Gene Summary

Gene:UGT1A1; UDP glucuronosyltransferase 1 family, polypeptide A1
Summary:This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. The preferred substrate of this enzyme is bilirubin, although it also has moderate activity with simple phenols, flavones, and C18 steroids. Mutations in this gene result in Crigler-Najjar syndromes types I and II and in Gilbert syndrome. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:UDP-glucuronosyltransferase 1-1
Source:NCBIAccessed: 25 June, 2015


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 25 June 2015 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.

  • Chromosome 2
  • Risk Factors
  • Risk Assessment
  • Camptothecin
  • Organoplatinum Compounds
  • Transcriptional Activation
  • Pyrimidines
  • Glucuronosyltransferase
  • Substrate Specificity
  • Urinary System Cancers
  • Colorectal Cancer
  • Thymidylate Synthase
  • Restriction Fragment Length Polymorphism
  • Neutropenia
  • Xeroderma Pigmentosum Group D Protein
  • Topoisomerase I Inhibitors
  • Regression Analysis
  • Prostate Cancer
  • Technology, Pharmaceutical
  • Promoter Regions
  • Small Cell Lung Cancer
  • Stress, Psychological
  • Taxoids
  • Genotype
  • Thyroxine
  • Transcription Factors
  • Prodrugs
  • Urinary System Cancers
  • DNA Sequence Analysis
  • Tumor Markers
  • TATA Box
  • Stomach Cancer
  • Transfection
  • Vomiting
  • ras Proteins
  • Quality of Life
  • Pharyngeal Neoplasms
  • Single Nucleotide Polymorphism
  • Receptors, Progesterone
  • Soy Foods
Tag cloud generated 25 June, 2015 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: UGT1A1 (cancer-related)

Kalia M
Biomarkers for personalized oncology: recent advances and future challenges.
Metabolism. 2015; 64(3 Suppl 1):S16-21 [PubMed] Related Publications
Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells and oncology is a branch of medicine that deals with tumors. The last decade has seen significant advances in the development of biomarkers in oncology that play a critical role in understanding molecular and cellular mechanisms which drive tumor initiation, maintenance and progression. Clinical molecular diagnostics and biomarker discoveries in oncology are advancing rapidly as we begin to understand the complex mechanisms that transform a normal cell into an abnormal one. These discoveries have fueled the development of novel drug targets and new treatment strategies. The standard of care for patients with advanced-stage cancers has shifted away from an empirical treatment strategy based on the clinical-pathological profile to one where a biomarker driven treatment algorithm based on the molecular profile of the tumor is used. Recent advances in multiplex genotyping technologies and high-throughput genomic profiling by next-generation sequencing make possible the rapid and comprehensive analysis of the cancer genome of individual patients even from very little tumor biopsy material. Predictive (diagnostic) biomarkers are helpful in matching targeted therapies with patients and in preventing toxicity of standard (systemic) therapies. Prognostic biomarkers identify somatic germ line mutations, changes in DNA methylation, elevated levels of microRNA (miRNA) and circulating tumor cells (CTC) in blood. Predictive biomarkers using molecular diagnostics are currently in use in clinical practice of personalized oncotherapy for the treatment of five diseases: chronic myeloid leukemia, colon, breast, lung cancer and melanoma and these biomarkers are being used successfully to evaluate benefits that can be achieved through targeted therapy. Examples of these molecularly targeted biomarker therapies are: tyrosine kinase inhibitors in chronic myeloid leukemia and gastrointestinal tumors; anaplastic lymphoma kinase (ALK) inhibitors in lung cancer with EML4-ALk fusion; HER2/neu blockage in HER2/neu-positive breast cancer; and epidermal growth factor receptors (EGFR) inhibition in EGFR-mutated lung cancer. This review presents the current state of our knowledge of biomarkers in five selected cancers: chronic myeloid leukemia, colorectal cancer, breast cancer, non-small cell lung cancer and melanoma.

Brauze D, Fijalkiewicz K, Szaumkessel M, et al.
Diversified expression of aryl hydrocarbon receptor dependent genes in human laryngeal squamous cell carcinoma cell lines treated with β-naphthoflavone.
Toxicol Lett. 2014; 231(1):99-107 [PubMed] Related Publications
The aryl hydrocarbon receptor (AhR) mediates a variety of biological responses to ubiquitous environmental pollutants. In this study the effect of administration of β-naphthoflavone (BNF), potent AhR ligand, on the expression of AhR, AhRR, CYP1A1, CYP1A2, CYP1B1, NQO1, GSTA1, ALDH3A1 and UGT1A genes encoding the enzymes controlled by AhR were examined in thirteen laryngeal tumor cell lines and in HepaRG cell line. The analyzed cell lines were derived from patients with squamous laryngeal cancer, with history of cigarette smoking and without signs of human papillomavirus types 16 and 18 infection in investigated cells. Quantitative real-time RT-PCR analysis revealed huge interindividual differences in expression of genes from AhR regulatory network. Our results strongly suggest predominant effect of DNA methylation on induction of CYP1A1 expression by AhR ligands as well. Our results indicate that differentiated HepaRG cell line appeared to be very good substitute for human liver in studies on xenobiotic metabolism by AhR regulated enzymes.

Cruz JE, Saksena R, Jabbour SK, et al.
The power of genes: a case of unusually severe systemic toxicity after localized hepatic chemoembolization with irinotecan-eluted microspheres for metastatic colon cancer.
Ann Pharmacother. 2014; 48(12):1646-50 [PubMed] Related Publications
OBJECTIVE: To report a case of systemic irinotecan toxicity following regional transarterial chemoembolization with drug-eluting beads loaded with irinotecan (DEBIRI-TACE) in a patient later found to have a homozygous mutation for UGT1A1*28.
CASE SUMMARY: An 80-year-old woman presented with a cecal colon cancer with synchronous metastases to the liver. After resection of the primary tumor, the patient underwent DEBIRI-TACE with 100 mg of irinotecan to treat the residual disease in the liver. A week after this procedure, the patient developed grade 4 neutropenia, and later, alopecia. Eventually, it was found that the patient had a mutation of UDP glucuronosyltransferase 1 family polypeptide A1 (UGT1A1), which provided a reasonable explanation for the observed reaction.
DISCUSSION: The toxic effects of irinotecan are well understood. Patients with genetic polymorphisms of the genes encoding for the enzyme UGT1A1 may have increased incidence of irinotecan-associated toxicities because of decreased clearance of the active metabolite SN38 via the glucuronidation pathway. To date, there have been limited publications describing systemic adverse events following TACE or DEBIRI-TACE and, based on a thorough literature search, none following these procedures in patients with UGT1A1 polymorphisms. Based on the scoring results of the Naranjo algorithm (7), we are confident in attributing the observed reaction to the patient's genetic polymorphism.
CONCLUSION: Although genetic testing prior to the initiation of irinotecan therapy is not currently recommended, assessment of UGT1A1 polymorphism is warranted when severe adverse events typical of systemic therapy manifest following DEBIRI-TACE.

Marino N, Collins JW, Shen C, et al.
Identification and validation of genes with expression patterns inverse to multiple metastasis suppressor genes in breast cancer cell lines.
Clin Exp Metastasis. 2014; 31(7):771-86 [PubMed] Related Publications
Metastasis suppressor genes (MSGs) have contributed to an understanding of regulatory pathways unique to the lethal metastatic process. When re-expressed in experimental models, MSGs block cancer spread to, and colonization of distant sites without affecting primary tumor formation. Genes have been identified with expression patterns inverse to a single MSG, and found to encode functional, druggable signaling pathways. We now hypothesize that common signaling pathways mediate the effects of multiple MSGs. By gene expression profiling of human MCF7 breast carcinoma cells expressing a scrambled siRNA, or siRNAs to each of 19 validated MSGs (NME1, BRMS1, CD82, CDH1, CDH2, CDH11, CASP8, MAP2K4, MAP2K6, MAP2K7, MAPK14, GSN, ARHGDIB, AKAP12, DRG1, CD44, PEBP1, RRM1, KISS1), we identified genes whose expression was significantly opposite to at least five MSGs. Five genes were selected for further analysis: PDE5A, UGT1A, IL11RA, DNM3 and OAS1. After stable downregulation of each candidate gene in the aggressive human breast cancer cell line MDA-MB-231T, in vitro motility was significantly inhibited. Two stable clones downregulating PDE5A (phosphodiesterase 5A), an enzyme involved in the regulation of cGMP-specific signaling, exhibited no difference in cell proliferation, but reduced motility by 47 and 66 % compared to the empty vector-expressing cells (p = 0.01 and p = 0.005). In an experimental metastasis assay, two shPDE5A-MDA-MB-231T clones produced 47-62 % fewer lung metastases than shRNA-scramble expressing cells (p = 0.045 and p = 0.009 respectively). This study demonstrates that previously unrecognized genes are inversely related to the expression of multiple MSGs, contribute to aspects of metastasis, and may stand as novel therapeutic targets.

Tourkantonis IS, Peponi E, Syrigos KN, Saif MW
Pharmacogenetics in pancreatic cancer.
JOP. 2014; 15(4):335-9 [PubMed] Related Publications
Pancreatic cancer is an aggressive malignancy with a poor overall survival rate. Given advances in pharmacogenomics, numerous gene mutations have been identified that could be potential targets for drug development. Therefore, future research strategies may identify prognostic and predictive markers aiming to improve outcome by maximizing efficacy whilst lowering toxicity. In this commentary, we summarize several interesting results regarding pancreatic cancer pharmacogenetics that have been presented in the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting. In particular, we focus on Abstract #4124, which investigated the potential predictive role of human equilibrative nucleoside transporter 1 (hENT1) in patients treated with adjuvant gemcitabine for pancreatic cancer, on Abstract #4125, which examined the tolerability of a modified FOLFORINOX study based on UGT1A1*28 genotype guided dosing of IRI in patients with advanced pancreatic cancer, and on Abstract #4130, which confirmed the predictive role of circulating tumor and invasive cells (CTICs) from patients with unresectable pancreatic cancer in second-line chemotherapy treatment setting.

Yamasaki S, Tanimoto K, Kohno K, et al.
UGT1A1 *6 polymorphism predicts outcome in elderly patients with relapsed or refractory diffuse large B-cell lymphoma treated with carboplatin, dexamethasone, etoposide and irinotecan.
Ann Hematol. 2015; 94(1):65-9 [PubMed] Related Publications
The uridine diphosphate glucuronosyltransferase (UGT) gene 1A1*6 polymorphism, which affects irinotecan metabolism, has been associated with improved survival in lymphoma patients treated with of carboplatin, dexamethasone, etoposide and irinotecan (CDE-11). This study assessed the efficacy of CDE-11 relative to the UGT1A1*6 polymorphism in 27 elderly patients with relapsed or refractory diffuse large B-cell lymphoma who were ineligible for high-dose chemotherapy plus autologous stem cell transplantation. The 2-year survival rate after initial CDE-11 treatment was significantly higher in patients with than without UGT1A1*6 (57% vs. 5%). The most common grade 4 adverse event in patients with the UGT1A1*6 genotypes was neutropenia (88.9%), but there were no gastrointestinal adverse events or treatment-related deaths. Disease progression was the most frequent cause of death. CDE-11 was well tolerated and provided clinical benefit to elderly patients with relapsed or refractory diffuse large B-cell lymphoma. The response to CDE-11 likely correlated with UGT1A1*6 polymorphisms, but further prospective studies are warranted to optimize irinotecan-based chemotherapies relative to UGT1A1 polymorphism.

Wang Y, Masuyama H, Nobumoto E, et al.
The inhibition of constitutive androstane receptor-mediated pathway enhances the effects of anticancer agents in ovarian cancer cells.
Biochem Pharmacol. 2014; 90(4):356-66 [PubMed] Related Publications
BACKGROUND: Ovarian cancer is commonly treated with anticancer agents; however, many tumors become resistant. Resistance is regulated, in part, by P-glycoprotein, which is encoded by the gene multiple drug resistance 1 (MDR1) and functions as a transmembrane efflux pump for the elimination of anticancer agents. Constitutive androstane receptor (CAR) is a nuclear receptor that regulates drug metabolism through control of MDR1 and other genes.
PURPOSE: We examined whether the inhibition of CAR-mediated pathway could influence the cytotoxicity of three anticancer drugs, cisplatin, paclitaxel, and arsenic trioxide, in ovarian cancer cells.
RESULTS: We observed that the cell proliferation of several ovarian cell lines expressing CAR significantly increased when CITCO was combined with anticancer agents compared with any anticancer agent alone. The up-regulation of MDR1 and UGT1A1 by anticancer agents was further enhanced in the presence of CITCO. We confirmed that combining CITCO with anticancer agents induced significantly lower levels of apoptosis than those achieved with any single anticancer drug. CAR down-regulation by RNA interference caused a significant increase in cell growth inhibition and enhancement of apoptosis in the presence of anticancer agents. Combination of CITCO with any anticancer agents significantly enhanced CAR-mediated transcription compared with any anticancer agents alone and CAR down-regulation completely inhibited the transcription in the presence of CITCO and/or anticancer agents.
CONCLUSION: Inhibition of CAR pathway could be a novel therapeutic approach for the augmentation of sensitivity to anticancer agents, or to overcome resistance, in the treatment of ovarian cancer.

Zahreddine HA, Culjkovic-Kraljacic B, Assouline S, et al.
The sonic hedgehog factor GLI1 imparts drug resistance through inducible glucuronidation.
Nature. 2014; 511(7507):90-3 [PubMed] Free Access to Full Article Related Publications
Drug resistance is a major hurdle in oncology. Responses of acute myeloid leukaemia (AML) patients to cytarabine (Ara-C)-based therapies are often short lived with a median overall survival of months. Therapies are under development to improve outcomes and include targeting the eukaryotic translation initiation factor (eIF4E) with its inhibitor ribavirin. In a Phase II clinical trial in poor prognosis AML, ribavirin monotherapy yielded promising responses including remissions; however, all patients relapsed. Here we identify a novel form of drug resistance to ribavirin and Ara-C. We observe that the sonic hedgehog transcription factor glioma-associated protein 1 (GLI1) and the UDP glucuronosyltransferase (UGT1A) family of enzymes are elevated in resistant cells. UGT1As add glucuronic acid to many drugs, modifying their activity in diverse tissues. GLI1 alone is sufficient to drive UGT1A-dependent glucuronidation of ribavirin and Ara-C, and thus drug resistance. Resistance is overcome by genetic or pharmacological inhibition of GLI1, revealing a potential strategy to overcome drug resistance in some patients.

Angstadt AY, Hartman TJ, Lesko SM, et al.
The effect of UGT1A and UGT2B polymorphisms on colorectal cancer risk: haplotype associations and gene–environment interactions.
Genes Chromosomes Cancer. 2014; 53(6):454-66 [PubMed] Free Access to Full Article Related Publications
UDP-glucuronosyltransferases (UGTs) play an important role in the phase II metabolism of exogenous and endogenous compounds. As colorectal cancer (CRC) etiology is thought to involve the biotransformation of dietary factors, UGT polymorphisms may affect CRC risk by altering levels of exposure. Genotyping of over 1800 Caucasian subjects was completed to identify the role of genetic variation in nine UGT1A and five UGT2B genes on CRC risk. Unconditional logistic regression and haplotype analyses were conducted to identify associations with CRC risk and potential gene-environment interactions. UGT1A haplotype analysis found that the T-G haplotype in UGT1A10 exon 1 (block 2: rs17864678, rs10929251) decreased cancer risk for the colon [proximal (OR = 0.28, 95% CI = 0.11–0.69) and for the distal colon (OR = 0.32, 95% CI = 0.12–0.91)], and that the C-T-G haplotype in the 3′ region flanking the UGT1A shared exons (block 11: rs7578153, rs10203853, rs6728940) increased CRC risk in males (OR = 2.56, 95% CI = 1.10–5.95). A haplotype in UGT2B15 containing a functional variant (rs4148269, K523T) and an intronic SNP (rs6837575) was found to affect rectal cancer risk overall (OR = 2.57, 95% CI = 1.21–5.04) and in females (OR = 3.08, 95% CI = 1.08–8.74). An interaction was found between high NSAID use and the A-G-T haplotype (block 10: rs6717546, rs1500482, rs7586006) in the UGT1A shared exons that decreased CRC risk. This suggests that UGT genetic variation alters CRC risk differently by anatomical sub-site and gender and that polymorphisms in the UGT1A shared exons may have a regulatory effect on gene expression that allows for the protective effect of NSAIDs on CRC risk.

Acquaviva J, He S, Zhang C, et al.
FGFR3 translocations in bladder cancer: differential sensitivity to HSP90 inhibition based on drug metabolism.
Mol Cancer Res. 2014; 12(7):1042-54 [PubMed] Related Publications
UNLABELLED: Activating mutations and/or overexpression of FGFR3 are common in bladder cancer, making FGFR3 an attractive therapeutic target in this disease. In addition, FGFR3 gene rearrangements have recently been described that define a unique subset of bladder tumors. Here, a selective HSP90 inhibitor, ganetespib, induced loss of FGFR3-TACC3 fusion protein expression and depletion of multiple oncogenic signaling proteins in RT112 bladder cells, resulting in potent cytotoxicity comparable with the pan-FGFR tyrosine kinase inhibitor BGJ398. However, in contrast to BGJ398, ganetespib exerted pleiotropic effects on additional mitogenic and survival pathways and could overcome the FGFR inhibitor-resistant phenotype of FGFR3 mutant-expressing 97-7 and MHG-U3 cells. Combinatorial benefit was observed when ganetespib was used with BGJ398 both in vitro and in vivo. Interestingly, two additional FGFR3 fusion-positive lines (RT4 and SW480) retained sensitivity to HSP90 inhibitor treatment by the ansamycins 17-AAG and 17-DMAG yet displayed intrinsic resistance to ganetespib or AUY922, both second-generation resorcinol-based compounds. Both cell lines, compared with RT112, expressed considerably higher levels of endogenous UGT1A enzyme; this phenotype resulted in a rapid glucuronidation-dependent metabolism and subsequent efflux of ganetespib from SW780 cells, thus providing a mechanism to account for the lack of bioactivity.
IMPLICATIONS: Pharmacologic blockade of the molecular chaperone HSP90 represents a promising approach for treating bladder tumors driven by oncogenic gene rearrangements of FGFR3. Furthermore, UDP-glucuronosyltransferase enzyme expression may serve as a predictive factor for clinical response to resorcinol-based HSP90 inhibitors.

Han FF, Guo CL, Yu D, et al.
Associations between UGT1A1*6 or UGT1A1*6/*28 polymorphisms and irinotecan-induced neutropenia in Asian cancer patients.
Cancer Chemother Pharmacol. 2014; 73(4):779-88 [PubMed] Related Publications
PURPOSE: Neutropenia is a life-threatening side effect of irinotecan, and uridine diphosphate glucuronosyltransferases (UGTs) gene polymorphisms are considered to be one of the predictive markers of irinotecan-related toxicities. Many studies have demonstrated that patients bearing UGT1A1*28 have a higher risk of severe neutropenia on toxicity of irinotecan. However, UGT1A1 (TA7/TA7) was very rare in Asian populations. Some researches reported that UGT1A1*28 and/or UGT1A1*6 could predict irinotecan-induced toxicities in Asian populations, but controversial conclusions still remained. This study aims to investigate the association between UGT1A1 gene polymorphisms *6, *6/*28 and irinotecan-related neutropenia in Asian cancer patients receiving irinotecan regimen chemotherapy.
EXPERIMENTAL DESIGN: Meta-analyses were done to assess the relationship between UGT1A1*6 or UGT1A1*6/*28 and irinotecan-induced neutropenia.
RESULTS: The risk of neutropenia was significantly higher among patients with a UGT1A1*6 genotype than among those carrying the UGT1A1*1 allele(s) [odds ratio (OR) 3.276; 95 % confidence interval (CI) 1.887-5.688; P = 0.000 (*6/*6 vs. *1/*6 or *1/*1)], [OR 1.542; 95 % CI 1.180-2.041; P = 0.001 (*6/*6 or *1/*6 vs. *1/*1)]. Also, the risk was significantly higher among patients with a UGT1A1*6/*28 than among those carrying the UGT1A1*1 allele(s) [OR 3.275; 95 % CI 2.152-4.983; P = 0.000 (*6/*6 or *28/*28 or *6/*28 vs. *1/*6 or *1/*28 or *1/*1)].
CONCLUSIONS: In conclusion, the UGT1A1*6 and UGT1A1*6/*28 genotypes were associated with an increased risk of irinotecan-induced neutropenia in Asian cancer patients.

Karakosta M, Kalotychou V, Kostakis A, et al.
UGT1A1*28 polymorphism in chronic lymphocytic leukemia: the first investigation of the polymorphism in disease susceptibility and its specific cytogenetic abnormalities.
Acta Haematol. 2014; 132(1):59-67 [PubMed] Related Publications
Chronic lymphocytic leukemia (CLL) has been recently attributed to a combination of genetic predisposition and exposure to environmental factors. UDP-glucuronosyltransferase (UGT)1A1*28 is an inborn polymorphism that results in significant downregulation of uridine diphosphate glucuronyltransferase 1-1 (UGT1A1) activity, one of the most critical metabolizing enzymes involved in the detoxification of toxic substances, some of which contribute to CLL pathogenesis. Here, for the first time, we investigated the putative impact of UGT1A1*28 on CLL incidence and on the formation of the most common chromosomal abnormalities of CLL. UGT1A1*28 was investigated in 109 CLL patients and 108 healthy controls, and was associated with karyotypic and fluorescence in situ hybridization (FISH) results. A significant high frequency of the mutant genotype was observed in patients carrying abnormal FISH patterns, especially del(11q) and +12, which are CLL-specific abnormalities. We also observed a significant association between UGT1A1*28 and the intermediate to unfavorable cytogenetic CLL risk groups. No difference, though, was observed in genotypes between patients and controls. Therefore, we could suggest that UGT-deficient individuals may be at a greater risk for developing CLL-specific abnormalities. Our study might serve as a starting point to consider UGT1A1*28 polymorphism as one of the possible predisposing factors of CLL pathogenesis.

Xie FW, Peng YH, Chen X, et al.
Regulation and expression of aberrant methylation on irinotecan metabolic genes CES2, UGT1A1 and GUSB in the in-vitro cultured colorectal cancer cells.
Biomed Pharmacother. 2014; 68(1):31-7 [PubMed] Related Publications
OBJECTIVE: To evaluate the aberrant methylation gene expression related to the irinotecan (CPT-11) metabolic enzymes in different colorectal cancer cell strains; provide new thoughts and measures for reverse of tumor drug resistance.
METHODS: Studied the aberrant methylation state of CES2, UGT1A1 and GUSB in eight colorectal cancer cell strains through MSP method; and analyze the expression of the target gene after being dealt with DAC.
RESULTS: UGT1A1 showed methylation in five cell strains, while CES2 and GUSB respectively showed consistent unmethylation or hemimethylation. After being dealt with DAC, CES2 and GUSB mRNA showed different expressions but not significant. The expression quantity of UGT1A1mRNA in the low-expression cell strains increased significantly. The expression of UGT1A1 protein where POSITIVE presented low expression was up-regulated to different degrees. Negative tropism was found in CES2 and UGT1A1.
CONCLUSION: Methylation in UGT1A1 gene expression silencing as an important mechanism; methylation could provide an effective target for methylation regulation intervening in the treatment of CPT-11. Meanwhile, studies found that the changes in expressions of CES2 and GUSB might be resulted from some unknown target that still existed during the regulation, or from the influence of methylation in the non-core zone of promoters on the gene transcription.

Hirata K, Nagata N, Kato T, et al.
Prospective phase II trial of second-line FOLFIRI in patients with advanced colorectal cancer including analysis of UGT1A1 polymorphisms: FLIGHT 2 study.
Anticancer Res. 2014; 34(1):195-201 [PubMed] Related Publications
AIM: This is a multicenter phase II study to assess the efficacy and toxicity of FOLFIRI treatment agents in full and the influence of UGT1A1*28 polymorphism in Japanese patients with advanced/metastatic colorectal cancer (mCRC).
PATIENTS AND METHODS: Fifty patients with mCRC participated in this study. Treatment consisted of FOLFIRI (irinotecan; 150 mg/m(2)) as second-line chemotherapy; 34 patients consented to the evaluation of UGT1A1 genotype.
RESULTS: The overall response rate was 12% for all 50 evaluable patients; 31 patients (62.0%) had stable disease, and only in 12 (24.0%) did disease progress. The median progression-free survival was 5.8 months. The tolerance treatment was acceptable, with only 15 out of 50 patients (30%) experiencing grade 3/4 neutropenia, and grade 4 thrombocytopenia was observed in only one case. Grade 3 non-hematological adverse reactions included stomatitis in three, diarrhea in one, and a clinically insignificant increase in serum alkaline phosphatases in one patient, respectively. There was no definite relation between the UGT1A1*28 polymorphism and toxicity.
CONCLUSION: Standard FOLFIRI regimen can be administered to Japanese patients. The results showed good tolerability and efficacy for second-line FOLFIRI, provided that evaluation of UGT1A1 polymorphism is properly implemented before the start of the chemotherapy.

Kim do Y, Paek TY, Oh SY, et al.
Pretreatment selection of regimen according to genetic analysis improves the efficacy of chemotherapy in the first line treatment of metastatic colorectal cancer.
J Surg Oncol. 2014; 109(3):250-4 [PubMed] Related Publications
BACKGROUND AND OBJECTIVES: Metastatic colon cancer patients are treated with the chemotherapy regimens, FOLFOX and FOLFIRI, in either order. So far, we cannot predict the response of chemotherapeutic agent, so it is necessary to find which regimen is adequate before starting chemotherapy.
METHODS: Enrolled patients are randomized into either conventional treatment or planned treatment preceded by pretreatment genetic analysis. Blood samples of patients in planned treatment group (N = 53) were analyzed for the genetic polymorphism before selection of chemotherapeutic agents. Target genes were XPD-751, GSTP-1-105, XRCC1-399 for oxaliplatin, UGT1A1 for irinotecan. The response was measured by computed tomographic scan after completion of three cycles of chemotherapy.
RESULTS: Overall response rate was significantly higher in planned group (67.9% vs. 46.3%, P = 0.020). In FOLFOX group, response rate was significantly improved in the planned patients(77.1% vs. 50%, P = 0.018). In FOLFIRI group, the difference didn't reach statistical significance (50% vs. 42.5%, P = 0.776).
CONCLUSIONS: We found significantly improved response rates in the chemotherapy of metastatic colon cancer by pretreatment genetic analysis, especially in FOLFOX group.

Liu M, Wang Q, Liu F, et al.
UDP-glucuronosyltransferase 1A compromises intracellular accumulation and anti-cancer effect of tanshinone IIA in human colon cancer cells.
PLoS One. 2013; 8(11):e79172 [PubMed] Free Access to Full Article Related Publications
BACKGROUND AND PURPOSE: NAD(P)H: quinone oxidoreductase 1 (NQO1) mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation is the dominant metabolic pathway of tanshinone IIA (TSA), a promising anti-cancer agent. UGTs are positively expressed in various tumor tissues and play an important role in the metabolic elimination of TSA. This study aims to explore the role of UGT1A in determining the intracellular accumulation and the resultant apoptotic effect of TSA.
EXPERIMENTAL APPROACH: We examined TSA intracellular accumulation and glucuronidation in HT29 (UGT1A positive) and HCT116 (UGT1A negative) human colon cancer cell lines. We also examined TSA-mediated reactive oxygen species (ROS) production, cytotoxicity and apoptotic effect in HT29 and HCT116 cells to investigate whether UGT1A levels are directly associated with TSA anti-cancer effect. UGT1A siRNA or propofol, a UGT1A9 competitive inhibitor, was used to inhibit UGT1A expression or UGT1A9 activity.
KEY RESULTS: Multiple UGT1A isoforms are positively expressed in HT29 but not in HCT116 cells. Cellular S9 fractions prepared from HT29 cells exhibit strong glucuronidation activity towards TSA, which can be inhibited by propofol or UGT1A siRNA interference. TSA intracellular accumulation in HT29 cells is much lower than that in HCT116 cells, which correlates with high expression levels of UGT1A in HT29 cells. Consistently, TSA induces less intracellular ROS, cytotoxicity, and apoptotic effect in HT29 cells than those in HCT116 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol can decrease TSA glucuronidation and simultaneously improve its intracellular accumulation, as well as enhance TSA anti-cancer effect.
CONCLUSIONS AND IMPLICATIONS: UGT1A can compromise TSA cytotoxicity via reducing its intracellular exposure and switching the NQO1-triggered redox cycle to metabolic elimination. Our study may shed a light in understanding the cellular pharmacokinetic and molecular mechanism by which UGTs determine the chemotherapy effects of drugs that are UGTs' substrates.

Xie FW, Peng Y, Chen X, et al.
Relationship between the expression of CES2, UGT1A1, and GUSB in colorectal cancer tissues and aberrant methylation.
Neoplasma. 2014; 61(1):99-109 [PubMed] Related Publications
Irinotecan (CPT-11) is considered an important drug in the treatment of colorectal cancer, but its continuous administration reduces its sensitivity and influences the curative effect. The metabolism of CPT-11 is mainly controlled by carboxy-lesterase (CES), UDP-glucuronosyltransferase 1A (UGT1A), and β-glucuronidase (GUSB). Studies to date have shown that methylation acts as an important mechanism for gene expression to suppress the metabolic enzymes of many chemotherapeutics. This study, which selected 99 colorectal cancer patients, 23 of whom had paracancerous tissues and eight of whom had large intestine adenomas, aimed to investigate the correlation between the protein expression of the CPT-11 metabolic enzyme genes CES2, UGT1A1, and GUSB and various clinical pathological parameters of colorectal cancer tissues, as well as the relationship between methylation regulation and the gene expression of CES2, UGT1A1, and GUSB. We used immunohistochemistry staining, methylation-specific PCR, and clinical status to reveal the possible regulatory targets of chemotherapeutic resistance in colorectal cancer and to provide new ideas and countermeasures to reverse anti-cancer drug resistance and chemosensitization. The results showed that the expression of CES2, UGTA1A1, and GUSB varies in colorectal pathology tissues and that the expression of CES2 is somewhat related to tumor staging. This relationship is likely caused by the gene regulation of UGT1A1 and GUSB, and other regulation mechanisms may also be involved. The methylation of the CES2 gene is irrelevant to the morbidity associated with colorectal cancer. The GUSB gene showed no significant differences in methylation, and the hemi-methylation was also positive, the regulating ability of which needs to be verified. The potential role of these genes in the colorectal cancer progression, which may be directly related to the methylation regulation of UGT1A1, requires further research. The promoter of the UGT1A1 gene in colorectal cancer cells is methylated, which is an important mechanism of UGT1A1 gene silencing and can be regarded as the target point of research for CPT-11 drug resistance and control mechanisms for the reversal of drug resistance.

Rouleau M, Roberge J, Bellemare J, Guillemette C
Dual roles for splice variants of the glucuronidation pathway as regulators of cellular metabolism.
Mol Pharmacol. 2014; 85(1):29-36 [PubMed] Related Publications
Transcripts of the UGT1A gene, encoding half of human UDP-glucuronosyltransferase (UGT) enzymes, undergo alternative splicing, resulting in active enzymes named isoforms 1 (i1s) and novel truncated isoforms 2 (i2s). Here, we investigated the effects of depleting endogenous i2 on drug response and attempted to unveil any additional biologic role(s) for the truncated novel UGT proteins. We used an integrated systems biology approach that combines RNA interference with unbiased global genomic and proteomic screens, and used HT115 colorectal cancer cells as a model. Consistent with previous evidence suggesting that i2s negatively regulate i1s through protein-protein interactions, i2-depleted cells were less sensitive to drug-induced cell death (IC50 of 0.45 ± 0.05 µM versus 0.22 ± 0.03 µM; P = 0.006), demonstrating that modulation of i2 levels meaningfully impacts drug bioavailability and cellular response. We also observed reduced production of reactive oxygen species by 30% (P < 0.05), and an enhanced expression (>1.2-fold; P < 0.05) of several proteins, such as hemoglobin α genes and superoxide dismutase 1, that have network functions associated with antioxidant properties. Interaction proteomics analysis of endogenous proteins from the cellular model, mainly in human intestine but also in kidney tissues, further uncovered interactions between i2s (but not i1s) and the antioxidant enzymes catalase and peroxiredoxin 1, which may influence antioxidant potential through sequestration of these novel partners. Our findings demonstrate for the first time dual roles for i2s in the cellular defense system as endogenous regulators of drug response as well as in oxidative stress.

Yashiro M, Nishii T, Hasegawa T, et al.
A c-Met inhibitor increases the chemosensitivity of cancer stem cells to the irinotecan in gastric carcinoma.
Br J Cancer. 2013; 109(10):2619-28 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Cancer stem cells (CSCs) may be postulated mediators of the chemoresistance. This study aimed to determine an effective signal inhibitor with effects on the proliferation of CSCs in combination with anticancer drugs.
METHODS: We used three gastric cancer cell lines and three side population (SP)-enriched CSC cell lines. We examined the combined effects of inhibitors against stemness signals, including c-Met inhibitor SU11274, and five anticancer drugs on the CSC proliferation and mRNA expression of chemoresistance-associated genes.
RESULTS: The IC50 of irinotecan in SP-enriched CSC was 10.5 times higher than parent OCUM-2M cells, whereas that of oxaliplatin, taxol, gemcitabine, and 5-fluorouracil was 2.0, 2.8, 2.0, and 1.2, respectively. The SP cell lines had higher expression levels of UGT1A1, ABCG2, and ABCB1 than their parent cell lines. There was a synergistic antiproliferative effect with a combination of SU11274 and SN38 in SP cells, but not other inhibitors. The SU11274 significantly decreased the expression of UGT1A1, but not ABCG2 and ABCB1. The SN38 plus SU11274 group more effectively suppressed in vivo tumour growth by OCUM-2M/SP cells than either group alone.
CONCLUSION: Cancer stem cells have chemoresistance to irinotecan. The c-Met inhibitor may be a promising target molecule for irinotecan-based chemotherapy of gastric cancer.

Hirasawa A, Zama T, Akahane T, et al.
Polymorphisms in the UGT1A1 gene predict adverse effects of irinotecan in the treatment of gynecologic cancer in Japanese patients.
J Hum Genet. 2013; 58(12):794-8 [PubMed] Related Publications
Irinotecan is a key chemotherapeutic drug used to treat many tumors, including cervical and ovarian cancers; however, irinotecan can cause toxicity, particularly in the presence of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene polymorphisms, which are associated with reduced enzyme activity. Here, we investigated the prevalence of three different variants of UGT1A1 (UGT1A1*6, UGT1A1*27 and UGT1A1*28) and their relationships with irinotecan-induced adverse events in patients with gynecologic cancer, who are treated with lower doses of irinotecan than patients with other types of solid tumors. Fifty-three female patients treated with irinotecan and 362 female patients not treated with irinotecan were screened for UGT1A1*6, UGT1A1*27 and UGT1A1*28. Homozygosity for UGT1A1*6 or heterozygosity for UGT1A1*6/*28 was associated with a high risk of severe absolute neutrophil count decrease or diarrhea (odds ratios: 16.03 and 31.33, respectively). In contrast, serum bilirubin levels were not associated with irinotecan toxicity. Homozygosity for UGT1A1*6/*6 and heterozygosity for UGT1A1*6/*28 were associated with an increased risk of absolute neutrophil count and/or diarrhea in Japanese gynecologic cancer patients, despite the lower doses of irinotecan used in these patients. UGT1A1*6 and UGT1A1*28 are potential predictors of severe absolute neutrophil decrease and diarrhea caused by low-dose irinotecan in gynecologic cancer patients.

Hazama S, Mishima H, Tsunedomi R, et al.
UGT1A1*6, 1A7*3, and 1A9*22 genotypes predict severe neutropenia in FOLFIRI-treated metastatic colorectal cancer in two prospective studies in Japan.
Cancer Sci. 2013; 104(12):1662-9 [PubMed] Related Publications
UNLABELLED: Retrospective studies have suggested that UDP-glucuronosyltransferase (UGT)1A1, UGT1A7, and UGT1A9 predict severe toxicity and efficacy of irinotecan-containing regimens. We prospectively evaluated the impact of UGT1A genotypes and haplotypes on severe toxicity and efficacy in patients treated with fluorouracil, leucovorin, and irinotecan combination chemotherapy (FOLFIRI) for metastatic colorectal cancer (mCRC) from the two prospective multicenter phase II studies in Japan. The FLIGHT1 study was a first-line FOLFIRI trial, and FLIGHT2 was a FOLFOX-refractory, second-line FOLFIRI trial. A total of 73 patients agreed to additional analysis, and were genotyped for UGT1A polymorphisms, UGT1A1*28 (TA6>TA7), UGT1A1*6 (211G>A), UGT1A1*27 (686C>A), UGT1A1*60 (-3279T>G), UGT1A1*93 (-3156G>A), UGT1A7 (-57T>G), UGT1A7*3 (387T>G, 622T>C), and UGT1A9*22 (T9>T10). Of 73 patients, 34 developed G3/4 severe hematological toxicities. The toxicities were significantly more frequent in patients with UGT1A1*6 (211A), UGT1A7 (387G), and UGT1A9*22 reference alleles (T9). Haplotype I, which consists of all favorable alleles, was associated with a significant reduction in hematologic toxicity (P = 0.031). In contrast, haplotype II, which contains four high-risk alleles, showed significantly higher hematologic toxicity than the other haplotypes (P = 0.010). Six out of seven patients who were homozygous for UGT1A1*28 or *6 experienced severe hematological toxicity despite the fact that their response rate was not impaired (42.9%). We concluded that UGT1A polymorphisms, especially UGT1A1*6, are important for the prediction of severe toxicity of FOLFIRI in northeast Asian populations. In this regard, haplotype analyses should substantially impact the prediction of severe hematological toxicities of FOLFIRI. (

De Mattia E, Toffoli G, Polesel J, et al.
Pharmacogenetics of ABC and SLC transporters in metastatic colorectal cancer patients receiving first-line FOLFIRI treatment.
Pharmacogenet Genomics. 2013; 23(10):549-57 [PubMed] Related Publications
OBJECTIVE: Membrane transporters are widely recognized as important determinants of drug disposition and response, generating increasing interest on the pharmacological implications of their genetic variations. The aim of this study was to elucidate the predictive/prognostic role of ATP-binding cassette (ABC) and solute carrier (SLC) protein polymorphisms on irinotecan (FOLFIRI regimen) outcome.
PATIENTS AND METHODS: A total of 250 White metastatic colorectal cancer patients homogenously treated with a first-line FOLFIRI regimen were genotyped for a panel of variants in five transporter genes. The primary study endpoints were the response rate (partial or complete response), overall survival, and time to progression. Toxicity was considered a secondary endpoint. Irinotecan pharmacokinetic data of 71 patients were used for polymorphism functional analysis.
RESULTS: Two variants of the ABCG2 (-15622C>T, rs7699188) gene were found to be predictive (P < 0.01) of the response rate. High-order relationships of ABC/SLC markers with previously investigated genetic (UGT1A1 polymorphisms) and nongenetic (primary tumor site) factors that helped determine the response rate were highlighted. A prognostic effect of the ABCB1 rs2032582 variant on patient overall survival emerged (P = 0.0074). The ABCG2 rs7699788 variant was also seen to be associated with grade 3-4 nonhematological toxicity (P = 0.0012). The ABCG2 (-15622C>T, rs7699188) and ABCB1 (rs2032582) polymorphisms were not found to be associated with pharmacokinetic parameters.
CONCLUSION: This study showed that ABC/SLC polymorphisms have a crucial contribution toward the FOLFIRI outcome. This could represent a further step toward personalized therapy.

Kim SY, S Hong Y, K Shim E, et al.
S-1 plus irinotecan and oxaliplatin for the first-line treatment of patients with metastatic colorectal cancer: a prospective phase II study and pharmacogenetic analysis.
Br J Cancer. 2013; 109(6):1420-7 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: S-1 is an oral fluoropyrimidine that mimics infusional 5-fluorouracil. The aim of this phase II trial was to explore the clinical efficacy of the triplet regimen TIROX, which consists of S-1, irinotecan and oxaliplatin.
METHODS: Forty-two chemo-naive patients with metastatic colorectal cancer (mCRC) were planned to be enrolled and be treated with irinotecan 150 mg m(-2) followed by oxaliplatin 85 mg m(-2) on day 1 and S-1 80 mg m(-2) per day from day 1 to 14 every 3 weeks. Polymorphisms in the UGT1A1, UGT1A6, UGT1A7 and CYP2A6 genes were analysed.
RESULTS: Between July 2007 and February 2008, 43 patients were enrolled. An objective response was noted in 29 patients (67.4%, 95% confidence interval: 53.4-81.4), of which 2 achieved durable complete responses. The median progression-free survival was 10.0 months and the median overall survival was 19.2 months. Significant grade 3 or 4 adverse events were neutropenia (45.2%), febrile neutropenia (9.5%), diarrhoea (7.1%) and vomiting (9.5%). Increased gastrointestinal toxicities were associated with the presence of UGT1A6*2 or UGT1A7*3 and an improved tumour response was noted in those without variant alleles of CYP2A6 or UGT1A1*60.
CONCLUSION: The combination of S-1, irinotecan and oxaliplatin showed favourable efficacy and tolerability in untreated patients with mCRC.

Clendenen T, Zeleniuch-Jacquotte A, Wirgin I, et al.
Genetic variants in hormone-related genes and risk of breast cancer.
PLoS One. 2013; 8(7):e69367 [PubMed] Free Access to Full Article Related Publications
Sex hormones play a key role in the development of breast cancer. Certain polymorphic variants (SNPs and repeat polymorphisms) in hormone-related genes are associated with sex hormone levels. However, the relationship observed between these genetic variants and breast cancer risk has been inconsistent. We conducted a case-control study nested within two prospective cohorts to assess the relationship between specific genetic variants in hormone-related genes and breast cancer risk. In total, 1164 cases and 2111 individually-matched controls were included in the study. We did not observe an association between potential functional genetic polymorphisms in the estrogen pathway, SHBG rs6259, ESR1 rs2234693, CYP19 rs10046 and rs4775936, and UGT1A1 rs8175347, or the progesterone pathway, PGR rs1042838, with the risk of breast cancer. Our results suggest that these genetic variants do not have a strong effect on breast cancer risk.

Williamson SC, Mitter R, Hepburn AC, et al.
Characterisations of human prostate stem cells reveal deficiency in class I UGT enzymes as a novel mechanism for castration-resistant prostate cancer.
Br J Cancer. 2013; 109(4):950-6 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Evidence increasingly supports that prostate cancer is initiated by the malignant transformation of stem cells (SCs). Furthermore, many SC-signalling pathways are shown to be shared in prostate cancer. Therefore, we planned transcriptome characterisation of adult prostate SCs as a strategy to consider new targets for cancer treatment.
METHODS: Intuitive pathway analysis was used for putative target discovery in 12 matched selections of human prostate SCs, transiently amplifying cells and terminally differentiated cells. These were pooled into three groups according to the stage of differentiation for mRNA microarray analysis. Targets identified were validated using uncultured primary tissue (n=12), functional models of prostate cancer and a tissue microarray consisting of benign (n=42) and malignant prostate (n=223).
RESULTS: A deficiency in class 1 UDP glucuronosyltransferase (UGT) enzymes (UGT1A) was identified in prostate SCs, which are involved in androgen catabolism. Class 1 UGT enzyme expression was also downregulated in cancer SCs and during progression to metastatic castration-resistant prostate cancer (CRPC). Reduction of UGT1A expression in vitro was seen to improve cell survival and increase androgen receptor (AR) activity, as shown by upregulation of prostate-specific antigen expression.
INTERPRETATION: Inactivation of intracellular androgen catabolism represents a novel mechanism to maintain AR activity during CRPC.

Sun D, Jones NR, Manni A, Lazarus P
Characterization of raloxifene glucuronidation: potential role of UGT1A8 genotype on raloxifene metabolism in vivo.
Cancer Prev Res (Phila). 2013; 6(7):719-30 [PubMed] Free Access to Full Article Related Publications
Raloxifene is a second-generation selective estrogen receptor modulator used for the prevention and treatment of osteoporosis and the prevention of breast cancer in postmenopausal women. Raloxifene is extensively metabolized by glucuronidation to form raloxifene-6-glucuronide (ral-6-Gluc) and raloxifene-4'-glucuronide (ral-4'-Gluc). The goal of the present study was to determine whether functional polymorphisms in active UGTs could play a role in altered raloxifene glucuronidation in vivo. Using homogenates from HEK293 UGT-overexpressing cell lines, raloxifene was shown to be glucuronidated primarily by the hepatic UGTs 1A1 and 1A9 and the extra-hepatic UGTs 1A8 and 1A10; no detectable raloxifene glucuronidation activity was found for UGT2B enzymes. Functional UGT1A1 transcriptional promoter genotypes were significantly (Ptrend = 0.005) associated with ral-6-Gluc formation in human liver microsomes, and, consistent with the decreased raloxifene glucuronidation activities observed in vitro with cell lines overexpressing UGT1A8 variants, the UGT1A8*2 variant was significantly (P = 0.023) correlated with total raloxifene glucuronide formation in human jejunum homogenates. While ral-4'-Gluc exhibited 1:100th the anti-estrogenic activity of raloxifene itself as measured by binding to the estrogen receptor, raloxifene glucuronides comprised about 99% of the circulating raloxifene dose in raloxifene-treated subjects, with ral-4'-Gluc comprising ~70% of raloxifene glucuronides. Plasma ral-6-Gluc (Ptrend = 0.0025), ral-4'-Gluc (Ptrend = 0.001), and total raloxifene glucuronides (Ptrend = 0.001) were increased in raloxifene-treated subjects who were predicted slow metabolizers [UGT1A8 (*1/*3)] versus intermediate metabolizers [UGT1A8 (*1/*1) or UGT1A8 (*1/*2)] versus fast metabolizers [UGT1A8 (*2/*2). These data suggest that raloxifene metabolism may be dependent on UGT1A8 genotype and that UGT1A8 genotype may play an important role in overall response to raloxifene.

Hirose K, Yamashita K, Takada H, et al.
Usefulness of one-point plasma SN-38G/SN-38 concentration ratios as a substitute for UGT1A1 genetic information after irinotecan administration.
Int J Clin Oncol. 2014; 19(2):397-402 [PubMed] Related Publications
BACKGROUND: It was recently reported that genetic polymorphisms of UDP glucuronyltransferase-1 polypeptide A1 (UGT1A1), a glucuronidation enzyme, were associated with irinotecan (CPT-11) metabolism. The active metabolite of CPT-11, 7-ethyl-10-hydroxycamptothecin (SN-38) was glucuronidated (SN-38G) by UGT1A1. Genetic polymorphisms of UGT1A1 were associated with potentially serious adverse events, including neutropenia. Several studies have suggested that the dose of CPT-11 should be decreased in patients homozygous for UGT1A1*6 or UGT1A1*28, or double heterozygotes (*6/*28). However, the reference dose for patients with these genetic polymorphisms is unclear.
METHODS: We investigated the relationship between the SN-38G/SN-38 concentration ratio and the dose of CPT-11 in 70 patients with colorectal cancer who received FOLFIRI-based regimens, by measuring the plasma concentrations of CPT-11, SN-38, and SN-38G.
RESULTS: The SN-38G/SN-38 concentration ratio was lower in patients who were homozygous for UGT1A1*6, heterozygous for UGT1A1*6 or UGT1A1*28, or were double heterozygotes compared with patients with wild-type genes. The relative decreases in the SN-38G/SN-38 concentration ratio in patients homozygous for UGT1A1*6 and in double heterozygotes were greater than in patients heterozygous for UGT1A1*6 or UGT1A1*28. Interestingly, decreases in the SN-38G/SN-38 concentration ratio were associated with decreases in the neutrophil count and the final infusion dose of CPT-11.
CONCLUSION: Our results suggest that the SN-38G/SN-38 concentration ratio is an important factor for guiding dose adjustments, even in patients with wild-type genes. Therefore, the SN-38G/SN-38 concentration ratio, as an index of the patient's metabolic capacity, is useful for assessing dose adjustments of CPT-11.

Cortejoso L, García MI, García-Alfonso P, et al.
Differential toxicity biomarkers for irinotecan- and oxaliplatin-containing chemotherapy in colorectal cancer.
Cancer Chemother Pharmacol. 2013; 71(6):1463-72 [PubMed] Related Publications
PURPOSE: Oxaliplatin or irinotecan is usually administered jointly with fluoropyrimidines in colorectal cancer patients treated with chemotherapy. Both drugs have different toxicity patterns. Biomarkers for predicting high-risk severe adverse reactions can help select the best treatment.
METHODS: A retrospective analysis of 106 colorectal cancer patients receiving an oxaliplatin-based treatment and 56 receiving an irinotecan-based treatment was performed. One copy number variant (GSTT1) and nine polymorphisms in irinotecan and oxaliplatin metabolism, transport or DNA repair genes (ABCB1, UGT1A1, XRCC1, ERCC1, ERCC2, GSTP1) were genotyped by SNaPshot, polymerase chain reactions' length fragments, or copy number assays.
RESULTS: In irinotecan-treated patients, T allele of ABCB1C1236T SNP was associated with a lower risk of asthenia(OR = 0.047; 95 % CI = 0.004–0.493; P = 0.011) and Tallele of ABCB1 C3435T SNP was associated with a lower risk of diarrhea (OR = 0.177; 95 % CI = 0.034–0.919;P = 0.039), and individuals with two copies of GSTT1 gene had a lower risk for asthenia (OR = 0.093; 95 %CI = 0.011–0.794; P = 0.030). In oxaliplatin-treated patients, carriers of one or two T variants of Asn118Asn ERCC1 SNP had a lower risk for neutropenia(OR = 0.205; 95 % CI = 0.061–0.690; P = 0.01) [corrected].
CONCLUSIONS: These biomarkers could help oncologists select the best treatment by reducing toxicity associated with irinotecan or oxaliplatin in colorectal cancer patients, thus increasing their quality of life.

Liu X, Cheng D, Kuang Q, et al.
Association of UGT1A1*28 polymorphisms with irinotecan-induced toxicities in colorectal cancer: a meta-analysis in Caucasians.
Pharmacogenomics J. 2014; 14(2):120-9 [PubMed] Free Access to Full Article Related Publications
A meta-analysis in Caucasians was conducted to investigate the possible association of uridine diphosphate glucuronosyltransferase (UGT) 1A1 gene polymorphisms with irinotecan (IRI)-induced neutropenia and diarrhoea in colorectal cancer (CRC). We searched PubMed and Embase until May 2012 to identify eligible studies, extracted data, assessed methodological quality, and performed statistical analysis using REVMAN 5.1 and R software. Subgroups meta-analyses were performed in groups representing different IRI combination regimens and IRI doses. Sixteen trials were included. UGT1A1*28/*28 genotype was associated with more than fourfold (odds ratio (OR)=4.79, 95% confidence intervals (CI): 3.28-7.01; P<0.00001) and threefold (OR=3.44, 95% CI: 2.45-4.82; P<0.00001) increases in the risk of neutropenia when compared with wild type and with at least one UGT1A1*1 allele, respectively. UGT1A1*1/*28 genotype had an OR of 1.90 (95% CI: 1.44-2.51; P<0.00001) for an increased risk of neutropenia. A twofold increase in risk of diarrhoea was associated with UGT1A1*28/*28 genotype (OR=1.84, 95% CI: 1.24-2.72; P=0.002). In subgroup meta-analysis, the higher incidence of diarrhoea in UGT1A1*28/*28 patients was limited to studies where when IRI was given at higher doses (OR=2.37, 95% CI: 1.39-4.04; P=0.002) or combined with 5-fluorouracil (FU or analogue) (OR=1.78, 95% CI: 1.16-2.75; P=0.009). Genotyping of UGT1A1*28 polymorphism before treatment for CRC can tailor IRI therapy and reduce the IRI-related toxicities. IRI-combined 5-FU (or analogue) and a high-dose IRI therapy enhance IRI-induced diarrhoea among patients bearing the UGT1A1*28 allele. Although the toxicity relationships were much stronger with the UGT1A1*28 homozygous variant, associations were also found with the UGT1A1*28 heterozygous variant.

Liu X, Cheng D, Kuang Q, et al.
Association between UGT1A1*28 polymorphisms and clinical outcomes of irinotecan-based chemotherapies in colorectal cancer: a meta-analysis in Caucasians.
PLoS One. 2013; 8(3):e58489 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Whether UGT1A1*28 genotype is associated with clinical outcomes of irinotecan (IRI)-based chemotherapy in Colorectal cancer (CRC) is an important gap in existing knowledge to inform clinical utility. Published data on the association between UGT1A1*28 gene polymorphisms and clinical outcomes of IRI-based chemotherapy in CRC were inconsistent.
METHODOLOGY/PRINCIPAL FINDINGS: Literature retrieval, trials selection and assessment, data collection, and statistical analysis were performed according to the PRISMA guidelines. Primary outcomes included therapeutic response (TR), progression-free survival (PFS) and overall survival (OS). We calculated odds ratios (OR) and hazard ratios (HR) with 95% confidence intervals (CI). Twelve clinical trials were included. No statistical heterogeneity was detected in analyses of all studies and for each subgroup. Differences in TR, PFS and OS for any genotype comparison, UGT1A1*28/*28 versus (vs) UGT1A1*1/*1 (homozygous model), UGT1A1*1/*28 vs UGT1A1*1/*1 (heterozygous model), and UGT1A1*28/*28 vs all others (recessive model, only for TR) were not statistically significant. IRI dose also did not impact upon TR and PFS differences between UGT1A1 genotype groups. A statistically significant increase in the hazard of death was found in Low IRI subgroup of the homozygous model (HR = 1.48, 95% CI = 1.06-2.07; P = 0.02). The UGT1A1*28 allele was associated with a trend of increase in the hazard of death in two models (homozygous model: HR = 1.22, 95% CI = 0.99-1.51; heterozygous model: HR = 1.13, 95% CI = 0.96-1.32). These latter findings were driven primarily by one single large study (Shulman et al. 2011).
CONCLUSIONS/SIGNIFICANCE: UGT1A1*28 polymorphism cannot be considered as a reliable predictor of TR and PFS in CRC patients treated with IRI-based chemotherapy. The OS relationship with UGT1A1*28 in the patients with lower-dose IRI chemotherapy requires further validation.

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