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Study of Imlunestrant, Fulvestrant, Exemestane, and Abemaciclib for Patients with Advanced Estrogen Receptor Positive, HER2 Negative Breast Cancer

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying treatments for breast cancer, specifically in patients with a type of breast cancer that is estrogen receptor positive (ER+) and HER2 negative (HER2-). These patients have cancer that is either locally advanced or has spread to other parts of the body. The study involves several treatments: a new drug called imlunestrant, a combination of imlunestrant with another drug called abemaciclib, and standard treatments chosen by the study doctor, which may include either fulvestrant or exemestane.

The purpose of the study is to compare how well these treatments work in controlling the cancer. Participants will be randomly assigned to one of the treatment groups. Some will receive imlunestrant alone, some will receive the standard treatment chosen by the doctor, and others will receive a combination of imlunestrant and abemaciclib. The study will monitor the progress of the cancer and how it responds to the treatment over time.

Throughout the study, participants will take the medications either as tablets or as injections, depending on the treatment group they are in. The study aims to provide valuable information on the effectiveness of these treatments in managing advanced breast cancer, particularly in patients who have already been treated with drugs that block estrogen production.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, the patient is assigned to one of three groups. Each group receives a different treatment regimen for advanced breast cancer that is positive for estrogen receptors and negative for HER2.

    The study involves comparing the effectiveness of different treatments in patients who have previously been treated with hormone therapy.

  2. Step 2

    Treatment group assignment

    The patient is randomly assigned to one of the following treatment groups:

    Arm A: Receives imlunestrant, a medication taken orally.

    Arm B: Receives the investigator's choice of endocrine therapy, which could be either fulvestrant (administered as an injection) or exemestane (taken orally).

    Arm C: Receives a combination of imlunestrant and abemaciclib, both taken orally.

  3. Step 3

    Medication administration

    For patients in Arm A, imlunestrant is taken orally as prescribed by the study protocol.

    For patients in Arm B, if fulvestrant is chosen, it is administered as an injection. If exemestane is chosen, it is taken orally.

    For patients in Arm C, both imlunestrant and abemaciclib are taken orally according to the study's dosing schedule.

  4. Step 4

    Monitoring and assessments

    Throughout the study, the patient's health and response to treatment are closely monitored.

    Regular assessments are conducted to evaluate the progression of the disease and the effectiveness of the treatment.

  5. Step 5

    Study duration

    The study is expected to continue until February 15, 2027.

    The duration of participation for each patient may vary depending on individual response to treatment and other factors.

Who can join the trial?

6 criteria

  • Participants must have **HR+ HER2- breast cancer**. This means the cancer grows in response to hormones but does not have a protein called HER2.
  • Participants must have cancer that is **advanced** or has **spread to another part of the body**. This means the cancer is in a later stage or has moved from its original location.
  • Participants must have already received a drug that **blocks the production of estrogen**. Estrogen is a hormone that can help some breast cancers grow.
  • Participants must have **adequate body organ function**. This means the organs in the body, like the liver and kidneys, are working well enough.
  • Participants must be in **fair to good health**. This means they should generally feel well and not have serious health problems.
  • Participants must be able to **swallow capsules/tablets**. This means they can take medicine by mouth in pill form.

Who cannot join the trial?

5 criteria

  • Patients who have a different type of cancer other than breast cancer cannot participate.
  • Patients who are not within the specified age range for the study cannot participate.
  • Patients who are not part of the specified clinical trial groups cannot participate.
  • Patients who are not female or male, as specified by the study, cannot participate.
  • Patients who are considered part of a vulnerable population, which means they might need special protection or care, cannot participate.
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Investigated drugs

  • Imlunestrant

    is a medication being studied for its potential to treat certain types of breast cancer. It works by targeting and blocking estrogen receptors, which can help slow down or stop the growth of cancer cells that rely on estrogen to grow.

  • Fulvestrant

    is a type of endocrine therapy used in the treatment of breast cancer. It works by blocking and degrading estrogen receptors, which can help prevent the cancer cells from receiving the signals they need to grow.

  • Exemestane

    is another form of endocrine therapy used to treat breast cancer. It functions by reducing the amount of estrogen produced in the body, which can help slow the growth of cancer cells that depend on estrogen.

  • Abemaciclib

    is a medication used in combination with other therapies to treat breast cancer. It works by inhibiting certain proteins that are involved in cell division, thereby slowing down the growth and spread of cancer cells.

What is already known about the treatment

  • Imlunestrant

    Imlunestrant is administered orally and is currently being studied in clinical trials for its effectiveness in treating estrogen receptor-positive, HER2-negative locally advanced or metastatic breast cancer. It is not yet widely available in medical practice as it is still under investigation. The medication works by blocking estrogen receptors, which can slow down or stop the growth of cancer cells that rely on estrogen. Imlunestrant is classified as a selective estrogen receptor degrader (SERD).

  • Abemaciclib

    Abemaciclib is taken orally and is approved for use in treating certain types of breast cancer, including hormone receptor-positive, HER2-negative breast cancer. It is often used in combination with other therapies. Abemaciclib works by inhibiting proteins called cyclin-dependent kinases 4 and 6 (CDK4/6), which are involved in cell division, thereby slowing the growth of cancer cells. It belongs to the class of medications known as CDK4/6 inhibitors.

Investigated diseases

Breast Cancer – Breast cancer is a disease where cells in the breast grow uncontrollably. It typically begins in the ducts or lobules of the breast. As the disease progresses, it can spread to nearby tissues and lymph nodes. The growth of cancer cells can form a lump or mass in the breast. Over time, the cancer may metastasize to other parts of the body. The progression and symptoms can vary depending on the type and stage of the cancer.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-506786-63-00Protocol codeJ2J-OX-JZLCEstimated enrolment874 patientsSponsorEli Lilly & Co.

sourced from the EU Clinical Trials Register and site verification

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