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Medline ® Abstract for Reference 134

of 'Dosing of anticancer agents in adults'

Predictive role of the UGT1A1, UGT1A7, and UGT1A9 genetic variants and their haplotypes on the outcome of metastatic colorectal cancer patients treated with fluorouracil, leucovorin, and irinotecan.
Cecchin E, Innocenti F, D'Andrea M, Corona G, De Mattia E, Biason P, Buonadonna A, Toffoli G
J Clin Oncol. 2009;27(15):2457. Epub 2009 Apr 13.
PURPOSE: UGT1A1*28 is considered the main pharmacogenetic predictor of the toxicity outcome of irinotecan-treated patients. We evaluated the effect of other UGT1A variants and haplotypes involved in 7-ethyl-10-hydroxycamptothecin (SN-38) glucuronidation on severe toxicity and efficacy of fluorouracil, leucovorin, and irinotecan (FOLFIRI).
PATIENTS AND METHODS: In addition to UGT1A1*28, UGT1A1*60, UGT1A1*93, UGT1A7*3, and UGT1A9*22 were genotyped in 250 metastatic colorectal cancer patients, and associations with severe hematologic and nonhematologic toxicity, objective response, time to progression (TTP), and overall survival were evaluated. In a subset of 71 patients, pharmacokinetic data were also available.
RESULTS: UGT1A7*3 was the only marker of severe hematologic toxicity after the first cycle (odds ratio [OR], 3.94; 95% CI, 1.05 to 14.82; P = .04) in a multivariate analysis. It was also associated with glucuronidation ratio (SN-38G areaunder the curve [AUC]/SN-38 AUC) and biliary index (irinotecan AUC) x (SN-38 AUC/SN-38G AUC). Haplotype I (all the reference sequence alleles but UGT1A9*22) was a predictor of severe hematologic toxicity during the entire course of therapy (OR, 0.39; 95% CI, 0.19 to 0.82; P = .01), together with sex (OR, 2.08; 95% CI, 1.01 to 4.28; P = .05). In addition to UGT1A1*28, haplotype II (all the variant alleles but UGT1A9*22) was associated with a response rate (OR, 8.61; 95% CI, 1.75 to 42.38; P = .01). UGT1A1*28 was the only marker associated with TTP.
CONCLUSION: We propose that UGT1A variants additional to UGT1A1*28 might improve the prediction of the outcome of colorectal cancer patients treated with FOLFIRI. A UGT1A haplotype-based approach might be an efficacious strategy to achieve treatment individualization of FOLFIRI.
Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico, National Cancer Institute, Aviano, Italy.