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

N/ANot Yet RecruitingNCT07012707

Peking Union Medical College Hospital172 enrolled

Overview

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 Type

OBSERVATIONAL

Enrollment

172

Conditions

Breast Cancer

Eligibility

Sex: FEMALEMin age: 18 YearsMax age: 80 Years

Medical Language ↔ Plain English

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.

Outcomes

Primary Outcomes

diagnostic accuracy of 18F-FAPI PET/CT for detecting residual axillary lymph node metastases after NAT

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).

Time frame: Through study completion, an average of 3 years.