Gilbert's Syndrome and irinotecan toxicity: combination with UDP-glucuronosyltransferase 1A7 variants increases risk

BACKGROUND: Gilbert's syndrome is characterized by a functional promoter single nucleotide polymorphism (SNP) of the UDP-glucuronosyltransferase (UGT) 1A1 gene and represents a pharmacogenetic risk factor for irinotecan toxicity, but study data remain controversial. The active CPT-11 metabolite 7-ethyl-10-hydroxycamptothecin is detoxified by several UGT1A proteins, which include UGT1A7 with a high specific activity that may contribute to the risk of irinotecan toxicity in Gilbert's syndrome patients. METHODS: Genotyping of the UGT1A1*28, UGT1A7 N129K/R131K, and UGT1A7-57T/G variants was done in 105 irinotecan-treated patients with metastatic colorectal cancer; adverse events were documented during all 297 treatment cycles and analyzed by Cochran-Mantel-Haenszel, Mann-Whitney, and chi2 tests. RESULTS: The presence of UGT1A7 but not UGT1A1 variants was associated with at least one adverse event. In patients combining all three variants, thrombocytopenia and leukopenia were significantly more frequent. The overall incidence of adverse events was significantly higher (P = 0.0035) in carriers of the UGT1A risk alleles, who also had significantly higher rate of dose reductions. CONCLUSIONS: Irinotecan toxicity is more likely in patients with Gilbert's syndrome carrying the UGT1A1*28 allele combined with reduced function UGT1A7 N129K/R131K and UGT1A7-57T/G SNP. Based on the ability of UGT1A7 to metabolize and eliminate the active irinotecan metabolite 7-ethyl-10-hydroxycamptothecin, the UGT1A1/UGT1A7 SNP combination haplotype appears to be a superior risk predictor than Gilbert's syndrome alone.     

Severe CPT-11 toxicity in patients with Gilbert's syndrome: Two case reports

Background: CPT-11 is hydrolyzed to its active metabolite SN-38, which is mainly eliminated through conjugation by hepatic uridine diphosphate glucuronosyl transferases (UGTs) to the glucuronide (SN-38G) derivative. Preclinical studies showed that UGT*1.1 is the isozyme responsible for SN-38 glucuronidation. Patients with Gilbert's syndrome have deficient UGT*1.1 activity, therefore may have an increased risk for related CPT-11 toxicity.Patients and methods: Two patients with metastatic colon cancer and Gilbert's syndrome were treated with CPT-11 based chemotherapy. CPT-11, SN-38 and SN-38G pharmacokinetics parameters were obtained. Serum bilirubin was analysed by alkaline methanolysis and HPLC.Results: Both patients presented grade 4 neutropenia and/or diarrhea (NCI-CTC) in every treatment cycle. Biliary index (after Gupta et al) values were well above 4000.Conclusion: We present the first clinical evidence linking bilirubin glucuronidation status and CPT-11 related toxicity. The severe toxicity experienced by the two patients with Gilbert's syndrome treated with CPT-11 based chemotherapy has a genetic basis. Individuals with Gilbert's syndrome have an enhanced risk for CPT-11 toxicity. Unconjugated serum bilirubin could be predictive parameter of CPT-11 toxicity.     

UGT1A1 polymorphism can predict hematologic toxicity in patients treated with irinotecan.

PURPOSE: Irinotecan (CPT-11) is approved in metastatic colorectal cancer treatment and can cause severe toxicity. The main purpose of our study was to assess the role of different polymorphisms on the occurrence of hematologic toxicities and disease-free survival in high-risk stage III colon cancer patients receiving 5-fluorouracil (5FU) and CPT-11 adjuvant chemotherapy regimen in a prospective randomized trial. EXPERIMENTAL DESIGN: Four hundred patients were randomized in a phase III trial comparing LV5FU2 to LV5FU2 + CPT-11. DNA from 184 patients was extracted and genotyped to detect nucleotide polymorphism: 3435C>T for ABCB1, 6986A>G for CYP3A5, UGT1A1*28 and -3156G>A for UGT1A1. RESULTS: Genotype frequencies were similar in both treatment arms. In the test arm, no significant difference was observed in toxicity or disease-free survival for ABCB1 and CYP3A5 polymorphisms. UGT1A1*28 homozygous patients showed more frequent severe hematologic toxicity (50%) than UGT1A1*1 homozygous patients (16.2%), P = 0.06. Moreover, patients homozygous for the mutant allele of -3156G>A UGT1A1 polymorphism showed more frequent severe hematologic toxicity (50%) than patients homozygous for wild-type allele (12.5%), P = 0.01. This toxicity occurred significantly earlier in homozygous mutant than wild-type homozygous patients (P = 0.043). In a Cox model, the hazard ratio for severe hematologic toxicity is significantly higher for patients with the A/A compared with the G/G genotype [hazard ratio, 8.4; 95% confidence interval, 1.9-37.2; P = 0.005]. CONCLUSIONS: This study supports the clinical utility of identification of UGT1A1 promoter polymorphisms before LV5FU2 + CPT-11 treatment to predict early hematologic toxicity. The -3156G>A polymorphism seems to be a better predictor than the UGT1A1 (TA)(6)TAA>(TA)(7)TAA polymorphism.     

Prevalence of topoisomerase I genetic mutations and UGT1A1 polymorphisms associated with irinotecan in individuals of Asian descent

Topoisomerase I (TOP-I) mutations have been shown to be correlated to irinotecan resistance in vitro. However, the prevalence of TOP-I germline mutations has yet to be systematically elucidated. On the other hand, polymorphisms of UGT1A1 have been shown to be associated with CPT-11 toxicity in clinical situations. The primary aim of this study was to investigate the prevalence of mutations in the TOP-I exons associated with CPT-11 resistance, including untreated cancer tissue. A secondary aim was to confirm the less frequent UGT1A1*28 and more frequent UGT1A1*6 in individuals of Asian descent compared to Caucasians and individuals of African descent. The prevalence of 5 reported TOP-I mutations in exons was investigated in volunteers (n=236) using DNA sequencing of the PCR products. The prevalence of TOP-I mutations in untreated lung cancer tissues (n=16) was also investigated. Additionally, 3 UGT1A1 polymorphisms, UGT1A1*6, *27 and *28, were investigated in volunteers (n=126). There were no mutations of TOP-I in any of the 236?subjects or in the untreated lung tissues. Among 128?subjects, the distribution of homozygous polymorphisms of UGT1A1 was: UGT1A1*28 in 3 (2.4%) and UGT1A1*6 in 4 (3.2%) subjects, and co-occurrence of heterozygous polymorphisms for both UGT1A1*6 and UGT1A1*28 in 4 (3.2%) subjects, and for UGT1A1*27 and UGT1A1*28 in 1 subject (0.8%). The Hardy-Weinberg deviation test showed there was no significant deviation from the equilibrium, and the association analysis indicated no significant linkage between UGT1A1*6 and UGT1A1*28. In conclusion, TOP-I genetic mutations correlated to CPT-11 resistance were not detected in any of the subjects and untreated lung cancer tissues. Less frequent UGT1A1*28 and more frequent UGT1A1*6 were confirmed in East Asian individuals compared to Caucasians and individuals of African descent. Linkage disequilibrium was not detected between UGT1A1*6 and UGT1A1*28.     

UGT1A7 and UGT1A9 polymorphisms predict response and toxicity in colorectal cancer patients treated with capecitabine/irinotecan.

PURPOSE: Capecitabine and irinotecan are commonly used in the treatment of metastatic colorectal cancer (CRC). We hypothesized that germline polymorphisms within genes related to drug target (thymidylate synthase) or metabolizing enzymes (UDP-glucuronosyltransferase, UGT) would impact response and toxicity to the combination of capecitabine plus irinotecan (CPT-11). EXPERIMENTAL DESIGN: Sixty-seven patients with measurable CRC were treated with irinotecan i.v. (100 or 125 mg/m(2)) on days 1 and 8 and capecitabine orally (900 or 1,000 mg/m(2), twice daily) on days 2 through 15 of each 3-week cycle. Genomic DNA was extracted from peripheral blood and genotyped using Pyrosequencing, GeneScan, and direct sequencing (Big Dye terminator) technologies. RESULTS: The overall objective response rate was 45% with 21 patients (31%) exhibiting grade 3 or 4 diarrhea and 3 patients (4.5%) demonstrating grade 3 or 4 neutropenia in the first two cycles. Low enzyme activity UGT1A7 genotypes, UGT1A7*2/*2 (six patients) and UGT1A7*3/*3 (seven patients), were significantly associated with antitumor response (p = 0.013) and lack of severe gastrointestinal toxicity (p = 0.003). In addition, the UGT1A9 -118 (dT)(9/9) genotype was significantly associated with reduced toxicity (p = 0.002) and increased response (p = 0.047). There were no statistically significant associations between UGT1A1, UGT1A6, or thymidylate synthase genotypes and toxicity or tumor response. CONCLUSIONS: These data strongly suggest that UGT1A7 and/or UGT1A9 genotypes may be predictors of response and toxicity in CRC patients treated with capecitabine plus irinotecan. Specifically, patients with genotypes conferring low UGT1A7 activity and/or the UGT1A9 (dT)(9/9) genotype may be particularly likely to exhibit greater antitumor response with little toxicity.     

Clinical Observations on Associations Between the UGT1A1 Genotype and Severe Toxicity of Irinotecan

Background: Severe toxicity is commonly observed in cancer patients receiving irinotecan (CPT-11)UDPglucuronosyltransferase1A1 (UGT1A1) catalyzes the glucuronidation of the active metabolite SN-38 but therelationship between UGT1A1 and severe toxicity remains unclear. Our study aimed to assess this point to guideclinical use of CPT-11. Materials and Methods: 89 cancer patients with advanced disease received CPT-11-basedchemotherapy for at least two cycles. Toxicity, including GI and hematologic toxicity was recorded in detail andUGT1A1 variants were genotyped. Regression analysis was used to analyse relationships between these variablesand tumor response. Results: The prevalence of grade III-IV diarrhea was 10.1%, this being more common inpatients with the TA 6/7 genotype (5 of 22 patients, 22.7%) (p<0.05). The prevalence of grade III-IV neutropeniawas 13.4%and also highest in patients with the TA 6/7 genotype (4 of 22 patients; 18.2%) but without significance(p>0.05). The retreatment total bilirubin levels were significantly higher in TA6/7 patients (mean, 12.75μmol/L)with compared to TA6/6 (mean, 9.92 μmol/L) with p<0.05. Conclusions: Our study support the conclusion thatpatients with a UGT1A1*28 allele (s) will suffer an increased risk of severe irinotecan-induced diarrhea, whetherwith mid-or low-dosage. However, the UGT1A1*28 allele (s) did not increase severe neutropenia. Higher serumtotal bilirubin is an indication that patients UGT1A1 genotype is not wild-type, with significance for clinic usageof CPT-11.     

UGT1A1基因多态性与伊立替康为主方案治疗晚期结直肠癌的毒性和疗效的相关性分析

目的 探讨中国汉族人结直肠癌患者尿苷二磷酸葡糖苷酸转移酶1A1（UGT1A1）基因多态性分布,评价UGT1A1基因多态性与伊立替康（CPT-11）为主方案治疗晚期结直肠癌的毒性和疗效的关系。方法 以CPT-11为主的FOLFIRI方案（CPT-11 180mg／m²）和IFL方案（CPT-11 125mg／m²）治疗晚期结直肠癌,检测患者的UGT1A1*28和UGT1A1*6基因型,分析UGT1A1基因多态性及其与化疗毒性、疗效和预后的相关性。结果 共纳入192例患者,189例行UGT1A1*28和UGT1A1*6基因型检测,野生型占37.6％,1个位点变异型占43.9％,2个位点突变异型占18.5％。183例可评价毒副反应,3～4级中性粒细胞减少的发生率为26.6％（51／183）;3～4级迟发性腹泻的发生率为15.1％（29／183）。2个位点变异的患者3～4级迟发性腹泻发生率显著高于野生型患者（26.5％vs.9.0％,P=0.021）。UGT1A1*28野生型、杂合突变型、纯合突变型的2～4级迟发性腹泻的发生率分别为29.6％、37.5％和88.9％,差异具有统计学意义（P=0.02）。UGT1A1*28纯合突变者4级中性粒细胞减少的发生率为33.3％,高于UGT1A1*28野生型的9.6％,但差异无统计学意义（P=0.07）。Logistic多因素分析显示UGT1A1*28和UGT1A1*6基因型是2～4级迟发性腹泻的影响因素。CPT-11剂量高者的3～4级中性粒细胞减少（OR=5.666,95%CI：2.088～15.377,P=0.001）和2～4级迟发性腹泻（OR=4.481,95%CI：1.568～12.807,P=0.005）发生率也显著升高。158例可评价疗效,获CR 3例、PR 30例、SD 91例、PD 34例,总有效率为20.9％。2个位点变异患者的有效率为33.3％,高于野生型的15.3％,但差异无统计学意义（P=0.063）。治疗时间在6周以下者疾病进展的风险显著增加（OR=6.106,95％CI：1.680～22.197,P=0.006）。Cox多因素分析显示,ECOG评分、治疗时间及治疗方案是影响患者预后的独立因素,而UGT1A1基因多态性与预后无关。结论 UGT1A1*28和UGT1A1*6基因型2个位点变异的患者应用CPT.11为主方案化疗的不良反应发生率较高,但疗效较好,由不良反应导致的治疗时间缩短可能会影响其获得更好的疗效。     

Usefulness of one-point plasma SN-38G/SN-38 concentration ratios as a substitute for UGT1A1 genetic information after irinotecan administration

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.     

UGT1A1 genotypes and glucuronidation of SN-38, the active metabolite of irinotecan

Background: Irinotecan (CPT-11) is metabolized by esterase to form a SN-38, which is further conjugated by UGT1A1. Genetic polymorphism has been shown in a promoter region of UGT1A1 and is related to its activity. We investigated whether there might be an inter-individual difference in pharmacokinetics of SN-38 and its glucuronide, depending on the genotypes of UGT1A1.Patients and methods: Nine male patients with lung cancer were treated with irinotecan (50 mg/m²) and carboplatin. Pharmacokinetic parameters were calculated with full sampling plasma data. Genotypes were determined by analyzing the sequence of TATA box of UGT1A1 of genomic DNA from the patients.Results: The genotyping analysis revealed one heterozygote (6/7) and one homozygote (7/7) for (TA)₇TAA allele (UGT1A1^*28). The remaining seven patients were homozygote for (TA)₆TAA allele (6/6, wild type). The metabolic ratios (SN-38/SN-38 glucuronide) in the patient with 7/7 genotype were uncharacteristically higher than those in the patients with other genotypes (6/6 and 6/7). Biliary index was 6980 versus 2180 ± 1110 (range 840–3730) in patients with 7/7 versus 6/6 genotypes, respectively.Conclusion: These results support the idea that the patient with 7/7 genotype has an impaired capacity for glucuronidation of SN-38.     

UGTIA1基因多态性与IP方案治疗小细胞肺癌毒性和疗效相关性分析

目的：探讨尿苷二磷酸葡萄糖转移酶1A1（UGTIA1）基因多态性与伊立替康联合顺铂（IP方案）治疗广泛期小细胞肺癌的不良反应和疗效相关性。方法：选取中国医学科学院肿瘤医院2009-01-01-2012-12-31初治广泛期小细胞肺癌患者48例,采用伊立替康联合顺铂化疗方案,分析其临床治疗效果和不良反应及其与UGT1A1基因多态性的相关性。结果：48例小细胞肺癌患者IP方案化疗后CR3例,PR32例,SD4侧,PD9例,总有效率为73．0％,疾病控制率为81．3％。主要毒副作用为中性粒细胞减少34例,贫血29例,血小板减少14例,恶心呕吐38例,迟发性腹泻26例,便秘15例,脱发5例,乏力38例,转氨酶升高14例,心电图异常9例。UGT1A1＊28基因多态性的分布为TA6／6野生型基因34例,TA6／7杂合突变型基因11例,TA7／7纯合突变型基因3例;UGT1A1＊6基因多态性的分布为G／C野生型基因33例,A／G杂合突变型基因13例,A／A纯合突变型基因2例。UGT1A1基因多态性与临床疗效无明显相关性,P〉0．05。提示UGT1A1突变型基因可增加患者发生迟发性腹泻的风险,而对中性粒细胞减少无影响。Logistic多因素回归分析结果显示,UGT1A1＊28、UGT1A1＊6、ECOG评分和治疗周期数对迟发性腹泻有明显影响;同时ECOG评分和治疗周期数对中性粒细胞减少存在影响。结论：UGT1A1突变基因对患者迟发性腹泻有明显影响,UGT1A1基因多态性检测可为临床应用伊立替康联合顺铂相关不良反应的预测提供依据,对临床用药安全具有重要意义。     

伊立替康联合顺铂或5-FU治疗UGT1A1*28野生型TA6/6患者不良反应的比较

目的：比较尿苷二磷酸葡萄糖醛酸转移酶1A1（UGT1A1）*28启动子为野生型的TA6/6患者在使用伊立替康（irinotecan,CPT-11）联合顺铂与CPT-11联合5-FU/亚叶酸钙治疗时不良反应方面的差异。方法根据采取的治疗方案将98例UGT1A1*28野生型TA6/6患者分为CPT-11联合顺铂组（IP组,n＝47）和CPT-11联合5-FU/亚叶酸钙组（FOLFIRI组,n＝51）,对患者进行UGT1A1*28启动子多态性检测,比较不良反应差异。结果在总体3～4级不良反应方面,IP组的发生率（61.7%）明显高于FOLFIRI组（39.2%）,且组间差异具有统计学意义（P=0.026）。在血液学不良反应方面,IP组3～4级白细胞减少、中性粒细胞减少、血小板减少和血红蛋白减少发生率分别为34.0%、51.1%、14.9%和8.5%,FOLFIRI组的发生率分别为11.8%、29.4%、2.0%、0,组间差异均有统计学意义（均P＜0.05）;在非血液学方面,FOLFIRI组3～4级迟发性腹泻发生率为9.8%,IP组未发生3～4级腹泻,两组间发生率的差异有统计学意义（P=0.028）。结论 UGT1A1*28野生型TA6/6患者在接受CPT-11联合顺铂和CPT-11联合5-FU/亚叶酸钙两种化疗方案治疗的不良反应谱存在差异;应用CPT-11时,不但要考虑到UGT1A1*28启动子多态性对不良反应的影响,而且还要考虑CPT-11联合不同药物出现不良反应情况。     

UGT1A1 gene variations and irinotecan treatment in patients with metastatic colorectal cancer

SN-38 is the active metabolite of irinotecan and it is metabolised through conjugation by uridine diphosphate glucuronosyl transferase (UGT1A1). The major toxicity of irinotecan therapy is diarrhoea, which has been related to the enzymatic activity of UGT1A1. We examined the influence of the UGT1A1 gene promoter polymorphism in the toxicity profile, in the response rate and in the overall survival (OS) in 95 patients with metastatic colorectal cancer treated with an irinotecan-containing chemotherapy. Genotypes were determined by analysing the sequence of TATA box of UGT1A1 of genomic DNA from the patients. Clinical parameters and genotypes were compared by univariate and multivariate statistical methods. The more frequent adverse effects were asthenia (34 patients), diarrhoea (29 patients) and neutropenia (20 patients). Severe diarrhoea was observed in 7/10 homozygous (70%) and 15/45 heterozygous (33%) in comparison to 7/40 (17%) wild-type patients (P=0.005). These results maintained the statistical significance in logistic regression analysis (P=0.01) after adjustment for other clinical relevant variables. The presence of severe haematological toxicity increased from wild-type patients to UGT1A1(*)28 homozygotes, but without achieving statistical significance. No relationship was found between the UGT1A1(*)28 genotypes and infection, nausea or mucositis. In univariate studies, patients with the UGT1A1(*)28 polymorphism showed a trend to a poorer OS (P=0.09). In the multivariate analysis, the genotype was not related to clinical response or to OS. The role of the UGT1A1 genotype as a predictor of toxicity in cancer patients receiving irinotecan demands the performance of a randomized trial to ascertain whether genotype-adjusted dosages of the drug can help to establish safe and effective doses not only for patients with the UGT1A1(*)28 homozygous genotype but also for those with the most common UGT1A1 6/6 or 6/7 genotype.     

UGT1A1*28 polymorphism predicts irinotecan-induced severe toxicities without affecting treatment outcome and survival in patients with metastatic colorectal carcinoma

BACKGROUND: It is known that the uridine-diphosphoglucuronosyl transferase 1A1 (UGT1A1)*28 polymorphism reduces UGT1A1 enzyme activity, which may lead to severe toxicities in patients who receive irinotecan. This study was conducted to assess the influence of this polymorphism on the efficacy and toxicity of irinotecan treatment in Chinese patients with metastatic colorectal carcinoma (CRC). METHODS: In total, 128 patients with metastatic CRC who had received previous treatment with irinotecan plus 5-fluorouracil/leucovorin were analyzed retrospectively. Genomic DNA samples were obtained from patients' leukocytes, and genotypes were determined by analyzing the sequence of TATA boxes in the UGT1A1 gene. The influence of the UGT1A1*28 polymorphism on toxicity and treatment outcome was analyzed. RESULTS: Approximately 20% of patients were identified with the UGT1A1*28 polymorphism, including 15.6% (n = 20 patients) with the thymine-adenine (TA)6/TA7 genotype and 4.7% (n = 6 patients) with the TA7/TA7 genotype. The remaining 79.7% of patients (n = 102) had wild type TA6/TA6. Marked increases in grade 3 or 4 neutropenia (53.8% vs 4.9%; P < .01), neutropenic fever (38.5% vs 3.9%; P < .01), diarrhea (26.9% vs 5.9%; P < .01), and pretreatment bilirubin level (23.1% vs 8.8%; P = .04) were observed in patients who had the TA6/TA7 or TA7/TA7 genotypes. Patients' pretreatment bilirubin levels correlated well with irinotecan-induced neutropenia (P < .01). It was noted that, although the requirement for irinotecan dose reduction was significantly greater in patients who had this genetic variant (42.3% vs 12.7%; P < .01), it did not affect the response rate to irinotecan-based chemotherapy (42.3% vs 45.1%; P = .80), and it did not significantly affect progression-free survival (10 months vs 11 months; P = .94) or overall survival (19 months vs 18 months; P = .84). CONCLUSIONS: The current data suggested that the UGT1A1*28 polymorphism may be a key determinant for predicting irinotecan-induced severe toxicities without affecting treatment outcome for patients with metastatic CRC. Further prospective studies are warranted for using this polymorphism to optimize irinotecan-based chemotherapy.     

Linkage disequilibrium of UGT1A1 *6 and UGT1A1 *28 in relation to UGT1A6 and UGT1A7 polymorphisms

UDP-glucuronosyltransferase (UGT) enzymes are responsible for the glucuronidation and detoxification of many endogenous or exogenous xenobiotics. Gilbert's syndrome (GS) and Crigler Najjar syndrome type 2 (CNS-II) are characterized by unconjugated hyperbilirubinemia due to reduced enzymatic activity of UGT1A1. Recent studies have demonstrated the frequent co-existence of UGT1A1 *28 (-53 [TA]6>7) with other polymorphisms of UGT1A6 and UGT1A7. This finding suggests the occurrence of linkage disequilibrium (LD) among UGT1A1, UGT1A6 and UGT1A7 polymorphisms. UGT1A1 *6 (211G>A, G71R) and UGT1A1 *28 are common in Asian populations. In the present study, we investigated the LD of UGT1A1 *6 and UGT1A1 *28 in relation to UGT1A6 and UGT1A7 polymorphisms. Exon 1 of UGT1A1, UGT1A6 and UGT1A7 was sequenced using genomic DNA isolated from peripheral leukocytes of 390 Japanese subjects. LD and haplotypes were analyzed using SNPAlyze ver. 5.0 software. UGT1A1 *6 had a strong LD in relation to UGT1A6 variants including 541A>G and 552A>C (D'=0.846-0.848, r(2)=0.413-0.438) and UGT1A7 variants including 387T>G, 391C>A, 392G>A and 622T>C (D'=0.667-0.858, r(2)=0.207-0.413). UGT1A1 *28 had a lower degree of LD than UGT1A1 *6 in relation to these variants (D'=0.245-0.401, r(2)=0.025-0.063). All the haplotypes with G71R lacked -53[TA]6>7. The present study showed for the first time that the LD of UGT1A1 *6 in relation to UGT1A6 and 1A7 polymorphisms is far stronger than UGT1A1 *28. The UGT1A1 *6 allele appears to be independent of the UGT1A1 *28 allele. Although patients with GS and CNS-II are believed to have good prognosis, a subgroup of GS or CNS-II patients with the UGT1A1 *6 polymorphism might be at risk of abnormal drug metabolism and of developing malignant disease.     

川东北地区人群结直肠癌患者UGT1A1*28基因多态性与伊立替康所致毒副反应的相关性

目的:观察结直肠癌患者UGT1A1*28基因多态性的分布频率,了解UGT1A1*28基因多态性与结直肠癌患者应用伊立替康联合5-氟尿嘧啶化疗毒副反应的相关性。方法:从384例接受伊立替康联合氟尿嘧啶一线化疗的晚期结直肠癌病例中采外周血提取DNA。采用PCR 法扩增目的基因片段,直接测序法分析UGT1A1*28基因多态性。临床观察并评价患者化疗毒副反应分级,统计分析UGT1A1*28基因表型与化疗毒副反应相关性。结果:全部 384例患者 UGT1A1*28基因多态性分布情况:TA6/6野生基因型287例(74.7％),TA6/7杂合基因型73例（19.0％）,TA7/7纯合基因型24例（6.3％）。化疗毒副反应和UGT1A1*28基因多态性进行临床单因素分析显示UGT1A1*28基因纯合型TA7/7、杂合型TA6/7与3-4度白细胞减少、中性粒细胞减少、腹泻、胆红素升高具有明显相关性（P<0.01）,UGT1A1*28基因纯合型TA7/7及杂合型TA6/7患者发生中性粒细胞减少的风险较UGT1A1*28基因野生型TA6/6患者高5.625倍（OR=5.625）。UGT1A1*28基因纯合型TA7/7和UGT1A1*28基因杂合型TA6/7患者发生腹泻的风险较UGT1A1*28基因野生型TA6/6患者高6.778倍（OR=6.778）。结论:UGT1A1*28基因纯合型TA7/7及杂合型TA6/7患者应用伊立替康化疗后发生重度中性粒细胞减少、重度腹泻的风险高于UGT1A1*28基因野生型TA6/6,为临床伊立替康用药选择、剂量调整、毒副反应的提前干预提供理论依据。     

Polymorphisms of UDP-glucuronosyltransferase gene and irinotecan toxicity: a pharmacogenetic analysis

Irinotecan unexpectedly causes severe toxicity of leukopenia or diarrhea. Irinotecan is metabolized to form active SN-38, which is further conjugated and detoxified by UDP-glucuronosyltransferase (UGT) 1A1 enzyme. Genetic polymorphisms of the UGT1A1 would affect an interindividual variation of the toxicity by irinotecan via the alternation of bioavailability of SN-38. In this case-control study, retrospective review of clinical records and determination of UGT1A1 polymorphisms were performed to investigate whether a patient with the variant UGT1A1 genotypes would be at higher risk for severe toxicity by irinotecan. All patients previously received irinotecan against cancer in university hospitals, cancer centers, or large urban hospitals in Japan. We identified 26 patients who experienced severe toxicity and 92 patients who did not. The relationship was studied between the multiple variant genotypes (UGT1A1*28 in the promoter and UGT1A1*6, UGT1A1*27, UGT1A1*29, and UGT1A1*7 in the coding region) and the severe toxicity of grade 4 leukopenia (< or =0.9 x 10(9)/liter) and/or grade 3 (watery for 5 days or more) or grade 4 (hemorrhagic or dehydration) diarrhea. Of the 26 patients with the severe toxicity, the genotypes of UGT1A1*28 were homozygous in 4 (15%) and heterozygous in 8 (31%), whereas 3 (3%) homozygous and 10 (11%) heterozygous were found among the 92 patients without the severe toxicity. Multivariate analysis suggested that the genotype either heterozygous or homozygous for UGT1A1*28 would be a significant risk factor for severe toxicity by irinotecan (P < 0.001; odds ratio, 7.23; 95% confidence interval, 2.52-22.3). All 3 patients heterozygous for UGT1A1*27 encountered severe toxicity. No statistical association of UGT1A1*6 with the occurrence of severe toxicity was observed. None had UGT1A1*29 or UGT1A1*7. We suggest that determination of the UGT1A1 genotypes might be clinically useful for predicting severe toxicity by irinotecan in cancer patients. This research warrants a prospective trial to corroborate the usefulness of gene diagnosis of UGT1A1 polymorphisms prior tb irinotecan chemotherapy.     

Uridine diphosphate glucuronosyl transferase 1A1 promoter polymorphism predicts the risk of gastrointestinal toxicity and fatigue induced by irinotecan-based chemotherapy

BACKGROUND: In the current Phase II study, the authors evaluated the association between genomic polymorphic variants in uridine diphosphate glucuronosyl transferase (UGT1A1), methylenetetrahydrofolate reductase (MTHFR), and thymidylate synthase (TS) genes, and the incidence of the adverse effects of irinotecan and raltitrexed in previously heavily treated patients with metastatic colorectal carcinoma. METHODS: Fifty-six patients received irinotecan (at a dose of 80 mg/m(2) on Days 1, 8, 15, and 22 every 5 wks), combined with raltitrexed (at a dose of 3 mg/m(2) every 3 wks). Genotyping for the MTHFR C677T polymorphism, the TATA box region in the UGT1A1 promoter, and tandem repeats in the TS promoter was performed on genomic DNA extracted from blood. Nineteen variables related to patient, disease, and treatment characteristics, together with genotypes, were analyzed using a binary logistic regression model with stepwise selection to evaluate their correlation with adverse reactions. RESULTS: Toxicities (determined according to the National Cancer Institute Common Toxicity Criteria) were evaluated in 169 cycles. Grade 3/4 neutropenia was reported to occur in 2% of cycles, Grade 2-4 nausea was reported to occur in 19% of cycles, Grade 2-4 emesis was reported to occur in 9% of cycles, Grade 2-4 diarrhea was reported to occur in 20% of cycles, Grade 2/3 fatigue was reported to occur in 11% of cycles, and Grade 3/4 hepatic toxicity was reported to occur in 7% of cycles. Homozygosis for six TA repeats in the promoter region of the UGT1A1 gene was found to be the main predictive factor for diarrhea (P < 0.00005), emesis (P = 0.0001), and fatigue (P = 0.007). Homozygosis for two tandem repeats in the TS promoter was found to be predictive of a reduced incidence of fatigue (P = 0.044). MTHFR C677T polymorphism was not found to be associated with any adverse reaction. CONCLUSIONS: In the current study, UGT1A1 promoter polymorphism was found to be predictive of the risk of diarrhea, emesis, and fatigue caused by chemotherapy with irinotecan and raltitrexed. Screening for UGT1A1 promoter polymorphism may be clinically useful for identifying patients at a higher risk of developing a severe or potentially life-threatening toxicity after irinotecan-based chemotherapy.     

Pharmacokinetic and pharmacogenetic determinants of the activity and toxicity of irinotecan in metastatic colorectal cancer patients

This study aims at establishing relationships between genetic and non-genetic factors of variation of the pharmacokinetics of irinotecan and its metabolites; and also at establishing relationships between the pharmacokinetic or metabolic parameters and the efficacy and toxicity of irinotecan. We included 49 patients treated for metastatic colorectal cancer with a combination of 5-fluorouracil and irinotecan; a polymorphism in the UGT1A1 gene (TA repeat in the TATA box) and one in the CES2 gene promoter (830C>G) were studied as potential markers for SN-38 glucuronidation and irinotecan activation, respectively; and the potential activity of CYP3A4 was estimated from cortisol biotransformation into 6beta-hydroxycortisol. No pharmacokinetic parameter was directly predictive of clinical outcome or toxicity. The AUCs of three important metabolites of irinotecan, SN-38, SN-38 glucuronide and APC, were tentatively correlated with patients' pretreatment biological parameters related to drug metabolism (plasma creatinine, bilirubin and liver enzymes, and blood leukocytes). SN-38 AUC was significantly correlated with blood leukocytes number and SN-38G AUC was significantly correlated with plasma creatinine, whereas APC AUC was significantly correlated with plasma liver enzymes. The relative extent of irinotecan activation was inversely correlated with SN-38 glucuronidation. The TATA box polymorphism of UGT1A1 was significantly associated with plasma bilirubin levels and behaved as a significant predictor for neutropoenia. The level of cortisol 6beta-hydroxylation predicted for the occurrence of diarrhoea. All these observations may improve the routine use of irinotecan in colorectal cancer patients. UGT1A1 genotyping plus cortisol 6beta-hydroxylation determination could help to determine the optimal dose of irinotecan.     

UGT1A1基因多态性与伊立替康临床用药安全性及疗效的关系

目的：研究 UGT1A1基因多态性与伊立替康治疗结直肠癌患者的不良反应及疗效之间的关系。方法：自外周血中抽提基因组 DNA,进行 PCR 扩增,应用直接测序法分析2012年3月至2013年3月,于我院行基因检测的65例结直肠癌患者 UGT1A1*28和 UGT1A1*6基因多态性的分布情况。并对这65例应用含伊立替康方案化疗的患者出现的不良反应及化疗疗效,进行观察记录,比较不同基因型间的差异。结果：65例患者中,UGT1A1*28野生型 TA6／6有49例（75．4％）,杂合突变型 TA6／7有14例（21．5％）,纯合突变型TA7／7有2例（3．1％）。UGT1A1*6野生型 G／G 有47例（72．3％）,杂合突变型 G／A 有15例（23．1％）,纯合突变型 A ／A 有3例（4．6％）。在以上65例结直肠癌患者中,UGT1A1基因启动子区28位点,TA6／6、TA6／7和TA7／7型,发生3级以上腹泻者分别为8．2％、37．5％;发生3级以上中性粒细胞减少者分别为28．6％、62．5％。UGT1A1基因启动子区6位点,G／G、G／A 和 A ／A 型,发生3级以上腹泻者分别为12．8％、44．4％;发生3级以上中性粒细胞减少者分别为14．9％、22．2％。各组之间疗效无统计学差异。结论：患者 UGT1A1*28和UGT1A1*6多态性分布基本一致,UGT1A1*28突变型可以使应用含伊立替康化疗患者发生3级以上腹泻和中性粒细胞减少的风险增加。UGT1A1*6突变型可增加3级以上腹泻的发生风险。因此,UGT1A1基因型的检测对伊立替康相关的不良反应有一定的预测作用,可提高用药安全性,在临床用药中起到了指导作用。     

Clinical implications of UGT1A1*28 genotype testing in colorectal cancer patients

BACKGROUND:

Metastatic colorectal cancer is frequently treated with irinotecan, a topoisomerase‐I inhibitor. The UGT1A1 gene encodes for an enzyme that metabolizes irinotecan, and its genetic variants were shown to be associated with increased drug toxicity. We evaluated clinical outcomes associated with the UGT1A1*28 variant.

METHODS:

The study included 329 colorectal cancer patients from the Israeli population‐based Molecular Epidemiology of Colorectal Cancer study who were treated with a chemotherapy regimen that included irinotecan. Patients with metastases or disease recurrence were followed up for a median period of 2 years after occurrence of the event. Study end points were appearance of grade 3‐4 hematological and gastroenterological toxicity, hospitalization due to toxic events (mostly neutropenia, fever, diarrhea, or vomiting), length of hospitalization, and overall survival. UGT1A1*28 was genotyped from peripheral blood DNA by fragment analysis and reported as number of TATA sequence repeats in the promoter of the gene.

RESULTS:

The 7/7 variant of UGT1A1*28 was detected in 11.9% of the 329 participants. Grade 3‐4 hematological toxicity was significantly higher in 7/7 carriers compared with 6/7 and 6/6 carriers (48.0%,10.2%, and 7.7% respectively; P < .001), as was the risk of toxicity‐related hospitalization (45.8%, 25.3%, and 14.4% respectively; P = .001). Both short‐term death within 2 months of treatment start (12.8%, 5.2%, and 2.9%, respectively) and median overall survival (1.6, 2.0, and 2.4 years, respectively; P = .01) were significantly worse in the 7/7 carriers. The age/stage‐adjusted hazard ratio for patients with the 7/7 genotype compared with 6/6 was 1.7 (95% confidence interval, 1.1‐2.3).

CONCLUSIONS:

The UGT1A1*28 7/7 genotype is strongly associated with severe hematological toxicity and higher hospitalization rate and predicts lower survival of colorectal cancer in users of irinotecan. Cancer 2011. © 2011 American Cancer Society.