UGT1A1 genotype-specific phase I and pharmacokinetic study for combination chemotherapy with irinotecan and cisplatin: a Saitama Tumor Board study.

Genotyping of UGTI1Al could be useful for prediction of severe toxicities for patients treated with irinotecan; however, genotype-based recommended dose (RD) has not been established. The aim of the present study was to determine the RD of irinotecan in combination with cisplatin (CPT-P) for individuals with or without UGT1A1 polymorphisms. According to polymorphisms of UGTIAl*28, *6, and *27, RDs were determined by three-case cohort methods for patients with wild-type and heterotype, and by inter-patient dose escalation for homotype patients. Pharmacokinetic studies were also evaluated. During May 2009 and July 2011, 18 Japanese patients were enrolled; 16 patients with ovarian carcinoma, and two cases with cervical cancer. The RD of irinotecan was determined as 50 mg/m2 for the patients with wild-type, 40 mg/m2 for those with heterotype, and 30 mg/m2 for homotype UGT IAl genotype. Patients with homotype UGTIAl1 alleles had a significantly lower glucuronidation ratio in comparison with UGTIAI wild-type and heterotype cases. UGT1A1 genotype-based RDs of irinotecan in CPT-P therapy were determined. Further studies to investigate efficacy of the RD including response evaluation are needed to confirm the present results.