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Measuring HER2 levels in metastatic breast cancer patients

QuantifyHER: Quantitative Immunofluorescence and/or RT-qPCR for Measuring HER2 in HER2-low Metastatic Breast Cancer

Observational Abramson Cancer Center at Penn Medicine · NCT06551116

This study is testing a new way to measure HER2 levels in patients with low HER2 metastatic breast cancer to see if it can help identify who will benefit from a specific treatment.

Quick facts

Study typeObservational
Enrollment200 (estimated)
Ages18 Years and up
SexAll
SponsorAbramson Cancer Center at Penn Medicine Academic / other
Locations37 sites (San Francisco, California and 36 other locations)
Trial IDNCT06551116 on ClinicalTrials.gov

What this trial studies

This observational study aims to evaluate the effectiveness of a quantitative HER2 assay in distinguishing between responders and non-responders among patients with HER2-low metastatic breast cancer receiving T-Dxd treatment. It includes patients with confirmed metastatic breast cancer who have a 1+ level of HER2 expression as determined by local laboratories. The study will utilize archival tissue for biomarker assessment and requires measurable disease at the start of treatment. The goal is to improve patient outcomes by identifying those who are likely to benefit from therapy.

Who should consider this trial

Good fit: Ideal candidates include adults over 18 with histologically confirmed metastatic breast cancer and a 1+ level of HER2 expression.

Not a fit: Patients with HER2-negative metastatic breast cancer or those without measurable disease may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to more personalized treatment strategies for patients with HER2-low metastatic breast cancer.

How similar studies have performed: Other studies have shown promise in using quantitative assays for HER2 assessment, suggesting potential for success in this approach.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Women and men age \> 18 years
* Metastatic breast cancer, histologically- confirmed. Any estrogen receptor (ER) status is allowed. ER status will be determined by local laboratory assessment utilizing ASCO/CAP guidelines.
* Primary and/or metastatic tumor with 1+ level of expression of HER2 by immunohistochemistry as determined by local laboratory assessment utilizing ASCO/CAP guidelines.
* Measurable disease by cross-sectional imaging at the start of treatment. Patients with measurable bone-only disease or active brain metastases are eligible.
* Archival tissue available for biomarker assessment. One specimen should be the most recent metastatic biopsy. If HER2 1+ status was determined on a different specimen (either primary or metastatic tissue), that specimen is also required. Samples obtained from bone metastases that were processed via decalcification methods are not eligible.
* Intention to initiate therapy with T-DXd (Enhertu) at FDA-approved dose and schedule as next line of therapy. If T-DXd was already initiated, patients must be registered within 30 days of initiation.
* Ability to provide informed consent

Exclusion Criteria:

* Concurrent Her2-overexpressing metastatic breast cancer (as confirmed by a metastatic biopsy with IHC 3+ or IHC 2+ with FISH amplified as per standard ASCO/CAP guidelines)

Where this trial is running

San Francisco, California and 36 other locations

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.
View on ClinicalTrials.gov → Find more trials like this →
Conditions HER2-positive Metastatic Breast Cancer
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.