Breast CancerFEStasticNCT05088785
Dynamic and Test-retest Whole Body [18F]FES PET Imaging in Patients With Metastatic ER+ Breast Cancer
A study testing FES in people with Breast Cancer, run by Amsterdam UMC, location VUmc at 1 site in Netherlands.
Trial summary
16a-18F-fluoro-17b-estradiol ([18F]FES) is radioactive labeled estradiol, developed for in vivo visualization of the estrogen receptor (ER) using positron emission tomography (PET). Read more about this study
- Who is it for?
- Ages 18 years and older, women only
- Conditions the study is for
- Breast Cancer
- What is being tested?
- FES
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 1 siteNetherlands
- Study dates
- 11 Oct 2021to Dec 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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
- Women only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Histologically proven metastatic ER+ (>10% positive stained cells using immunohistochemistry) breast cancer on the latest biopsy
- Postmenopausal females aged 18 years or older at screening. Postmenopausal status is defined as one of the following:
- age ≥60 years
- age <60 years and amenorrhea for >12 months in the absence of interfering hormonal therapies (such as LH-RH agonists and ER-antagonists)
- patient age <60 years using LH-RH agonists should continue LH- RH-agonists until after the PET procedures
- previous bilateral oophorectomy or medically confirmed ovarian failure
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- [18F]FDG PET, CT and/or a bone scan should be performed as part of routine clinical staging (≤4 weeks prior to screening)
- Patients should have metastases in the scanning field of view, all located outside of the liver
- Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-2
- Estimated glomerular filtration rate (eGFR) ≥30 ml/min
- Written and signed informed consent
Who cannot join
- History with another cancer within the last 5 years, except cancer treated with curative intent and no evidence of disease as judged by the treating physician
- Use of selective estrogen receptor modulators (SERMs) or downregulators (SERDs) for current breast cancer such as Tamoxifen/Fulvestrant (≤5 weeks prior to screening) or investigational drug therapy
- Pregnancy or lactating women
- Any medical, psychological or social condition that may interfere with the subject's safety and participation in the study, will lead to exclusion from this study
Trial locations and contacts
1 site in 1 country.
Netherlands1 site
Amsterdam UMC - location VUmc
Amsterdam, North Holland, 1081 HV
About this study
16a-18F-fluoro-17b-estradiol ([18F]FES) is radioactive labeled estradiol, developed for in vivo visualization of the estrogen receptor (ER) using positron emission tomography (PET). To date, [18F]FES PET has been mainly explored as a diagnostic imaging tool to assess ER expression, thereby identifying locations of disease and their potential sensitivity to endocrine therapy, respectively. The primary aim of this project is to extend the application of [18F]FES PET as a baseline diagnostic imaging biomarker for ER expression to use it as an (early) treatment response marker. However, for such an application, visual assessment alone may not be sufficient and a more rigorous quantitative image analysis is needed. Therefore, in this project we shall first derive the optimal pharmacokinetic model for full quantitative analysis of [18F]FES uptake and, subsequently, we shall assess the validity of simplified, clinically feasible, quantitative parameters of [18F]FES uptake in 5 patients with metastatic estrogen receptor positive (ER+) breast cancer (part A). In addition, the repeatability of these simplified parameters will then be investigated in another 10 patients (part B).
- Conditions
- Breast Cancer
- Being tested
- FES
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
FESDrug
[18F]FES PET imaging.
| Study group | Role | What they receive |
|---|---|---|
| Part A: dynamic FES PET imaging | Experimental | All patients included in part A will receive a dynamic FES PET/CT scan. Receives: Drug: FES |
| Part B: whole body static FES PET imaging | Experimental | All patients included in part B will receive a whole body static FES PET/CT scan twice within 1 week. Receives: Drug: FES |
What is being measured
The primary outcome is the main question the study is designed to answer.
FES uptake in lesions: Ki (net influx rate) or VT (volume of distribution) values
FES uptake in lesions will be expressed as Ki or VT values
Measured: 1 year
Secondary outcomes (1)
SUV and TBR values
Quantification of FES uptake in lesions will be assessed by determining standardized uptake values and tumor-to-blood ratios.
Measured: 1 year.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Oct 2021
- Study start11 Oct 2021
- Primary completionDec 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- More trials run by Amsterdam UMC, location VUmcThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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 N/A
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Enrolment
- 15 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Amsterdam UMC, location VUmc
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, C. Menke- van der Houven van Oordt, Amsterdam UMC, location VUmc
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05088785
- Sponsor's protocol ID
- NL76658.029.21
- Acronym
- FEStastic
- Status last verified
- Oct 2025
- First submitted
- 7 Oct 2021
- Last updated
- 27 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 27 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Dynamic and Test-retest Whole Body [18F]FES PET Imaging in Patients With Metastatic ER+ Breast Cancer
- ClinicalTrials.gov ID
- NCT05088785
- Acronym / sponsor ID
- FEStastic / NL76658.029.21
- Conditions
- Breast Cancer
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 15 participants (estimated)
- Lead sponsor
- Amsterdam UMC, location VUmcUniversity, hospital or other
- Study start
- 11 Oct 2021 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 22 Oct 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
16a-18F-fluoro-17b-estradiol ([18F]FES) is radioactive labeled estradiol, developed for in vivo visualization of the estrogen receptor (ER) using positron emission tomography (PET). To date, [18F]FES PET has been mainly explored as a diagnostic imaging tool to assess ER expression, thereby identifying locations of disease and their potential sensitivity to endocrine therapy, respectively. The primary aim of this project is to extend the application of [18F]FES PET as a baseline diagnostic imaging biomarker for ER expression to use it as an (early) treatment response marker. However, for such an application, visual assessment alone may not be sufficient and a more rigorous quantitative image analysis is needed. Therefore, in this project we shall first derive the optimal pharmacokinetic model for full quantitative analysis of [18F]FES uptake and, subsequently, we shall assess the validity of simplified, clinically feasible, quantitative parameters of [18F]FES uptake in 5 patients with metastatic estrogen receptor positive (ER+) breast cancer (part A). In addition, the repeatability of these simplified parameters will then be investigated in another 10 patients (part B).
Study design
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Part A: dynamic FES PET imaging | Experimental | Drug: FESAll patients included in part A will receive a dynamic FES PET/CT scan. |
| Part B: whole body static FES PET imaging | Experimental | Drug: FESAll patients included in part B will receive a whole body static FES PET/CT scan twice within 1 week. |
Who may qualify
- Ages
- 18 years and older
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Histologically proven metastatic ER+ (>10% positive stained cells using immunohistochemistry) breast cancer on the latest biopsy
- Postmenopausal females aged 18 years or older at screening. Postmenopausal status is defined as one of the following:
- [18F]FDG PET, CT and/or a bone scan should be performed as part of routine clinical staging (≤4 weeks prior to screening)
- Patients should have metastases in the scanning field of view, all located outside of the liver
- Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-2
Key exclusion criteria (4 listed)
- History with another cancer within the last 5 years, except cancer treated with curative intent and no evidence of disease as judged by the treating physician
- Use of selective estrogen receptor modulators (SERMs) or downregulators (SERDs) for current breast cancer such as Tamoxifen/Fulvestrant (≤5 weeks prior to screening) or investigational drug therapy
- Pregnancy or lactating women
- Any medical, psychological or social condition that may interfere with the subject's safety and participation in the study, will lead to exclusion from this study
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| FES[18F]FES PET imaging. | Drug | Part A: dynamic FES PET imaging, Part B: whole body static FES PET imaging |
Primary outcome
FES uptake in lesions: Ki (net influx rate) or VT (volume of distribution) values
Time frame: 1 year
FES uptake in lesions will be expressed as Ki or VT values
1 secondary outcome
SUV and TBR values
Time frame: 1 year.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 May 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing FES in people with Breast Cancer, run by Amsterdam UMC, location VUmc at 1 site in Netherlands.
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 11 inclusion and 4 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 27 May 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 Netherlands. 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.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
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?
FES uptake in lesions: Ki (net influx rate) or VT (volume of distribution) values (time frame: 1 year). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 27 May 2026; AzTrials last refreshed its copy on 7 Nov 2026.