The findings are particularly relevant in metastatic breast cancer, where treatment decisions often rely on a combination of imaging, clinical assessment and other biomarkers. Additional insight into biological treatment effect may support more informed decisions on whether to continue treatment, switch therapy or intensify follow-up. The three presentations are also relevant from a broader care and development perspective. Better understanding of how tumor activity changes during treatment may, over time, support earlier intervention, more informed trial eligibility decisions and avoidance of costs associated with ineffective treatment.

“We are pleased to see three new posters including TKa data presented at ESMO Breast 2026,” said Amy Williams, Head of Clinical Development and Medical Affairs at Biovica. “Together, they highlight how TKa can provide a dynamic view of tumor proliferation across different treatment settings. The breadth of the data further supports the role of TKa as a functional efficacy biomarker in metastatic breast cancer and oncology drug development.”

TKa is a blood-based biomarker of tumor proliferation and can provide a dynamic view of biological tumor activity during treatment. The titles of three posters are:

• Longitudinal evaluation of serum thymidine kinase 1 activity in patients with metastatic breast cancer (mBC) treated with trastuzumab deruxtecan (T-DXd)
• Circulating tumor DNA (ctDNA) and serum thymidine kinase activity (sTKa) in patients with endocrine resistant MBC treated with palbociclib and fulvestrant (P+F) in the PYTHIA trial
• Distinct sTK1 behavior in first line chemotherapy and endocrine therapy in the PASIPHAE phase II trial