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Using elacestrant to treat ER+/HER2- breast cancer patients with ctDNA relapse

Elacestrant for Treating ER+/HER2- Breast Cancer Patients With ctDNA Relapse

PHASE3 · European Organisation for Research and Treatment of Cancer - EORTC · NCT05512364

This study is testing if a new drug called elacestrant can help women with ER-positive, HER2-negative breast cancer who have had a relapse, compared to their usual treatment.

Quick facts

PhasePHASE3
Study typeInterventional
Enrollment220 (estimated)
Ages18 Years and up
SexAll
SponsorEuropean Organisation for Research and Treatment of Cancer - EORTC (network)
Drugs / interventionschemotherapy
Locations94 sites (Anderlecht and 93 other locations)
Trial IDNCT05512364 on ClinicalTrials.gov

What this trial studies

This international, multi-center, randomized, open-label phase III trial compares the efficacy of elacestrant against standard endocrine therapy in patients with ER-positive, HER2-negative breast cancer who have experienced a relapse indicated by circulating tumor DNA (ctDNA). Patients will undergo ctDNA screening to identify those who are ctDNA-positive and have no distant metastasis. Eligible participants will be randomly assigned to receive either elacestrant or their current endocrine treatment. The trial aims to evaluate the superiority of elacestrant in improving patient outcomes.

Who should consider this trial

Good fit: Ideal candidates include adults with histologically confirmed ER-positive, HER2-negative breast cancer who are ctDNA-positive and have completed prior treatments.

Not a fit: Patients with distant metastasis or those who do not meet the ctDNA positivity criteria may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a more effective option for patients with ER+/HER2- breast cancer who are at high risk of recurrence.

How similar studies have performed: Other studies have shown promise in using ctDNA as a biomarker for treatment decisions in breast cancer, suggesting that this approach may be effective.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

1. ctDNA screening phase:

   Main inclusion criteria:

   • Female (both pre- and postmenopausal) or male patients with histologically confirmed ER positive (regardless of PR),

   HER2 negative breast cancer, according to local pathologist:
   * ER-positive defined as ≥ 10% of cells staining positive for ER or Allred proportion score ≥3
   * HER2-negative defined as a score of 0, 1+ by immunohistochemistry (IHC) or a negative in situ hybridization (ISH) based on single-probe average HER2 copy number, as per American Society of Clinical Oncology guidelines
   * Intermediate to high risk of recurrence after definitive treatment for early breast cancer, defined as:

   FOR PATIENTS TREATED WITH PRIMARY SURGERY:
   * Any patient with ≥ 4 positive axillary lymph nodes (stage pN2-3).
   * 1-3 positive axillary lymph nodes (stage pN1) and either:
   * Tumour size ≥ 5 cm or/and
   * Histologic grade 3 or/and
   * Ki67≥20% or/and
   * High genomic risk defined as Oncotype Dx Recurrence Score \>=26, Mammaprint high risk, Prosigna score \>40 or EPclin risk score \>=4.0.
   * Negative axillary lymph nodes (stage pN0) and tumour size ≥ 5 cm and either
   * Histologic grade 3 a or/and
   * Ki67≥20% and/or
   * High genomic risk defined as Oncotype Dx Recurrence Score \>=26, Mammaprint high risk, Prosigna score \>60 or EPclin risk score \>=4.0. FOR PATIENTS TREATED WITH NEOADJUVANT

   SYSTEMIC TREATMENT FOLLOWED BY SURGERY:
   * Patient may have received neoadjuvant endocrine therapy or neoadjuvant chemotherapy provided that:
   * The initial tumour and/or the tumour after surgery meet the criteria above defined for patients treated with primary surgery or the initial tumour was staged as cT4anyN and
   * There is no pathological complete response, defined as no invasive disease in the breast and axilla (ypT0/is ypN0).
   * Age ≥18 years
   * Patients must have received at least 1 year and up to 7.5 years of ET and planned to continue adjuvant ET during ctDNA screening phase
   * Previous adjuvant CDK4/6 inhibitor or PARP-inhibitor treatment is allowed provided it is completed
   * Invasive multicentric / multifocal disease is allowed provided that all the tested foci are ER+ HER2-. A sample from the highest-risk one, according to the investigator decision based on the size and grade, should be sent to Natera to build the patient ctDNA assay.
   * Available tumour sample from resected or biopsied tissue, with a tumour content of ≥20% (30% preferred) either before or after macro dissection (if performed) and a cell viability of a minimum 100 cells.
   * Core Needle Biopsies (CNB): recommended minimum of four (4) cores per block
   * Fine Needle Aspirates (FNA) are not accepted
   * The following sample types are acceptable:
   * 6-10 unstained slides (charged and unbaked) of 10μm each (or 12-19 unstained slides at 5 μm each), PLUS one contiguous H\&E slide. Minimum total tissue thickness must be 60μm OR
   * FFPE tissue block with 25mm2 minimum surface area
   * Written informed consent must be given according to ICH/GCP, and national/local regulations.

   Main exclusion criteria:
   * Suspected recurrent disease or known conflicts with the inclusion and exclusion criteria for the randomised trial
   * Prior treatment with any SERD or investigational ER antagonist
   * Previous history of invasive breast cancer
   * Previous history of any other malignancy within the last 5 years, except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ.
   * Previous history of bone marrow and/or organ transplant
   * Bilateral breast cancer
   * Participation in another clinical study, with the exception of the SURVIVE study and observational (non-interventional) and non-drug intervention clinical studies. Note: patients participating in interventional studies may participate once they enter the follow-up period of the study
   * Blood transfusion within 3 months prior to registration or during the screening.
2. Randomised trial:

Main inclusion criteria:

* ctDNA positive according to the Signatera ctDNA assay (main study ctDNA test) or other ctDNA assay approved for diagnostic purposes.
* Patients must meet the eligibility criteria for the screening phase, with the exception of the tissue sample requirements.
* Patients must receive adjuvant ET at the time of the ctDNA positive test
* Absence of locoregional and/or metastatic disease and/or new malignancy, as investigated by:
* Mammogram (unilateral in case of mastectomy; not required in patients having undergone bilateral mastectomy) NOTE: if local investigator plans to use MRIs instead of mammograms during the study, MRI will have to be performed at baseline.
* CT thorax and abdomen/pelvis with IV contrast. In case of any contra-indications (medical or regulatory): CT thorax without contrast + MRI abdomen/pelvis.
* Technetium-99m bone scintigraphy
* Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1
* Adequate organ function
* Women of childbearing potential (WOCBP) must have a negative highly sensitive serum or urine pregnancy test within 7 days prior to randomisation.

Main exclusion criteria:

* Any unresolved toxic effect of prior therapies or surgical procedures of Grade ≥ 2 according to Common Terminology Criteria of Adverse Events (CTCAE) v5.0, with the exception of alopecia, peripheral neuropathy and other toxicities not considered a safety risk for the participant at investigator's discretion
* Unable or unwilling to avoid over-the-counter medications, dietary/herbal supplements, and/or foods that are moderate/strong inhibitors or inducers of CYP3A4 activity
* Known difficulty in tolerating oral medications or conditions which would impair absorption of oral medications
* Any of the following cardiovascular disorders within 3 months before enrolment:
* myocardial infarction
* stroke
* severe/unstable angina
* symptomatic cardiac arrhythmia
* prolonged QTcF ≥ Grade 3 (i.e., \> 500 msec)
* heart failure ≥ Class III as defined by the New York Heart Association (NYHA) guidelines
* Child-Pugh Score greater than Class A
* Uncontrolled significant active infections (≥ grade 3 according to CTCAE version 5), including active hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency Virus (HIV)
* Coagulopathy or any history of coagulopathy within the past 6 months, including history of deep vein thrombosis or pulmonary embolism

Where this trial is running

Anderlecht and 93 other locations

+44 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: ER-positive Breast Cancer, HER2-negative Breast Cancer, Stage IIB Breast Cancer, Stage III Breast Cancer

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.