RECRUITING Phase 2 ClinicalTrials.gov

A Study of Imlunestrant (LY3484356) in Premenopausal Women With Estrogen Receptor-Positive (ER+) Human Epidermal Growth Factor Receptor 2 Negative (HER2-) Early Breast Cancer

Sponsor: Eli Lilly and Company • ClinicalTrials.gov ID: NCT07287098

Registry updated: 2026-10-08

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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.

Interventions

Imlunestrant (Drug)
Given orally
Goserelin (Drug)
Given SC
Tamoxifen 20 mg (Drug)
Given orally

Eligibility criteria

Inclusion Criteria: 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. Exclusion Criteria: 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.

Conditions

Breast Neoplasms

Locations

University of Alabama at Birmingham — Birmingham, Alabama, United States
Ironwood Cancer & Research Centers — Chandler, Arizona, United States
Mayo Clinic in Arizona - Phoenix — Phoenix, Arizona, United States
City of Hope — Duarte, California, United States
City of Hope Orange County Lennar Foundation Cancer Center — Irvine, California, United States
USC/Norris Comprehensive Cancer Center — Los Angeles, California, United States
UCLA Hematology/Oncology - Parkside — Santa Monica, California, 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
AdventHealth Altamonte Springs — Altamonte Springs, Florida, United States
Mayo Clinic in Florida — Jacksonville, Florida, United States
Winship Cancer Institute — Atlanta, Georgia, United States
Indiana University Melvin and Bren Simon Cancer Center — Indianapolis, Indiana, 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
Wilmot Cancer Institute — Rochester, New York, United States
New York Cancer and Blood Specialists — Shirley, New York, United States
University of North Carolina Medical Center — Chapel Hill, North Carolina, 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
University of Texas MD Anderson Cancer Center — Houston, Texas, United States
Houston Methodist Hospital — Houston, Texas, United States
Oncology Consultants P.A. — Houston, Texas, United States
Baylor Scott & White Medical Center - Round Rock — Round Rock, Texas, United States
Huntsman Cancer Institute — Salt Lake City, Utah, United States
The University of Vermont Medical Center Inc. — Burlington, Vermont, United States
University of Virginia Health System — Charlottesville, Virginia, United States
Inova Schar Cancer Institute — Fairfax, Virginia, United States
Cliniques universitaires Saint-Luc — Brussels, Belgium
Antwerp University Hospital — Edegem, Belgium
UZ Leuven — Leuven, Belgium
CHRU de Brest — Brest, France
Centre de Cancérologie du Grand Montpellier — Montpellier, France
Hôpital Privé Des Côtes d'Armor — Plérin, France
Institut Curie - site Saint-Cloud — Saint-Cloud, France
Gustave Roussy — Villejuif, France
Evangelisches Krankenhaus Bergisch Gladbach — Bergisch Gladbach, Germany
Praxis am Volkspark — Berlin, Germany
Onkologische Schwerpunktpraxis Bielefeld — Bielefeld, Germany
Augusta-Kranken-Anstalt — Bochum, Germany
Gynaekologisches Zentrum Bonn — Bonn, Germany
Marienhospital Bottrop — Bottrop, Germany
Onkologisch - Hämatologische Schwerpunktpraxis — Bremen, Germany
Medizinische Universität Lausitz- Carl Thiem — Cottbus, Germany
Gemeinschaftspraxis Hämatologie - Onkologie Freiberg-Richter, Jacobasch, Illmer, Wolf — Dresden, Germany
Universitaetsklinikum Erlangen — Erlangen, Germany
Kliniken Essen-Mitte, Evangelische Huyssens-Stiftung — Essen, Germany
Universitaetsklinikum Essen — Essen, Germany
Agaplesion Markus Krankenhaus — Frankfurt, Germany
Mammazentrum HH - Krankenhaus Jerusalem — Hamburg, Germany
Praxisklinik Harburg — Hamburg, Germany
Frauenärzte am Bahnhofsplatz — Hildesheim, Germany
Universitaetsklinikum Schleswig-Holstein Campus Kiel — Kiel, Germany
Evangelisches Krankenhaus Bethesda Mönchengladbach — Mönchengladbach, Germany
Klinikum der Ludwig-Maximilians-Universitaet Muenchen — München, Germany
Rotkreuzklinikum München gemeinnützige GmbH — München, Germany
Ruppiner Kliniken — Neuruppin, Germany
Klinikum Ernst von Bergmann — Potsdam, Germany
MVZ für Hämatologie und Onkologie Ravensburg GmbH - Studienzentrum — Ravensburg, Germany
Klinikum Mutterhaus der Borromäerinnen — Trier, Germany
Universitaetsklinikum Tuebingen — Tübingen, Germany
Universitaetsklinikum Ulm — Ulm, Germany
Klinik Weinheim — Weinheim, Germany
Helios HSK Wiesbaden — Wiesbaden, Germany
Marien Hospital Witten — Witten, Germany
HELIOS Klinikum Wuppertal — Wuppertal, Germany
St. Vincent's University Hospital — Dublin, Ireland
St. James's Hospital — Dublin, Ireland
Galway University Hospital — Galway, Ireland
Ente Ospedaliero Ospedali Galliera — Genova, Italy
Humanitas — Milan, Italy
Istituto Europeo di Oncologia IRCCS — Milan, Italy
Humanitas Istituto Clinico Catanese — Misterbianco, Italy
Nuovo Ospedale di Prato-S.Stefano — Prato, Italy
Fondazione Policlinico Universitario Agostino Gemelli — Roma, Italy
Kaohsiung Medical University Chung-Ho Memorial Hospital — Kaohsiung City, Taiwan
China Medical University Hospital — Taichung, Taiwan
Taichung Veterans General Hospital — Taichung, Taiwan
National Cheng Kung University Hospital — Tainan, Taiwan
Mackay Memorial Hospital — Taipei, Taiwan
Chang Gung Medical Foundation-Linkou Branch — Taoyuan, Taiwan

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