Prospective Study of UDP-gluconoryltransferase 2B17 Genotype as a Predictive Marker of Exemestane PK and PD
Aromatase inhibitors have led to significant improvements in clinical outcomes for women with postmenopausal hormone receptor-positive advanced breast cancer. However, there is a notable absence of phase III comparisons among the three agents and therefore no clear indication of the superiority of one AI over the others. Furthermore, there remains a distinct lack of predictive biomarkers of AI efficacy and toxicity to inform clinical decisions. The metabolic pathways of exemestane have recently been delineated and UGT2B17 is the most active hepatic gluconoryltransferase responsible for the glucuronidation of the crucial active exemestane metabolite, 17-dihydroxyexemestane. The UGT2B17*2/*2 deletion genotype is associated with markedly reduced glucuronidation of 17-dihydroxyexemestane in vitro and is found more commonly in Asians than Caucasians (60-70% vs less than 10%). Our research group recently demonstrated significant reduction in glucuronidation of vorinostat, a UGT2B17 substrate, with a trend towards improved clinical benefit rate and progression-free survival in Asian breast cancer patients who were UGT2B17*2 homozygotes treated with this compound. In-vivo studies correlating UGT2B17*2 genotype with exemestane pharmacokinetics and pharmacodynamics are lacking. We hypothesize that individuals with UGT2B17*2/*2 genotype have reduced glucuronidation of 17-dihydroxyexemestane and therefore have increased exposure to the active drug, resulting in improved treatment efficacy. We propose a study of exemestane in hormone receptor positive post-menopausal advanced breast cancer patients with prospective correlation of treatment outcome by UGT2B17 genotype. The primary endpoint is the correlation of genotype (UGT2B17*2/*2 vs those with at least one wild-type variant) with clinical benefit rate, and secondary endpoints include its association with exemestane pharmacokinetics, progression-free survival, overall survival and musculoskeletal toxicities.
|Study Design:||Endpoint Classification: Pharmacokinetics/Dynamics Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Treatment
|Official Title:||Prospective Study of UDP-gluconoryltransferase (UGT) 2B17 Genotype as a Predictive Marker of Exemestane Pharmacokinetics and Pharmacodynamics in Asian Women With Hormone Receptor-positive Advanced Breast Cancer|
- Correlation of UGT2B17*2 deletion genotype with clinical benefit rate (CBR) [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]The correlation of genotype (UGT2B17 *2/*2 versus those with at least one wild-type allele) with clinical benefit rate (CBR), defined as the percentage achieving CR, PR and SD in patients with measurable disease or the absence of disease progression in patients with non-measurable disease, lasting at least 24 weeks.
- Correlation of UGT2B17*2 deletion genotype with exemestane pharmacokinetics, objective response rates (ORR), progression-free survival (PFS), overall survival (OS) and musculoskeletal toxicities [ Time Frame: 24 months ] [ Designated as safety issue: No ]
The correlation of genotype (UGT2B17 *2/*2 versus those with at least one wild-type allele) with:
- Objective response rates (ORR), as defined by a best overall response of CR or PR.
- Progression-free survival (PFS), as defined by the time from the date of study enrollment until the first date of documented disease progression or death due to any cause, whichever occurs first.
- Overall survival (OS) as defined by the time from the date of study enrollment until the date of death due to any cause.
- Grade 2 and above musculoskeletal toxicities, as defined by the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v4.0.
- Pharmacokinetic parameters, in particular, AUC of exemestane-17-O-glucuronide, 17-dihydroexemestane and their ratio.
|Study Start Date:||August 2012|
|Estimated Study Completion Date:||August 2016|
|Estimated Primary Completion Date:||February 2015 (Final data collection date for primary outcome measure)|
Experimental: exemestane standard treatment
Patients will receive exemestane 25mg daily orally after a meal until progression of disease, intolerable toxicities, voluntary withdrawal or termination of the study.
Exemestane is commercially available and will be obtained locally from the manufacturer. There are no experimental treatments in this study.
Other Name: trade name Aromasin
This is a prospective non-randomised open-label study of exemestane in post-menopausal, hormone receptor positive advanced breast cancer patients, with pre-specified analysis of exemestane pharmacokinetics and pharmacodynamics according to UGT2B17 genotype (UGT2B17*2/*2 versus those with at least one wild-type allele). A total of 110 patients will be enrolled over a period of 30 months. Eligible patients will receive exemestane 25mg daily orally (as part of standard care) until progression of disease or intolerable toxicities. At the time of study entry, blood samples will be drawn for genotyping studies (for research purposes) but investigators will be blinded to the results. Pharmacokinetic sampling for exemestane and its metabolites will be performed at baseline and on day 29 (+/- 3 days) before dosing and 0.5, 1, 2, 4, 6, 8 and 24 hours after exemestane ingestion. Patients will be evaluated on an 8-weekly basis for toxicities and efficacy assessments during the first 6 months of treatment, followed by 12-weekly thereafter until disease progression, unacceptable toxicities, or patient withdrawal.
|Contact: Andrea LA Wong, MBBS||(65) 6772 email@example.com|
|Contact: Soo Chin Lee, MBBS||(65) 6772 firstname.lastname@example.org|
|National University Hospital||Recruiting|
|Singapore, Singapore, 119074|
|Contact: Andrea LA Wong, MBBS (65) 6772 5934 email@example.com|
|Sub-Investigator: Soo Chin Lee, MBBS|
|Sub-Investigator: Siew Eng Lim, MBBS|
|Sub-Investigator: Sing Huang Tan, MBBS|
|Principal Investigator:||Andrea LA Wong, MBBS||National University Hospital, Singapore|