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NCT Number: NCT07285993

Detection and Outcomes in Metastatic Invasive Lobular Breast Cancer Through Novel F-18 FAP PET

This study is a pilot clinical imaging trial of a prospective, head-to-head comparison of 18F-Fibroblast Activation Protein Inhibitor (FAPI)-74 PET/CT versus standard-of-care 18F-Fluorodeoxyglucose (FDG) PET/CT in 15 patients with metastatic invasive lobular breast cancer (ILC). Patients will undergo both 18F-FDG PET/CT and 18F-FAPI-74 PET/CT within a 2-week period (14 days + 7 days) to compare lesions, tumor detection rates, and PET lesion intensity, as well as to assess the clinical value of the PET scans from the treating physician's and the patient's perspective.

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Key information

Conditions

Breast Cancer Breast Diseases Breast Neoplasms Metastatic Invasive Lobular Breast Cancer Neoplasm Metastasis Neoplasms Neoplasms by Site Neoplastic Processes Pathologic Processes Pathological Conditions, Signs and Symptoms Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Phase 2

Primary location

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Provision of signed and dated informed consent form
  • Stated willingness to comply with all study procedures and lifestyle considerations and availability for the duration of the study
  • Females; Age > 18 years of age
  • Diagnosis of invasive lobular breast cancer, with pathologically confirmed metastatic disease.
  • ECOG performance status 0-2
  • No planned change in anticancer therapy between FDG and FAPI PET scans

Exclusion criteria

  • Patients who are pregnant or lactating
  • Patients who cannot undergo PET/CT scanning
  • Patients with total serum bilirubin or serum creatinine > 1.5 times the upper limit of normal

Treatment and study plan

18F-FAPI-74

Drug

FAPI scans will be performed as hybrid PET/CT examinations for attenuation correction and lesion localization. Each patient will be injected intravenously with 7 mCi +/- 2 mCi of 18F-FAPI-74 followed by a 20-minute (+/-10 min) uptake period.

18F-FDG

Drug

FDG PET/CT will be performed per standard-of-care protocol at Mount Sinai Hospital. Patients will fast for at least 6 hours before FDG administration and plasma glucose levels will be checked to ensure < 200 mg/dL. Each patient will be injected intravenously with 15 mCi +/- 20% of 18F-FDG.

PET/CT

Procedure

FAPI PET/CT images will be acquired from the top of skull to mid-thigh. FDG PET/CT images will be acquired from the skull base to mid-thigh after a 60-min uptake period. Outside FDG PET/CT performed at another institutional can be accepted, if image quality and acquisition is comparable to standard-of-care protocol at Mount Sinai Hospital.

Primary outcomes

  1. Proportion of lesions detected by 18F-FAPI-74 PET/CT

    Time frame: End of study, at 1 month

    Proportion of lesions detected by 18F-FAPI-74 PET/CT but not by 18F-FDG PET/CT. All lesions will be mapped across both imaging modalities to determine whether they were detected by FAPI PET/CT but not by FDG PET/CT.

Secondary outcomes

  1. Proportion of lesions detected by 18F-FDG PET/CT but not by 18F-FAPI-74 PET/CT

    Time frame: End of study, at 1 month

    All lesions will be mapped across both imaging modalities to determine whether they were detected by FDG PET/CT but not by FAPI PET/CT.

  2. Proportion of concordant lesions detected by both 18F-FAPI-74 PET/CT and 18F-FDG PET/CT

    Time frame: End of study, at 1 month

    All lesions will be mapped across both imaging modalities to determine whether they were detected by both FAPI PET/CT and FDG PET/CT (i.e., concordant detection).

  3. Tumor detection rate

    Time frame: End of study, at 1 month

    Tumor detection rate, defined as the proportion (%) of patients with >1 lesion on 18F-FAPI-74 PET/CT compared to 18F-FDG PET/CT

  4. SUVmax of the hottest lesion (lesion with highest SUVmax) on 18F-FAPI-74 PET/CT compared to 18F-FDG PET/CT and mean SUVmax across all lesions

    Time frame: End of study, at 1 month

    SUVmax of each lesion identified on both 18F-FAPI-74 PET/CT and 18F-FDG PET/CT.

    Two summary metrics will be derived per patient per modality:

    Hottest lesion SUVmax: Defined as the highest SUVmax value among all detected lesions per patient per modality.

    Overall SUVmax: model lesion-level SUVmax values

  5. Tumor-to-background ratio (TBR)

    Time frame: End of study, at 1 month

    Tumor-to-Background Ratio (TBR) will be defined as the SUVmax of the hottest lesion divided by the SUVmax of two background regions: the liver and the aortic blood pool.

  6. Number of participants with change in therapeutic management decisions

    Time frame: End of study, at 1 month

    Number of participants with change in therapeutic management decisions following review of 18F-FAPI-74 PET/CT compared to decisions based on 18F-FDG PET/CT alone

    For each patient, an initial therapeutic management plan will be recorded based on findings from the 18F-FDG PET/CT scan alone. After the subsequent review of the 18F-FAPI-74 PET/CT scan, a revised management plan will be documented, reflecting any changes informed by the additional imaging data.

  7. Change in disease status assessment

    Time frame: End of study, at 1 month

    Change in disease status assessment (responding, stable, progressing) by treating physicians following review of 18F-FAPI-74 PET/CT compared to assessment based on 18F-FDG PET/CT alone Treating physicians will assign a disease status classification (responding, stable, or progressing) based on available clinical and imaging data from 18F-FDG PET/CT and then after reviewing the 18F-FAPI-74 PET/CT scan. We will summarize the distribution of disease status before and after the FAPI scan, along with the number and percentages of patients whose disease status assessment changed following the FAPI scan, along with the specific nature of those changes.

Study contacts

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

Ilda Bander

CONTACT

[email protected]

(212) 241-0763

Rashmi Unawane

CONTACT

[email protected]

(212) 824-2385

Sponsors and collaborators

Lead sponsor

Randy Yeh

Other

Collaborators

  • The Society of Nuclear Medicine and Molecular Imaging

Registry information

Official study title

Improving Detection and Outcomes in Patients With Metastatic Invasive Lobular Breast Cancer Through Novel F-18 FAPI PET Imaging

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Dec 16, 2025
Registry last updated
May 1, 2026

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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