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

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.

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Key information

Conditions

Breast Cancer Breast Diseases Breast Neoplasms Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year–80 year

Sex eligibility

Female

Study type

Observational

Who can participate

Healthy volunteers accepted: No

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

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.

Treatment and study plan

Primary outcomes

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).

Study contacts

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

Ru Yao

CONTACT

[email protected]

+861069158724

Sponsors and collaborators

Lead sponsor

Peking Union Medical College Hospital

Other

Registry information

Important dates

Study start: 2025
Primary completion: 2027
Study completion: 2030
First posted: Jun 10, 2025
Registry last updated: Jun 10, 2025

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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