CYP2D6 activity in patients with metastatic breast cancer treated with single agent tamoxifen: results from ECOG-ACRIN E3108.

ABSTRACT:

Purpose

In tamoxifen-treated individuals, reduced-function genetic variants in the CYP2D6 gene or inhibition of the enzyme result in low circulating endoxifen concentrations. We assessed the impact of reduced CYP2D6 activity and circulating endoxifen concentrations on breast cancer outcomes.

Patients and methods

Patients with locally advanced or stage IV hormone receptor-positive breast cancer were enrolled in this single arm phase II trial and received open label tamoxifen 20 mg PO daily. The primary objective was to assess CYP2D6 poor metabolizer (PM) vs intermediate and normal metabolizer status (IM + NM) with progression-free survival (PFS). CYP2D6 phenotype was determined from whole blood samples (Roche Amplichip), and secondary endpoint evaluated endoxifen concentratio

SUBMITTER: Stearns V 

PROVIDER: S-EPMC12167464 | biostudies-literature | 2025 Feb

REPOSITORIES: biostudies-literature