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

What Was Tested

In this phase 2 trial, researchers set out to test Goserelin.

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.

It had five arms (groups): Cohort 1 Arm A (experimental), Cohort 1 Arm B - Imlunestrant + Goserelin (experimental), Cohort 1 Arm C - Tamoxifen (active comparator), Cohort 2 Arm A - Imlunestrant (experimental) and Cohort 2 Arm B - Tamoxifen (active comparator).

Imlunestrant will be given orally.

Imlunestrant will be given orally and goserelin will be given subcutaneously (SC).

Tamoxifen will be given orally.

The registry classes the interventions as drug.

Who Took Part

Enrollment: 600 planned participants were the target.

It was open to women only aged from 18 years with no upper age limit.

Healthy volunteers were not accepted; participants needed the condition being studied.

Examples of who could join: 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. Have adequate organ function.

The full record lists 15 inclusion and 20 exclusion criteria; among the exclusions: have bilateral invasive metastatic, occult primary, or inflammatory breast cancer; have had prior bilateral oophorectomy or ovarian ablation; have a serious medical condition.

How the Study Was Run

It was run as a randomized, parallel-group and open-label study.

Because people in this Goserelin study were split into groups at random, differences between the groups are less likely to reflect who happened to join each one.

Groups ran in parallel: each of the participants stayed in one arm throughout.

Nothing was hidden in this open-label Goserelin study: the participants and staff both knew the treatment.

It started in 2026-05-13 with completion listed for 2029-01.

It ran at 87 sites in United States (34), Germany (30), Italy (6), Taiwan (6), France (5) and Belgium (3).

Its stated primary purpose is treatment.

What Was Measured

Researchers chose this as the main measure: Change from Baseline in Antigen Kiel (Ki-67) Expression (time frame: Baseline, Day 29). Rate of Symptomatic Ovarian Cysts (time frame: Up to Day 180).

It also tracked 3 secondary outcomes, for example Change from Baseline in Estrogen Receptor (ER) Expression, Change from Baseline in Progesterone Receptor (PR) Expression and Rate of Complex Ovarian Cysts.

What This Means in Plain Language

Put simply, this is a phase 2, randomized trial of Goserelin in 600 people.

With 600 participants it is a large trial for this field.

It is still recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Goserelin compound page, all human trials.