Prognostic performance of thymidine kinase 1 activity in patients with hormone receptor-positive and HER2-negative metastatic breast cancer treated with CDK4/6 and aromatase inhibitors.

ABSTRACT:

Purpose

Thymidine kinase 1 activity (TKa) has previously been demonstrated as a prognostic biomarker for progression-free survival (PFS) in hormone receptor-positive, HER2-negative metastatic breast cancer (MBC), but its optimal use remains undefined. This study evaluated the prognostic performance of TKa across multiple sampling time points and thresholds in patients receiving first-line CDK4/6 inhibitor plus aromatase inhibitor therapy.

Methods

TKa was measured (DiviTum® assay) at baseline (BL), cycle 1 day 15 (C1D15), and cycle 2 day 1 (C2D1) in patients enrolled in the PDM-MBC study (n = 90). Thresholds for PFS discrimination were identified using maximally selected rank statistics, with predefined cut-offs tested for comparison. Prognostic performance was assessed using

SUBMITTER: Brown NL 

PROVIDER: S-EPMC12894156 | biostudies-literature | 2026 Feb

REPOSITORIES: biostudies-literature