Application and Comparison of [68Ga]Ga-FAPI-04 PET, [18F]FDG PET, and Contrast-Enhanced MRI in Predicting Pathological Response to Neoadjuvant Chemotherapy in Breast Cancer Patients

NCT07553741 | Completed

• 1 other identifier: LCP-2505
• Study Type: interventional
• Target: 27
• Locations: 1 country
• Sites: 1

Brief Summary

This is a prospective, single-center cohort study enrolling patients with axillary lymph node-positive or locally advanced breast cancer, consistent with the indications for neoadjuvant therapy in routine clinical practice and as recommended by local guidelines. Different neoadjuvant chemotherapy (NAC) regimens were selected according to breast cancer subtypes. All patients underwent 68Ga-FAPI PET/MRI, 18F-FDG PET/CT, and contrast-enhanced MRI before the initiation of NAC and again after completion of NAC but prior to surgery. Surgical treatment was subsequently performed, and pathologic complete response (pCR) was determined based on postoperative histopathologic findings. For patients with pathologically confirmed axillary lymph node metastasis or locally advanced breast cancer, NAC may reduce TNM stage and even achieve pCR in the breast and/or axilla. This is particularly evident in HER2-positive and triple-negative breast cancer, for which multiple studies have reported pCR rates of approximately 45%-75% and 40%-65%, respectively. NAC may therefore provide opportunities for breast- or axilla-conserving treatment, reducing complications associated with axillary dissection while improving cosmetic outcomes. In addition, NAC enables assessment of tumor sensitivity to systemic therapy. However, accurate and effective methods for evaluating treatment response after NAC remain lacking. Conventional imaging modalities, such as ultrasound and MRI, demonstrate limited sensitivity and specificity. Although 18F-FDG PET/CT can be used to monitor pathologic response after NAC, its diagnostic performance is influenced by inflammation and metabolic factors, shows limited sensitivity for small lesions, and is relatively costly; thus, it is not widely used in clinical practice for response evaluation. Fibroblast activation protein (FAP) is predominantly expressed in cancer-associated fibroblasts (CAFs) within the tumor stroma and promotes tumor growth, invasion, and drug resistance through multiple mechanisms. Under physiologic conditions, FAP expression is low in most adult tissues but is significantly upregulated in breast cancer. Moreover, 68Ga-FAPI has demonstrated superior imaging performance compared with \^18F-FDG in breast cancer. This study aims to evaluate the feasibility and accuracy of 68Ga-FAPI PET/MRI, compared with 18F-FDG PET/CT and contrast-enhanced breast MRI, in assessing response to NAC in breast cancer, thereby providing additional evidence for clinical decision-making. This is a dynamic cohort study that plans to enroll 27 patients with operable or locally advanced breast cancer, tumor size \>5 cm, or lymph node-positive disease. Baseline imaging with 68Ga-FAPI PET/MRI, 18F-FDG PET/CT, and contrast-enhanced breast MRI will be performed within 10 days before initiation of NAC. Patients will then receive standard NAC according to subtype and clinical guidelines. Follow-up imaging with the same modalities will be conducted between 2 weeks after completion of NAC and within 10 days before surgery. Surgery will then be performed, and patients will be classified into pCR and non-pCR groups based on postoperative pathology. Imaging findings from 68Ga-FAPI PET/MRI, 18F-FDG PET/CT, and breast MRI will be compared with histopathologic results to evaluate their ability to predict pCR. Postoperative follow-up will be conducted to assess prognosis, supported by evidence from MRI, CT, ultrasound, and laboratory examinations. The minimum follow-up duration will be ≥12 months.

Conditions

Breast Cancer

Outcome Measures

Primary Outcomes (6)

• 18F-FDG PET analysis

  PET parameter (SUV in g/ml) changes between both scans will be measured.

  Baseline and 21-28 days after the last cycle of neoadjuvant chemotherapy (each cycle is 21days)

• 18F-FDG PET analysis

  PET parameter (MTV in cm3) changes between both scans will be measured.

  Baseline and 21-28 days after the last cycle of neoadjuvant chemotherapy (each cycle is 21days)

• 18F-FDG PET analysis

  PET parameter (TLG in g/ml\*cm3) changes between both scans will be measured.

  Baseline and 21-28 days after the last cycle of neoadjuvant chemotherapy (each cycle is 21days)

• 68Ga-FAPI-04 PET analysis

  PET parameter (SUV in g/ml) changes between both scans will be measured.

  Baseline and 21-28 days after the last cycle of neoadjuvant chemotherapy (each cycle is 21days)

• 68Ga-FAPI-04 PET analysis

  PET parameter (MTV in cm3) changes between both scans will be measured.

  Baseline and 21-28 days after the last cycle of neoadjuvant chemotherapy (each cycle is 21days)

• 68Ga-FAPI-04 PET analysis

  PET parameter (TLG in g/ml\*cm3) changes between both scans will be measured.

  Baseline and 21-28 days after the last cycle of neoadjuvant chemotherapy (each cycle is 21days)

Study Arms (1)

neoadjuvant chemotherapy

EXPERIMENTAL

It is planned to include 27 patients with operable or locally advanced breast cancer, tumor size \>5 cm, or positive lymph nodes. Within ten days before the start of neoadjuvant therapy, baseline examinations including 68Ga-FAPI PET/MRI, 18F-FDG PET/CT, and contrast-enhanced breast MRI will be completed. Subsequently, standard neoadjuvant therapy will be administered according to treatment guidelines based on each subtype. Two weeks after neoadjuvant therapy until ten days before surgery, 68Ga-FAPI PET/MRI, 18F-FDG PET/CT, and contrast-enhanced breast MRI preoperative examinations will be completed, followed by surgical treatment. Finally, based on postoperative pathological results, patients will be divided into the pCR group and non-pCR group, and the results of 68Ga-FAPI PET/MRI, 18F-FDG PET/CT, and breast MRI will be compared with pathological results to evaluate their ability to predict pCR.

Drug: 68Ga-FAPI-04; Drug: 18F-FDG

Interventions

68Ga-FAPI-04 DRUG

A fibroblast activation protein (FAP) -targeted PET imaging agent

neoadjuvant chemotherapy

18F-FDG DRUG

A general glucose metabolism imaging agent

neoadjuvant chemotherapy

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Female, aged 18-70 years Pathologically confirmed primary breast cancer TNM stage T2-4N0M0/T1-4N1-3M0 No prior treatment No severe hematologic, cardiac, pulmonary, hepatic, or renal dysfunction, and no immunodeficiency diseases Patients must have good physical condition, ECOG score of 0-1 Female patients of childbearing potential must agree to use effective contraception during the study Signed written informed consent

You may not qualify if:

• Unwilling to undergo 68Ga-FAPI PET/MRI scan Unable to tolerate chemotherapy or surgery Previous history of other malignancies or prior antitumor treatment Evidence of distant metastasis Immunodeficiency or autoimmune disease History of monoclonal antibody allergy Pregnant or breastfeeding women Presence of active infection Patients with mental illness or cognitive impairment

Sponsors & Collaborators

• Union Hospital, Tongji Medical College, Huazhong University of Science and Technology: lead

Study Sites (1)

China, Hubei Province

Wuhan, Hubei, 430022, China

Location

MeSH Terms

Conditions

Breast Neoplasms

Interventions

68Ga-FAPI; Fluorodeoxyglucose F18

Condition Hierarchy (Ancestors)

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

Intervention Hierarchy (Ancestors)

Deoxyglucose; Deoxy Sugars; Carbohydrates

Study Officials

• Chunping Liu

  Tongji Medical College, Huazhong University of Science and Technology

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: DIAGNOSTIC
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 14, 2026
• First Posted: April 28, 2026
• Study Start: April 1, 2025
• Primary Completion: December 31, 2025
• Study Completion: April 1, 2026
• Last Updated: April 28, 2026

Record last verified: 2026-04

Locations

CN (1)