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.
OBJECTIVE
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).


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 area under 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.


CONCLUSIONS
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.
Cecchin
Erika
E
Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico, National Cancer Institute, Aviano, Italy.
Innocenti
Federico
F
D'Andrea
Mario
M
Corona
Giuseppe
G
De Mattia
Elena
E
Biason
Paola
P
Buonadonna
Angela
A
Toffoli
Giuseppe
G
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D019540:Area Under Curve; D014408:Biomarkers, Tumor / Q000235:genetics; D002166:Camptothecin / Q000031:analogs & derivatives / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005472:Fluorouracil / Q000627:therapeutic use; D014453:Glucuronosyltransferase / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D002955:Leucovorin / Q000627:therapeutic use; D015810:Linkage Disequilibrium; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D016896:Treatment Outcome; D000090264:UDP-Glucuronosyltransferase 1A9
D014408:Biomarkers, Tumor; C000715591:UGT1A9 protein, human; D014453:Glucuronosyltransferase; D000090264:UDP-Glucuronosyltransferase 1A9; C524630:UGT1A7 protein, human; D002955:Leucovorin; D005472:Fluorouracil; D002166:Camptothecin