Rationale and Trial Design of PFB-03 Study: Diagnostic Performance and Clinical Application of 18F-FAPI-PET/CT for Detecting Axillary Lymph Node Metastasis in Breast Cancer Patients After Neoadjuvant Therapy

June 7, 2025 updated by: ZHOU Yidong, Peking Union Medical College Hospital
Axillary lymph node (ALN) status is a crucial prognostic factor in breast cancer. Accurate, non-invasive methods for evaluating axillary lymph node metastasis after neoadjuvant therapy (NAT) are needed to optimize surgical decisions and minimize patient morbidity. Fibroblast Activation Protein Inhibitor (FAPI) PET/CT targets cancer-associated fibroblasts and may improve diagnostic accuracy. This study aims to assess the diagnostic performance and clinical utility of 18F-FAPI PET/CT in detecting ALN metastasis after NAT in breast cancer patients. This prospective, single-center study will enroll breast cancer patients with cT1-4N0-1M0 stage before NAT, who will undergo pre-surgical 18F-FAPI PET/CT followed by sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND) guided by protocol stratification based on FAPI PET/CT and clinical findings. The primary endpoint is the diagnostic accuracy of 18F-FAPI PET/CT for ALN metastasis versus pathology. Secondary endpoints include false-negative rates (FNR) of SLNB, lymphedema rates, and long-term outcomes such as local recurrence and survival rates.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
172

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

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

This study is designed as a single-center, prospective observational diagnostic accuracy trial. It will be conducted at the Department of Breast Sugery and Nuclear Medicine of PUMCH, Beijing, China, between June 2025 and May 2027. The study population consists of stage cT1-4N0-1M0 breast cancer patients with who received NAT (Fig. 1). After completion of NAT, surgical approach (ALND/SLNB) is guided by protocol stratification based on 18F-FAPI PET/CT and clinical findings. There is no randomization in this study, and all enrolled patients will undergo the index test and the reference standard surgical evaluation.

Description

Inclusion Criteria:

  • Must provide written informed consent
  • Female at 18-80 years of age
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0-1
  • With anticipated survival of at least 36 months
  • Pathologically confirmed invasive breast cancer with clinical stage of T1-4N0-1M0
  • Received standard NAT for BC (including either neoadjuvant chemotherapy or neoadjuvant targeted therapy, or a combination)
  • Have willingness to take the 18F-FAPI PET/CT imaging
  • With adequate organ function (neutrophil count ≥ 1.5 × 10⁹/L; platelet count ≥ 90 × 10⁹/L; hemoglobin ≥ 90 g/L; total bilirubin ≤ 1.5 × upper limit of normal [ULN]; alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × ULN; blood urea nitrogen (BUN) and serum creatinine (Cr) ≤ 1.5 × ULN; international normalized ratio (INR) ≤ 1.5 × ULN, activated partial thromboplastin time (APTT) ≤ 1.5 × ULN).

Exclusion Criteria:

  • Evidence of distant metastatic disease (M1)
  • Pregnant or lactating women
  • Failure to complete the planned NAT
  • Prior surgical intervention in the ipsilateral axilla
  • Diagnosis of any other malignancy within the past 5 years (exceptions: adequately treated non-melanoma skin cancer, cervical carcinoma in situ, papillary thyroid cancer)
  • Known hypersensitivity to the FAPI tracer or any excipients
  • With any serious uncontrolled medical condition that would make the patient unsuitable for surgery or PET/CT (e.g. unstable cardiac disease, severe claustrophobia unresponsive to anxiolytics, renal failure preventing CT contrast if needed)
  • Failure to lie still for imaging (about 20-30 minutes) or adhere to follow-up due to psychiatric, cognitive, or social reasons.

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

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Double positive
If clinical exam and 18F-FAPI PET/CT are positive for ALN involvement both before and after NAT, the patient proceeds directly to ALND as per standard guidelines.
Single Positive
If clinically/pathologically node-positive (c/pN1) pre-NAT but becomes clinically and 18F-FAPI PET/CT negative post-NAT, the patient undergoes ALND as per standard guidelines. However, within this ALND procedure, sentinel lymph nodes (SLNs) will be identified and sent separately for pathological analysis to assess the FNR of FAPI-PET guided SLNB evaluation in this specific scenario, without additional trauma or cost to the patient.
Double Negative
Includes two subgroups: (a) Patients who were clinically/pathologically node-negative pre-NAT and remain clinically and 18F-FAPI PET/CT negative post-NAT. (b) Patients who were clinically node-negative pre- and post-NAT, but 18F-FAPI-PET/CT becomes positive post-NAT. Within Cohort 3, management depends on patient preference: either proceed directly to ALND or undergo SLNB first (using dual tracer). If SLNB is positive, completion ALND follows; if negative, ALND is omitted. Dual tracer methods include methylene blue, contrast-enhanced ultrasound, or radionuclide imaging.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
diagnostic accuracy of 18F-FAPI PET/CT for detecting residual axillary lymph node metastases after NAT
Time Frame: Through study completion, an average of 3 years.

The primary endpoint of the study is the diagnostic accuracy of 18F-FAPI PET/CT for detecting residual axillary lymph node metastases after NAT, on a patient-level analysis. This will be assessed by calculating:

i)Sensitivity: proportion of patients with pathologically proven residual nodal metastasis who had a positive 18F-FAPI PET/CT (true positive rate).

ii)Specificity: proportion of patients with no residual nodal metastasis (pathologic nodal pCR) who had a negative PET/CT (true negative rate).

iii)Positive predictive value (PPV): probability that a PET-positive patient truly has nodal disease on pathology.

iv)Negative predictive value (NPV): probability that a PET-negative patient is truly node-negative on pathology.

v)Overall accuracy: proportion of all patients correctly classified by PET (true positives + true negatives divided by total).
Through study completion, an average of 3 years.

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Peking Union Medical College Hospital

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 31, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 31, 2030

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
May 26, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 7, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
June 10, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 10, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 7, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • PUMCH-PFB03

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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