UPCC 09124 QuantifyHER: Quantitative Immunofluorescence and/or RT-qPCR for Measuring HER2 in HER2-low Metastatic Breast Cancer

Investigating the Accuracy of HER2 Assay in Metastatic Breast Cancer

Enrolling By Invitation
18 years or above
All
Phase N/A
200 participants needed
1 Location

Brief description of study

This study will assess whether a quantitative, HER2 assay can accurately and reliably discriminate between responders and non-responders among patients with HER2 IHCI+ metastatic breast cancer who are receiving T-Dxd.

Eligibility of study

You may be eligible for this study if you meet the following criteria:

  • Conditions: HER2-positive Metastatic Breast Cancer
  • Age: 18 years or above
  • Gender: All

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)

This study investigates the effectiveness of a quantitative HER2 assay in distinguishing between patients with HER2 IHC1+ metastatic breast cancer who respond to treatment and those who do not. The purpose is to determine if this assay can reliably identify patients who are likely to benefit from receiving investigational medications for their condition.

Participants will undergo procedures including quantitative immunofluorescence and/or RT-qPCR testing to measure HER2 levels. This testing involves analyzing tumor tissue samples to assess HER2 expression, which plays a role in the growth of some breast cancers.

  • Who can participate: Adults over the age of 18 with metastatic breast cancer, confirmed through histological analysis, are eligible. Participants must have a primary or metastatic tumor with a 1+ level of HER2 expression and measurable disease as assessed by imaging.
  • Study details: Participants will provide tissue samples for biomarker assessment, including recent metastatic biopsies. They must be starting or have recently started treatment with the investigational medication T-DXd. An inactive substance that looks like the investigational medicine/vaccine but does not contain any medicine may be used as a placebo.
Updated on 08 Jul 2026. Study ID: 24-0764
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Study is selecting its participants from a population, or group of people, decided on by the researchers in advance.

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