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

NCT ID: NCT07287098

Last Updated: 2026-01-15

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

NOT_YET_RECRUITING

Clinical Phase

PHASE2

Total Enrollment

600 participants

Study Classification

INTERVENTIONAL

Study Start Date

2026-01-31

Study Completion Date

2029-12-31

Brief Summary

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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. 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.

Detailed Description

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Conditions

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Breast Neoplasm Female

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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Imlunestrant

Imlunestrant will be given orally

Group Type ACTIVE_COMPARATOR

Imlunestrant

Intervention Type DRUG

Given Orally

Imlunestrant + Goserelin

Imlunestrant will be given orally and Goserelin will be given Subcutaneously (SC)

Group Type ACTIVE_COMPARATOR

Imlunestrant + Goserelin

Intervention Type DRUG

Imlunestrant will be given orally and Goserelin will be administered SC

pre-filled syringe

Intervention Type DEVICE

SC

Tamoxifen

Tamoxifen will be given orally

Group Type ACTIVE_COMPARATOR

Tamoxifen 20 mg

Intervention Type DRUG

Given Orally

Interventions

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Imlunestrant

Given Orally

Intervention Type DRUG

Imlunestrant + Goserelin

Imlunestrant will be given orally and Goserelin will be administered SC

Intervention Type DRUG

Tamoxifen 20 mg

Given Orally

Intervention Type DRUG

pre-filled syringe

SC

Intervention Type DEVICE

Other Intervention Names

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LY3484356 LY3484356

Eligibility Criteria

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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 \>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 5 years of any adjuvant ET.
* Be able to swallow capsules or tablets.
* Be premenopausal women
* Have adequate organ function.
* 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.

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
* 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 presence of ovarian cysts 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.
* 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.
Minimum Eligible Age

18 Years

Eligible Sex

FEMALE

Accepts Healthy Volunteers

No

Sponsors

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Eli Lilly and Company

INDUSTRY

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Call 1-877-CTLILLY (1-877-285-4559) or 1-317-615-4559 Mon - Fri 9AM - 5PM Eastern time (UTC/GMT - 5 hours, EST)

Role: STUDY_DIRECTOR

Eli Lilly and Company

Locations

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Indiana University Health University Hospital

Indianapolis, Indiana, United States

Site Status

Oncology Consultants P.A.

Houston, Texas, United States

Site Status

Cliniques universitaires Saint-Luc

Brussels, , Belgium

Site Status

Antwerp University Hospital

Edegem, , Belgium

Site Status

UZ Leuven

Leuven, , Belgium

Site Status

CHRU de Brest

Brest, , France

Site Status

Centre de Cancérologie du Grand Montpellier

Montpellier, , France

Site Status

Hôpital Privé Des Côtes d'Armor

Plérin, , France

Site Status

Universitaetsklinikum Erlangen

Erlangen, , Germany

Site Status

Ente Ospedaliero Ospedali Galliera

Genova, , Italy

Site Status

Humanitas

Milan, , Italy

Site Status

Humanitas Istituto Clinico Catanese

Misterbianco, , Italy

Site Status

Nuovo Ospedale di Prato-S.Stefano

Prato, , Italy

Site Status

Fondazione Policlinico Universitario Agostino Gemelli

Roma, , Italy

Site Status

Countries

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United States Belgium France Germany Italy

Central Contacts

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There may be multiple sites in this clinical trial 1-877-CTLILLY (1-877-285-4559)

Role: CONTACT

1-317-615-4559

Facility Contacts

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Role: primary

713-600-0900

Role: primary

3227645435

Role: primary

003216345129

Role: primary

467926155

Role: primary

+4991318533572

Role: primary

0105634501

Role: primary

0039028224 4089

Role: primary

+39 0574 802531

Role: primary

00390630157337

Related Links

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Other Identifiers

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2025-523258-15-00

Identifier Type: CTIS

Identifier Source: secondary_id

J2J-MC-JZLL

Identifier Type: OTHER

Identifier Source: secondary_id

27511

Identifier Type: -

Identifier Source: org_study_id

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