Gene Summary

Gene:CYP2C8; cytochrome P450 family 2 subfamily C member 8
Aliases: CPC8, CYPIIC8, CYP2C8DM, MP-12/MP-20
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 its expression is induced by phenobarbital. The enzyme is known to metabolize many xenobiotics, including the anticonvulsive drug mephenytoin, benzo(a)pyrene, 7-ethyoxycoumarin, and the anti-cancer drug taxol. This gene is located within a cluster of cytochrome P450 genes on chromosome 10q24. Several transcript variants encoding a few different isoforms have been found for this gene. [provided by RefSeq, Nov 2010]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:cytochrome P450 2C8
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (16)
Pathways:What pathways are this gene/protein implicaed in?
Show (3)

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.

  • Cytochrome P-450 Enzyme System
  • Steroid 16-alpha-Hydroxylase
  • Receptor Protein-Tyrosine Kinases
  • Stomach Cancer
  • Risk Factors
  • Haplotypes
  • Messenger RNA
  • Polymorphism
  • Cytochrome P-450 CYP3A
  • Ovarian Cancer
  • Phytogenic Anticancer Agents
  • Cancer Gene Expression Regulation
  • Tumor Burden
  • Genetic Association Studies
  • Chromosome 10
  • Thiazolidinediones
  • Restriction Fragment Length Polymorphism
  • Tamoxifen
  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Single Nucleotide Polymorphism
  • Sex Characteristics
  • Pharmacogenetics
  • Genetic Predisposition
  • Cytochrome P-450 CYP2C8
  • ATP Binding Cassette Transporter, Subfamily B
  • Young Adult
  • Statistics as Topic
  • Cytochrome P-450 CYP2C9
  • Multiple Myeloma
  • Genotype
  • Bladder Cancer
  • Aryl Hydrocarbon Hydroxylases
  • Paclitaxel
  • Drug Resistance
  • Vomiting
  • Genetic Variation
  • Breast Cancer
  • Paraneoplastic Polyneuropathy
  • Antineoplastic Agents
  • Gene Expression Profiling
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

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: CYP2C8 (cancer-related)

Li C, Zhou D, Jiang X, et al.
Identifying hepatocellular carcinoma-related hub genes by bioinformatics analysis and CYP2C8 is a potential prognostic biomarker.
Gene. 2019; 698:9-18 [PubMed] Related Publications
Hepatocellular carcinoma (HCC) is one type of the most common malignancies. However, the underlying molecular mechanisms involved in the development of HCC remain unknown. To identify the candidate genes in the progression of HCC, gene expression profiles GSE14520, GSE54236, GSE57957 and GSE64041 were downloaded from the Gene Expression Omnibus database (GEO). A total of 405 tumor and 399 para-carcinoma samples from patients with HCC were examined to identify the differentially expressed genes (DEGs), followed by function enrichment analyses including Gene Ontology (GO) functions and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. A total of 78 DEGs were screened, including 62 downregulated genes and 16 upregulated genes. Subsequently, the protein-protein interaction network (PPI) was constructed using the Search Tool for Retrieval of Interacting Genes (STRING) database. The module analysis and Hub genes validation were performed using Cytoscape software. Hierarchical clustering of hub genes was evaluated using UCSC Cancer Genomics Browser. Survival analyses of Hub genes were performed using Kaplan Meier Plotter database. Genes specifically expressed in the liver were analyzed using GENEVESTIGATOR database. CYP2C8 was identified as one of the most promising molecules among all the candidate genes. The expression profile of CYP2C8 in HCC was analyzed using ONCOMINE and UALCAN database. The expression levels of CYP2C8 in HCC samples and hepatoma cells were verified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry analysis. In summary, DEGs and hub genes were identified in the present study, which provides novel insight on the development of HCC. CYP2C8 was downregulated in HCC and could be a potential prognostic biomarker.

Wang X, Liao X, Yang C, et al.
Identification of prognostic biomarkers for patients with hepatocellular carcinoma after hepatectomy.
Oncol Rep. 2019; 41(3):1586-1602 [PubMed] Free Access to Full Article Related Publications
Hepatocellular carcinoma (HCC) is a lethal malignancy with high morbidity and mortality rates worldwide. The identification of prognosis‑associated biomarkers is crucial to improve HCC patient survival. The present study aimed to explore potential predictive biomarkers for HCC. Differentially expressed genes (DEGs) were analyzed in the GSE36376 dataset using GEO2R. Hub genes were identified and further investigated for prognostic value in HCC patients. A risk score model and nomogram were constructed to predict HCC prognosis using the prognosis‑associated genes and clinical factors. Pearson's correlation was employed to show interactions among hub genes. Gene enrichment analysis was performed to identify detailed biological processes and pathways. A total of 71 DEGs were obtained and seven (ADH4, CYP2C8, CYP2C9, CYP8B1, SLC22A1, TAT and HSD17B13, all adjusted P≤0.05) of the 10 hub genes were identified as prognosis‑related genes for survival analysis in HCC patients, including alcohol dehydrogenase 4 (class II), pi polypeptide (ADH4), cytochrome p450 family 2 subfamily C member 8 (CYP2C8), cytochrome P450 family 2 subfamily C member 9 (CYP2C9), cytochrome P450 family 8 subfamily B member 1 (CYP8B1), solute carrier family 22 member 1 (SLC22A1), tyrosine aminotransferase (TAT) and hydroxysteroid 17‑β dehydrogenase 13 (HSD17B13). The risk score model could predict HCC prognosis and the nomogram visualized gene expression and clinical factors of probability for HCC prognosis. The majority of genes showed significant Pearson's correlations with others (41 Pearson correlations P≤0.01, four Pearson correlations P>0.05). GO analysis revealed that terms such as 'chemical carcinogenesis' and 'drug metabolism‑cytochrome P450' were enriched and may prove helpful to elucidate the mechanisms of hepatocarcinogenesis. Hub genes ADH4, CYP2C8, CYP2C9, CYP8B1, SLC22A1, TAT and HSD17B13 may be useful as predictive biomarkers for HCC prognosis.

Ren X, Ji Y, Jiang X, Qi X
Downregulation of CYP2A6 and CYP2C8 in Tumor Tissues Is Linked to Worse Overall Survival and Recurrence-Free Survival from Hepatocellular Carcinoma.
Biomed Res Int. 2018; 2018:5859415 [PubMed] Free Access to Full Article Related Publications
Objective: This study aimed to evaluate the links between CYP450 family genes in tumor tissues and hepatocellular carcinoma (HCC) outcomes.
Methods: Gene Expression Omnibus (GEO) databases GSE14520 and GSE36376 were used to identify differential expressed CYP450 genes between tumor and nontumor tissues and related to HCC clinicopathological features and survivals.
Results: Seven CYP450 genes including CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2E1, CYP3A4, and CYP4A11 were downregulated in tumor tissues, which were validated in both GSE14520 and GSE36376. HCC patients with CYP2A6 and CYP2C8 low levels in tumor tissues suffered from poorer overall survival (OS) compared to those with high CYP2A6 and CYP2C8 in GSE14520 profile (log ranks
Conclusion: Downregulation of CYP2A6 and CYP2C8 in tumor tissues links to poorer OS and RFS in HCC patients.

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.

Cliff J, Jorgensen AL, Lord R, et al.
The molecular genetics of chemotherapy-induced peripheral neuropathy: A systematic review and meta-analysis.
Crit Rev Oncol Hematol. 2017; 120:127-140 [PubMed] Related Publications
Chemotherapy-induced peripheral neuropathy (CIPN) can adversely affect completion of systemic anti-cancer treatment and cause long-term morbidity. Increasingly pharmacogenetic studies have been performed to explore susceptibility to this important adverse effect. A systematic review was conducted to identify pharmacogenetic studies, assess their quality and findings and undertake meta-analysis where possible. 93 studies were included. Notable methodological issues included lack of standardisation and detail in phenotype definition and acknowledgement of potential confounding factors. Insufficient data was presented in many studies meaning only a minority could be included in meta-analysis showing mainly non-significant effects. Nonetheless, SNPs in CYP2C8, CYP3A4, ARHGEF10, EPHA and TUBB2A genes (taxanes), FARS2, ACYP2 and TAC1 (oxaliplatin), and CEP75 and CYP3A5 (vincristine) are of potential interest. These require exploration in large cohort studies with robust methodology and well-defined phenotypes. Seeking standardisation of phenotype, collaboration and subsequently, individual-patient-data meta-analysis may facilitate identifying contributory SNPs which could be combined in a polygenic risk score to predict those most at risk of CIPN.

Wittliff JL, Sereff SB, Daniels MW
Expression of Genes for Methylxanthine Pathway-Associated Enzymes Accompanied by Sex Steroid Receptor Status Impacts Breast Carcinoma Progression.
Horm Cancer. 2017; 8(5-6):298-313 [PubMed] Related Publications
Consumption of methylxanthine alkaloids appears to induce activities by antagonizing adenosine receptors, implicated in breast cancer behavior in vitro. Our goal was to evaluate expression of genes for methylxanthine receptors and metabolizing enzymes to assess risk of breast carcinoma recurrence. Clinical outcomes, estrogen/progestin receptor results, and gene expression assays guided selection. RNA was isolated from laser capture microdissection-procured carcinoma cells for microarray using established protocols. Gene expression levels of eight methylxanthine receptors, eight metabolizing enzymes, and various phosphodiesterases were retrieved from microarray results. Univariable Cox regressions and Kaplan-Meier plots were determined for each gene with R software. Individually, lower expressions of PDE4A, CYP2A6, or CYP2E were related to decreased progression-free survival (PFS) and overall survival (OS). PDE1A over-expression predicted decreased PFS and OS. ADORA2B and RYR1 over-expressions predicted diminished OS. ER+ cancers exhibited lower ADORA1, ADORA2B, and RYR1 and elevated PDE4A, CYP2A6, and CYP2E expressions. Of PR+ carcinomas, diminished ADORA2B and RYR1 and elevated expressions of ADORA3, PDE4A, CYP2C8, and CYP2E were noted. Least absolute shrinkage and selection operator (LASSO) revealed that CYP2E, PDE1A, and PDE4A expressions collectively predicted PFS whereas ADORA1, CYP2E, PDE1A, PDE1B, and PDE4A expressions jointly predicted OS. Models were clinically significant when validated externally. LASSO also derived a six-gene model and five-gene model that predicted PFS of ER- or PR- carcinomas, respectively. Similarly, five-gene and four-gene models predicted OS in ER- or PR- carcinomas, respectively. Collectively, expression of genes involved in methylxanthine action and metabolism in single-cell types predicted clinical outcomes of breast carcinoma indicating promise for developing diagnostics and design of new therapeutics.

Li C, Wang Q, Ma J, et al.
Integrative Pathway Analysis of Genes and Metabolites Reveals Metabolism Abnormal Subpathway Regions and Modules in Esophageal Squamous Cell Carcinoma.
Molecules. 2017; 22(10) [PubMed] Free Access to Full Article Related Publications
Aberrant metabolism is one of the main driving forces in the initiation and development of ESCC. Both genes and metabolites play important roles in metabolic pathways. Integrative pathway analysis of both genes and metabolites will thus help to interpret the underlying biological phenomena. Here, we performed integrative pathway analysis of gene and metabolite profiles by analyzing six gene expression profiles and seven metabolite profiles of ESCC. Multiple known and novel subpathways associated with ESCC, such as 'beta-Alanine metabolism', were identified via the cooperative use of differential genes, differential metabolites, and their positional importance information in pathways. Furthermore, a global ESCC-Related Metabolic (ERM) network was constructed and 31 modules were identified on the basis of clustering analysis in the ERM network. We found that the three modules located just to the center regions of the ERM network-especially the core region of Module_1-primarily consisted of aldehyde dehydrogenase (ALDH) superfamily members, which contributes to the development of ESCC. For Module_4, pyruvate and the genes and metabolites in its adjacent region were clustered together, and formed a core region within the module. Several prognostic genes, including GPT, ALDH1B1, ABAT, WBSCR22 and MDH1, appeared in the three center modules of the network, suggesting that they can become potentially prognostic markers in ESCC.

Kastritis E, Melea P, Bagratuni T, et al.
Genetic factors related with early onset of osteonecrosis of the jaw in patients with multiple myeloma under zoledronic acid therapy.
Leuk Lymphoma. 2017; 58(10):2304-2309 [PubMed] Related Publications
Specific genetic polymorphisms (SNPs) have been correlated with the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in small series. We screened 140 myeloma patients (36 patients with and 104 without BRONJ) for the presence of previously identified SNPs in PPARG and CYP2C8 genes. All the patients received exclusively zolendronic acid (ZA) therapy and were followed prospectively for BRONJ. SNPs in both genes were associated with a higher risk of development of early BRONJ, occurring within less than 2 years of ZA therapy (59% vs. 16%, p = .022 for PPARG and 29% vs. 7%, p = .07 for CYP2C8) and a shorter time to develop BRONJ (59% versus 12%, p = .011 for PPARG and 29% versus 0% at 2 years, p = .037 for CYP2C8), independently of indices of poor oral hygiene. Thus, although preliminary, our data indicate that the presence of SNPs in PPARG and CYP2C8 genes may be associated with increased risk of early BRONJ.

Chen Y, Huang W, Chen F, et al.
Pregnane X receptors regulate CYP2C8 and P-glycoprotein to impact on the resistance of NSCLC cells to Taxol.
Cancer Med. 2016; 5(12):3564-3571 [PubMed] Free Access to Full Article Related Publications
Cytochrome P450 2C8 (CYP2C8) is one of the enzymes that primarily participate in producing metabolisms of medications and P-glycoprotein (P-gp) has been regarded as one of the important molecules in chemotherapeutically induced multidrug resistance (MDR). In addition, the pregnane X receptor (PXR) is involved in regulating both CYP2C8 and P-gp. We aim to research the effect of PXR on Taxol-resistant non-small-cell lung cancer (NSCLC cells) via regulating CYP2C8 and P-gp. NSCLC cells were treated with SR12813, LY335979, or PXR siRNA. Cell counting kit (CCK-8) assay was used to detect cell vitality. Colony formation assay was used to observe cell proliferation. Western blotting, real-time polymerase chain reaction (RT-PCR), and immunofluorescence staining were conducted to analyze the expressions of PXR, CYP2C8, and P-gp. Taxol and its metabolic products were detected by high-performance liquid chromatography (HPLC). The expression of PXR in A549 cell line was higher than that in other cell lines. The accumulation of PXR was observed in the nucleus after cells were treated with SR12813. Besides, SR12813 induced higher expressions of CYP2C8 and P-gp proteins. We also discovered that pretreatment with SR12813 reversed the inhibition of cell viability and proliferation after the Taxol treatment in comparison to the SR12813 untreated group. Furthermore, the hydroxylation products of Taxol analyzed by HPLC were increased in comparison to the SR12813 untreated group, indicating that high expressions of CYP2C8 and P-gp enhanced the resistance of A549 cells to Taxol. For cells treated with PXR siRNA, cell viability, cell proliferation, and Taxol metabolites were significantly reduced after the Taxol treatment in comparison to the siRNA-negative group. The cell viability, cell proliferation, and Taxol metabolites were regulated by the expressions of PXR, P-gp, and CYP2C8. That is, PXR expression has an important effect on the resistance of NSCLC cells to Taxol via upregulating P-gp and CYP2C8.

Lam SW, Frederiks CN, van der Straaten T, et al.
Genotypes of CYP2C8 and FGD4 and their association with peripheral neuropathy or early dose reduction in paclitaxel-treated breast cancer patients.
Br J Cancer. 2016; 115(11):1335-1342 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The purpose of this study was to evaluate single-nucleotide polymorphisms (SNPs) in genes encoding key metabolising enzymes or involved in pharmacodynamics for possible associations with paclitaxel-induced peripheral neuropathy.
METHODS: The study population consists of 188 women from the multicenter, randomised, phase II ATX trial (BOOG2006-06; EudraCT number 2006-006058-83) that received paclitaxel and bevacizumab without or with capecitabine as first-line palliative therapy of HER2-negative metastatic breast cancer. Genotyping of CYP2C8*3 (c.416G>A), CYP3A4*22 (c.522-191C>T), TUBB2A (c.-101T>C), FGD4 (c.2044-236G>A) and EPHA5 (c.2895G>A) was performed by real-time PCR. Toxicity endpoints were cumulative dose (1) until first onset of grade ⩾1 peripheral neuropathy and (2) until first paclitaxel dose reduction from related toxicity (NCI-CTCAE version 3.0). SNPs were evaluated using the Kaplan-Meier method, the Gehan-Breslow-Wilcoxon test and the multivariate Cox regression analysis.
RESULTS: The rate of grade ⩾1 peripheral neuropathy was 67% (n=126). The rate of dose reduction was 46% (n=87). Age ⩾65 years was a risk factor for peripheral neuropathy (HR=1.87, P<0.008), but not for dose reduction. When adjusted for age, body surface area and total cumulative paclitaxel dose, CYP2C8*3 carriers had an increased risk of peripheral neuropathy (HR=1.59, P=0.045). FGD4 c.2044-236 A-allele carriers had an increased risk of paclitaxel dose reduction (HR per A-allele=1.38, P=0.036) when adjusted for total cumulative paclitaxel dose.
CONCLUSIONS: These findings may point towards clinically useful indicators of early toxicity, but warrant further investigation.

Zhang X, Zhang M, Hou Y, et al.
Single-cell analyses of transcriptional heterogeneity in squamous cell carcinoma of urinary bladder.
Oncotarget. 2016; 7(40):66069-66076 [PubMed] Free Access to Full Article Related Publications
Cell-to-cell expression heterogeneity within a single tumor is a common phenotype among various cancer types including squamous cell carcinoma. To further study the fundamentals and importance of heterogeneity of cell functions and its potential mechanisms, we performed single-cell RNA-seq (scRNA-seq) on human squamous cell carcinoma of the bladder (SCCB) and its corresponding physiologically normal epithelia. Extensive differentially expressed genes were uncovered by comparing cancer and normal single cells, which were preferentially enriched in cancer-correlated pathways, such as p53 signaling and bladder cancer pathway. Furthermore, the most diversely expressed genes were particularly enriched in MAPK signaling pathway, such as CACNG4, CACNA1E and CACNA1H, which involve in cancer evolution and heterogeneity formation. Co-expression network and hub-gene analyses revealed several remarkable "hub genes" of each regulatory module. Some of them are cancer related, such as POU2F3, NKD1 and CYP2C8, while LINC00189, GCC2 and OR9Q1 genes are rarely reported in human diseases. The genes within an interesting module are highly correlated with others, which could be treated as potential targets for SCCB patients. Our findings have fundamental implications for SCCB biology and therapeutic strategies.

Ruiz-Pinto S, Pita G, Patiño-García A, et al.
Identification of genetic variants in pharmacokinetic genes associated with Ewing Sarcoma treatment outcome.
Ann Oncol. 2016; 27(9):1788-93 [PubMed] Related Publications
BACKGROUND: Despite the effectiveness of current treatment protocols for Ewing sarcoma (ES), many patients still experience relapse, and survival following recurrence is <15%. We aimed to identify genetic variants that predict treatment outcome in children diagnosed with ES.
PATIENTS AND METHODS: We carried out a pharmacogenetic study of 384 single-nucleotide polymorphisms (SNPs) in 24 key transport or metabolism genes relevant to drugs used to treat in pediatric patients (<30 years) with histologically confirmed ES. We studied the association of genotypes with tumor response and overall survival (OS) in a discovery cohort of 106 Spanish children, with replication in a second cohort of 389 pediatric patients from across Europe.
RESULTS: We identified associations with OS (P < 0.05) for three SNPs in the Spanish cohort that were replicated in the European cohort. The strongest association observed was with rs7190447, located in the ATP-binding cassette subfamily C member 6 (ABCC6) gene [discovery: hazard ratio (HR) = 14.30, 95% confidence interval (CI) = 1.53-134, P = 0.020; replication: HR = 9.28, 95% CI = 2.20-39.2, P = 0.0024] and its correlated SNP rs7192303, which was predicted to have a plausible regulatory function. We also replicated associations with rs4148737 in the ATP-binding cassette subfamily B member 1 (ABCB1) gene (discovery: HR = 2.96, 95% CI = 1.08-8.10, P = 0.034; replication: HR = 1.60, 95% CI = 1.05-2.44, P = 0.029), which we have previously found to be associated with poorer OS in pediatric osteosarcoma patients, and rs11188147 in cytochrome P450 family 2 subfamily C member 8 gene (CYP2C8) (discovery : HR = 2.49, 95% CI = 1.06-5.87, P = 0.037; replication: HR = 1.77, 95% CI = 1.06-2.96, P = 0.030), an enzyme involved in the oxidative metabolism of the ES chemotherapeutic agents cyclophosphamide and ifosfamide. None of the associations with tumor response were replicated.
CONCLUSION: Using an integrated pathway-based approach, we identified polymorphisms in ABCC6, ABCB1 and CYP2C8 associated with OS. These associations were replicated in a large independent cohort, highlighting the importance of pharmacokinetic genes as prognostic markers in ES.

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.

Boora GK, Kanwar R, Kulkarni AA, et al.
Testing of candidate single nucleotide variants associated with paclitaxel neuropathy in the trial NCCTG N08C1 (Alliance).
Cancer Med. 2016; 5(4):631-9 [PubMed] Free Access to Full Article Related Publications
Paclitaxel-induced peripheral neuropathy (PIPN) cannot be predicted from clinical parameters and might have a pharmacogenomic basis. Previous studies identified single nucleotide variants (SNV) associated with PIPN. However, only a subset of findings has been confirmed to date in more than one study, suggesting a need for further re-testing and validation in additional clinical cohorts. Candidate PIPN-associated SNVs were identified from the literature. SNVs were retested in 119 patients selected by extreme phenotyping from 269 in NCCTG N08C1 (Alliance) as previously reported. SNV genotyping was performed by a combination of short-read sequencing analysis and Taqman PCR. These 22 candidate PIPN SNVs were genotyped. Two of these, rs7349683 in the EPHA5 and rs3213619 in ABCB1 were found to be significantly associated with PIPN with an Odds ratios OR = 2.07 (P = 0.02) and OR = 0.12 (P = 0.03), respectively. In addition, three SNVs showed a trend toward a risk- or protective effect that was consistent with previous reports. The rs10509681 and rs11572080 in the gene CYP2C8*3 showed risk effect with an OR = 1.49 and rs1056836 in CYP1B1 showed a protective effect with an OR = 0.66. None of the other results supported the previously reported associations, including some SNVs displaying an opposite direction of effect from previous reports, including rs1058930 in CYP2C8, rs17222723 and rs8187710 in ABCC2, rs10771973 in FGD4, rs16916932 in CACNB2 and rs16948748 in PITPNA. Alliance N08C1 validated or supported a minority of previously reported SNV-PIPN associations. Associations previously reported by multiple studies appeared to have a higher likelihood to be validated by Alliance N08C1.

Szalai R, Ganczer A, Magyari L, et al.
Interethnic differences of cytochrome P450 gene polymorphisms may influence outcome of taxane therapy in Roma and Hungarian populations.
Drug Metab Pharmacokinet. 2015; 30(6):453-6 [PubMed] Related Publications
Taxanes are widely used microtubule-stabilizing chemotherapeutic agents in the treatment of cancers. Several cytochrome P450 gene variants have been proven to influence taxane metabolism and therapy. The purpose of this work was to determine the distribution of genetic variations of CYP1B1, CYP2C8 and CYP3A5 genes as the first report on taxane metabolizer cytochrome P450 gene polymorphisms in Roma and Hungarian populations. A total of 397 Roma and 412 Hungarian healthy subjects were genotyped for CYP1B1 c.4326C > G, CYP2C8 c.792C > G and CYP3A5 c.6986A > G variant alleles by PCR-RFLP assay and direct sequencing. We found significant differences in the frequencies of homozygous variant genotypes of CYP1B1 4326 GG (p = 0.002) and CYP3A5 6986 GG (p < 0.001) between Roma and Hungarian populations. Regarding minor allele frequencies, for CYP2C8 a significantly increased prevalence was found in 792G allele frequency in the Hungarian population compared to the Roma population (5.83% vs. 2.14%, p = 0.001). Our results can be used as possible predictive factors in population specific treatment algorithms to developing effective programs for a better outcome in patients treated with taxanes.

Lee MY, Apellániz-Ruiz M, Johansson I, et al.
Role of cytochrome P450 2C8*3 (CYP2C8*3) in paclitaxel metabolism and paclitaxel-induced neurotoxicity.
Pharmacogenomics. 2015; 16(9):929-37 [PubMed] Related Publications
AIM: The CYP2C8*3 allele has been suggested as a risk factor for paclitaxel-induced neuropathy but the data hitherto published are conflicting.
MATERIALS & METHODS: In total 435 patients were investigated with respect to maximum neuropathy grade and accumulated paclitaxel dose. The enzymatic properties of CYP2C8.3 variant were analyzed using heterologous mammalian HEK293 cell expression system.
RESULTS: No significant association between CYP2C8*3 allele and neuropathy was found, although a trend was observed. The paclitaxel and amodiaquine metabolism by CYP2C8.3 were found similar to CYP2C8.1, whereas CYP2C8.3 was more efficient in the metabolism of rosiglitazone.
CONCLUSION: These results indicate a difference in substrate specificity between CYP2C8.1 and CYP2C8.3; however, the CYP2C8*3 allele has no major impact on paclitaxel metabolism in vitro or of paclitaxel-induced neuropathy in vivo. Original submitted on 6 February 2015; revision submitted on 9 April 2015.

Thomas M, Bayha C, Vetter S, et al.
Activating and Inhibitory Functions of WNT/β-Catenin in the Induction of Cytochromes P450 by Nuclear Receptors in HepaRG Cells.
Mol Pharmacol. 2015; 87(6):1013-20 [PubMed] Related Publications
The WNT/β-catenin signaling pathway has been identified as an important endogenous regulator of hepatic cytochrome P450 (P450) expression in mouse liver. In particular, it is involved in the regulation of P450 expression in response to exposure to xenobiotic agonists of the nuclear receptors constitutive androstane receptor (CAR), aryl hydrocarbon receptor (AhR), and Nrf2. To systematically elucidate the effect of the WNT/β-catenin pathway on the regulation and inducibility of major human P450 enzymes, HepaRG cells were treated with either the WNT/β-catenin signaling pathway agonist, WNT3a, or with small interfering RNA directed against β-catenin, alone or in combination with a panel of activating ligands for AhR [2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)], CAR [6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime (CITCO)], pregnane X receptor (PXR) [rifampicin], and peroxisome proliferator-activated receptor (PPAR) α [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid (WY14,643)]. Assessment of P450 gene expression and enzymatic activity after downregulation or activation of the WNT/β-catenin pathway revealed a requirement of β-catenin in the AhR-, CAR-, and PXR-mediated induction of CYP1A, CYP2B6 and CYP3A4 (for CAR and PXR), and CYP2C8 (for PXR) gene expression. By contrast, activation of the WNT/β-catenin pathway prevented PPARα-mediated induction of CYP1A, CYP2C8, CYP3A4, and CYP4A11 genes, suggesting a dominant-negative role of β-catenin in PPARα-mediated regulation of these genes. Our data indicate a significant effect of the WNT/β-catenin pathway on the regulation of P450 enzymes in human hepatocytes and reveal a novel crosstalk between β-catenin and PPARα signaling pathways in the regulation of P450 expression.

Bosó V, Herrero MJ, Santaballa A, et al.
SNPs and taxane toxicity in breast cancer patients.
Pharmacogenomics. 2014; 15(15):1845-58 [PubMed] Related Publications
AIM: In order to identify genetic variants associated with taxanes toxicity, a panel with 47 SNPs in 20 genes involved in taxane pathways was designed.
PATIENTS & METHODS: Genomic DNA of 113 breast cancer patients was analyzed (70 taking docetaxel, 43 taking paclitaxel).
RESULTS: Two SNPs associated with docetaxel toxicity were identified: CYP3A4*1B with infusion-related reactions; and ERCC1 Gln504Lys with mucositis (p≤0.01). Regarding paclitaxel toxicity: CYP2C8 HapC and CYP2C8 rs1934951 were associated with anemia; and ERCC1 Gln504Lys with neuropathy (p≤0.01).
CONCLUSION: Genes involved in DNA repair mechanisms and reactive oxygen species levels influence taxane toxicity in cancer patients treated with chemotherapy schemes not containing platinum. These findings could lead to better treatment selection for breast cancer patients.

Ng T, Chan M, Khor CC, et al.
The genetic variants underlying breast cancer treatment-induced chronic and late toxicities: a systematic review.
Cancer Treat Rev. 2014; 40(10):1199-214 [PubMed] Related Publications
A systematic review was performed to describe the findings from 19 genetic association studies that have examined the genetic variants underlying four common treatment-induced chronic and late toxicities in breast cancer patients, and to evaluate the quality of reporting. Three out of 5 studies found an association between HER2 lle655Val polymorphisms and trastuzumab-induced cardiotoxicity. Two studies found a positive association between cognitive impairment and the Val allele of the COMT gene and the ε4 allele of the apolipoprotein E gene. Genetic associations were established between fatigue and the G/G genotype of IL6-174 and TNF-308, and the Met allele of the COMT gene in 4 studies. Among studies (N=8) that evaluated the genetic associations underlying peripheral neuropathy, CYP2C8∗3 variant is commonly reported as the associated gene. Most studies failed to conform to the major criteria listed in the STREGA guidelines, with a lack of transparent reporting of methods and results.

Sprouse AA, Herbert BS
Resveratrol augments paclitaxel treatment in MDA-MB-231 and paclitaxel-resistant MDA-MB-231 breast cancer cells.
Anticancer Res. 2014; 34(10):5363-74 [PubMed] Related Publications
BACKGROUND: Resveratrol (RES) inhibits cell growth, induces apoptosis and augments chemotherapeutics in multiple cancer types, although its effects on drug-resistant cancer cells are unknown.
MATERIALS AND METHODS: To study the effects of resveratrol in triple-negative breast cancer cells that are resistant to the common cancer drug, paclitaxel, a novel paclitaxel-resistant cell line was generated from the MDA-MB-231 cell line.
RESULTS: The resistant MDA-MB-231/PacR cells exhibited a 12-fold increased resistance to paclitaxel. RES treatment reduced cell proliferation and colony formation and increased senescence and apoptosis in both parental and resistant cells. Importantly, RES augmented the effects of paclitaxel in both cell lines. Up-regulation of the MDR1 and CYP2C8 genes were shown to be potential mechanisms of paclitaxel resistance in the resistant cells.
CONCLUSION: RES, both alone and in combination with paclitaxel, may be useful in the treatment of paclitaxel-sensitive and paclitaxel-resistant triple-negative breast cancer cells.

Tulsyan S, Agarwal G, Lal P, Mittal B
Significant role of CYP450 genetic variants in cyclophosphamide based breast cancer treatment outcomes: a multi-analytical strategy.
Clin Chim Acta. 2014; 434:21-8 [PubMed] Related Publications
BACKGROUND: Cyclophosphamide (CP), an alkylating chemotherapeutic drug, is catalyzed by the Phase I cytochrome P450 (CYPs) isozymes - CYP3A4, CYP3A5, CYP2B6, CYP2C8, CYP2C9 and CYP2C19. Hence this study aimed to elucidate the influence of genetic variants in CYP450 metabolizing enzymes on breast cancer treatment outcomes, using multi-analytical approaches.
METHODS: Treatment response was noticed in 111 patients whereas 234 patients were followed for myelo-toxicity. Eight known functional single nucleotide polymorphisms (SNPs) in six CYP450 genes were selected for the study on the basis of CP metabolizing enzyme polymorphisms. The possible functional effects of CYP450 polymorphisms were determined by online Web servers F-SNP. Multifactor dimensionality reductions (MDR), haplotype analysis were combined with logistic regression to characterize gene-gene interaction model with treatment outcomes.
RESULTS: Haplotype analysis revealed significant association of G(rs10509681)-*1(rs1799853)-*3(rs1057910)-G(rs4244285) on chromosome 10 with overall toxicity (P=0.024) and grade 2-4 leucopenia (P=0.03). On MDR analysis, CYP3A5*3, CYP2C19*2, CYP2B6*5 yielded the highest testing accuracy for treatment response (0.60) and CYP2C8*3, CYP2C9*2 for overall toxicity (0.50).
CONCLUSION: Multi-analytical approaches may provide a better clinical prediction of pharmacogenetic based treatment outcomes in breast cancer patients.

Hertz DL, Roy S, Jack J, et al.
Genetic heterogeneity beyond CYP2C8*3 does not explain differential sensitivity to paclitaxel-induced neuropathy.
Breast Cancer Res Treat. 2014; 145(1):245-54 [PubMed] Free Access to Full Article Related Publications
The development of paclitaxel-induced peripheral neuropathy (PIPN) is influenced by drug exposure and patient genetics. The purpose of this analysis was to expand on a previous reported association of CYP2C8*3 and PIPN risk by investigating additional polymorphisms in CYP2C8 and in hundreds of other genes potentially relevant to paclitaxel pharmacokinetics. Clinical data was collected prospectively in an observational registry of newly diagnosed breast cancer patients. Patients treated with paclitaxel-containing regimens were genotyped using the Affymetrix DMET™ Plus chip. Patients who carried the CYP2C8*2, *3, or *4 variant were collapsed into a low-metabolizer CYP2C8 phenotype for association with PIPN. Separately, all SNPs that surpassed quality control were assessed individually and as a composite of genetic ancestry for associations with PIPN. 412 paclitaxel-treated patients and 564 genetic markers were included in the analysis. The risk of PIPN was significantly greater in the CYP2C8 low-metabolizer group (HR = 1.722, p = 0.018); however, the influences of the *2 and *4 SNPs were not independently significant (*2: p = 0.847, *4: p = 0.408). One intronic SNP in ABCG1 (rs492338) surpassed the exploratory significance threshold for an association with PIPN in the Caucasian cohort (p = 0.0008) but not in the non-Caucasian replication group (p = 0.54). Substantial genetic variability was observed within self-reported racial groups but this genetic variability was not associated with risk of grade 2+ PIPN. The pharmacogenetic heterogeneity within a cohort of breast cancer patients is dramatic, though we did not find evidence that this heterogeneity directly influences the risk of PIPN beyond the contribution of CYP2C8*3.

Tulsyan S, Chaturvedi P, Singh AK, et al.
Assessment of clinical outcomes in breast cancer patients treated with taxanes: multi-analytical approach.
Gene. 2014; 543(1):69-75 [PubMed] Related Publications
Polymorphisms in genes encoding CYPs (Phase I) and ABCB1 (Phase III) enzymes may attribute to variability of efficacy of taxanes. The present study aims to find the influence of CYP and ABCB1 gene polymorphisms on taxanes based clinical outcomes. 132 breast cancer patients treated with taxanes based chemotherapy were genotyped for CYP3A4*1B, CYP3A5*3, CYP1B1*3, CYP2C8*3, ABCB1 1236C>T, 2677G>T/A and 3435C>T polymorphisms using PCR-RFLP. Associations of genetic variants with clinical outcomes in terms of response in 58 patients receiving neo-adjuvant chemotherapy (NACT), and chemo-toxicity in 132 patients were studied. Multifactor dimensionality reduction (MDR) analysis was performed to evaluate higher order gene-gene interactions with clinical outcomes. Pathological response to taxane based NACT was associated with GA genotype as well as A allele of CYP3A5*3 polymorphism (Pcorr=0.0465, Pcorr=0.0465). Similarly, association was found in dominant model of CYP3A5*3 polymorphism with responders (Pcorr=0.0465). Haplotype analysis further revealed ACYP3A4-ACYP3A5 haplotype to be significantly associated with responders (Pcorr=0.048). In assessing toxicity, significant association of variant (TT) genotype and T allele of ABCB1 2677G>T/A polymorphism, was found with 'grade 1 or no leucopenia' (Pcorr=0.0465, Pcorr=0.048). On evaluating higher order gene-gene interaction models by MDR analysis, CYP3A5*3; ABCB11236C>T and ABCB1 2677G>T/A; ABCB1 3435C>T and CYP1B1*3 showed significant association with treatment response, grade 2-4 anemia and dose delay/reduction due to neutropenia (P=0.024, P=0.004, P=0.026), respectively. Multi-analytical approaches may provide a better assessment of pharmacogenetic based treatment outcomes in breast cancer patients treated with taxanes.

Alcazar-González GA, Calderón-Garcidueñas AL, Garza-Rodríguez ML, et al.
Comparative study of polymorphism frequencies of the CYP2D6, CYP3A5, CYP2C8 and IL-10 genes in Mexican and Spanish women with breast cancer.
Pharmacogenomics. 2013; 14(13):1583-92 [PubMed] Related Publications
AIM: Pharmacogenetic studies in breast cancer (BC) may predict the efficacy of tamoxifen and the toxicity of paclitaxel and capecitabine. We determined the frequency of polymorphisms in the CYP2D6 gene associated with activation of tamoxifen, and those of the genes CYP2C8, CYP3A5 and DPYD associated with toxicity of paclitaxel and capecitabine. We also included a IL-10 gene polymorphism associated with advanced tumor stage at diagnosis.
PATIENTS & METHODS: Genomic DNAs from 241 BC patients from northeast Mexico were genotyped using DNA microarray technology.
RESULTS: For tamoxifen processing, CYP2D6 genotyping predicted that 90.8% of patients were normal metabolizers, 4.2% ultrarapid, 2.1% intermediate and 2.9% poor metabolizers. For paclitaxel and the CYP2C8 gene, 75.3% were normal, 23.4% intermediate and 1.3% poor metabolizers. Regarding the DPYD gene, only one patient was a poor metabolizer. For the IL-10 gene, 47.1% were poor metabolizers.
CONCLUSION: These results contribute valuable information towards personalizing BC chemotherapy in Mexican women.

White KL, Vierkant RA, Fogarty ZC, et al.
Analysis of over 10,000 Cases finds no association between previously reported candidate polymorphisms and ovarian cancer outcome.
Cancer Epidemiol Biomarkers Prev. 2013; 22(5):987-92 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Ovarian cancer is a leading cause of cancer-related death among women. In an effort to understand contributors to disease outcome, we evaluated single-nucleotide polymorphisms (SNP) previously associated with ovarian cancer recurrence or survival, specifically in angiogenesis, inflammation, mitosis, and drug disposition genes.
METHODS: Twenty-seven SNPs in VHL, HGF, IL18, PRKACB, ABCB1, CYP2C8, ERCC2, and ERCC1 previously associated with ovarian cancer outcome were genotyped in 10,084 invasive cases from 28 studies from the Ovarian Cancer Association Consortium with over 37,000-observed person-years and 4,478 deaths. Cox proportional hazards models were used to examine the association between candidate SNPs and ovarian cancer recurrence or survival with and without adjustment for key covariates.
RESULTS: We observed no association between genotype and ovarian cancer recurrence or survival for any of the SNPs examined.
CONCLUSIONS: These results refute prior associations between these SNPs and ovarian cancer outcome and underscore the importance of maximally powered genetic association studies.
IMPACT: These variants should not be used in prognostic models. Alternate approaches to uncovering inherited prognostic factors, if they exist, are needed.

Jabir RS, Naidu R, Annuar MA, et al.
Pharmacogenetics of taxanes: impact of gene polymorphisms of drug transporters on pharmacokinetics and toxicity.
Pharmacogenomics. 2012; 13(16):1979-88 [PubMed] Related Publications
Interindividual variability in drug response and the emergence of adverse drug effects are the main causes of treatment failure in cancer therapy. Functional membrane drug transporters play important roles in altering pharmacokinetic profile, resistance to treatment, toxicity and patient survival. Pharmacogenetic studies of these transporters are expected to provide new approaches for optimizing therapy. Taxanes are approved for the treatment of various cancers. Circulating taxanes are taken up by SLCO1B3 into hepatocytes. The CYP450 enzymes CYP3A4, CYP3A5 and CYP2C8 are responsible for the conversion of taxanes into their metabolites. Ultimately, ABCB1 and ABCC2 will dispose the metabolites into bile canaliculi. Polymorphisms of genes encoding for proteins involved in the transport and clearance of taxanes reduce excretion of the drugs, leading to development of toxicity in patients. This review addresses current knowledge on genetic variations of transporters affecting taxanes pharmacokinetics and toxicity, and provides insights into future direction for personalized medicine.

Seredina TA, Goreva OB, Talaban VO, et al.
Association of cytochrome P450 genetic polymorphisms with neoadjuvant chemotherapy efficacy in breast cancer patients.
BMC Med Genet. 2012; 13:45 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The enzymes of the cytochrome P450 family (CYPs) play an important role in the metabolism of a great variety of anticancer agents; therefore, polymorphisms in genes encoding for metabolizing enzymes and drugs transporters can affect drug efficacy and toxicity.
METHODS: The genetic polymorphisms of cytochrome P450 were studied in 395 patients with breast cancer by RLFP analysis.
RESULTS: Here, we studied the association of functionally significant variant alleles of CYP3A4, CYP3A5, CYP2B6, CYP2C8, CYP2C9 and CYP2C19 with the clinical response to neoadjuvant chemotherapy in breast cancer patients. A significant correlation was observed between the CYP2C9*2 polymorphism and chemotherapy resistance (OR = 4.64; CI 95% = 1.01 - 20.91), as well as between CYP2C9*2 heterozygotes and chemotherapy resistance in women with nodal forms of breast cancer and a cancer hereditary load (OR = 15.50; CI 95% = 1.08 - 826.12) when the potential combined effects were examined. No significant association between chemotherapy resistance and the other examined genotypes and the potential combined clinical and tumour-related parameters were discovered.
CONCLUSION: In conclusion, CYP2C9*2 was associated with neoadjuvant chemotherapy resistance (OR = 4.64; CI 95% = 1.01 - 20.91) in the population of interest.

Chokkalingam AP, Metayer C, Scelo GA, et al.
Variation in xenobiotic transport and metabolism genes, household chemical exposures, and risk of childhood acute lymphoblastic leukemia.
Cancer Causes Control. 2012; 23(8):1367-75 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Recent studies suggest that environmental exposures to pesticides, tobacco, and other xenobiotic chemicals may increase risk of childhood acute lymphoblastic leukemia (ALL). We sought to evaluate the role of genes involved in xenobiotic transport and metabolism in childhood ALL risk, both alone and in conjunction with household chemical exposures previously found to be associated with childhood ALL risk.
METHODS: We conducted a population-based epidemiologic study of 377 cases and 448 controls in California, utilizing a haplotype-based approach to evaluate 42 xenobiotic transport and metabolism genes in conjunction with data on self-reported household chemical exposures.
RESULTS: We identified significant associations of childhood ALL risk with haplotypes of ABCB1, ARNT, CYP2C8, CYP1A2, CYP1B1, and IDH1. In addition, certain haplotypes showed significant joint effects with self-reported household chemical exposures on risk of childhood ALL. Specifically, elevated risks associated with use of paints in the home (ever) and indoor insecticides (pre-birth) were limited to subjects carrying specific haplotypes of CYP2C8 and ABCB1, respectively.
CONCLUSIONS: Our results provide support for a role of xenobiotic transport and metabolism pathways in risk of childhood ALL and indicate that genes in these pathways may modulate the risk of disease associated with use of common household chemicals. Additional studies are needed to confirm these findings and localize specific causal variants.

Hertz DL, Motsinger-Reif AA, Drobish A, et al.
CYP2C8*3 predicts benefit/risk profile in breast cancer patients receiving neoadjuvant paclitaxel.
Breast Cancer Res Treat. 2012; 134(1):401-10 [PubMed] Free Access to Full Article Related Publications
Paclitaxel is one of the most frequently used chemotherapeutic agents for the treatment of breast cancer patients. Using a candidate gene approach, we hypothesized that polymorphisms in genes relevant to the metabolism and transport of paclitaxel are associated with treatment efficacy and toxicity. Patient and tumor characteristics and treatment outcomes were collected prospectively for breast cancer patients treated with paclitaxel-containing regimens in the neoadjuvant setting. Treatment response was measured before and after each phase of treatment by clinical tumor measurement and categorized according to RECIST criteria, while toxicity data were collected from physician notes. The primary endpoint was achievement of clinical complete response (cCR) and secondary endpoints included clinical response rate (complete response+partial response) and grade 3+ peripheral neuropathy. The genotypes and haplotypes assessed were CYP1B1*3, CYP2C8*3, CYP3A4*1B/CYP3A5*3C, and ABCB1*2. A total of 111 patients were included in this study. Overall, cCR was 30.1% to the paclitaxel component. CYP2C8*3 carriers (23/111, 20.7%) had higher rates of cCR (55% vs. 23%; OR=3.92 [95% CI: 1.46-10.48], corrected p=0.046). In the secondary toxicity analysis, we observed a trend toward greater risk of severe neuropathy (22% vs. 8%; OR=3.13 [95% CI: 0.89-11.01], uncorrected p=0.075) in subjects carrying the CYP2C8*3 variant. Other polymorphisms interrogated were not significantly associated with response or toxicity. Patients carrying CYP2C8*3 are more likely to achieve clinical complete response from neoadjuvant paclitaxel treatment, but may also be at increased risk of experiencing severe peripheral neurotoxicity.

Balla B, Vaszilko M, Kósa JP, et al.
New approach to analyze genetic and clinical data in bisphosphonate-induced osteonecrosis of the jaw.
Oral Dis. 2012; 18(6):580-5 [PubMed] Related Publications
OBJECTIVES: Osteonecrosis of the jaw (ONJ) is a major complication associated with long-term use of bisphosphonates (BP). We aimed to investigate the effect of CYP2C8 rs1934951 SNP and its relationship to a number of clinical and biochemical factors in 46 Hungarian subjects with bisphosphonate-induced ONJ.
METHODS: Blood samples were collected from each subject and genomic DNA was extracted. SNP analysis of CYP2C8 gene was carried out by predesigned TaqMan primer/probe sets. The genetic data together with clinical and biochemical variables were evaluated by chi-square test, logistic regression, and principal component analysis (PCA).
RESULTS: The risk of mandibular localization of ONJ was 19.2-fold higher in subjects with AG genotype than in normal GG genotype. PCA revealed strong positive correlations between maxillar localization of ONJ and a group of variables including intravenous BP application and serum lipid markers. Mandibular localization of ONJ was correlated positively with serum calcium, 25-hydroxy-vitamin D and PTH levels, oral BP application, and the length of BP therapy. The degree of the disease and the number of recurrences were correlated with the application of hormone-deprivation therapy for breast cancer patients.
CONCLUSION: The statistical approach applying PCA to our data may contribute to the better understanding of factors playing role in the development of bisphosphonate-induced ONJ.

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