The study included scoping review and key stakeholder interviews in four focus countries - Indonesia, Malaysia, Singapore, and Thailand. The current landscape of PM adoption was evaluated based on an assessment framework of six key themes - healthcare system, governance, access, awareness, implementation, and data. Six PM programs were evaluated for their financing and implementation mechanisms.
RESULTS: The findings revealed SEA has progressed in adopting PM especially Singapore and Thailand. A regional pharmacogenomics research network has been established. However, PM policies and programs vary significantly. As most PM programs are champion-driven and the available funding is limited, the current PM distribution has the potential to widen existing health disparities. Low PM awareness in the society and the absence of political support with financial investment are fundamental barriers. There is a clear need to broaden opportunities for critical discourse about PM especially for policymakers. Multi-stakeholder, multi-country strategies need to be prioritized in order to leverage resources and expertise.
CONCLUSIONS: Adopting PM remains in its infancy in SEA. To achieve an effective PM adoption, it is imperative to balance equity issues across diverse populations while improving efficiency in healthcare.

PMID: 30367635 [PubMed - in process]

Oral co-administration of fluconazole with tramadol markedly increases plasma and urine concentrations of tramadol and the O-desmethyltramadol metabolite (M1) in healthy dogs.

Drug Metab Dispos. 2018 Oct 26;:

Authors: Perez Jimenez TE, Kukanich B, Joo H, Mealey KL, Grubb TL, Greene SA, Court MH

Abstract
Tramadol is used frequently in the management of mild to moderate pain conditions in dogs. This use is controversial because multiple reports in treated dogs demonstrate very low plasma concentrations of O-desmethyltramadol (M1), the active metabolite. The objective of this study was to identify a drug that could be co-administered with tramadol to increase plasma M1 concentrations thereby enhancing analgesic efficacy. In vitro studies were initially conducted to identify a compound that inhibited tramadol metabolism to N-desmethyltramadol (M2) and M1 metabolism to N,O didesmethyltramadol (M5) without reducing tramadol metabolism to M1. A randomized crossover drug-drug interaction study was then conducted by administering this inhibitor or placebo with tramadol to 12 dogs. Blood and urine samples were collected to measure tramadol, tramadol metabolites, and inhibitor concentrations. After screening 86 compounds, fluconazole was the only drug found to inhibit M2 and M5 formation potently without reducing M1 formation. Four hours after tramadol administration to fluconazole-treated dogs, there were marked statistically significant (P<0.001; Wilcoxon signed-rank test) increases in plasma tramadol (31-fold higher) and M1 (39-fold higher) concentrations when compared to placebo-treated dogs. Conversely, plasma M2 and M5 concentrations were significantly lower (11-fold and 3-fold, respectively; P<0.01) in fluconazole-treated dogs. Metabolite concentrations in urine followed a similar pattern. This is the first study to demonstrate a potentially beneficial drug-drug interaction in dogs through enhancing plasma tramadol and M1 concentrations. Future studies are needed to determine whether adding fluconazole can enhance the analgesic efficacy of tramadol in healthy dogs and in clinical patients experiencing pain.

PMID: 30366901 [PubMed - as supplied by publisher]

Histo-molecular oncogenesis of pancreatic cancer: From precancerous lesions to invasive ductal adenocarcinoma.

World J Gastrointest Oncol. 2018 Oct 15;10(10):317-327

Authors: Riva G, Pea A, Pilati C, Fiadone G, Lawlor RT, Scarpa A, Luchini C

Abstract
Pancreatic cancer is a lethal malignancy, whose precursor lesions are pancreatic intraepithelial neoplasm, intraductal papillary mucinous neoplasm, intraductal tubulopapillary neoplasm, and mucinous cystic neoplasm. To better understand the biology of pancreatic cancer, it is fundamental to know its precursors and to study the mechanisms of carcinogenesis. Each of these precursors displays peculiar histological features, as well as specific molecular alterations. Starting from such pre-invasive lesions, this review aims at summarizing the most important aspects of carcinogenesis of pancreatic cancer, with a specific focus on the recent advances and the future perspectives of the research on this lethal tumor type.

PMID: 30364837 [PubMed]

Implementing Clinical Pharmacogenomics in the Classroom: Student Pharmacist Impressions of an Educational Intervention Including Personal Genotyping.

Pharmacy (Basel). 2018 Oct 23;6(4):

Authors: Frick A, Benton C, Suzuki O, Dong O, Howard R, El-Sabae H, Wiltshire T

Abstract
Pharmacogenomics provides a personalized approach to pharmacotherapy by using genetic information to guide drug dosing and selection. However, partly due to lack of education, pharmacogenomic testing has not been fully implemented in clinical practice. With pharmacotherapy training and patient accessibility, pharmacists are ideally suited to apply pharmacogenomics to patient care. Student pharmacists (n = 222) participated in an educational intervention that included voluntary personal genotyping using 23andMe. Of these, 31% of students completed both pre- and post-educational interventions to evaluate their attitudes and confidence towards the use of pharmacogenomics data in clinical decision making, and 55% of this paired subset obtained personal genotyping. McNemar's test and the Wilcoxon signed-rank test were used to analyze responses. Following the educational intervention, students regardless of genotyping were more likely to recommend personal genotyping (36% post-educational intervention versus 19% pre-educational intervention, p = 0.0032), more confident in using pharmacogenomics in the management of drug therapy (51% post-educational intervention versus 29% pre-educational intervention, p = 0.0045), and more likely to believe that personalized genomics would have an important role in their future pharmacy career (90% post-educational intervention versus 51% pre-educational intervention, p = 0.0072) compared to before receiving the educational intervention. This educational intervention positively influenced students' attitudes and confidence regarding pharmacogenomics in the clinical setting. Future studies will examine the use of next-generation sequencing assays that selectively examine pharmacogenes in the education of student pharmacists.

PMID: 30360487 [PubMed]

Genetic Polymorphisms and In Silico Mutagenesis Analyses of CYP2C9, CYP2D6, and CYPOR Genes in the Pakistani Population.

Genes (Basel). 2018 Oct 22;9(10):

Authors: Ahmed S, Zhou J, Zhou Z, Chen SQ

Abstract
Diverse distributions of pharmacogenetically relevant variants of highly polymorphic CYP2C9, CYP2D6 and CYPOR genes are responsible for some varied drug responses observed across human populations. There is limited data available regarding the pharmacogenetic polymorphisms and frequency distributions of major allele variants in the Pakistani population. The present in silico mutagenesis study conducted on genotype pharmacogenetic variants and comparative analysis with a global population aims to extend the currently limited pharmacogenetic available evidence for the indigenous Pakistani population. Extracted genomic DNA from 244 healthy individuals' venous blood samples were amplified for distinct variant loci in the CYP2C9, CYP2D6 and CYPOR genes. Two-way sequencing results were compared with standard PubMed data and sequence variant loci confirmed by Chromas. This study revealed significant variations in CYP2C9 (rs1799853, rs1057910 and rs72558189), CYP2D6 (rs16947 and rs1135840), and CYPOR (rs1057868, rs781919285 and rs562750402) variants in intraethnic and interethnic frequency distributions. In silico mutagenesis and three-dimensional protein structural alignment analysis approaches clearly exposed the possible varied impact of rare CYPOR (rs781919285 and rs562750402) single nucleotide polymorphisms (SNPs) and confirmed that the influences of CYP2C9 and CYP2D6 variants are consistent with what was found in earlier studies. This investigation highlighted the need to study pharmacogenetic relevance loci and documentation since evidence could be utilized to elucidate genetic backgrounds of drug metabolism, and provide a basis for future pharmacogenomic studies and adequate dose adjustments in Pakistani and global populations.

PMID: 30360443 [PubMed]

Pharmacogenetic considerations for migraine therapies.

Expert Opin Drug Metab Toxicol. 2018 Oct 26;:

Authors: Capi M, Gentile G, Lionetto L, Salerno G, Cipolla F, Curto M, Borro M, Martelletti P

Abstract
INTRODUCTION: Migraine is a common neurological disorder with a complex pathophysiology. It has been estimated that incidence between adults of current headache disorder is about 50%. Different studies show that this condition has an important and complex genetic component in response to drug therapy. Areas covered: This review shows and summarizes the importance of the polymorphisms associated with the major antimigraine drug metabolizing enzymes. The research of bibliographic databases has involved only published peer-reviewed articles from indexed journals. Expert opinion: Pharmacogenetics is based on the identification of polymorphism and promises personalized therapy with efficacy and reduction of adverse events. The association between genotype and an altered metabolizer status could guide clinical decision to evade concomitant treatments and adverse events. The introduction of routine genetic testing could help to choose the efficacy drug on the individual and genetic profile.

PMID: 30362834 [PubMed - as supplied by publisher]

Standard fluoropyrimidine dosages in chemoradiation therapy result in an increased risk of severe toxicity in DPYD variant allele carriers.

Eur J Cancer. 2018 Oct 18;:

Authors: Lunenburg CATC, Henricks LM, Dreussi E, Peters FP, Fiocco M, Meulendijks D, Toffoli G, Guchelaar HJ, Swen JJ, Cecchin E, Schellens JHM, Gelderblom H

Abstract
BACKGROUND: Prospective DPYD genotyping prevents severe fluoropyrimidine (FP)-induced toxicity by decreasing dosages in DPYD variant allele carriers. FP dosages in chemoradiation therapy (CRT) are lower than those in other FP-containing regimens. Pharmacogenetic guidelines do not distinguish between regimens, leaving physicians in doubt to apply dose reductions. Our aim was to investigate severe toxicity in DPYD variant allele carriers receiving CRT.
METHODS: Medical records of 828 patients who received FP-based CRT were reviewed from three centres. Severe (grade ≥III) toxicity in DPYD variant allele carriers receiving upfront FP dose reductions according to pharmacogenetic dosing guidelines and DPYD variant allele carriers not receiving FP dose reductions was compared with DPYD wild-type patients receiving standard dose of FPs in CRT.
RESULTS: DPYD variant allele carriers treated with standard dosages (N = 34) showed an increased risk of severe gastrointestinal (adjusted OR = 2.58, confidence interval [CI] = 1.02-6.53, P = 0.045) or severe haematological (adjusted OR = 4.19, CI = 1.32-13.25, P = 0.015) toxicity compared with wild-type patients (N = 771). DPYD variant allele carriers who received dose reductions (N = 22) showed a comparable frequency of severe gastrointestinal toxicity compared with wild-type patients, but more (not statistically significant) severe haematological toxicity. Hospitalisations for all DPYD variant allele carriers were comparable, independent of dose adjustments; however, the mean duration of hospitalisation was significantly shorter in the dose reduction group (P = 0.010).
CONCLUSIONS: Standard FP dosages in CRT resulted in an increased risk of severe toxicity in DPYD variant allele carriers. We advise to apply FP dose reductions according to current guidelines in DPYD variant allele carriers starting CRT.

PMID: 30361102 [PubMed - as supplied by publisher]

Gap between the US and Japan in coverage of pharmacogenomic biomarkers by health insurance programs: More coverage is needed in Japan.

Drug Metab Pharmacokinet. 2018 Sep 01;:

Authors: Hikino K, Fukunaga K, Mushiroda T

Abstract
In this study, we aimed to understand the gap in coverage of pharmacogenomic (PGx) biomarkers between Japan and the US. PGx biomarkers (1) in the Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines; (2) that are CPIC level A or B; or (3) have US Food and Drug Administration (FDA)-approved drug labels, were determined. Subsequently, their coverage by US health insurance companies and the National Health Insurance (NHI) in Japan was investigated. We identified the top six health insurance companies with the largest market shares in the US and investigated the coverage for the PGx biomarkers by these health insurers, Medicare, Medicaid, and the NHI in Japan. We found that 19.9% of these biomarkers are covered by the six companies (10.0%, the CPIC guidelines; 25.1%, the FDA-approved drug labels). The coverage of somatic and germline biomarkers was respectively 86.8% and 8.5% in the US and 56.3% and 0.6% in Japan. A few germline PGx biomarkers are covered both in Japan and the US, but the coverage of both somatic and germline biomarkers was lower in Japan. Therefore, more coverage should be considered to improve patient outcomes after prescribing medications in Japan.

PMID: 30360950 [PubMed - as supplied by publisher]

Effects of ABCC2 and SLCO1B1 Polymorphisms on Treatment Responses in Thai Metastatic Colorectal Cancer Patients Treated with Irinotecan-Based Chemotherapy

Asian Pac J Cancer Prev. 2018 Oct 26;19(10):2757-2764

Authors: Treenert A, Areepium N, Tanasanvimon S

Abstract
Purpose: Irinotecan is an anticancer medicine which is used mostly in metastatic colorectal cancer (mCRC) treatment as second or third line chemotherapy. Several factors affect its efficacy and toxicity, including pharmacogenomics. This study aimed to investigate the impacts of ABCC2 and SLCO1B1 polymorphisms on treatment responses in irinotecan-based chemotherapy in 49 Thai mCRC patients. Materials and Methods: Forty-nine participants with mCRC enrolled in this study received irinotecan-based chemotherapy from January to June 2017. Genotypic analyses of ABCC2 (C>T, rs717620) and SLCO1B1 (A>G, rs2306283) were performed. Treatment responses were evaluated after at least three cycles of chemotherapy were given. Results: Allele frequencies of ABCC2 (C>T) and SLCO1B1 (A>G) were found at 18.37% and 78.57%, respectively. Neither was associated with treatment responses. However, combined genotypes of ABCC2 and SLCO1B1 tended to be associated with clinical benefits in terms of partial responses (PR) and stable disease (SD). All patients (100%) with at least one variant allele of SLCO1B1 and ABCC2 were in a PR or SD group, while patients with other genotypes had progressive disease (PD) at 45.5% to 70%, (p = 0.059). Conclusion: The combined effect of ABCC2 and SLCO1B1 polymorphisms tended to be associated with treatment responses in irinotecan-based treated mCRC patients. Therefore, such polymorphisms could be factors impacting inter-individual variation of irinotecan efficacy in Thai mCRC patients.

PMID: 30360603 [PubMed - in process]

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pharmacogenomics

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24 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results:

pharmacogenomics

These pubmed results were generated on 2018/10/26

PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

Revisiting the Role of Thiopurines in Inflammatory Bowel Disease Through Pharmacogenomics and Use of Novel Methods for Therapeutic Drug Monitoring.

Front Pharmacol. 2018;9:1107

Authors: Lim SZ, Chua EW

Abstract
Azathioprine and 6-mercaptopurine, often referred to as thiopurine compounds, are commonly used in the management of inflammatory bowel disease. However, patients receiving these drugs are prone to developing adverse drug reactions or therapeutic resistance. Achieving predefined levels of two major thiopurine metabolites, 6-thioguanine nucleotides and 6-methylmercaptopurine, is a long-standing clinical practice in ensuring therapeutic efficacy; however, their correlation with treatment response is sometimes unclear. Various genetic markers have also been used to aid the identification of patients who are thiopurine-sensitive or refractory. The recent discovery of novel Asian-specific DNA variants, namely those in the NUDT15 gene, and their link to thiopurine toxicity, have led clinicians and scientists to revisit the utility of Caucasian biomarkers for Asian individuals with inflammatory bowel disease. In this review, we explore the limitations associated with the current methods used for therapeutic monitoring of thiopurine metabolites and how the recent discovery of ethnicity-specific genetic markers can complement thiopurine metabolites measurement in formulating a strategy for more accurate prediction of thiopurine response. We also discuss the challenges in thiopurine therapy, alongside the current strategies used in patients with reduced thiopurine response. The review is concluded with suggestions for future work aiming at using a more comprehensive approach to optimize the efficacy of thiopurine compounds in inflammatory bowel disease.

PMID: 30349479 [PubMed]

Repurposing of Bromocriptine for Cancer Therapy.

Front Pharmacol. 2018;9:1030

Authors: Seo EJ, Sugimoto Y, Greten HJ, Efferth T

Abstract
Bromocriptine is an ergot alkaloid and dopamine D2 receptor agonist used to treat Parkinson's disease, acromegaly, hyperprolactinemia, and galactorrhea, and more recently diabetes mellitus. The drug is also active against pituitary hormone-dependent tumors (prolactinomas and growth-hormone producing adenomas). We investigated, whether bromocriptine also inhibits hormone-independent and multidrug-resistant (MDR) tumors. We found that bromocriptine was cytotoxic towards drug-sensitive CCRF-CEM, multidrug-resistant CEM/ADR5000 leukemic cells as well as wild-type or multidrug-resistant ABCB5-transfected HEK293 cell lines, but not sensitive or BCRP-transfected multidrug-resistant MDA-MB-231 breast cancer cells. Bromocriptine strongly bound to NF-κB pathway proteins as shown by molecular docking and interacted more strongly with DNA-bound NF-κB than free NF-κB, indicating that bromocriptine may inhibit NF-κB binding to DNA. Furthermore, bromocriptine decreased NF-κB activity by a SEAP-driven NF-κB reporter cell assay. The expression of MDR-conferring ABC-transporters (ABCB1, ABCB5, ABCC1, and ABCG2) and other resistance-mediating factors (EGFR, mutated TP53, and IκB) did not correlate with cellular response to bromocriptine in a panel of 60 NCI cell lines. There was no correlation between cellular response to bromocriptine and anticancer drugs usually involved in MDR (e.g., anthracyclines, Vinca alkaloids, taxanes, epipodophyllotoxins, and others). COMPARE analysis of microarray-based mRNA expression in these cell lines revealed that genes from various functional groups such as ribosomal proteins, transcription, translation, DNA repair, DNA damage, protein folding, mitochondrial respiratory chain, and chemokines correlated with cellular response to bromocriptine. Our results indicate that bromocriptine inhibited drug-resistant tumor cells with different resistance mechanisms in a hormone-independent manner. As refractory and otherwise drug-resistant tumors represent a major challenge to successful cancer chemotherapy, bromocriptine may be considered for repurposing in cancer therapy.

PMID: 30349477 [PubMed]

Severe toxicity to capecitabine due to a new variant at a donor splicing site in the dihydropyrimidine dehydrogenase (DPYD) gene.

Cancer Manag Res. 2018;10:4517-4522

Authors: García-González X, López-Tarruella S, García MI, González-Haba E, Blanco C, Salvador-Martin S, Jerez Y, Thomas F, Jarama M, Sáez MS, Martín M, López-Fernández LA

Abstract
Severe, life-threatening adverse reactions to capecitabine sometimes occur in the treatment of solid tumors. Screening for dihydropyrimidine dehydrogenase (DPYD) deficiency is encouraged before start of treatment, but the genetic variants that are commonly analyzed often fail to explain toxicities seen in clinical practice. Here we describe the case of a 79-year-old Caucasian female with breast cancer who presented with life-threatening, rapidly increasing toxicity after 1 week of treatment with capecitabine and for whom routine genetic DPYD test resulted negative. DPYD exon sequencing found variant c.2242+1G>T at the donor splicing site of exon 19. This variant is responsible for skipping of exon 19 and subsequent generation of a non-functional DPYD enzyme. This variant has not been described previously but was found in three other members of the patient's family. With this case, we show that exon sequencing of DPYD in patients who experience marked toxicity to fluoropyrimidines and test negative for commonly evaluated variants can prove extremely useful for identifying new genetic variants and better explain adverse reactions causality.

PMID: 30349384 [PubMed]

Report of Confirmation of the rs7853758 and rs885004 Haplotype in SLC28A3.

Genet Test Mol Biomarkers. 2018 Oct 23;:

Authors: Stansberry WM, Swart M, Medeiros EB, Skaar TC, Pratt VM

Abstract
AIMS: To validate a laboratory-developed test for the nucleoside transporter, SLC28A3, which has been associated with an increased risk of anthracycline-induced cardiomyopathy.
METHODS: We used Taqman® allele discrimination to test for two variants of the SLC28A3 gene: rs7853758 (c.1381C>T) and rs885004 (c.862-360C>T).
RESULTS: During the validation process, we noted that several DNA samples obtained from the Coriell Cell Repository (Camden, NJ) were positive for both the c.1381 C > T and c.862-360C>T variants and another variant allele for either c.1381 C > T or c.862-360C>T (e.g., c.1381C>T homozygous/c.862-360C>T heterozygous, c.1381C>T homozygous/c.862-360C>T homozygous). We used de-identified DNA samples from trios of family members (mother, father, and child) to establish that the c.1381 C > T and c.862-360C>T variant alleles could be inherited in cis on the same chromosome.
CONCLUSIONS: Samples containing three variant alleles suggest that the c.1381 C > T and c.862-360C>T are in cis on the chromosome in some individuals and may have implications when calculating anthracycline-induced cardiomyopathy risk. In this study, we confirm a novel haplotype of SLC28A3 using familial studies.

PMID: 30351207 [PubMed - as supplied by publisher]

Breakthrough cancer genome analysis in time and space: novel oncotargets and early drug development.

Pharmacogenomics. 2018 Oct 23;:

Authors: Kyrochristos ID, Ziogas DE, Antoniou P, Mitsis M, Lykoudis EG, Roukos DH

PMID: 30348059 [PubMed - as supplied by publisher]

Predicting smoking abstinence with biological and self-report measures of adherence to varenicline: Impact on pharmacogenetic trial outcomes.

Drug Alcohol Depend. 2018 09 01;190:72-81

Authors: Peng AR, Schnoll R, Hawk LW, Cinciripini P, George TP, Lerman C, Tyndale RF

Abstract
INTRODUCTION: Adherence to pharmacotherapies for tobacco dependence, such as varenicline, is necessary for effective treatment. The relationship between varenicline adherence, determined by commonly used indirect (i.e., self-reported pill counts) and infrequently used direct (i.e., varenicline levels) methods, and abstinence outcomes have not been previously examined, nor has their impact on the outcomes of a genetically randomized clinical trial been assessed.
METHODS: At Week 1 following target quit date, self-reported pill count and salivary varenicline levels were obtained from participants (N = 376) in a smoking cessation clinical trial (NCT01314001). Point-prevalence abstinence was biochemically-verified by salivary cotinine at Week 1 and by exhaled carbon monoxide at Week 1, end-of-treatment, 6 and 12 months following treatment. Blood nicotine metabolite ratio (NMR) was obtained at baseline.
RESULTS: Adherent individuals based on varenicline levels were significantly more likely to be abstinent than non-adherent individuals at Week 1 (odds ratios [ORs] 1.92-3.16, p's≤0.006), end-of-treatment (OR = 2.53, p = .004), and six months following treatment (OR = 2.30, p = .03). In contrast, pill counts did not consistently predict abstinence. Including direct measures of adherence enhanced the association between rate of nicotine metabolism (NMR) and end-of-treatment abstinence; normal metabolizers (NMR ≥ 0.31) were significantly more likely than slow metabolizers (NMR < 0.31) to be abstinent at end-of-treatment (OR = 2.00, p = .005).
CONCLUSION: Adherence based on salivary varenicline, rather than on pill counts, is predictive of Week 1 abstinence, irrespective of the biomarker of abstinence assessed, and of long-term abstinence. Direct measures of adherence enhance the ability to assess the impact of a biomarker or genetic marker on abstinence outcomes.

PMID: 29986268 [PubMed - indexed for MEDLINE]

Repaglinide-irbesartan drug interaction: effects of SLCO1B1 polymorphism on repaglinide pharmacokinetics and pharmacodynamics in Chinese population.

Eur J Clin Pharmacol. 2018 Aug;74(8):1021-1028

Authors: Pei Q, Liu JY, Yin JY, Yang GP, Liu SK, Zheng Y, Xie P, Guo CX, Luo M, Zhou HH, Li X, Liu ZQ

Abstract
PURPOSE: On account of the potential inhibition of OATP1B1 (organic anion transporting polypeptide) by angiotensin II receptor blockers (ARBs) and the effects of SLCO1B1 (solute carrier organic anion transporter family member) polymorphism, the aim of current study is to assess the impact of ARBs on the pharmacokinetics (PK) and pharmacodynamics (PD) of repaglinide in Chinese healthy volunteers with different SLCO1B1 genotypes.
METHODS: The in vitro study was conducted on irbesartan, valsartan, olmesartan, and losartan by using HEK293 cells transfected with OATP1B1. Data on drug interactions between repaglinide and irbesartan from 21 healthy Chinese-Han male volunteers were collected and analyzed.
RESULTS: IC50 from in vitro study suggested irbesartan was the most potent inhibitor of OATP1B1 transporter. Clinical data from single dose of repaglinide indicated SLCO1B1 c.521 T>C polymorphism influenced the PK and PD of repaglinide in healthy Chinese-Han male volunteers. In subjects with SLCO1B1 c.521 TT genotype, irbesartan comedication increased the exposure of repaglinide. In details, the peak plasma concentration [Cmax] increased 84% (P = 0.003) and the area under the curve of plasma concentration 0-8 h [AUC0-8] increased 34% (P = 0.004), while the minimum blood glucose concentration [Cmin] decreased 33.8% (P = 0.005). No significant change was observed in repaglinide exposure in subjects with SLCO1B1 c.521 TC genotype in presence or absence of irbesartan.
CONCLUSION: SLCO1B1 c.521 T>C polymorphism affects the PK of repaglinide in Chinese population. Irbesartan increased repaglinide exposure in subjects with SLCO1B1 c.521 TT genotype, but not SLCO1B1 c.521 TC genotype.

PMID: 29748863 [PubMed - indexed for MEDLINE]

Whole-exome sequencing reveals microsatellite DNA markers for response to dofetilide initiation in patients with persistent atrial fibrillation: A pilot study.

Clin Cardiol. 2018 Jun;41(6):849-854

Authors: Kinney N, Larsen TR, Kim DM, Varghese RT, Poelzing S, Garner HR, AlMahameed ST

Abstract
BACKGROUND: Dofetilide is a class III antiarrhythmic drug effective for the treatment of atrial fibrillation (AF). Dofetilide initiation (DI) associates with corrected QT interval (QTc) prolongation. Significant QTc prolongation during DI mandates dose adjustment or discontinuation of the drug. Microsatellite DNA are novel genetic markers associated with congenital and acquired health conditions.
HYPOTHESIS: DNA microsatellite polymorphism may associate with QTc response to dofetilide initiation in patients with persistent AF.
METHODS: We performed whole-exome sequencing in a cohort of patients with persistent AF undergoing DI. Electrocardiographic variables and clinical data were assessed. We defined patients as eligible for DI when no significant QTc prolongation (>20% compared with baseline) was seen with a 500-μg dose. We defined patients as ineligible for DI when significant QTc prolongation was seen during DI with 500 μg. We investigated polymorphisms for 11 919 DNA microsatellite loci in relation to QTc response to DI.
RESULTS: During the study, 14 consecutive patients with persistent AF presenting for DI were enrolled. Whole-exome sequencing revealed 14 different microsatellite loci in the 2 groups. All genes or proximal genes that harbor these loci are known to have expression in the human heart. Two genes, MYH6 and TRAK2, are known to have expression in the atria. TRAK2 is known to interact with KCNJ2, the inward-rectifier potassium channel 1.
CONCLUSIONS: Microsatellite DNA polymorphisms seem to associate with QTc response to DI therapy in patients with persistent AF who are deemed otherwise eligible for dofetilide therapy.

PMID: 29671888 [PubMed - indexed for MEDLINE]

mRNA expression of drug metabolism enzymes and transporter genes at birth using human umbilical cord blood.

Fundam Clin Pharmacol. 2018 Aug;32(4):422-435

Authors: Neyro V, Elie V, Médard Y, Jacqz-Aigrain E

Abstract
Growth and maturation changes are mainly responsible for differences in drug pharmacokinetics and pharmacodynamics observed between adults and children, especially neonates. Ontogeny of drug-metabolizing enzymes and transporters plays an important role in drugs interindividual pharmacokinetic variability but data are limited in both term and preterm neonates. This study aimed to characterize mRNA expression of the main drug-metabolizing enzymes and transport proteins involved in drug disposition, using umbilical cord blood (UCB), according to gender, gestational age, and genetic background. A large panel of genes was quantified as follows: cytochrome P450 system (n = 12), UGT family (n = 6), TPMT and transporters (n = 3), in 56 samples of UCB of twin neonates. Gene expression was measured using real-time reverse transcription polymerase chain reaction with 18S rRNA as the endogenous control for normalization of data. Relative expression of the samples was expressed using the 2-ΔΔCt method for comparison of gene expression levels. Twenty genes were expressed in UCB at birth with variable levels of expression and tissue-specific gene expression when compared to data on the fetal liver. Gestational age, gender, and genetic background influenced the expression of the genes tested. Easily accessible UCB samples will enable further studies to evaluate the influence of covariates. This suggests that these covariates need to be considered when assessing substrate drugs disposition mediated by these metabolizing enzymes and transporters in the neonatal population.

PMID: 29436076 [PubMed - indexed for MEDLINE]