54658

UGT1A1

UDP glucuronosyltransferase 1 family, polypeptide A1;UGT1A1;UDP glucuronosyltransferase 1 family, polypeptide A1

UDP glycosyltransferase 1 family, polypeptide A1|UDP-glucuronosyltransferase 1-1|UDP-glucuronosyltransferase 1-A|UDP-glucuronosyltransferase 1A1|UGT-1A|UGT1*1|UGT1-01|UGT1.1|bilirubin UDP-glucuronosyltransferase 1-1|bilirubin UDP-glucuronosyltransferase i

2q37

protein-coding

AIM: To investigate the correlation between uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1) gene polymorphisms and irinotecan-associated side effects and parameters of drug efficacy in patients with metastatic colorectal cancer (mCRC) receiving a low-dose weekly irinotecan chemotherapeutic regimen. METHODS: Genotypes were retrospectively evaluated by gene scan analysis on the ABI 310 sequencer of the TATAA box in the promoter region of the UGT1A1 gene in blood samples from 105 patients who had received 1st line irinotecan-based chemotherapy for mCRC. RESULTS: The distribution of the genotypes was as follows: wild type genotype (WT) (6/6) 39.0%, heterozygous genotype (6/7) 49.5%, and homozygous genotype (7/7) 9.5%. The overall response rate (OR) was similar between patients carrying the (6/7, 7/7) or the WT genotype (6/6) (44.3% vs 43.2%, P = 0.75). Neither time to progression [(TTP) 8.1 vs 8.2 mo, P = 0.97] nor overall survival [(OS) 21.2 vs 18.9 mo, P = 0.73] differed significantly in patients who carried the (6/6) when compared to the (6/7, 7/7) genotype. No significant differences in toxicity were observed: Grade 3 and 4 delayed diarrhoea [(6/7, 7/7) vs (6/6); 13.0% vs 6.2%, P =0.08], treatment delays [(6/7, 7/7) vs (6/6); 25.1% vs 19.3%, P =0.24] or dose reductions [(6/7, 7/7) vs (6/6); 21.5% vs 27.2%, P =0.07]. CONCLUSION: This analysis demonstrates the non-significant influence of the UGT1A1 gene polymorphism on efficacy and rate of irinotecan-associated toxicity in mCRC patients receiving low-dose irinotecan based chemotherapy.

PURPOSE We aimed to identify the maximum-tolerated dose (MTD) of irinotecan in patients with cancer with UGT1A1*1/*1 and *1/*28 genotypes. We hypothesize that the patients without the *28/*28 genotype tolerate higher doses of irinotecan. PATIENTS AND METHODS Patients undergoing first-line treatment for metastatic colorectal cancer (CRC) eligible for treatment with irinotecan plus infusional fluorouracil/leucovorin (FOLFIRI) were screened for the UGT1A1*28/*28 genotype and excluded from the study. Fifty-nine white patients with either the *1/*1 or the *1/*28 genotype were eligible for dose escalation of irinotecan. The starting dose of biweekly irinotecan was 215 mg/m(2) for both genotype groups, whereas the dose of infusional fluorouracil was fixed. Pharmacokinetic data of irinotecan and metabolites were also obtained. Results The dose of irinotecan was escalated to 370 mg/m(2) in patients with the *1/*28 genotype and to 420 mg/m(2) in those with the *1/*1 genotype. Dose-limiting toxicities (DLTs) were observed in two of four of *1/*28 patients at 370 mg/m(2) and in two of three of *1/*1 patients at 420 mg/m(2). No DLTs were observed in 10 *1/*28 patients at 310 mg/m(2) and in 10 *1/*1 patients at 370 mg/m(2); hence these dose levels were the MTD for each genotype group. The most common grade 3 to 4 toxicities were neutropenia and diarrhea. The pharmacokinetics of irinotecan and SN-38 exhibit linear kinetics. CONCLUSION The recommended dose of 180 mg/m(2) for irinotecan in FOLFIRI is considerably lower than the dose that can be tolerated when patients with the UGT1A1*28/*28 genotype are excluded. Prospective genotype-driven studies should test the efficacy of higher irinotecan doses in the FOLFIRI schedule.

AIM: We performed a phase II study of irinotecan with 5'-deoxy-5-fluorouridine (5'-DFUR) for metastatic colorectal cancer based on UDP-glucuronosyltransferase (UGT) 1A1 polymorphism. PATIENTS AND METHODS: A total of 28 patients were enrolled. The dose of irinotecan was 150 mg/m(2) for patients with the *1/*1 wild-type genotype, and 70 mg/m(2) for those with the *1/*28 mutated genotype. The primary end-point was the response rate (RR); secondary end-points were safety, time to treatment failure (TTF), and overall survival (OS). RESULTS: In 28 patients total, genotype was wild-type in 22 and mutated in six. The RR was *1/*1 (22.7%; wild-type) vs. *1/*28 (16.7%; mutated); the median TTF was 5 months vs. 4.5 months, and the median OS was 13 months vs. 17.5 months, respectively. None of these differences were significant. Toxicities of grade 3 or higher were neutropenia (9.0% vs. 0%, respectively) and diarrhea (13.6% vs. 0%, respectively). CONCLUSION: This genotype-oriented therapy was effective and safe, and thus appears useful for patients who have complications or advanced age.