Background and objective: SN-38 is the active metabolite of irinotecan (CPT-11) and mainly responsible of hematological and intestinal toxicity after CPT-11 treatments. SN-38 is inactivated into SN-38G by uridine diphosphate glucuronosyltransferase (UGT) enzymes. Some polymorphism of these enzymes leads lower clearance (CL) of SN-38 and therefore bigger exposition and bigger risk of hematological and/or intestinal toxicity (1). Therefore, the goal of this study has been to evaluate the influence of genetic polymorphism in UGT1A1, UGT1A7 and UGT1A9 on the population pharmacokinetics of CPT-11 and its metabolites, SN-38 and SN-38G on Caucassian cancer population. Methods: Plasma concentrations of CPT-11, SN-38 and SN-38G from 72 patients were pooled to develop a joint population pharmacokinetic model using NONMEM 7. The effect of age, sex, body surface area, total bilirubin, co-medication, tumor type, and UGT1A1, UGT1A7 and UGT1A9 genotypes on the model parameters was evaluated. Results: The typical values (between-subject variability; %) of the irinotecan, SN-38 and SN-38G clearances were 42,9 L/h (56,4%), 1340 L/h (76,8%) and 188 L/h (70,1%), respectively. Clearance in patients with some allele (heterozygous or homozygous) associated with low enzymatic activity of UGT1A1*28 was a 35,7% lower (CI 95%: 6,7 - 64,7; p=0,003) than in wild-type patients. Additionally, linkage dissequilibrium indicates a strong interaction between functional UGT1A1, UGT1A7 and UGT1A9 polymorphisms related to the alteration of the UGT enzyme activity. Conclusion: The impact of UGT1A1*28 genotype on the systemic exposure of SN-38 justifies its routine determination in patients receiving CPT-11 and subsequent dose adjustment. Citation Format: Belen Valenzuela, Mario González-Sales, Vanessa Escudero, Elena Navarro, Carlos Perez-Ruixo, Joseba Rebollo, Ramon González-Manzano, Juan José Pérez-Ruixo. Influence of genetic polymorphism in UGT1A1, UGT1A7 and UGT1A9 on irinotecan, SN-38 and SN-38G pharmacokinetics. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2213. doi:10.1158/1538-7445.AM2013-2213
e14563 Background: To the best of our knowledge only one previous report in asian lung cancer patients (pts) assesed UGT1A1, A7 and A9 genotypes along with irinotecan pharmacokinetics (Han et al. JCO 2006; 24: 2237–44). We set out to evaluate UGT1A1, A7 and A9 genotypes in caucasian cancer patients and their relationship with both irinotecan toxicity and irinotecan pharmacokinetics. Methods: UGT1A1, A7 and A9 genotypes were obtained from blood genomic DNA by direct sequencing. The area under the time-concentration curve (AUC) of SN-38 and SN-38G were calculated. The ratio between these AUCs (AUC SN-38G /AUC SN-38) was also calculated. Associations between pharmacokinetics parameters and the UGT1A genotypes were assessed by univariate analysis. Toxicity was collected using standard NCI grading criteria. Statistical correlation between presence of grade III and IV toxicity and UGT1A1,A7 and A9 genotypes was done by Pearson's Chi square. At least 80 patients (with both genotype and pharmacokinetics) are needed to achieve enough statistical power. Results: At the time of writing this abstract, complete genotyping and toxicity data from 59 patients were available. Sex (females 17, males 42). Median age 60 (range 25–88). Pathology (no. pts): lung (26), colon (17), others (16). 21 pts. (35.59%) had received previous chemotherapy. All but 5 pts received doses of irinotecan between 120 and 150 mg/m2. Median no. of cycles 6 (range 1–15). The frequencies of the different UGT1A1, A7 and A9 genotypes are similar to those previously reported. At least one episode of grade III or IV leukopenia was present in 19 pts. (32.2%), and grade III diarrea in 11 pts (18.6%). No statistically significant correlation was found between presence of leukopenia grades III and IV, and the genotypes UGT1A1,A7, and A9 (P=0.687, P=0.156 and P=0.476, respectively). Diarrea grade III was not statistically significantly associated with UGT1A1 (P=0.318), A7 (P=0.318) and A9 (P=0.158). 21 out of 59 pts. had pharmacokinetics (PK) data available. In genotype-PK association analysis, UGT1A1,A7 and A9 were not statistically associated with AUC SN-38G / AUC SN-38 ratios (P=0.844, P=0.911, P=0.431, respectively). Conclusions: Patients are still being accrued to achieve the targeted size. No significant financial relationships to disclose.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.