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Estrogen Receptor PositivePhase 2NCT04692103

Serial FES PET/CT to Measure Hormone Expression in Patients Undergoing Endocrine Targeted Therapy

A Phase 2 study testing F-18 16 Alpha-Fluoroestradiol, Positron Emission Tomography and Computed Tomography in people with Estrogen Receptor Positive and Primary or Recurrent Breast Carcinoma, run by University of Washington at 1 site in United States.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This clinical trial studies use of F-18 16 alpha-fluoroestradiol ([F-18] FES) positron emission tomography (PET)/computed tomography (CT) in measuring tumor hormone receptor expression in patients undergoing endocrine-targeted therapy for newly diagnosed breast cancer or breast cancer that has come back or spread to… Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
F-18 16 Alpha-Fluoroestradiol, Positron Emission Tomography and Computed Tomography
Type of treatment
Surgery or procedure
Could I receive a placebo?
No, everyone receives an active treatment
How many people
2 participants
Where
1 siteUnited States
Study dates
10 Jul 2021to 30 Apr 2041
Phase
Phase 2
Are there results?
Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Adult, non-pregnant patients with biopsy-proven or clinically obvious primary, recurrent or metastatic breast cancer
  • Breast cancer from ER+ primary that is seen on other imaging tests. Tumor ER expression must have been confirmed by immunohistocytochemistry of primary tumor or recurrent disease.
  • At least one site of disease 1.5 cm or greater is needed to meet the spatial resolution limits of PET imaging.
  • Patients must have been off tamoxifen or other estrogen receptor blocking agents for at least 6 weeks and off chemotherapy for 3 weeks for the initial baseline FES.
  • Patients must be selected for an endocrine targeted therapy regimen for treatment of their breast cancer by the referring oncologist. Selected treatments may be part of experimental treatment protocols for which the patient would be separately consented.
  • Patients must be willing to undergo serial imaging procedures.
  • Patients must agree to allow access to clinical records regarding response to treatment and long term follow up.
  • Ability to understand and the willingness to sign a written informed consent document.

Who cannot join

  • An inability to lie still for the tests
  • Individuals weighing more than 300 lb. (this is the weight limit of the scanner table)
  • Pregnant or lactating. Women of childbearing potential with either a positive or no pregnancy test at baseline are excluded.
  • Any other life-threatening illness (e.g. serious, uncontrolled concurrent infection or clinically significant cardiac disease - congestive heart failure, symptomatic coronary artery disease, cardiac arrhythmia not well controlled with medication).
  • Use of tamoxifen, faslodex, DES or any other ER blocking agent < 6 weeks or chemotherapy < 3 weeks prior to imaging scan.
  • Uncontrolled diabetes mellitus (fasting glucose > 200 mg/dL)
  • Adult patients who require monitored anesthesia for PET scanning.

Trial locations and contacts

1 site in 1 country.

United States1 site

  • Fred Hutch/University of Washington Cancer Consortium

    Seattle, Washington, 98109

Other trials in United States

About this study

Official title: Serial [F-18] Fluoroestradiol (FES) PET Imaging to Evaluate Endocrine-targeted Therapy

This clinical trial studies use of F-18 16 alpha-fluoroestradiol ([F-18] FES) positron emission tomography (PET)/computed tomography (CT) in measuring tumor hormone receptor expression in patients undergoing endocrine-targeted therapy for newly diagnosed breast cancer or breast cancer that has come back or spread to other places in the body. Comparing results of diagnostic procedures done before, during, and after hormone therapy may help measure a patient's response to treatment.

Read the detailed description

OUTLINE:

Patients undergo F-18 FES PET/CT scan at baseline. Patients also undergo F-18 FES PET/CT and FDG PET/CT between 1-12 weeks after starting therapy, and then 1-12 weeks after the second FES PET/CT scan. Repeat FDG PET may be omitted in patients on selective estrogen receptor degrader.

After completion of study, patients are followed up for up to 20 years.

Being tested
F-18 16 Alpha-Fluoroestradiol, Positron Emission Tomography, Computed Tomography, Fludeoxyglucose F-18, Laboratory Biomarker Analysis
Medical subject headings
Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • F-18 16 Alpha-FluoroestradiolDrug

    Also called F-18 FES, FES, Fluorine-18 16 alpha-fluoroestradiol, Fluoroestradiol F-18

    Undergo F-18 FES PET/CT

  • Positron Emission TomographyProcedure or surgery

    Also called Medical Imaging, PET Scan, Positron Emission Tomography Scan, Positron-Emission Tomography

    Undergo F-18 FES PET/CT

  • Computed TomographyProcedure or surgery

    Also called CAT Scan, Computerized Axial Tomography, CT scan

    Undergo F-18 FES PET/CT

  • Fludeoxyglucose F-18Drug

    Also called FDG, Fluorodeoxyglucose F18, 18FDG

    Undergo FDG PET/CT

  • Positron Emission TomographyProcedure or surgery

    Also called Medical Imaging, PET, PET Scan

    Undergo FDG PET/CT

  • Computed TomographyProcedure or surgery

    Also called CAT Scan

    Undergo FDG PET/CT

  • Laboratory Biomarker AnalysisOther

    Correlative studies

Study groups in NCT04692103
Study groupRoleWhat they receive
Diagnostic (F-18 FES PET/CT)ExperimentalPatients undergo F-18 FES PET/CT scan at baseline. Patients also undergo F-18 FES PET/CT and FDG PET/CT between 1-12 weeks after starting therapy, and then 1-12 weeks after the second FES PET/CT scan. Repeat FDG PET may be omitted in patients on selective estrogen receptor degrader.
Receives: Drug: F-18 16 Alpha-Fluoroestradiol; Procedure: Positron Emission Tomography; Procedure: Computed Tomography; Drug: Fludeoxyglucose F-18; Other: Laboratory Biomarker Analysis

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change in F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV) - Avg SULmax

    FES uptake will be quantified using lean body mass adjusted SUV (SUL). Percentage change in FES average SULmax between baseline and a second FES scan will be calculated for up to 3 lesions per patient.

    Measured: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)

  2. F-18 16 Alpha-fluoroestradiol (FES) Uptake

    Quantitative measures of FES uptake for each disease site will be determined by drawing regions-of-interest on lesions to determine maximal FES uptake (SUVmax) per lesion. Up to 10 sites seen on the static torso survey will be quantified.

    Measured: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)

  3. Proportion of Patients With a Threshold of Percentage Change, or That Surpass a Targeted Follow-up F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV)

    The number of patients showing a 20% increase in FES uptake (SULmean or SUVmax) compared to baseline from the first to second scan using a 90% Wilson score binomial confidence interval.

    Measured: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)

Secondary outcomes (1)

  1. Time to Disease Progression

    Time to disease progression will be measured as the time from the start of endocrine therapy to the time the patient is first recorded as having disease progression.

    Measured: From start of therapy up to 20 years

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted31 Dec 2020
  2. Study start10 Jul 2021
  3. Primary completion1 Oct 2021
  4. Study completion30 Apr 2041 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Diagnosis
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
2 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04692103
Sponsor's protocol ID
RG1007834
Other IDs
10465
Status last verified
Apr 2026
First submitted
30 Dec 2020
Last updated
1 Jul 2026
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing F-18 16 Alpha-Fluoroestradiol, Positron Emission Tomography and Computed Tomography in people with Estrogen Receptor Positive and Primary or Recurrent Breast Carcinoma, run by University of Washington at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 8 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 1 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 21 Feb 2023). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in F-18 16 Alpha-fluoroestradiol (FES) Standardized Uptake Value (SUV) - Avg SULmax (time frame: From time of first F-18 FES-PET/CT scan to time of second F-18 FES-PET/CT scan (approximately 1-12 weeks)). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04692103.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Jul 2026.

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