Evaluation of [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT for Predicting Pathological Complete Response After Neoadjuvant Chemotherapy in HER2 Positive Early Breast Cancer (GATHER)

May 12, 2026 updated by: Centre Henri Becquerel

Evaluation of [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT for Predicting Pathological Complete Response After Neoadjuvant Chemotherapy in HER2 Positive Early Breast Cancer (GATHER): a Study Protocol for a Monocentric, Prospective, Interventional, Phase 2, Imaging Biomarker Trial.

The GATHER trial aim to evaluate the diagnostic performance of [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT in predicting pCR following neoadjuvant chemotherapy. This study is part of the development of new functional, non-invasive approaches with the aim of offering personalized therapeutic approaches.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

In early-stage HER2-positive breast cancer, neoadjuvant chemotherapy is frequently required, and pathological complete response (pCR) correlates with excellent prognosis. However, no non-invasive imaging method reliably predicts pCR, making surgery mandatory despite its aesthetic, functional, and psychological burden. Recently, new functional imaging tracers targeting the HER2 protein have been developed. Among these, [68Ga]Ga-NOTA-anti-HER2-sdAb is of particular interest due to its molecular characteristic; it has demonstrated favorable safety profile and ability to identify HER2+ cells in vivo. This trial evaluates its ability to predict pCR, with the prospect of paving the way for future therapeutic de escalation and surgical sparing.

Study Type

Interventional

Enrollment (Estimated)

42

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Female aged 18 years or older
  • Histologically proven HER2-positive early breast cancer, defined as IHC 3+ or IHC 2+ with ISH amplification
  • Indication for neoadjuvant chemotherapy combined with anti-HER2 targeted therapy followed by surgery, as determined by a multidisciplinary tumor board
  • ECOG performance status of 0 or 1
  • Affiliated to or beneficiary of a social protection scheme
  • Written informed consent signed prior to any study-specific procedure

Exclusion Criteria:

  • Pregnant or breastfeeding women

    • Patient not treated with curative intent
    • History of ipsilateral breast cancer treated by surgery and/or radiotherapy
    • Lobular histology
    • Known contraindication or hypersensitivity to [68Ga]Ga-NOTA-anti-HER2-sdAb or any of its radiopharmaceutical excipients
    • Known contraindication or hypersensitivity to [18F]F-FDG or any of its radiopharmaceutical excipients
    • Concurrent enrollment in another clinical trial evaluating radiopharmaceuticals
    • Patient under guardianship, curatorship, or judicial protection
    • Patient deprived of liberty
    • Inability to understand the study or comply with trial constraints due to linguistic, psychological, or geographical barriers

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: [68Ga]Ga-NOTA-anti-HER2-sdAb Positron Emission Tomography
Patients will undergo an [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT before neoadjuvant chemotherapy and 15 days prior the scheduled surgery
Other: [68Ga]Ga-NOTA-anti-HER2-sdAb Positron Emission Tomography
Patients will undergo an [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT before neoadjuvant chemotherapy and 15 days prior the scheduled surgery

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Concordance rate between the response estimated by [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT and the invasive pathological complete response
Time Frame: 2 weeks after surgery
The concordance rate is defined as the proportion of patients correctly classified by the post-therapeutic PET/CT compared to the gold standard histopathological assessment (ypT0/is ypN0).
2 weeks after surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Concordance rate between the response estimated by [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT and the pCR on both invasive and non-invasive components
Time Frame: two weeks after surgery
The concordance rate is calculated as the proportion of correctly classified patients compared to the non-invasive pCR definition (ypT0 ypN0), in addition to the invasive definition (ypT0/is ypN0)
two weeks after surgery
Comparison of the diagnostic performance of [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT against other conventional imaging modalities in predicting the invasive pCR
Time Frame: Two weeks after surgery
ΔSUV is defined as the relative change in SUVmax between the baseline and post-therapeutic [68Ga]Ga-NOTA-anti-HER2-sdAb PET/CT, compared according to invasive pathological complete response (ypT0/is ypN0).
Two weeks after surgery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Centre Henri Becquerel

Investigators

  • Principal Investigator: Florian Clatot, MD, PhD, Centre Henri Becquerel

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 1, 2026

Primary Completion (Estimated)

September 1, 2027

Study Completion (Estimated)

March 1, 2028

Study Registration Dates

First Submitted

May 12, 2026

First Submitted That Met QC Criteria

May 12, 2026

First Posted (Actual)

May 18, 2026

Study Record Updates

Last Update Posted (Actual)

May 18, 2026

Last Update Submitted That Met QC Criteria

May 12, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CHB25.04
  • 2025-523286-23-00 (Ctis)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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