Zarate R.,University of Navarra |
Rodriguez J.,Unit for the Research and Treatment of Gastrointestinal Malignancies |
Bandres E.,University of Navarra |
Patio-Garcia A.,University of Navarra |
And 7 more authors.
British Journal of Cancer | Year: 2010
Background: A dose-finding study was performed to evaluate the dose-limiting toxicity (DLT), maximum-tolerated dose (MTD) and the recommended dose (RD) of escalating the doses of capecitabine and fixed doses of irinotecan and oxaliplatin on a biweekly schedule for metastatic colorectal cancer patients (mCRC). A pharmacogenomic analysis was performed to investigate the association between SNPs and treatment outcome. Methods: Eighty-seven chemotherapy-nave mCRC patients were recruited through a two-step study design; 27 were included in the dose-finding study and 60 in the pharmacogenomic analysis. Oxaliplatin (85 mg m-2) and CPT-11 (150 mg m-2), both on day 1, and capecitabine doses ranging from 850 to 1500 mg m-2 bid on days 1-7 were explored. Peripheral blood samples were used to genotype 13 SNPs in 10 genes related to drug metabolism or efficacy. Univariate and multivariate Cox analysis was performed to examine associations between SNPs, ORR and PFS.Results: The capecitabine RD was 1000 mg m2 bid. Diarrhoea and neutropenia were the DLTs. After a median follow-up of 52.5 months, the median PFS and OS were 12 (95% CI; 10.6-13.4) and 27 months (95% CI; 17.2-36.8), respectively.The GSTP1-G genotype, the Köhne low-risk category and use of a consolidation approach strongly correlated with decreased risk of progression. Patients with all favourable variables showed a median PFS of 42 months vs 3.4 months in the group with all adverse factors. A superior clinical response was obtained in patients with one GSTP1-G allele as compared with GSTP1-AA carriers (P=0.004).Conclusion: First-line therapy with oxaliplatin, irinotecan and capecitabine is efficient and well-tolerated. The GSTP1 polymorphism AG status was significantly associated with ORR and PFS in mCRC treated with this triplet therapy. © 2010 Cancer Research UK All rights reserved.