Gene Summary

Gene:CYP2C19; cytochrome P450 family 2 subfamily C member 19
Aliases: CPCJ, CYP2C, P450C2C, CYPIIC17, CYPIIC19, P450IIC19
Summary:This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum and is known to metabolize many xenobiotics, including the anticonvulsive drug mephenytoin, omeprazole, diazepam and some barbiturates. Polymorphism within this gene is associated with variable ability to metabolize mephenytoin, known as the poor metabolizer and extensive metabolizer phenotypes. The gene is located within a cluster of cytochrome P450 genes on chromosome 10q24. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:cytochrome P450 2C19
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (21)
Pathways:What pathways are this gene/protein implicaed in?
Show (5)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • drug, Thalidomide
  • Stereoisomerism
  • Aryl Hydrocarbon Hydroxylases
  • Tamoxifen
  • Oligonucleotide Array Sequence Analysis
  • Tandem Mass Spectrometry
  • Voriconazole
  • Urocortins
  • Smoking
  • Proguanil
  • Stomach Cancer
  • Genetic Predisposition
  • Polymorphism
  • Mixed Function Oxygenases
  • Polymerase Chain Reaction
  • Solid Phase Extraction
  • Cytochrome P-450 Enzyme System
  • Cyclophosphamide
  • Antineoplastic Agents
  • ATP Binding Cassette Transporter, Subfamily B
  • Cytochrome P-450 CYP3A
  • Rhabdomyolysis
  • CYP2D6
  • Tobacco, Smokeless
  • Chromosome 10
  • Cytochrome P-450 CYP2C19
  • Liver Cancer
  • Breast Cancer
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Prostate Cancer
  • Genotype
  • Single Nucleotide Polymorphism
  • Reproducibility of Results
  • Vinorelbine
  • Lung Cancer
  • Stomach Ulcer
  • Antineoplastic Agents, Hormonal
  • Case-Control Studies
  • Asian Continental Ancestry Group
  • Triple Negative Breast Cancer
  • Restriction Fragment Length Polymorphism
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: CYP2C19 (cancer-related)

Berrandou T, Mulot C, Cordina-Duverger E, et al.
Association of breast cancer risk with polymorphisms in genes involved in the metabolism of xenobiotics and interaction with tobacco smoking: A gene-set analysis.
Int J Cancer. 2019; 144(8):1896-1908 [PubMed] Related Publications
Single nucleotide polymorphisms (SNPs) in genes involved in xenobiotics metabolism (XM) are suspected to play a role in breast cancer risk. However, previous findings based on a SNP by SNP approach need to be replicated taking into account the combined effects of multiple SNPs. We used a gene-set analysis method to study the association between breast cancer risk and genetic variation in XM genes (seen as a set of SNPs) and in the XM pathway (seen as a set of genes). We also studied the interaction between variants in XM genes and tobacco smoking. The analysis was conducted in a case-control study of 1,125 cases and 1,172 controls. Using a dedicated chip, genotyping data of 585 SNPs in 68 XM genes were available. Genetic variation in the whole XM pathway was significantly associated with premenopausal breast cancer risk (p = 0.008). This association was mainly driven by genetic variation in NAT2, CYP2C18, CYP2C19, AKR1C2 and ALDH1A3. The association between the XM gene pathway and breast cancer was observed among current and previous smokers, but not among never smokers (p = 0.013 for interaction between XM genes and tobacco smoking status). The association with breast cancer risk indicates that XM genes variants may play a role in breast carcinogenesis through their detoxification function of environmental pollutants, such as those contained in tobacco smoke.

Guo XG, Wang ZH, Dong W, et al.
Specific CYP450 Genotypes in the Chinese Population Affect Sorafenib Toxicity in HBV/HCV-associated Hepatocellular Carcinoma Patients.
Biomed Environ Sci. 2018; 31(8):586-595 [PubMed] Related Publications
OBJECTIVE: The purpose of this study was to screen for frequencies of different CYP450 genotypes in the Chinese population and explore the relationship between sorafenib toxicity and CYP450 polymorphism.
METHODS: A total of 600 peripheral blood samples were obtained from two groups for this study. The first group of 300 samples were from Chinese patients with HBV/HCV-associated HCC, while the remaining 300 samples were from a healthy population of recruited subjects. Allele-specific PCR and long-fragment gene sequencing was used to identify the frequencies of CYP450 polymorphism. Aflatoxin-induced HCC rat models expressing CYP3A4*1, CYP3A5*3, CYP2C19*2, and CYP2D6*10 were established and treated with sorafenib at certain time points. Hepatic and renal function, along with plasma concentration of sorafenib, were monitored regularly.
RESULTS: The most common forms of CYP mutations in the Chinese population were identified. The levels of sorafenib plasma concentration, as well as damage to hepatic and renal function in aflatoxin-induced HCC rat models varied significantly across the different CYP genotypes.
CONCLUSION: The mutational frequencies of CYP3A5, CYP3A4, CYP2C19, and CYP2D6 genotypes varied among different ethnic groups and populations. Individuals with CYP3A5*3 demonstrated minimal sorafenib metabolism, which led to severe hepatic and renal damage. Inter-individual variability in sorafenib-toxicity may be interpreted by CYP450 genetic polymorphisms, suggesting that identification of CYP polymorphism within a certain population should be considered in sorafenib therapy.

Elfaki I, Mir R, Almutairi FM, Duhier FMA
Cytochrome P450: Polymorphisms and Roles in Cancer, Diabetes and Atherosclerosis
Asian Pac J Cancer Prev. 2018; 19(8):2057-2070 [PubMed] Free Access to Full Article Related Publications
Cytochromes P450s (CYPs) constitute a superfamily of enzymes that catalyze the metabolism of drugs and other substances. Endogenous substrates of CYPs include eicosanoids, estradiol, arachidonic acids, cholesterol, vitamin D and neurotransmitters. Exogenous substrates of CYPs include the polycyclic aromatic hydrocarbons and about 80% of currently used drugs. Some isoforms can activate procarcinogens to ultimate carcinogens. Genetic polymorphisms of CYPs may affect the enzyme catalytic activity and have been reported among different populations to be associated with various diseases and adverse drug reactions. With regard of drug metabolism, phenotypes for CYP polymorphism range from ultrarapid to poor metabolizers. In this review, we discuss some of the most clinically important CYPs isoforms (CYP2D6, CYP2A6, CYP2C19, CYP2C9, CYP1B1 and CYP1A2) with respect to gene polymorphisms and drug metabolism. Moreover, we review the role of CYPs in renal, lung, breast and prostate cancers and also discuss their significance for atherosclerosis and type 2 diabetes mellitus.

Kalra S, Kaur RP, Ludhiadch A, et al.
Association of CYP2C19*2 and ALDH1A1*1/*2 variants with disease outcome in breast cancer patients: results of a global screening array.
Eur J Clin Pharmacol. 2018; 74(10):1291-1298 [PubMed] Related Publications
PURPOSE: Cyclophosphamide and doxorubicin (adjuvant chemotherapy) are commonly used to treat breast cancer patients. Variation in the genes involved in pharmacodynamics and pharmacokinetics of these drugs plays an important role in prediction of drug response and survival. The present study was carried out with an aim to evaluate the variation in all the genes involved in pharmacokinetic and pharmacodynamics pathways of cyclophosphamide and doxorubicin, and correlate specific variants with disease outcome in breast cancer patients from the Malwa region of Punjab.
METHODS: A total of 250 confirmed breast cancer patients were involved in the study. Genotyping was performed on an Illumina Infinium HD assay platform using a Global Screening Array (GSA) microchip. GenomeStudio (Illumina, Inc.) was used for data preprocessing and a p value less than or equal to 5 × 10-8 was considered statistically significant. To rule out the influence of confounding risk factors, a step-wise multivariate regression analysis was carried out to evaluate the association of genotype with overall clinical outcome.
RESULTS: Two gene variants, CYP2C19 (G681A) and ALDH1A1*2 (17 bp deletion), were found to be significantly associated with the disease outcome, including overall survival, recurrence and metastasis, in breast cancer patients on adjuvant therapy. Both these genes are involved in the pharmacokinetics of cyclophosphamide. However, none of the variants in the genes involved in pharmacokinetics and pharmacodynamics of doxorubicin were found to have any significant impact on disease outcome in the studied group.
CONCLUSION: CYP2C19 (G681A) variant and ALDH1A1*2 emerged as two important biomarkers associated with bad outcome in breast cancer patients on adjuvant therapy.

Thota K, Prasad K, Basaveswara Rao MV
Detection of Cytochrome P450 Polymorphisms in Breast Cancer Patients May Impact on Tamoxifen Therapy
Asian Pac J Cancer Prev. 2018; 19(2):343-350 [PubMed] Free Access to Full Article Related Publications
Background: Breast cancer is the most common cancer among women worldwide. Tamoxifen (TAM), a selective estrogen receptor modulator, is widely used in its treatment. TAM is metabolized by cytochrome P450 (CYP450) enzymes, including CYP2D6, CYP3A5 and CYP2C19, whose genetic variations may have clinicopathological importance. However, reports on the association of various P450 polymorphisms with certain cancers are contradictory. Methods: We here investigated whether the prevalence of the four most common polymorphism in the CYP2D6*4 (G1934A), CYP2D6*10 (C188T), CYP3A5*3 and CYP2C19*2 alleles has any link with breast cancer using genomic DNA and polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. Results: Prevalences of CYP2D6*4, CYP2D6*10 and CYP2C19*2 genotypes were differed significantly (P = 0.01 and P = 0.004) between breast cancer patients and controls. The CYP3A5*3 genotype did not demonstrate statistically significant variation. Conclusion: Polymorphisms in CYP2 appear to be associated with breast cancer risk. Our data taken together with other reports indicates that drug resistance gene polymorphisms might be indicators of response to tamoxifen therapy in breast cancer cases.

Wang X, Yu T, Liao X, et al.
The prognostic value of CYP2C subfamily genes in hepatocellular carcinoma.
Cancer Med. 2018; 7(4):966-980 [PubMed] Free Access to Full Article Related Publications
Cytochrome P2C (CYP2C) subfamily members (CYP2C8, CYP2C9, CYP2C18, and CYP2C19) are known to participate in clinical drug metabolism. However, the association between CYP2C subfamily members and hepatocellular carcinoma (HCC) remains unclear. This study investigated the prognostic value of CYP2C subfamily gene expression levels with HCC prognosis. Data of 360 HCC patients in The Cancer Genome Atlas database and 231 in the Gene Expression Omnibus database were analyzed. Kaplan-Meier analysis and a Cox regression model were used to ascertain overall survival and recurrence-free survival, and to calculate median survival time using hazard ratios (HR) and 95% confidence intervals (CI). In TCGA database, low expression of CYP2C8, CYP2C9, and CYP2C19 in tumor tissue was associated with a short median survival time (all crude P = 0.001, adjusted P = 0.004, P = 0.047, and P = 0.020, respectively). In TCGA database, joint effects analysis of the combinations of CYP2C8 and CYP2C9, CYP2C8 and CYP2C19, and CYP2C9 and CYP2C19 revealed that high expression of two genes (group 4; group IV, group d) was associated with a reduced risk of death as compared to low expression (group 1, group I, and group a) (adjusted P = 0.005, P = 0.013, and P = 0.016, respectively). In TCGA database, joint effects analysis of CYP2C8, CYP2C9, and CYP2C19 showed that the risk of death from HCC was lower for groups C and D than for group A (adjusted P = 0.012 and P = 0.008, respectively). CYP2C8, CYP2C9, and CYP2C19 gene expression levels are potential prognostic markers of HCC following hepatectomy.

Xu W, McDonald-McGinn DM, Melchiorre AJ, et al.
Crouzon with Acanthosis Nigricans and Odontogenic Tumors: A Rare Form of Syndromic Craniosynostosis.
Cleft Palate Craniofac J. 2018; 55(2):296-300 [PubMed] Related Publications
Crouzon syndrome with acanthosis nigricans (CAN) is caused by a mutation in the fibroblast growth factor receptor ( FGFR) 3 gene that presents clinically as Crouzonoid craniofacial features in association with other anomalies such as acanthosis nigricans and benign odontogenic tumors. Diagnosis through the use of genetic mutational analysis is critical, as it alerts the surgeon to the need for careful screening for jaw tumors so that timely treatment in the form of curettage or segmental resection can be provided.

Tashiro M, Naito T, Kagawa Y, Kawakami J
Influence of cytochrome P450 genotype on the plasma disposition of prochlorperazine metabolites and their relationships with clinical responses in cancer patients.
Ann Clin Biochem. 2018; 55(3):385-393 [PubMed] Related Publications
Background Oral prochlorperazine, a dopamine D2 receptor antagonist, is largely metabolized to sulphoxide, 7-hydroxylate and N-desmethylate by cytochrome P450s (CYPs). This study evaluated the influence of CYP genotype on the plasma dispositions of prochlorperazine and its metabolites and their relationships with antiemetic efficacy and prolactin elevation in cancer patients. Methods Forty-eight cancer patients treated with oral prochlorperazine were enrolled. Plasma prochlorperazine and its metabolites concentrations and serum prolactin concentration were determined at 12 h after the evening dosing. The genotypes of CYP2C19, CYP2D6 and CYP3A5 and the incidences of nausea and vomiting were investigated. Results The plasma concentrations of the prochlorperazine metabolites were weakly correlated with that of the parent drug. The CYP genotypes did not affect the plasma concentrations of prochlorperazine and its metabolites. The plasma concentrations of prochlorperazine and its metabolites were not associated with the incidences of nausea and vomiting. The incidence of vomiting was significantly higher in females than in males. The serum prolactin concentration was weakly correlated with the plasma concentrations of prochlorperazine and its metabolites. The plasma concentrations of prochlorperazine metabolites rather than the parent drug had a weaker relation to serum prolactin concentration. Conclusions The CYP genotypes did not affect the plasma dispositions of prochlorperazine and its metabolites. The prochlorperazine metabolites did not have a strong effect on antiemetic efficacy, while they were slightly associated with prolactin secretion in cancer patients.

Lévi F, Karaboué A, Saffroy R, et al.
Pharmacogenetic determinants of outcomes on triplet hepatic artery infusion and intravenous cetuximab for liver metastases from colorectal cancer (European trial OPTILIV, NCT00852228).
Br J Cancer. 2017; 117(7):965-973 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The hepatic artery infusion (HAI) of irinotecan, oxaliplatin and 5-fluorouracil with intravenous cetuximab achieved outstanding efficacy in previously treated patients with initially unresectable liver metastases from colorectal cancer. This planned study aimed at the identification of pharmacogenetic predictors of outcomes.
METHODS: Circulating mononuclear cells were analysed for 207 single-nucleotide polymorphisms (SNPs) from 34 pharmacology genes. Single-nucleotide polymorphisms passing stringent Hardy-Weinberg equilibrium test were tested for their association with outcomes in 52 patients (male/female, 36/16; WHO PS, 0-1).
RESULTS: VKORC1 SNPs (rs9923231 and rs9934438) were associated with early and objective responses, and survival. For rs9923231, T/T achieved more early responses than C/T (50% vs 5%, P=0.029) and greatest 4-year survival (46% vs 0%, P=0.006). N-acetyltransferase-2 (rs1041983 and rs1801280) were associated with up to seven-fold more macroscopically complete hepatectomies. Progression-free survival was largest in ABCB1 rs1045642 T/T (P=0.026) and rs2032582 T/T (P=0.035). Associations were found between toxicities and gene variants (P<0.05), including neutropenia with ABCB1 (rs1045642) and SLC0B3 (rs4149117 and rs7311358); and diarrhoea with CYP2C9 (rs1057910), CYP2C19 (rs3758581), UGT1A6 (rs4124874) and SLC22A1 (rs72552763).
CONCLUSION: VKORC1, NAT2 and ABCB1 variants predicted for HAI efficacy. Pharmacogenetics could guide the personalisation of liver-targeted medico-surgical therapies.

Damkier P, Kjærsgaard A, Barker KA, et al.
CYP2C19*2 and CYP2C19*17 variants and effect of tamoxifen on breast cancer recurrence: Analysis of the International Tamoxifen Pharmacogenomics Consortium dataset.
Sci Rep. 2017; 7(1):7727 [PubMed] Free Access to Full Article Related Publications
The role of cytochrome P450 drug metabolizing enzymes in the efficacy of tamoxifen treatment of breast cancer is subject to substantial interest and controversy. CYP2D6 have been intensively studied, but the role of CYP2C19 is less elucidated, and we studied the association of CYPC19 genotype and recurrence of breast cancer. We used outcome and genotyping data from the large publicly available International Tamoxifen Pharmacogenomics Consortium (ITPC) dataset. Cox regression was used to compute the hazard ratios (HRs) for recurrence. CYP2C19 genotype data was available for 2 423 patients and the final sample cohort comprised 2 102 patients. CYP2C19*2 or *19 alleles did not influence DFS. For the CYP2C19*2 allele, the HR was 1.05 (CI 0.78-1.42) and 0.79 (CI 0.32-1.94) for hetero- and homozygote carriers, respectively. The corresponding HR for hetero- and homozygote carriers of the CYP2C19*17 allele were 1.02 (CI 0.71-1.46) and 0.57 (CI 0.26-1.24), respectively. Accounting for CYP2D6 genotype status did not change these estimates. We found no evidence to support a clinically meaningful role of CYP2C19 polymorphisms and response to tamoxifen in breast cancer patients and, consequently, CYP2C19 genotype status should not be included in clinical decisions on tamoxifen treatment.

Bhat GA, Bhat AB, Lone MM, Dar NA
Association of Genetic Variants of CYP2C19 and CYP2D6 with Esophageal Squamous Cell Carcinoma Risk in Northern India, Kashmir.
Nutr Cancer. 2017 May-Jun; 69(4):585-592 [PubMed] Related Publications
Genetic polymorphism in xenobiotic metabolizing enzymes (XMEs) is associated with various malignancies. However, the association of esophageal cancer with XMEs is mixed. The current study was aimed to explore the association of genetic polymorphisms of cytochrome (CYP) 2C19 and CYP2D6 genotypes with esophageal squamous cell carcinoma (ESCC) risk in Kashmir, India. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing methods were used for genotyping of 492 ESCC cases and equal number of individually matched controls. Conditional logistic regression models were used to assess odds ratios (ORs) and 95% confidence intervals. Increased ESCC risk was observed in subjects with variant genotypes of CYP2C19 (OR = 3.3) or CYP2D6 (OR = 2.1) and risk was higher (OR = 4.6) in subjects who harbored both the genotypes. Almost same but higher risk turned when subjects were smokers and carried a variant genotype of CYP2C19 (OR = 4.4) or CYP2D6 (OR = 4.7). Risk was appreciably increased in subjects who had family history of any cancer and also harbored a variant genotype of either CYP2C19 (OR = 15.5) or CYP2D6 (OR = 9.7). Subjects harboring a variant genotype of CYP2D6 showed an added risk when they used biomass as fuel (OR = 4.6). In conclusion, variant genotypes of CYP2C19 and CYP2D6 are associated with an increased risk of ESCC.

Ohnami S, Nagashima T, Urakami K, et al.
Whole exome sequencing detects variants of genes that mediate response to anticancer drugs.
J Toxicol Sci. 2017; 42(2):137-144 [PubMed] Related Publications
Certain interindividual differences affecting the efficacy of drug treatment and adverse drug reactions are caused by genetic variants, and their phenotypic effects differ among ethnic groups. In this study, we used whole exome sequencing (WES) systematically to identify germline mutations that influence the activities of drug-metabolizing enzymes, as well as that of a transporter. We analyzed DNA isolated from blood samples from 2,042 Japanese patients with diverse cancers. We identified sequence variants of CYP2B6 (rs3745274), CYP2C9 (rs1057910), CYP2C19 (rs4986893), CYP2C19 (rs4244285), TPMT (rs1142345), NAT2 (rs1799930), NAT2 (rs1799931), UGT1A1 (rs4148323), COMT (rs4680), ABCB1 (rs1045642), and CDA (rs60369023). Wider application of WES will help to determine the effects of mutations on the activities of proteins encoded by drug response genes, and the information gained will accelerate the development of personalized therapies for patients with cancer. Moreover, this knowledge may provide clues for preventing cancer before the onset of symptoms.

Biazi BI, Zanetti TA, Baranoski A, et al.
Cis-Nerolidol Induces Endoplasmic Reticulum Stress and Cell Death in Human Hepatocellular Carcinoma Cells through Extensive CYP2C19 and CYP1A2 Oxidation.
Basic Clin Pharmacol Toxicol. 2017; 121(4):334-341 [PubMed] Related Publications
Of late, many studies are attempting to find new molecules with anticancer properties, especially those with the capability to inhibit cell growth. The aim of this work was to evaluate nerolidol, a plant-based compound, as its cytotoxicity, genotoxicity, antiproliferative and apoptotic induction, cell cycle, mitochondrial membrane potential and RT-qPCR of transcripts related to those pathways in the human hepatocellular carcinoma cell line (HepG2/C3A). Only cis-nerolidol (C-NER) demonstrated cytotoxicity (100-250 μM) activity and was selected to conduct the following experiments. C-NER did not show genotoxic activity, but altered the mitochondrial membrane potential, reduced cell proliferation by arresting cell cycle in G1 phase and induced cell death. RT-qPCR showed that C-NER down-regulated genes related to apoptosis (BAK1, BAX, CAPN1, CASP8, CASP9, PARP1 and TP53), cell cycle (CCND1, CCNE1, CDK1 and CDK2), xenobiotic metabolism (CYP2D6 and CYP3A4) and paraptosis (IGF1R receptor). Up-regulation was seen in case of genes related to cell survival (BBC3 and MYC) and reticulum stress protein response (EIF2AK3 and ERN1) and xenobiotic metabolism (CYP1A2 and CYP2C19). We deduced that the antiproliferative activity of C-NER is attributable to its modulation of the cyclins and cyclin-dependent kinases as these proteins are necessary for G1/S phase transition. EIF2AK3, ERN1, CYP2C19 and CYP1A2 up-regulation suggests that endoplasmic reticulum stress was induced owing to the increased activity of cytochrome P450 enzymes. Caspase-independent cell death was also observed, indicating that another type of cell death, paraptosis, was triggered. Our results indicate that C-NER has considerable potential in anticancer therapy because it modulates important molecular targets of cell survival and proliferation.

Shu W, Chen L, Hu X, et al.
Cytochrome P450 Genetic Variations Can Predict mRNA Expression, Cyclophosphamide 4-Hydroxylation, and Treatment Outcomes in Chinese Patients With Non-Hodgkin's Lymphoma.
J Clin Pharmacol. 2017; 57(7):886-898 [PubMed] Related Publications
To investigate the impact of cytochrome P450 (CYP) genetic polymorphisms CYP2B6, CYP2C19, and CYP3A5 on mRNA expression, cyclophosphamide/4-hydroxycyclophosphamide pharmacokinetics, and treatment outcomes of the R-CHOP regimen (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) in Chinese patients with non-Hodgkin's lymphoma, 567 cases were investigated. Plasma concentrations of cyclophosphamide/4-hydroxycyclophosphamide were determined using liquid chromatography-tandem mass spectrometry and pharmacokinetic parameters calculated. The frequencies of CYP2B6*1/*29 and CYP2B6*1/*30 were 18 (3.2%) and 30 (5.3%), respectively. Liver samples with CYP2B6*29/*30, CYP2C19*2, CYP2B6*6, or CYP3A5*3 had significantly lower target mRNA expression. Samples with CYP2B6*6 and/or CYP2C19*2 had lower exposure to 4-hydroxycyclophosphamide, whereas those with CYP2B6*1G/*1H had higher exposure. Multivariate model showed that samples with CYP2C19*2 or CYP2B6 785A>raG had worse treatment response than samples with CYP3A5*3. CYP2C19*2, CYP2B6*6, CYP2B6*29, and CYP2B6*30 were protective factors for toxicity in the multivariate model. The best model for gene-gene interactions for treatment response contained CYP2C19*2, CYP2B6 785A>G, and CYP3A5*3 (cross-validation consistency [CVC], 8/10; P = .0035). The best prediction model for grade 2-4 toxicities had CYP2C19*2, CYP2B6 785A>G, and 516 G>T (CVC, 10/10; P < .0001). In previous reports, we were the first to report that the frequency of copy-number variations in CYP2B6 is higher among Chinese than among other ethnic populations. Genetic variations in CYP2B6, CYP2C19, and CYP3A5 dramatically affected the mRNA expression of proteins, the pharmacokinetics of 4-hydroxycyclophosphamide, and the R-CHOP treatment response in Chinese subjects. Patients carrying CYP3A5*3 were more likely to have a better treatment response, whereas patients with CYP2C19*2 or CYP2B6 516G>T, or CYP2B6 785A>G had higher tolerance to treatment.

Kuo SH, Yang SY, You SL, et al.
Polymorphisms of ESR1, UGT1A1, HCN1, MAP3K1 and CYP2B6 are associated with the prognosis of hormone receptor-positive early breast cancer.
Oncotarget. 2017; 8(13):20925-20938 [PubMed] Free Access to Full Article Related Publications
In this study, we investigated whether single nucleotide polymorphisms (SNPs) identified by genome-wide association study (GWAS) (MAP3K1, FGFR2, TNRC9, HCN1, and 5p12), and SNPs involved in the metabolism of estrogen (CYP19, COMT, ESR1, and UGT1A1), tamoxifen (CYP2C9, CYP2C19, CYP3A5, and CYP2D6), and chemotherapeutic agents (ABCB1, ALDH3A1, and CYP2B6) are associated with the prognoses of 414 hormone receptor (HR)-positive early breast cancers with negative or 1 to 3 nodal metastases. At a median follow-up period of 10.6 years, 363 patients were alive, and 51 (12.3%) had died. Multiple-adjusted hazard ratios (aHRs) and the corresponding 95% confidence intervals for distant disease-free survival (DDFS), disease-free survival (DFS), and overall survival (OS) in association with the genotypes of 34 SNPs from the above-mentioned 16 genes were evaluated, using the stepwise selection Cox model. We found that the SNP, ESR1-codon325 rs1801132 (G/G+G/C), was associated with a longer DDFS, whereas UGT1A1 rs4148323 (A/A+A/G), and HCN1 rs981782 (A/A+A/C) were significantly associated with poorer DDFS. MAP3K1 rs889312 (C/C) and CYP2B6 rs3211371 (T/C) were significantly associated with poor DFS, DDFS and OS. Among premenopausal women, MAP3K1 rs889312 (C/C), CYP2B6 rs3211371 (T/C), CYP2B6 rs4802101 (T/T), ABCB1 rs2032582 (C/C), and ALDH3A1 rs2231142 (G/G) were significantly associated with poor DDFS, DFS, or OS. Our results provide additional evidence that genetic polymorphisms observed in SNPs are associated with the prognoses of patients with HR-positive breast cancers; this may indicate different treatment strategies for these patients.

Tecza K, Pamula-Pilat J, Lanuszewska J, Grzybowska E
Genetic polymorphisms and response to 5-fluorouracil, doxorubicin and cyclophosphamide chemotherapy in breast cancer patients.
Oncotarget. 2016; 7(41):66790-66808 [PubMed] Free Access to Full Article Related Publications
Clinical resistance to chemotherapy is one of the major problems in breast cancer treatment. In this study we analyzed possible impact of 22 polymorphic variants on the treatment response in 324 breast cancer patients. Selected genes were involved in FAC chemotherapy drugs transport (ABCB1, ABCC2, ABCG2, SLC22A16), metabolism (CYP1B1, CYP2C19, GSTT1, GSTM1, GSTP1, TYMS, MTHFR, DPYD), drug-induced damage repair (ERCC1, ERCC2, XRCC1) and involved in regulation of DNA damage response and cell cycle control (ATM, TP53).Apart from preexisting metastases three polymorphic variants were independent prognostic high risk factors of lack of response to FAC chemotherapy. Our results showed that the response to treatment depended of the variability in genes engaged in drugs' transport (ABCC2 c.-24C>T, ABCB1 p.Ser893Ala/Thr) and in DNA repair machinery (ERCC2 p.Lys751Gln). Furthermore, the growing number of high-risk genotypes was reflected in gradual increase in risk of the non-responsiveness to treatment- from OR 2.68 for presence of two genotypes to OR 9.93 for carriers of all three negative genotypes in the group of all patients. Similar gene-dosage effect was observed in the subgroup of TNBCs. Also, TFFS significantly shortened with the increasing number of high-risk genotypes, with median of 54.4 months for carriers of one variant, to 51.5 and 34.9 months for the carriers of two and three genotypes, respectively.Our results demonstrate that results of cancer treatment are the effect of many clinical and genetic factors. It seems that multifactorial polymorphic models could be a potentially useful tool in personalization of cancer therapies. The novelty in our model is the over representation of triple negative breast cancer (TNBC) patients among the carriers of all unfavorable polymorphic variants. This finding contributes to the elucidation of the mechanisms of drug resistance in this subgroup of breast cancer patients.

Tang X, Ge L, Chen Z, et al.
Methylation of the Constitutive Androstane Receptor Is Involved in the Suppression of CYP2C19 in Hepatitis B Virus-Associated Hepatocellular Carcinoma.
Drug Metab Dispos. 2016; 44(10):1643-52 [PubMed] Related Publications
Hepatocellular carcinoma (HCC), one of the most dangerous malignancies with an increasing incidence and a high mortality rate, represents a major international health problem. HCC progression is known to involve genome-wide alteration of epigenetic modifications, leading to aberrant gene expression patterns. The activity of CYP2C19, an important member of the cytochrome P450 superfamily, was reported to be compromised in HCC, but the underlying mechanism remains unclear. To understand whether epigenetic modification in HCC is associated with a change in CYP2C19 activity, we evaluated the expression levels of CYP2C19 and its transcription factors by quantitative real-time polymerase chain reaction using mRNA extracted from both primary hepatocytes and paired tumor versus nontumor liver tissues of patients infected with hepatitis B virus (HBV). DNA methylation was examined by bisulfite sequencing and methylation-specific polymerase chain reaction. Our results indicated that CYP2C19 could be regulated by e-box methylation of the constitutive androstane receptor (CAR). Decreased CYP2C19 expression in tumorous tissues of HBV-infected patients with HCC was highly correlated with suppressed expression and promoter hypermethylation of CAR. Our study demonstrates that aberrant CAR methylation is involved in CYP2C19 regulation in HBV-related HCC and may play a role in liver tumorigenesis.

Tan EC, Lim HW, Lim ECP, Lee ST
A Novel Interferon Regulatory Factor 6 Mutation in an Asian Family With Van der Woude Syndrome.
Cleft Palate Craniofac J. 2017; 54(4):442-445 [PubMed] Related Publications
Van der Woude syndrome (VWS) is a rare autosomal dominant genetic disorder characterized by orofacial clefting and lip pits. Mutations in the transcription factor interferon regulatory factor 6 gene (IRF6) have been identified in individuals with VWS. We performed direct sequencing of the gene for molecular investigation of a proband with Bangladeshi-Malay ancestry. A novel transition mutation (c.113T>C), which resulted in an amino acid substitution (p.Ile38Thr) in the deoxyribonucleic acid-binding domain was detected. Testing of family members showed that the mutation segregated with the VWS phenotype for members of her immediate family. Although there is some phenotypic variability, all of the affected members are of the female gender.

Zhou J, Wen Q, Li SF, et al.
Significant change of cytochrome P450s activities in patients with hepatocellular carcinoma.
Oncotarget. 2016; 7(31):50612-50623 [PubMed] Free Access to Full Article Related Publications
The lack of information concerning individual variation in drug-metabolizing enzymes is one of the most important obstacles for designing personalized medicine approaches for hepatocellular carcinoma (HCC) patients. To assess cytochrome P450 (CYP) in the metabolism of endogenous and exogenous molecules in an HCC setting, the activity changes of 10 major CYPs in microsomes from 105 normal and 102 HCC liver tissue samples were investigated. We found that CYP activity values expressed as intrinsic clearance (CLint) differed between HCC patients and control subjects. HCC patient samples showed increased CLint for CYP2C9, CYP2D6, and CYP2E1 compared to controls. Meanwhile, CYP1A2, CYP2C8, and CYP2C19 CLint values decreased and CYP2A6, CYP2B6, and CYP3A4/5 activity was unchanged relative to controls. For patients with HCC accompanied by fibrosis or cirrhosis, the same activity changes were seen for the CYP isoforms, except for CYP2D6 which had higher values in HCC patients with cirrhosis. Moreover, CYP2D6*10 (100C>T), CYP2C9*3 (42614 A>C), and CYP3A5*3 (6986A>G) polymorphisms had definite effects on enzyme activities. In the HCC group, the CLint of CYP2D6*10 mutant homozygote was decreased by 95% compared to wild-type samples, and the frequency of this homozygote was 2.8-fold lower than the controls.In conclusion, the activities of CYP isoforms were differentially affected in HCC patients. Genetic polymorphisms of some CYP enzymes, especially CYP2D6*10, could affect enzyme activity. CYP2D6*10 allelic frequency was significantly different between HCC patients and control subjects. These findings may be useful for personalizing the clinical treatment of HCC patients as well as predicting the risk of hepatocarcinogenesis.

Powers JL, Buys SS, Fletcher D, et al.
Multigene and Drug Interaction Approach for Tamoxifen Metabolite Patterns Reveals Possible Involvement of CYP2C9, CYP2C19, and ABCB1.
J Clin Pharmacol. 2016; 56(12):1570-1581 [PubMed] Related Publications
Tamoxifen is metabolically activated to 4-hydroxytamoxifen and endoxifen by cytochrome P450 (CYP). CYP phenotypes have been correlated to tamoxifen outcomes, but few have considered drug interactions or combinations of genes. Fewer still have considered ABCB1, which encodes P-glycoprotein and transports active tamoxifen metabolites. We compared the concentrations of tamoxifen and metabolites in 116 breast cancer patients with predicted phenotypes for CYP2D6, CYP3A4, CYP3A5, CYP2C9, CYP2C19, and ABCB1 genotypes. A significant correlation between CYP2D6 phenotypes and tamoxifen metabolites was seen, strongest for endoxifen (P < .0001). Statistical fit of the data improved when using gene activity scores adjusted for known drug interactions. Concentration of tamoxifen was significantly higher (P = .02) for patients taking a CYP2C19 inhibitor. No significant relationships were found for other genes unless patients were subgrouped according to CYP2D6 phenotypes or ABCB1 genotypes. Lower concentrations of endoxifen and endoxifen/4-hydroxytamoxifen ratios were seen with impaired CYP2C9 (P = .05 and P = .03, respectively) if patients had the same CYP2D6 phenotype and were not taking a CYP2D6 or CYP2C19 inhibitor. Lower concentrations of 4-hydroxytamoxifen were seen for impaired CYP2C19 when ABCB1 SNP3435 was nonvariant (P = .04). With 3 impaired CYP phenotypes, endoxifen concentrations were lower than if only CYP2D6 was impaired (P = .05). When CYP2D6 was impaired, ABCB1 3435 CC (rs1045642) was associated with significantly higher endoxifen (P = .03). Thus, impairment in CYP2C9, CYP2C19, or ABCB1 contributes to a lower steady-state endoxifen concentration at the dose studied. These studies represent an improved way of examining relationships between pharmacogenetics, drug concentrations, and clinical outcomes and warrants study in larger populations.

Yamauchi K, Kokuryo T, Yokoyama Y, et al.
Prediction of Early Recurrence After Curative Resection of Colorectal Liver Metastasis and Subsequent S-1 Chemotherapy.
Anticancer Res. 2016; 36(5):2175-9 [PubMed] Related Publications
BACKGROUND: S-1, an oral 5-fluorouracil (5-FU)-based medicine that combines tegafur, gimeracil and oteracil potassium is commonly used as an adjuvant chemotherapeutic drug for the treatment of colorectal cancer.
PATIENTS AND METHODS: We enrolled 53 patients who underwent curative resection for colorectal cancer and liver metastasis (synchronous, n=24; metachronous, n=29). The subsequent adjuvant chemotherapy with oral S-1 administration was initiated within 56 days after liver resection. Recurrence was evaluated by imaging studies, that were performed during the first year after liver resection. Of the 53 patients, 25 who did not recur within 1 year were defined as being in the no-recurrence (NREC) group and the remaining 18 patients were defined as being in the early-recurrence (EREC) group. There were no significant differences in gene expression profiling for drug resistance and metabolism between the NREC group and the EREC group.
RESULTS: In synchronous liver metastasis, there was no significant difference in early recurrence between serum carcinoembryonic antigen (CEA) ≤5 ng/ml and serum CEA >5 ng/ml (8/24 vs. 16/24, respectively). In metachronous liver metastasis, the early recurrence rate was significantly higher in patients with CEA >5 ng/ml compared to patients with CEA ≤5 ng/ml (15/29 vs. 14/29, p=0.05). The expression of cytochrome P450 2C19 (CYP2C19) and ATP-binding cassette, sub-family B member 1 (ABCB1) were significantly lower in the EREC group (6/15) compared to the NREC group (9/15) in colorectal cancer with metachronous liver metastasis and with serum CEA >5 ng/ml.
CONCLUSION: Although the exact reason for down-regulation of these genes in the group with poor prognosis is unknown, the information obtained in this study may be useful in clinical practice for colorectal cancer.

Lim JS, Sutiman N, Muerdter TE, et al.
Association of CYP2C19*2 and associated haplotypes with lower norendoxifen concentrations in tamoxifen-treated Asian breast cancer patients.
Br J Clin Pharmacol. 2016; 81(6):1142-52 [PubMed] Free Access to Full Article Related Publications
AIM: The aim was to examine the influence of CYP2C19 variants and associated haplotypes on the disposition of tamoxifen and its metabolites, particularly norendoxifen (NorEND), in Asian patients with breast cancer.
METHODS: Sixty-six CYP2C19 polymorphisms were identified in healthy Asians (n = 240), of which 14 were found to be tightly linked with CYP2C19*2, CYP2C19*3 and CYP2C19*17. These 17 SNPs were further genotyped in Asian breast cancer patients receiving tamoxifen (n = 201). Steady-state concentrations of tamoxifen and its metabolites were quantified using liquid chromatography–mass spectrometry. Non-parametric tests and regression methods were implemented to evaluate genotypic–phenotypic associations and haplotypic effects of the SNPs.
RESULTS: CYP2C19 functional polymorphisms and their linked SNPs were not significantly associated with plasma concentrations of tamoxifen and its main metabolites N-desmethyltamoxifen, (Z)-4-hydroxytamoxifen and (Z)-Endoxifen. However, CYP2C19*2 and its seven linked SNPs were significantly associated with lower NorEND concentrations, MRNorEND/NDDM and MRNorEND/(Z)-END. Specifically, patients carrying the CYP2C19*2 variant allele A had significantly lower NorEND concentrations [median (range), GG vs. GA vs. AA: 1.51 (0.38–3.28) vs. 1.28 (0.30–3.36) vs. 1.15 ng ml−1 (0.26–2.45, P = 0.010)] as well as significantly lower MRNorEND/(Z)-END [GG vs. GA vs. AA: 9.40 (3.27–28.35) vs. 8.15 (2.67–18.9) vs. 6.06 (4.47–14.6), P < 0.0001] and MRNorEND/NDDM [GG vs. GA vs. AA: 2.75 (0.62–6.26) vs. 2.43 (0.96–4.18) vs. 1.75 (1.10–2.49), P < 0.00001]. CYP2C19 H2 haplotype, which included CYP2C19*2, was also significantly associated with lower NorEND concentrations (P = 0.0020), MRNorEND/NDDM (P < 0.0001) and MRNorEND/(Z)-END (P < 0.0001), indicating significantly lower formation rates of NorEND.
CONCLUSION: These data highlight the potential relevance of CYP2C19 pharmacogenetics in influencing NorEND concentrations in tamoxifen-treated patients, which may influence treatment outcomes.

Veal GJ, Cole M, Chinnaswamy G, et al.
Cyclophosphamide pharmacokinetics and pharmacogenetics in children with B-cell non-Hodgkin's lymphoma.
Eur J Cancer. 2016; 55:56-64 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: Variation in cyclophosphamide pharmacokinetics and metabolism has been highlighted as a factor that may impact on clinical outcome in various tumour types. The current study in children with B-cell non-Hodgkin's lymphoma (NHL) was designed to corroborate previous findings in a large prospective study incorporating genotype for common polymorphisms known to influence cyclophosphamide pharmacology.
METHODS: A total of 644 plasma samples collected over a 5 year period, from 49 B-cell NHL patients ≤ 18 years receiving cyclophosphamide (250 mg/m(2)), were used to characterise a population pharmacokinetic model. Polymorphisms in genes including CYP2B6 and CYP2C19 were analysed.
RESULTS: A two-compartment model provided the best fit of the population analysis. The mean cyclophosphamide clearance value following dose 1 was significantly lower than following dose 5 (1.83 ± 1.07 versus 3.68 ± 1.43 L/h/m(2), respectively; mean ± standard deviation from empirical Bayes estimates; P < 0.001). The presence of at least one CYP2B6*6 variant allele was associated with a lower cyclophosphamide clearance following both dose 1 (1.54 ± 0.11 L/h/m(2) versus 2.20 ± 0.31 L/h/m(2), P = 0.033) and dose 5 (3.12 ± 0.17 L/h/m(2) versus 4.35 ± 0.37 L/h/m(2), P = 0.0028), as compared to homozygous wild-type patients. No pharmacokinetic parameters investigated were shown to have a significant influence on progression free survival.
CONCLUSION: The results do not support previous findings of a link between cyclophosphamide pharmacokinetics or metabolism and disease recurrence in childhood B-cell NHL. While CYP2B6 genotype was shown to influence pharmacokinetics, there was no clear impact on clinical outcome.

Agarwal G, Tulsyan S, Lal P, Mittal B
Generalized Multifactor Dimensionality Reduction (GMDR) Analysis of Drug-Metabolizing Enzyme-Encoding Gene Polymorphisms may Predict Treatment Outcomes in Indian Breast Cancer Patients.
World J Surg. 2016; 40(7):1600-10 [PubMed] Related Publications
BACKGROUND: Prediction of response and toxicity of chemotherapy can help personalize the treatment and choose effective yet non-toxic treatment regimen for a breast cancer patient. Interplay of variations in various drug-metabolizing enzyme (DME)-encoding genes results in variable response and toxicity of chemotherapeutic drugs. Generalized multi-analytical (GMDR) approach was used to determine the influence of the combination of variants of genes encoding phase 0 (SLC22A16); phase I (CYP450, NQO1); phase II (GSTs, MTHFR, UGT2B15); and phase III (ABCB1) DMEs along with confounding factors on the response and toxicity of chemotherapeutic drugs in breast cancer patients.
METHODS: In an Indian breast cancer patient cohort (n = 234), response to neo-adjuvant chemotherapy (n = 111) and grade 2-4 toxicity to chemotherapy were recorded. Patients were genotyped for 19 polymorphisms selected in four phases of DMEs by PCR or PCR-RFLP or Taqman allelic discrimination assay. Binary logistic regression and GMDR analysis was performed. Bonferroni test for multiple comparisons was applied, and p value was considered to be significant at <0.025.
RESULTS: For ABCB1 1236C>T polymorphism, CT genotype was found to be significantly associated with response to NACT in uni-variate and multi-variate analysis (p = 0.018; p = 0.013). The TT genotype of NQO1 609C>T had a significant association with (absence of) grade 2-4 toxicity in uni-variate analysis (p = 0.021), but a non-significant correlation in multi-variate analysis. In GMDR analysis, interaction of CYP3A5*3, NQO1 609C>T, and ABCB1 1236C>T polymorphisms yielded the highest testing accuracy for response to NACT (CVT = 0.62). However, for grade 2-4 toxicity, CYP2C19*2 and ABCB1 3435C>T polymorphisms yielded the best interaction model (CVT = 0.57).
CONCLUSION: This pharmacogenetic study suggests a role of higher order gene-gene interaction of DME-encoding genes, along with confounding factors, in determination of treatment outcomes and toxicity in breast cancer patients. This can be used as a potential objective tool for individualizing breast cancer chemotherapy with high efficacy and low toxicity.

Yoshizawa Y, Sugimoto M, Sato Y, et al.
Factors associated with healing of artificial ulcer after endoscopic submucosal dissection with reference to Helicobacter pylori infection, CYP2C19 genotype, and tumor location: Multicenter randomized trial.
Dig Endosc. 2016; 28(2):162-72 [PubMed] Related Publications
BACKGROUND AND AIM: Healing speed of peptic ulcer is affected by a number of factors, including Helicobacter pylori (H. pylori) infection and intragastric pH. Acid inhibition exerted by proton pump inhibitors differs by CYP2C19 genotype. Herein, we investigated whether healing speed of artificial ulcers formed after endoscopic submucosal dissection (ESD) was influenced by H. pylori infection, CYP2C19 genotype, or other factors.
METHODS: A total of 96 H. pylori-positive patients with gastric tumors scheduled for ESD were randomly assigned to receive eradication therapy for H. pylori before ESD (pre-ESD eradication) (n = 44) or after (post-ESD eradication) (n = 52). Patients received eradication therapy consisting of lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 200 mg twice daily for 1 week. After ESD, lansoprazole 30 mg was given once daily for 8 weeks. Ulcer size was endoscopically measured on the next day and at 4 and 8 weeks after ESD.
RESULTS: Mean reduction rate of artificial ulcer area in the pre-ESD eradication group was 94.7% ± 5.5% at 4 weeks, which was similar to that in the post-ESD eradication group (94.7% ± 6.7%, P = 0.987), irrespective of CYP2C19 genotype. In multivariate analyses, location of gastric tumor (middle and upper, odds ratio: 4.05, 95% CI: 1.620-10.230, P = 0.003) was a factor for 97% reduction of artificial ulcer area at 4 weeks post-ESD, but CYP2C19 genotype and H. pylori infection were not.
CONCLUSION: Healing speed of ESD-induced artificial ulcer was affected by tumor location, but not by time of H. pylori eradication, resected size, or CYP2C19 genotype.

Bhat GA, Shah IA, Rafiq R, et al.
Family history of cancer and the risk of squamous cell carcinoma of oesophagus: a case-control study in Kashmir, India.
Br J Cancer. 2015; 113(3):524-32 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Only a few studies have examined the association between family history of cancer (FHC) and the risk of oesophageal squamous cell carcinoma (ESCC) in high incidence areas of ESCC. We conducted a case-control study to evaluate the relationship between FHC and ESCC risk in Kashmir, India, with analysis of detailed epidemiological data and information on multiple gene polymorphisms.
METHODS: We collected detailed information on FHC and a number of socio-demographic and lifestyle factors, and also obtained blood samples for genetic analysis from 703 histopathologically confirmed ESCC cases and 1664 individually matched controls. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs).
RESULTS: Participants who had FHC showed a strong association with ESCC risk, and the risk was stronger when first-degree relatives (FDRs) had FHC (OR=6.8; 95% CI=4.6-9.9). Having a sibling with a cancer showed the strongest association (OR=10.8; 95% CI=6.0-19.3), but having a child with a cancer was not associated with ESCC risk. A history of any cancer in the spouse was also associated with ESCC risk (OR=4.1; 95% CI=1.6-10.2). Those with two or more relatives with FHC were at a higher risk of ESCC. After restricting FHC to familial ESCC only, the above associations were strengthened, except when spouses were affected with ESCC (OR=2.5; 95% CI=0.7-8.9). When we examined the associations between several single-nucleotide polymorphisms and ESCC in those with and without FHC, the associations of variant genotypes in cytochrome P450 (CYP) 2C19 and CYP2D6 and the wild genotype of CYP2E1 with ESCC were much stronger in those with FHC. The FHC had an additive interaction with several risk factors of ESCC in this population.
CONCLUSION: Our results showed that FHC was strongly associated with ESCC risk in Kashmir. It seems both genetic factors and shared environment are involved in this association.

Rodríguez-Sanz M, García-Giralt N, Prieto-Alhambra D, et al.
CYP11A1 expression in bone is associated with aromatase inhibitor-related bone loss.
J Mol Endocrinol. 2015; 55(1):69-79 [PubMed] Related Publications
Aromatase inhibitors (AIs) used as adjuvant therapy in postmenopausal women with hormone receptor-positive breast cancer cause diverse musculoskeletal side effects that include bone loss and its associated fracture. About half of the 391 patients treated with AIs in the Barcelona-Aromatase induced bone loss in early breast cancer cohort suffered a significant bone loss at lumbar spine (LS) and/or femoral neck (FN) after 2 years on AI-treatment. In contrast, up to one-third (19.6% LS, 38.6% FN) showed no decline or even increased bone density. The present study aimed to determine the genetic basis for this variability. SNPs in candidate genes involved in vitamin D and estrogen hormone-response pathways (CYP11A1, CYP17A1, HSD3B2, HSD17B3, CYP19A1, CYP2C19, CYP2C9, ESR1, DHCR7, GC, CYP2R1, CYP27B1, VDR and CYP24A1) were genotyped for association analysis with AI-related bone loss (AIBL). After multiple testing correction, 3 tag-SNPs (rs4077581, s11632698 and rs900798) located in the CYP11A1 gene were significantly associated (P<0.005) with FN AIBL at 2 years of treatment. Next, CYP11A1 expression in human fresh bone tissue and primary osteoblasts was demonstrated by RT-PCR. Both common isoforms of human cholesterol side-chain cleavage enzyme (encoded by CYP11A1 gene) were detected in osteoblasts by western blot. In conclusion, the genetic association of CYP11A1 gene with AIBL and its expression in bone tissue reveals a potential local function of this enzyme in bone metabolism regulation, offering a new vision of the steroidogenic ability of this tissue and new understanding of AI-induced bone loss.

de Vries Schultink AH, Zwart W, Linn SC, et al.
Effects of Pharmacogenetics on the Pharmacokinetics and Pharmacodynamics of Tamoxifen.
Clin Pharmacokinet. 2015; 54(8):797-810 [PubMed] Free Access to Full Article Related Publications
The antiestrogenic drug tamoxifen is widely used in the treatment of estrogen receptor-α-positive breast cancer and substantially decreases recurrence and mortality rates. However, high interindividual variability in response is observed, calling for a personalized approach to tamoxifen treatment. Tamoxifen is bioactivated by cytochrome P450 (CYP) enzymes such as CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4/5, resulting in the formation of active metabolites, including 4-hydroxy-tamoxifen and endoxifen. Therefore, polymorphisms in the genes encoding these enzymes are proposed to influence tamoxifen and active tamoxifen metabolites in the serum and consequently affect patient response rates. To tailor tamoxifen treatment, multiple studies have been performed to clarify the influence of polymorphisms on its pharmacokinetics and pharmacodynamics. Nevertheless, personalized treatment of tamoxifen based on genotyping has not yet met consensus. This article critically reviews the published data on the effect of various genetic polymorphisms on the pharmacokinetics and pharmacodynamics of tamoxifen, and reviews the clinical implications of its findings. For each CYP enzyme, the influence of polymorphisms on pharmacokinetic and pharmacodynamic outcome measures is described throughout this review. No clear effects on pharmacokinetics and pharmacodynamics were seen for various polymorphisms in the CYP encoding genes CYP2B6, CYP2C9, CYP2C19 and CYP3A4/5. For CYP2D6, there was a clear gene-exposure effect that was able to partially explain the interindividual variability in plasma concentrations of the pharmacologically most active metabolite endoxifen; however, a clear exposure-response effect remained controversial. These controversial findings and the partial contribution of genotype in explaining interindividual variability in plasma concentrations of, in particular, endoxifen, imply that tailored tamoxifen treatment may not be fully realized through pharmacogenetics of metabolizing enzymes alone.

Peng XE, Chen HF, Hu ZJ, Shi XS
Independent and combined effects of environmental factors and CYP2C19 polymorphisms on the risk of esophageal squamous cell carcinoma in Fujian Province of China.
BMC Med Genet. 2015; 16:15 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The purpose of this study was to explore the effects of CYP2C19 gene polymorphisms and various environmental factors and their interactions on the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese Han population.
METHODS: A 1:2 frequency-matched case control study of 285 patients and 570 controls was conducted from June 2010 to May 2011 in AnXi of Fujian province, China. Environmental factors were investigated using a self-administered questionnaire and genotypes were determined using polymerase chain reaction restriction fragment length polymorphism based methods. Unconditional logistic regression models were used for statistical evaluation.
RESULTS: Current or former smoking, consumption of pickled vegetables or hot beverages/food, having a first degree relative with ESCC and history of reflux esophagitis were significantly associated with increased ESCC risk, whereas tea drinking and consumption of fresh vegetables and fruits were significantly associated with decreased risk. The CYP2C19*2 GA/AA genotype was significantly more prevalent in ESCC patients and individuals with at least one copy of the CYP2C19*2 A allele had a 3.19-fold increased risk (adjusted 95% confidence interval (CI): 2.21-4.61, P < 0.001) of ESCC compared with those without this allele. We found no significant associations between CYP2C19*3 genotypes and ESCC. The Cyp2C19*2 polymorphism appeared to have a multiplicative joint effect with tea drinking and hot beverage/food consumption (gene-tea drinking: P(interaction) = 0.042; hot beverage/food consumption: P(interaction) = 6.98 × 10(-6)) and an additive joint effect with pickled vegetable consumption (interaction contrast ratio = 1.96, 95% CI: 0.12-3.80).
CONCLUSIONS: Our findings suggest that the CYP2C19*2 polymorphism plays an important role in the development of ESCC in the Chinese population, modified by tea drinking and consumption of pickled vegetables or hot beverages/food. Further studies are warranted to confirm our results.

Theile D, Haefeli WE, Weiss J
Effects of adrenolytic mitotane on drug elimination pathways assessed in vitro.
Endocrine. 2015; 49(3):842-53 [PubMed] Related Publications
Mitotane (1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane, o,p'-DDD) represents one of the most active drugs for the treatment of adrenocortical carcinoma. Its metabolites 1,1-(o,p'-dichlorodiphenyl) acetic acid (=o,p'-DDA) and 1,1-(o,p'-dichlorodiphenyl)-2,2 dichloroethene (=o,p'-DDE) partly contribute to its pharmacological effects. Because mitotane has a narrow therapeutic index and causes pharmacokinetic drug-drug interactions, knowledge about these compounds' effects on drug metabolizing and transporting proteins is crucial. Using quantitative real-time polymerase chain reaction, our study confirmed the strong inducing effects of o,p'-DDD on mRNA expression of cytochrome P450 3A4 (CYP3A4, 30-fold) and demonstrated that other enzymes and transporters are also induced (e.g., CYP1A2, 8.4-fold; ABCG2 (encoding breast resistance cancer protein, BCRP), 4.2-fold; ABCB1 (encoding P-glycoprotein, P-gp) 3.4-fold). P-gp induction was confirmed at the protein level. o,p'-DDE revealed a similar induction profile, however, with less potency and o,p'-DDA had only minor effects. Reporter gene assays clearly confirmed o,p'-DDD to be a PXR activator and for the first time demonstrated that o,p'-DDE and o,p'-DDA also activate PXR albeit with lower potency. Using isolated, recombinant CYP enzymes, o,p'-DDD and o,p'-DDE were shown to strongly inhibit CYP2C19 (IC50 = 0.05 and 0.09 µM). o,p'-DDA exhibited only minor inhibitory effects. In addition, o,p'-DDD, o,p'-DDE, and o,p'-DDA are demonstrated to be neither substrates nor inhibitors of BCRP or P-gp function. In summary, o,p'-DDD and o,p'-DDE might be potential perpetrators in pharmacokinetic drug-drug interactions through induction of drug-metabolizing enzymes or drug transporters and by potent inhibition of CYP2C19. In tumors over-expressing BCRP or P-gp, o,p'-DDD and its metabolites should retain their efficacy due to a lack of substrate characteristics.

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