A study of the association between UGT1A1*28 variant allele of UGT1A1 gene and colonic phenotype of sporadic colorectal cancer

INTRODUCTION

The transcriptional activity of the UGT1A1 gene is modulated by a variable number of repetitions of the dinucleotide (TA) within its promoter region. By comparison to the most common allele (TA)₆ (UGT1A1*1), decreased activity is observed with increasing TA repetitions. The aim of this study was to determine whether the presence of the variant allele UGT1A1*28, harbouring seven TA repetitions, (TA)₇, in the homozygous state, is associated with precancerous colonic lesions and/or with specific colorectal cancer characteristics.

MATERIAL AND METHODS

All patients treated for colorectal cancer in a tertiary care centre, between January 2009 and December 2013, who had routine UGT1A1 genotyping for irinotecan dose-adjustment were included. Data were retrospectively collected.

RESULTS

292 patients were enrolled, including 23 UGT1A1*28/*28 homozygous (7.9%), 137 wild type homozygous (46.9%) and 132 heterozygous (45.2%). There were no significant differences in phenotypic colonic characteristics between homozygous and heterozygous patients carrying the UGT1A1*28 allele as compared to *1/*1 homozygous. Patients treated with aspirin were significantly more common in the UGT1A1*28/*28 homozygous group than in the other groups (7/23 (30.4%) compared to 22/269 (8.2%), p = 0.001).

CONCLUSION

Dinucleotide polymorphism in the promoter region of the UGT1A1 gene is not associated with a specific colonic phenotype in patients with sporadic colorectal cancer.

Pharmacogenetics of anti-cancer drugs: State of the art and implementation - recommendations of the French National Network of Pharmacogenetics

Individualized treatment is of special importance in oncology because the drugs used for chemotherapy have a very narrow therapeutic index. Pharmacogenetics may contribute substantially to clinical routine for optimizing cancer treatment to limit toxic effects while maintaining efficacy. This review presents the usefulness of pharmacogenetic tests for some key applications: dihydropyrimidine dehydrogenase (DPYD) genotyping for fluoropyrimidine (5-fluorouracil, capecitabine), UDP glucuronosylstransferase (UGT1A1) for irinotecan and thiopurine S-methyltransferase (TPMT) for thiopurine drugs. Depending on the level of evidence, the French National Network of Pharmacogenetics (RNPGx) has issued three levels of recommendations for these pharmacogenetic tests: essential, advisable, and potentially useful. Other applications, for which the level of evidence is still discussed, will be evoked in the final section of this review.

Pharmacogenetics-based personalized therapy: Levels of evidence and recommendations from the French Network of Pharmacogenetics (RNPGx)

More than 50 laboratories offer pharmacogenetic testing in France. These tests are restricted to a limited number of indications: prevention of serious adverse drug reactions; choice of most appropriate therapeutic option; dose adjustment for a specific drug. A very small proportion of these tests are mentioned in drug information labeling and the data provided (if any) are generally insufficient to ascertain whether a test is required and if it is useful. This article discusses the rationale for evaluating the performance and clinical usefulness of pharmacogenetics and provides, on behalf of the French national network of pharmacogenetics (RNPGx), three levels of recommendation for testing: essential, advisable, and possibly helpful.

UGT1A1 gene polymorphism is associated with toxicity and clinical efficacy of irinotecan-based chemotherapy in patients with advanced colorectal cancer

OBJECTIVES

To investigate the relationship between uridine diphosphate glucoronosyltransferase 1A1 (UGT1A1)*28/*6 and toxicity and clinical efficacy of irinotecan-based chemotherapy in patients with advanced colorectal cancer (CRC) in Xinjiang Uygur and Han population.

METHODS

A total of 183 patients (Uygur, 114; Han, 69) with advanced CRC who received the irinotecan-based chemotherapy were enrolled in this retrospective analysis. Polymerase chain reaction amplification and direct sequencing method were used for UGT1A1*28 and UGT1A1*6 polymorphism detection. The patients were followed up to analyze the relationship between different genotypes with adverse reactions and the clinical outcome of irinotecan-based chemotherapy.

RESULTS

Significant differences were found in genotype frequencies of UGT1A1*28 and UGT1A1*28/*6 between Uygur and Han (P = 0.02 and P = 0.002). Uygur and Han patients carrying wild UGT1A1*28 and *6 genotypes appeared to have significantly lower diarrhea incidence (I/II and III/IV) than those carrying mutant genotypes (all P < 0.05). In Uygur patients, UGT1A1*28 genotypes were related with objective response rate and disease control rate (P < 0.05). Compared with *1 allele *1/*1, *1 allele *1/*28*1/*28 mutant of UGT1A1*28 was associated with shorter OS in both Uygur and Han ethnicities (all P < 0.05). Compared with double allele variants (DW), single allele variants (SV), and double allele variants (DV) of UGT1A1*28/*6 were associated with shorter overall survival (OS) in Uygur and Han (all P < 0.05). Cox regression analysis revealed factors significantly influencing OS, including UGT1A1*28, UGT1A1*6, combined genotypes and chemotherapy line in Ugyur, and only combined genotypes in Han (all P < 0.05).

CONCLUSION

UGT1A1 gene polymorphism predicts irinotecan-related adverse reactions in advanced CRC patients of Xinjiang Uygur and Han nationality; UGT1A1 gene polymorphism is correlated with efficacy and prognosis in Uygur nationality, but only related to prognosis in Han nationality in irinotecan-based chemotherapy.