Clinical Significance of UDP-Glucuronosyltransferase 1A1*6 for Toxicities of Combination Chemotherapy with Irinotecan and Cisplatin in Gynecologic Cancers

Background: To investigate the effects of UDP-glucuronosyltransferase 1A1 (UGT1A1) *28, *6 and *27 in patients with gynecologic cancer who received chemotherapy with irinotecan and cisplatin. Methods: Patients eligible for this study had cervical or ovarian cancer treated with chemotherapy; a course of the regimen consisted of 60 mg/m2 of irinotecan on days 1, 8 and 15, and 60 mg/m2 of cisplatin on day 1 every 4 weeks. UGT1A1 polymorphisms and toxicities were analyzed. Results: From March 2007 to December 2007, 30 Japanese patients were enrolled; 24 ovarian carcinoma patients and 6 cervical cancer patients. The following genotypes of UGT1A1 were found: wild type in 17 patients (57%), *28 in 4 patients (13%), *6 in 8 patients (27%), *28*6 in 1 case (3%) and no case of *27 (0%). Grade 3/4 neutropenia, thrombocytopenia and diarrhea were significantly more frequent in *6 patients compared with wild-type patients. Also, in *6 patients irinotecan administration on days 8 or 15 was significantly more often omitted due to toxicities. In patients with *28 or *28*6, side effects were similar to those in patients with *6. Conclusion: In addition to UGT1A1*28, UGT1A1*6 might also be a key candidate to determine the dose of combination chemotherapy with irinotecan and cisplatin.