A Study of Imlunestrant (LY3484356) in Premenopausal Women With Estrogen Receptor-Positive (ER+) Human Epidermal Growth Factor Receptor 2 Negative (HER2-) Early Breast Cancer
Recruiting now · Phase 2
Conditions studied: Breast Neoplasms
In brief
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.
Key facts
- Study ID
- NCT07287098
- Run by
- Eli Lilly and Company
- People needed
- 600
- Starts
- 2026-05-13
- Expected to finish
- 2029-12-01
- Last updated by the study team
- 2026-08-06
Who can join
Age: 18 and older. Sex: female. Healthy volunteers: not accepted.
You may qualify if…
- Cohort 1:
- 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.
You may not qualify if…
- Cohort 1:
- 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 it is running
- Indiana University Melvin and Bren Simon Cancer Center — Indianapolis, Indiana, United States (enrolling)
- University of Texas MD Anderson Cancer Center — Houston, Texas, United States (enrolling)
- Oncology Consultants P.A. — Houston, Texas, United States (enrolling)
- Mayo Clinic in Arizona - Phoenix — Phoenix, Arizona, United States
- Banner MD Anderson Cancer Center at North Colorado Medical Center — Greeley, Colorado, United States
- Banner MD Anderson Cancer Center at McKee Medical Center — Loveland, Colorado, United States
- UCLA Hematology/Oncology - Parkside — Santa Monica, California, United States
- Winship Cancer Institute — Atlanta, Georgia, United States
- University of North Carolina Medical Center — Chapel Hill, North Carolina, United States
- University of Kentucky Chandler Medical Center — Lexington, Kentucky, United States
- Massachusetts General Hospital — Boston, Massachusetts, United States
- Dana-Farber Cancer Institute — Boston, Massachusetts, United States
- Mayo Clinic in Rochester, Minnesota — Rochester, Minnesota, United States
- Washington University School of Medicine — St Louis, Missouri, United States
- Memorial Sloan Kettering Cancer Center — New York, New York, United States
- New York Oncology Hematology, P.C. — Albany, New York, United States
- Wilmot Cancer Institute — Rochester, New York, United States
- New York Cancer and Blood Specialists — Shirley, New York, United States
- AdventHealth Altamonte Springs — Altamonte Springs, Florida, United States
- Cleveland Clinic — Cleveland, Ohio, United States
- Providence Portland Medical Center — Portland, Oregon, United States
- Providence St. Vincent Medical Center — Portland, Oregon, United States
- Tennessee Oncology — Nashville, Tennessee, United States
- USC/Norris Comprehensive Cancer Center — Los Angeles, California, United States
- Ironwood Cancer & Research Centers — Chandler, Arizona, United States
Full record on ClinicalTrials.gov
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