Identifying biomarkers for endocrine therapy resistance in lobular breast cancer

Integrating Minimally Invasive Biomarkers of Estrogen Signaling to Detect Endocrine Therapy Resistance in Metastatic Invasive Lobular Breast Cancer

Phase 2 Interventional University of Wisconsin, Madison · NCT06067503

This study is trying to find markers in the blood that can help doctors understand how well patients with lobular breast cancer respond to hormone therapy.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment8 (estimated)
Ages18 Years and up
SexAll
SponsorUniversity of Wisconsin, Madison Academic / other
Locations1 site (Madison, Wisconsin)
Trial IDNCT06067503 on ClinicalTrials.gov

What this trial studies

This pilot observational study aims to identify potential biomarkers that indicate response to endocrine therapy in patients with ER/PR-positive metastatic lobular breast cancer. Participants will undergo 18F-fluorofuranylnorprogesterone Positron Emission Tomography/Computed Tomography (FFNP-PET/CT) and liquid biopsies at the start of treatment and after four weeks. The study will correlate baseline levels and changes in estrogen signaling, as measured by FFNP-PET/CT and circulating tumor cells, with clinical responses and progression-free survival. This approach seeks to enhance understanding of treatment resistance in this patient population.

Who should consider this trial

Good fit: Ideal candidates include adults with biopsy-proven ER/PR-positive and HER2-negative advanced or metastatic lobular breast cancer who are starting new endocrine therapy.

Not a fit: Patients with active brain metastases or liver-only disease may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved strategies for predicting and overcoming resistance to endocrine therapy in lobular breast cancer patients.

How similar studies have performed: Other studies have explored biomarkers in breast cancer treatment, but this specific approach focusing on lobular breast carcinoma is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Willing to provide informed consent
2. Individuals at least 18 years of age
3. Have biopsy-proven ER/PR-positive (defined as ER ≥1 percent and PR ≥1 percent by IHC) and HER2-negative advanced or metastatic LBC starting new standard of care endocrine therapy
4. Adequate organ function as indicated by standard laboratory tests (CBC, liver function tests or CMP) allowing for systemic breast cancer treatment per treating oncologist
5. Patients with evaluable bone-only disease that is lytic or mixed lytic-sclerotic are eligible
6. Willing to comply with all study procedures and be available for the duration of the study
7. Disease may be measurable by RECIST 1.1 criteria or non-measurable. Lesion size must be at least 1cm. If only bone lesions present, they should be lytic or mixed lytic-sclerotic. If only liver lesions present, patient is not eligible.

Exclusion Criteria:

1. Patients with active brain metastases
2. Patients with liver-only disease are not eligible due to high background liver activity related to the radiopharmaceutical's hepatobiliary route of elimination
3. Unable to lie flat during or tolerate PET/CT
4. Patients with a history of allergic reaction attributable to compounds of similar chemical or biologic composition to FFNP
5. Presence of liver failure as judged by patient's treating physician
6. Individuals who are pregnant, lactating, or planning on becoming pregnant during the study
7. Not suitable for study participation due to other reasons at the discretion of the investigators
8. Patients with progesterone-receptor negative disease defined as PR \<1 percent by IHC

Where this trial is running

Madison, Wisconsin

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Metastatic CancerBreast CancerLobular Breast CarcinomaEndocrine Therapy Resistancecirculating tumor cellliquid biopsy
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.