Blood test could help personalize breast cancer therapy

NCT ID NCT05977036

Recruiting now Disease control Sponsor: Washington University School of Medicine Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study tests whether a blood test measuring thymidine kinase activity (TKa) can help doctors decide early if a patient's breast cancer treatment is working. Patients with HR+ HER2- metastatic breast cancer start standard therapy with a CDK4/6 inhibitor and endocrine therapy. If the blood test at day 15 shows the treatment isn't suppressing TKa, patients switch to a different therapy. The goal is to see if this early switch improves how long the cancer stays under control.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: CDK4/6 inhibitor plus endocrine therapy
What this could lead to: If successful, this could show that a simple blood test helps doctors choose the right treatment earlier, potentially improving how long the cancer is controlled.
What could go wrong: This is a small, early-phase study (65 people) without a control group, so results may not apply broadly. The blood test may not reliably predict treatment response.

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Conditions

The condition(s) this trial relates to.

breast cancer breast carcinoma breast neoplasm hormone receptor-positive breast cancer

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

METASTATIC BREAST CANCER UNRESECTABLE BREAST CANCER

Contacts and locations

Locations

Washington University School of Medicine
RECRUITING

St Louis, Missouri, 63110, United States

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