NCT07287098 · Eli Lilly and Company
A Study of Imlunestrant (LY3484356) in Premenopausal Women With Estrogen Receptor-Positive (ER+) Human Epidermal Growth Factor Receptor 2 Negative (HER2-) Early Breast Cancer
(preEMBER)
What this study is about
This study will include two groups of patients: group of participants 1 and group of participants 2. group of participants 1: will help researchers learn how a medicine called imlunestrant (LY3484356) affects a specific type of breast cancer. Some patients will take both imlunestrant and another treatment to suppress their ovarian function. Some will take it without ovarian suppression.
View original scientific description
This study will include two groups of patients: Cohort 1 and Cohort 2. Cohort 1: will help researchers learn how a medicine called imlunestrant (LY3484356) affects a specific type of breast cancer. Some patients will take both imlunestrant and another treatment to suppress their ovarian function. Some will take it without ovarian suppression. Researchers will compare the effects in breast cancer cells to those of another medicine called tamoxifen. All patients in this group will be premenopausal women who have a type of early breast cancer called estrogen receptor-positive, HER2-negative. The treatment in this group will last for up to 29 days. Cohort 2: will help researchers understand how imlunestrant affects the ovaries when it is taken without ovarian suppression. Researchers will compare the effects to those of another medicine called tamoxifen. This group will also include premenopausal women with the same type of breast cancer. The treatment in this group will last for up to 6 months.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Have histologically confirmed Stage I to III Estrogen Receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) invasive breast carcinoma with Ki-67 at least 10%
- Be willing and able to provide pre- and on-treatment tumor samples.
- Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
- Be able to swallow capsules or tablets.
- Be premenopausal women.
- If of childbearing potential must use 1 highly effective method of non-hormonal contraception while receiving study treatment and for the duration specified in protocol.
- Have adequate organ function. Cohort 2:
- Have a diagnosis of ER+, HER2- early-stage, resected, invasive breast cancer without evidence of distant metastasis
- Have undergone definitive loco-regional therapy.
- Have received at least 4.5 years of any adjuvant endocrine therapy (ET), or at least 2 years of adjuvant ET with no additional ovarian suppression planned.
- Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
- Be able to swallow capsules or tablets.
- Be premenopausal women
- If of childbearing potential must use 1 highly effective method of non-hormonal contraception while receiving study treatment and for the duration specified in protocol.
- Have adequate organ function.
Exclusion criteria
- Have bilateral invasive metastatic, occult primary, or inflammatory breast cancer.
- Have had prior bilateral oophorectomy or ovarian ablation.
- Have a serious medical condition
- Had major surgery within 28 days prior to randomization.
- Have a history of other cancer (except non melanoma skin cancer, Stage I uterine cancer, or carcinoma in situ of the cervix or other in situ cancer), unless in complete remission with no therapy for a minimum of 1 year.
- Plan to receive concurrent neoadjuvant therapy with any other non-protocol anticancer therapy.
- Have had any prior therapy for an invasive or non-invasive breast cancer.
- Have had prior radiotherapy to the ipsilateral chest wall for any malignancy.
- Have received prior anti-estrogen therapy, including for osteoporosis or prevention of breast cancer.
- Have had prior treatment with any Gonadotropin-releasing hormone (GnRH) agonist within 12 months prior to randomization.
- Receiving current exogenous reproductive hormone therapy Cohort 2:
- Have ovarian cyst(s) greater than (\>) 1 centimeter (cm) at screening.
- Have metastatic occult primary, or inflammatory breast cancer.
- Have had prior bilateral oophorectomy or ovarian ablation.
- Have a serious medical condition
- Had major surgery within 28 days prior to randomization.
- Have a history of other cancer (except non melanoma skin cancer or carcinoma in situ of the cervix or other in situ cancer), unless in complete remission with no therapy for a minimum of 1 year.
- Completed or discontinued prior adjuvant ET \>6 months prior to screening.
- Have received prior therapy with any selective estrogen receptor degrader (SERD).
- Receiving current exogenous reproductive hormone therapy.
Where
- Birmingham, Alabama
- Chandler, Arizona
- Los Angeles, California
- Santa Monica, California
- Greeley, Colorado
- Loveland, Colorado
- Altamonte Springs, Florida
- Atlanta, Georgia
- Indianapolis, Indiana
- Lexington, Kentucky
- Boston, Massachusetts
- St Louis, Missouri
And 14 more locations — see the full list below.
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 7, 2026 · Source of record for eligibility and locations