Overview

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

Status:
Recruiting

Trial end date:
2025-11-01

Target enrollment:

Participant gender:

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.

Phase:

Phase 1

Details

Lead Sponsor:

National Cancer Centre, Singapore

Collaborator:

National Medical Research Council (NMRC), Singapore

Treatments:

Tamoxifen