A Phase 3 interventional study of Elacestrant and Tamoxifen in ER-positive Breast Cancer, HER2-negative Breast Cancer and Stage IIB Breast Cancer, sponsored by European Organisation for Research and Treatment of Cancer - EORTC. Recruiting at 113 sites in 12 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-07.
Sponsored by European Organisation for Research and Treatment of Cancer - EORTC · Phase 3, Interventional, and Treatment
This is an international, multi-center, randomised, open label, superiority phase III trial of elacestrant vs standard endocrine therapy in patients with ER+/HER2- breast cancer and ctDNA relapse.
During the ctDNA screening phase, patients will be tested at different timepoints to detect the presence of ctDNA in their blood.
Patients who are found to be ctDNA-positive and have no evidence of distant metastasis, will be randomised 1:1 between standard endocrine treatment (the same they were receiving when tested ctDNA positive) versus elacestrant, provided they meet all eligibility criteria. After completion of the protocol treatment period, treatment will be left at the discretion of the treating physician.
International, multi-center, randomised, open label, superiority phase III trial of elacestrant vs standard endocrine therapy in patients with ER+/HER2- breast cancer and ctDNA relapse.
ctDNA screening phase: After verification of the eligibility criteria for screening, patients will enter the ctDNA screening phase of the study in which plasma samples will be collected and tested with ctDNA assay to detect the presence of ctDNA. The test will be performed every 6 months from study entry until the end of accrual (approximately 5.7 years). During the screening phase, patients will be treated with standard adjuvant endocrine therapy [either tamoxifen or an aromatase inhibitor (exemestane, anastrozole or letrozole)] and followed-up as per standard of care. The outcome of the serial ctDNA assessments performed during the screening phase will be disclosed to investigators.
Patients who are found to be ctDNA-negative at the end of the screening period will not be followed further in this study.
Patients who are found to be ctDNA-positive at one of the screening time points will undergo an imaging work-up to assess the presence of distant metastases.
Patients for whom the imaging work-up confirms no evidence of distant metastases or locoregional recurrence will be eligible for the randomised phase of the study provided they meet all other eligibility criteria. Patients for whom the imaging work-up shows evidence of distant metastases or locoregional recurrence will be excluded.
Patients will be randomised 1:1 within 4 weeks from the date of ctDNA detection (i.e., the date on which the results of the test are received) between standard endocrine treatment (the same they were receiving when tested ctDNA positive) versus elacestrant.
In the absence of a withdrawal criteria, treatment in both arms will be administered for:
After completion of the protocol treatment period, treatment will be left at the discretion of the treating physician.
Patients in both arms will undergo intensive follow-up with ctDNA tests at week 4 and week 16 after randomisation and every 16 weeks thereafter for a maximum of 3 years (36 months or 156 weeks) to assess ctDNA kinetics. In addition, the occurrence of distant metastases, locoregional recurrences and second cancers will be assessed via yearly mammograms and bone scans and 16-weekly CT scans thorax/abdomen for a maximum of 3 years after randomisation. Afterwards, follow-up will continue as per standard of care. All randomised patients will be followed-up until 3 years after the enrolment of the last patient.
End of study:
End of study occurs when all the following criteria have been satisfied:
All patients have completed their end of study visit. If a patient discontinues the follow-up due to withdrawal of consent, loss to follow-up, or death, the end of study participation is defined as the time point when one of these events occurred The trial is mature for all analyses defined in the protocol and the database has been cleaned and frozen for these analyses.
14,825 studies on the registry are indexed under Breast Neoplasms; 3,319 are open to participants now.
This study's planned enrollment of 220 is above the median of 72 across 10,896 interventional studies indexed under Breast Neoplasms.
Browse Breast Neoplasms studies →European Organisation for Research and Treatment of Cancer - EORTC is the lead sponsor of 352 studies on the registry; 23 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Inclusion Criteria:
ctDNA screening phase:
Main inclusion criteria:
negative breast cancer, according to local pathologist:
FOR PATIENTS TREATED WITH PRIMARY SURGERY:
SYSTEMIC TREATMENT FOLLOWED BY SURGERY:
Main exclusion criteria:
Main inclusion criteria:
Main exclusion criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HER2
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CTCAE grade
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
elacestrant 400 mg/day orally once daily on a continuous dosing schedule
Drug: Elacestrant
standard endocrine treatment - the same they were receiving at the time of ctDNA detection
Drug: Tamoxifen · Drug: Letrozole 2.5mg · Drug: Anastrozole 1mg · Drug: Exemestane 25 MG
400mg QD orally on a continuous dosing schedule
20 mg QD orally on a continuous dosing schedule
2.5 mg QD orally on a continuous dosing schedule
1 mg QD orally on a continuous dosing schedule
25 mg QD orally on a continuous dosing schedule
Distant metastasis free survival (DMFS)
Distant metastasis free survival (DMFS) defined as the time from randomisation until first distant metastatic recurrence or death from any cause, whichever occurs first
Time frame: Final DFMS will be 6.25 years after the first patient randomised.
Invasive disease-free survival (iDFS)
According to the STEEP criteria, it's defined as the time between the date of randomisation and the date of the first occurrence of one of the following events: loco-regional disease recurrence, distant metastasis, invasive contralateral breast cancer, invasive non-breast second cancer, or date of death from any cause
Time frame: Through study completion, up to 11.7 years
Relapse-free survival (RFS)
Relapse-free survival (RFS) rate according to the STEEP criteria, including locoregional recurrence, distant metastasis, deaths from any cause as events
Time frame: Through study completion, up to 11.7 years
Overall survival rate
Overall survival rate • Safety including but not limited to all adverse events, serious adverse events, laboratory abnormalities graded according to CTCAE version 5.0
Time frame: Through study completion, up to 11.7 years
Adverse events
Safety including but not limited to all adverse events, serious adverse events, laboratory abnormalities graded according to CTCAE version 5.0
Time frame: as of randomization until 30 days after administration of the last dose of protocol treatment.
Health Related Quality of Life QLQ-C30
European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core-30 (QLQ-C30). This is a patient-reported questionnaire composed of both multi-item scales and single-item measures. These include five functional scales, three symptom scales, a global health status / QoL scale, and six single items. All of the scales and single-item measures range in score from 0 to 100.A high scale score represents a higher response level. Thus a high score for a functional scale represents a high / healthy level of functioning, a high score for the global health status / QoL represents a high QoL, but a high score for a symptom scale / item represents a high level of symptomatology / problems. Assessments will be performed at 21 days before randomisation, 4 weeks, 16 weeks, 32 weeks, 48 weeks, 64 weeks, and 80 weeks after randomisation using the following measures: QLQ-C30
Time frame: weeks 4, 16, 32, 48, 64 and 80
Health Related Quality of Life EORTC IL146
Health-related quality of life (HRQoL) is a secondary endpoint in this trial. HRQoL assessment aims at 1. establishing the patient-reported tolerability profile in each treatment arm. 2. comparing the patient-reported benefit between the two treatment arms. Assessments will be performed at 21 days before randomisation, 4 weeks, 16 weeks, 32 weeks, 48 weeks, 64 weeks, and 80 weeks after randomisation using the following measures: EORTC IL146.
Time frame: weeks 4, 16, 32, 48, 64 and 80
Health Related Quality of Life QLQ-BR42
Health-related quality of life (HRQoL) is a secondary endpoint in this trial. HRQoL assessment aims at 1. establishing the patient-reported tolerability profile in each treatment arm. 2. comparing the patient-reported benefit between the two treatment arms. Assessments will be performed at 21 days before randomisation, 4 weeks, 16 weeks, 32 weeks, 48 weeks, 64 weeks, and 80 weeksafter randomisation using the following measures:QLQ-BR42
Time frame: weeks 4, 16, 32, 48, 64 and 80
Showing the first 100 of 113 sites across 12 countries. Choose a country and city above to see the rest.
Plan to share: No
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Started Dec 2023 (actual). Primary completion is estimated for Nov 2032, 106 months after the start.
Of 328 non-industry phase 3 interventional studies under Breast Neoplasms, half reached primary completion within 79 months of starting (the median), counting those still running; a quarter within 50 and three quarters within 127. This study's planned 106 months is above that.
Counting every sponsor, half of 600 studies reached it within 59 months; a quarter within 36 and three quarters within 96.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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Studies of the drug tested here: Elacestrant
European Organisation for Research and Treatment of Cancer - EORTC →