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)

Lilly

Status and phase: Not yet enrolling; Phase 2

Conditions: Breast Neoplasm Female

Treatments: Drug: Imlunestrant + Goserelin; Drug: Tamoxifen 20 mg; Drug: Imlunestrant; Device: pre-filled syringe

Study type: Interventional

Funder types: Industry

Identifiers

NCT07287098

2025-523258-15-00 (EU Trial (CTIS) Number)

J2J-MC-JZLL (Other Identifier)

27511

Details and patient eligibility

About

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.

Enrollment: 600 estimated patients

Sex: Female

Ages: 18+ years old

Volunteers: No Healthy Volunteers

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.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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600 participants in 3 patient groups

Imlunestrant

Active Comparator group

Description:

Imlunestrant will be given orally

Treatment:

Drug: Imlunestrant

Imlunestrant + Goserelin

Active Comparator group

Description:

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

Treatment:

Device: pre-filled syringe

Drug: Imlunestrant + Goserelin

Tamoxifen

Active Comparator group

Description:

Tamoxifen will be given orally

Treatment:

Drug: Tamoxifen 20 mg