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

April 27, 2026 updated by: Randy Yeh

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

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.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

15

Phase

  • Phase 2

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 Backup

Study Locations

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

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

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

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: 18F-FAPI-74 PET/CT and 18F-FDG PET/CT
Study participants will undergo both standard-of-care whole body 18F-FDG PET/CT scan and investigational whole-body scan 18F-FAPI-74 PET/CT.
Drug: 18F-FAPI-74
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.
Drug: 18F-FDG
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.
Procedure: PET/CT
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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
End of study, at 1 month

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
End of study, at 1 month
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).
End of study, at 1 month
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
End of study, at 1 month
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
End of study, at 1 month
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.
End of study, at 1 month
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.
End of study, at 1 month
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.
End of study, at 1 month

Collaborators and Investigators

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

Sponsor

Randy Yeh

Collaborators

The Society of Nuclear Medicine and Molecular Imaging

Investigators

  • Principal Investigator: Randy Yeh, MD, Icahn School of Medicine at Mount Sinai

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

June 1, 2026

Primary Completion (Estimated)

December 30, 2027

Study Completion (Estimated)

December 30, 2027

Study Registration Dates

First Submitted

December 11, 2025

First Submitted That Met QC Criteria

December 11, 2025

First Posted (Actual)

December 16, 2025

Study Record Updates

Last Update Posted (Actual)

May 1, 2026

Last Update Submitted That Met QC Criteria

April 27, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STUDY-25-00364
  • PRMC-25-041 (Other Identifier: Icahn School of Medicine at Mount Sinai)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The completed dataset is the sole property of the Sponsor-Investigator's institution and should not be exported to third parties, except for authorized representatives of appropriate Health/Regulatory Authorities, without permission from the Sponsor-investigator and their institution.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

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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