Recruiting

Blood tests to track genetic changes in advanced breast cancer

Plain-English translation of NCT06417801 on ClinicalTrials.gov ↗ · Source last updated October 2026 · Translation generated September 2026 · How we translate trials

What is this trial?

This research study is testing whether a special blood test can detect genetic changes in breast cancer tumors as well as or better than traditional tissue biopsies. Researchers want to understand how tumors change over time, especially in people taking aromatase inhibitors plus CDK4/6 inhibitors—a common combination therapy for advanced breast cancer. By comparing blood tests with tissue samples, they hope to find an easier way to monitor your cancer and predict how it might respond to treatment.

Currently, doctors rely on tissue biopsies (samples taken from tumors) to find genetic changes that affect treatment decisions, but blood tests are easier and less invasive. This trial aims to prove that blood tests alone might work just as well, giving patients a simpler way to monitor their cancer without repeated biopsies.

Do you qualify?

You likely qualify if…

you have been diagnosed with advanced hormone-sensitive, HER2-negative breast cancer (locally advanced or spread to other parts of your body)
you are 18 years or older, of any gender
you are able to provide a blood sample before starting or during your first-line treatment
you fall into one of three groups: newly diagnosed with no prior metastatic therapy, already on hormone therapy and CDK4/6 inhibitor therapy doing well, or your cancer has progressed despite hormone and CDK4/6 inhibitor treatment
you have archived or available tumor tissue from your primary tumor or a metastatic lesion

You likely don't qualify if…

your breast cancer is hormone-receptor negative or HER2-positive
you have already received multiple lines of hormone therapy for advanced cancer
you are unable or unwilling to provide blood samples for testing
you have active progressive disease (for Cohort 3)

What participation looks like

Depending on which group you join, you will provide blood samples at specific timepoints—before starting treatment, at 6 months into therapy, and potentially at follow-up visits. Researchers will compare your blood test results with tissue biopsies taken from your tumors to see if the blood test can reliably detect the same genetic changes. The study will track your health over time until your cancer progresses, so you may have multiple blood draws across several months or longer.

AI-generated summary from trial data · Sep 15, 2026 · Not medical advice

Trial locations(6 sites)

Brazil

Ensino E Terapia de Inovação Clínica Amo - Ética, Salvador, Estado de Bahia

Irmandade Da Santa Casa de Misericórdia de Porto Alegre, Porto Alegre, Rio Grande do Sul

Fundação Antonio Prudente - A.C. Camargo Cancer Center, São Paulo

Instituto D'Or de Pesquisa E Ensino - São Paulo, São Paulo

Research Site, São Paulo