Dose-determining and Dose-confirmatory Study to Investigate the Optimal Dose of Tamoxifen in Breast Cancer Patients According to Genotype Status of TCF20 rs932376

NCT ID: NCT04961632

Last Updated: 2024-02-01

Basic Information

• Recruitment Status: ACTIVE_NOT_RECRUITING
• Clinical Phase: PHASE1
• Total Enrollment: 75 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2020-12-23
• Study Completion Date: 2025-11-30

Brief Summary

The investigators hypothesize that the TCF20 rs932376 locus controls endoxifen levels in estrogen receptor (ER)-positive breast cancer patients on tamoxifen therapy and that the requirement of tamoxifen dose to achieve therapeutic levels of endoxifen varies according to the genotype status of the patient's at the TCF20 rs932376 locus.

Patients will receive escalating doses of tamoxifen according to their TCF20 rs932376 genotype status. Patients on 20mg tamoxifen daily for 8 weeks or longer will provide blood samples for analysis of tamoxifen and its metabolites. Patients assess with >30nM endoxifen concentrations will continue with 20mg tamoxifen dose. Patients who have endoxifen concentrations <30nM will receive dose increments of 10mg every 8 weeks until they achieve endoxifen threshold of >30nM or reach maximum dose level of 40mg/day.

Conditions

Breast Cancer

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: SEQUENTIAL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

Dose-determination

Group Type: EXPERIMENTAL

Tamoxifen

Intervention Type: DRUG

Patients taking 20mg tamoxifen will receive dose increments of 10mg every 8 weeks until endoxin threshold of \>30nM or the maximum dose of 40mg/day is reached. The escalated dose will be taken for 1 year before reverting back to 20mg.

Dose-confirmation

Group Type: EXPERIMENTAL

Tamoxifen

Intervention Type: DRUG

Patients will take tamoxifen at the ascribed genotype-determined dose as determined in the dose-determination phase.

Interventions

Tamoxifen

Patients taking 20mg tamoxifen will receive dose increments of 10mg every 8 weeks until endoxin threshold of \>30nM or the maximum dose of 40mg/day is reached. The escalated dose will be taken for 1 year before reverting back to 20mg.

Intervention Type: DRUG

Tamoxifen

Patients will take tamoxifen at the ascribed genotype-determined dose as determined in the dose-determination phase.

Intervention Type: DRUG

Eligibility Criteria

Inclusion Criteria

• Histologically or cytologically confirmed stage I to IV breast cancer
• Age greater than 21 years
• Estrogen- or progesterone-receptor positive tumours
• Patients receiving tamoxifen 20mg daily as monotherapy
• Patients currently taking tamoxifen in either adjuvant or metastatic setting for greater than or equal to 8 weeks (for Dose determination and confirmation phases)
• Patients who will commence on tamoxifen therapy in either adjuvant or metastatic setting (for Dose confirmation phase only)
• Written and informed consent from participating patients

Exclusion Criteria

• Patients with expected survival less than 6 months
• Patients who are human epidermal growth factor receptor 2 (HER2)-postitive
• Inability to provide informed consent
• Patients receiving CYP2D6 inhibitors or inducers within the past four weeks from the time of study enrollment. However, patients started in CYP2D6 inhibitors or inducers after commencing on tamoxifen therapy will not be excluded from the study.
• Pregnancy
• Patients with prior malignancies other than those who have received curative treatment for basal cell carcinoma of the skin or carcinoma in situ of the uterine cervix
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/ social situations that would limit compliance with study requirements.
• Patients who have documented prior allergic reaction to tamoxifen

• Minimum Eligible Age: 21 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National Medical Research Council (NMRC), Singapore

OTHER_GOV

Sponsor Role: collaborator

National Cancer Centre, Singapore

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Elaine Lim

Role: PRINCIPAL_INVESTIGATOR

National Cancer Centre, Singapore

Locations

National Cancer Centre

Singapore, , Singapore

Countries

Singapore

Other Identifiers

TCF20-BRE-01

Identifier Type: -

Identifier Source: org_study_id