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NCT Number: NCT06551116

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

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.

Recruiting

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Key information

Conditions

HER2-Positive Metastatic Breast Cancer

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

University of California San Francisco Medical Center, San Francisco, California, United States

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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)

Treatment and study plan

CE-10-IVD

Diagnostic Test

Leftover tumor tissue from a routine biopsy will be sent for analysis.

Primary outcomes

  1. Real-World Objective Response Rate

    Time frame: from date of first dose of T-DXd to date of last dose of T-DXd for each. Up to 100 months

    Association between quantitative HER2 expression (as a continuous variable) and real-world objective response rate

Secondary outcomes

  1. Real-World Progression Free Survival

    Time frame: from date of first dose of T-DXd to date of last dose of T-DXd for each.Up to 100 months

    Association between quantitative HER2 expression (as a continuous variable) and real world Progression Free Survival

  2. Real-World Progression Free Survival and Objective Response Rate by estrogen receptor expression

    Time frame: from date of first dose of T-DXd to date of last dose of T-DXd for each. Up to 100 months

    Association between HER2 expression by quantitative immunofluorescence and mRNA in HER2 IHC 1+ tumors and both rwORR and rwPFS, stratified by mRNA ER expression

  3. Threshold for HER2 QIF and/or mRNA levels

    Time frame: from date of first dose of T-DXd to date of last dose of T-DXd for each. Up to 100 months

    cut-off value for HER2 QIF, mRNA and the combination below which patients will not respond to T-DXd."

  4. Association between combined mRNA + QIF and real-world Objective Response Rate

    Time frame: from date of first dose of T-DXd to date of last dose of T-DXd for each. Up to 100 months

    Comparison, based on rwORR, of a linear combination of HER2 QIF and mRNA, versus either alone in ability to discriminate T-DXd responders from non- responders

Study contacts

Contact information is provided by the study sponsor or research team.

Angela DeMichele, MD

CONTACT

[email protected]

215-908-2599

Sponsors and collaborators

Lead sponsor

Abramson Cancer Center at Penn Medicine

Other

Collaborators

  • Danaher Inc.
  • Translational Breast Cancer Research Consortium

Registry information

Important dates

Study start
2024
Primary completion
2029
Study completion
2029
First posted
Aug 13, 2024
Registry last updated
Jul 8, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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