Irinotecan toxicity: genes or intestinal microflora?

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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 6β-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 6β-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 6β-hydroxylation determination could help to determine the optimal dose of irinotecan

UGT1A and TYMS genetic variants predict toxicity and response of colorectal cancer patients treated with first-line irinotecan and fluorouracil combination therapy

BACKGROUND: The impact of thymidylate synthase (TYMS) and UDP-glucoronosyltransferase 1A (UGT1A) germline polymorphisms on the outcome of colorectal cancer (CRC) patients treated with irinotecan plus 5-fluorouracil (irinotecan/5FU) is still controversial. Our objective was to define a genetic-based algorithm to select patients to be treated with irinotecan/5FU. METHODS: Genotyping of TYMS (5'TRP and 3'UTR), UGT1A1*28, UGT1A9*22 and UGT1A7*3 was performed in 149 metastatic CRC patients treated with irinotecan/5FU as first-line chemotherapy enrolled in a randomised phase 3 study. Their association with response, toxicity and survival was investigated by univariate and multivariate statistical analysis. RESULTS: TYMS 3TRP/3TRP genotype was the only independent predictor of tumour response (OR=5.87, 95% confidence interval (CI)=1.68-20.45; P=0.005). UGT1A1*28/*28 was predictive for haematologic toxicity (OR=6.27, 95% CI=1.09-36.12; P=0.04), specifically for neutropenia alone (OR=6.40, 95% CI=1.11-37.03; P=0.038) or together with diarrhoea (OR=18.87, 95% CI=2.14-166.67; P=0.008). UGT1A9*1/*1 was associated with non-haematologic toxicity (OR=2.70, 95% CI=1.07-6.82; P=0.035). Haplotype VII (all non-favourable alleles) was associated with non-haematologic toxicity (OR=2.11, 95% CI-1.12-3.98; P-0.02). CONCLUSION: TYMS and UGT1A polymorphisms influence on tumour response and toxicities derived from irinotecan/5FU treatment in CRC patients. A genetic-based algorithm to optimise treatment individualisation is proposed. British Journal of Cancer (2010) 103, 581-589. doi:10.1038/sj.bjc.6605776 www.bjcancer.com Published online 13 July 2010 (C) 2010 Cancer Research U

Prediction of irinotecan and 5-fluorouracil toxicity and response in patients with advanced colorectal cancer

Irinotecan and 5-fluorouracil (5-FU) are used to treat metastatic colorectal cancer. Irinotecan's active metabolite is inactivated by UDP-glucuronosyltransferase 1A1 (UGT1A1), which is deficient in Gilbert's syndrome. Irinotecan and metabolites are transported by P-glycoprotein, encoded by ABCB1. 5-FU targets folate metabolism through inhibition of thymidylate synthase (TYMS). Methylenetetrahydrofolate reductase (MTHFR) generates active folate necessary for haematopoiesis. We retrospectively genotyped 140 Swedish and Norwegian irinotecan and 5-FU-treated colorectal cancer patients from the Nordic VI clinical trial for selected variants of UGT1A1, ABCB1, TYMS and MTHFR. We found an increased risk of clinically relevant early toxicity in patients carrying the ABCB1 3435 T/T genotype, Odds ratio (OR)=3.79 (95% confidence interval (CI)=1.09–13.2), and in patients carrying the UGT1A1*28/*28 genotype, OR=4.43 (95% CI=1.30–15.2). Patients with UGT1A1*28/*28 had an especially high risk of neutropenia, OR=6.87 (95% CI=1.70–27.7). Patients who had reacted with toxicity during the first two cycles were in total treated with fewer cycles (P<0.001), and less often responded to treatment (P<0.001). Genetic variation in ABCB1 was associated with both early toxicity and lower response to treatment. Carriers of the ABCB1 1236T-2677T-3435T haplotype responded to treatment less frequently (43 vs 67%, P=0.027), and survived shorter time, OR=1.56 (95% CI=1.01–2.45)

Phase I Trial of Debio 1143, an Antagonist of Inhibitor of Apoptosis Proteins, Combined with Cisplatin Chemoradiotherapy in Patients with Locally Advanced Squamous Cell Carcinoma of the Head and Neck.

Debio 1143 is an oral antagonist of inhibitor of apoptosis proteins, which enhances tumor response with concomitant chemoradiotherapy. Addition of Debio 1143 to cisplatin-based chemoradiotherapy in locally advanced squamous cell carcinomas of the head and neck (LA-SCCHN) was evaluated in a phase I/II study to determine the MTD and recommended phase II dose (RP2D). Here, phase I results are reported. Treatment-naïve patients with LA-SCCHN (stages III/IVA/IVB) received Debio 1143 (100, 200, 300 mg/day), for 14 days every 3 weeks, with cisplatin (100 mg/m², every 3 weeks), for three cycles, and concomitant conventional fractionation radiotherapy (70 Gy/7 weeks). Dose-limiting toxicity (DLT) was evaluated over 9 weeks using continual reassessment. Fourteen patients were treated/evaluable for DLT. Median age was 64.5 years, and all patients were current/former smokers. Primary tumors were hypopharynx, oropharynx (all human papillomavirus/p16 negative), larynx, and oral cavity. Two of six patients at 200 mg/day had DLT (grade 3 tubular necrosis, grade 3 aspartate aminotransferase/alanine aminotransferase increase, grade 4 febrile neutropenia, and grade 3 lipase increase), which was considered the MTD and RP2D. Common grade 3-4 adverse events were dysphagia (36%) and mucositis (29%). Laboratory abnormalities were frequent and generally mild, including anemia, white blood cell decrease, and increased creatinine. Addition of Debio 1143 did not compromise chemotherapy administration. Overall locoregional control rate at 18 months was 85%. Overall response rate was 85%, including 69% complete responses. Progression-free survival rate at 24 months was 74%. The RP2D of Debio 1143 is 200 mg/day for 14 days, every 3 weeks, when combined with concomitant high-dose cisplatin chemoradiotherapy in LA-SCCHN. Debio 1143 addition to chemoradiotherapy was safe and manageable. Preliminary efficacy is encouraging and supports further development