Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not recruiting

Study on Giredestrant and Fulvestrant with CDK4/6 Inhibitor for Patients with ER+ HER2-Negative Advanced Breast Cancer Resistant to Endocrine Therapy

Verified siteRegistered drugNo placebo
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

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 estrogen receptor-positive, HER2-negative advanced breast cancer, a type of breast cancer that grows in response to the hormone estrogen and does not have an excess of the HER2 protein. The study will compare the effectiveness and safety of two medications: Giredestrant and Fulvestrant. Both medications will be used in combination with a CDK4/6 inhibitor, which is a type of drug that helps stop cancer cells from growing by targeting specific proteins involved in cell division.

The purpose of the study is to evaluate how well these treatments work in patients whose cancer has become resistant to previous hormone therapy. Participants will be randomly assigned to receive either Giredestrant or Fulvestrant, along with a CDK4/6 inhibitor. The study will monitor the participants over a period of time to assess the progression of the disease and any side effects experienced. The trial aims to provide insights into which treatment combination might be more effective in managing this type of breast cancer.

Throughout the study, participants will receive regular check-ups and assessments to track their health and the cancer's response to the treatment. The trial will also gather information on the overall survival of participants and any changes in their quality of life. This research is important for understanding better treatment options for patients with advanced breast cancer that is resistant to standard hormone therapies.

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, you will be randomly assigned to one of two groups. One group will receive the medication giredestrant combined with a CDK4/6 inhibitor, and the other group will receive fulvestrant combined with a CDK4/6 inhibitor.

  2. Step 2

    Medication administration

    If you are in the giredestrant group, you will take the medication orally in the form of a capsule. The dosage and frequency will be determined by the study team.

    If you are in the fulvestrant group, you will receive the medication as an injection into the muscle. The dosage and frequency will be determined by the study team.

    The CDK4/6 inhibitors used in the study include abemaciclib, ribociclib, and palbociclib. These are taken orally in the form of tablets. The specific medication, dosage, and frequency will be determined by the study team.

  3. Step 3

    Regular check-ups

    Throughout the study, you will have regular check-ups to monitor your health and the effects of the medication. These check-ups will include physical exams, blood tests, and imaging tests as needed.

    The study team will assess your condition and adjust your treatment plan if necessary.

  4. Step 4

    Progress monitoring

    Your progress will be monitored to evaluate the effectiveness of the treatment. This includes measuring progression-free survival, which is the time during which your disease does not worsen.

    Other aspects of your health and well-being will also be monitored, including any side effects you may experience.

  5. Step 5

    Completion of the study

    The study is expected to continue until December 2028. You will be informed about the completion of the study and any follow-up actions required.

    Upon completion, the study team will discuss the results with you and provide guidance on the next steps for your treatment.

Who can join the trial?

7 criteria

  • Must have **estrogen receptor (ER)-positive, HER2-negative advanced breast cancer**. This means the cancer grows in response to estrogen and does not have too much of a protein called HER2.
  • Must have a confirmed **ESR1 mutation** in a blood test called **ctDNA**. This is a specific change in the cancer's DNA.
  • Must have shown **resistance to prior standard adjuvant endocrine therapy (ET)**. This means the cancer came back during or after hormone therapy that lasted at least 12 months. If a treatment called **CDK4/6 inhibitor** was used, the cancer should have returned at least 12 months after stopping this treatment.
  • Must have **measurable disease** as defined by specific medical guidelines (RECIST v.1.1) or have cancer that is only in the bones and cannot be measured.
  • Must have an **Eastern Cooperative Oncology Group (ECOG) Performance Status** of 0 or 1. This is a scale that measures how well a person can perform daily activities. A score of 0 means fully active, and 1 means some symptoms but still able to do light work.
  • Must have **locally advanced or metastatic adenocarcinoma of the breast** that cannot be treated with the goal of curing it. The cancer must be confirmed as ER-positive and HER2-negative based on the most recent tumor biopsy or an archived sample.
  • Open to both **female and male** participants.

Who cannot join the trial?

5 criteria

  • Patients with other types of cancer that are not ER-positive or HER2-negative advanced breast cancer cannot participate. ER-positive means the cancer grows in response to the hormone estrogen. HER2-negative means the cancer does not have high levels of the protein HER2.
  • Patients who have not been diagnosed with an ESR1 mutation cannot participate. An ESR1 mutation is a change in the gene that can affect how the cancer responds to treatment.
  • Patients who are not within the specified age range for the study cannot participate. The age range is not specified here, but it is important to check if you meet the age criteria.
  • Patients who are not female or male cannot participate. The study is open to both genders.
  • Patients who are considered part of a vulnerable population may not be eligible. A vulnerable population includes groups who may have limited ability to give informed consent or are at higher risk of harm.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • Giredestrant

    is a medication being studied for its potential to treat advanced breast cancer. It works by targeting and blocking the estrogen receptor, which is a protein that can promote the growth of cancer cells. By blocking this receptor, giredestrant aims to slow down or stop the growth of cancer cells that rely on estrogen to grow. This medication is being tested to see if it can help patients who have already tried other hormone therapies but need additional treatment options.

  • Fulvestrant

    is another medication used in the study for treating advanced breast cancer. It also targets the estrogen receptor, but it works in a slightly different way compared to giredestrant. Fulvestrant binds to the estrogen receptor and causes it to break down, which reduces the number of receptors available for estrogen to bind to. This action helps to slow down the growth of cancer cells that depend on estrogen. Fulvestrant is often used when other hormone therapies are no longer effective.

  • CDK4/6 Inhibitor

    is a type of medication that is combined with either giredestrant or fulvestrant in this study. CDK4/6 inhibitors work by blocking certain proteins called cyclin-dependent kinases (CDK4 and CDK6) that are involved in cell division. By inhibiting these proteins, the medication helps to stop cancer cells from multiplying and spreading. This type of treatment is used to enhance the effectiveness of hormone therapies in patients with advanced breast cancer.

What is already known about the treatment

  • Giredestrant

    Giredestrant is administered orally and is currently being studied in clinical trials for its effectiveness in treating estrogen receptor-positive, HER2-negative advanced breast cancer, particularly in patients who have developed resistance to previous endocrine therapy. It works by selectively targeting and blocking estrogen receptors, which are proteins that can promote the growth of breast cancer cells. Giredestrant is classified as a selective estrogen receptor degrader (SERD), and its main therapeutic use is to slow down or stop the progression of certain types of breast cancer by interfering with the cancer cells' ability to use estrogen for growth.

  • Fulvestrant

    Fulvestrant is given as an injection into the muscle and is an established treatment for estrogen receptor-positive, HER2-negative advanced breast cancer, especially in cases where the cancer has become resistant to other endocrine therapies. It functions by binding to estrogen receptors and promoting their degradation, thereby reducing the cancer cells' ability to grow and multiply. Fulvestrant is also classified as a selective estrogen receptor degrader (SERD) and is used to manage breast cancer by blocking the effects of estrogen, which is necessary for the growth of some breast cancer cells.

Investigated diseases

Estrogen receptor-positive, HER2-negative advanced breast cancer – This type of breast cancer is characterized by cancer cells that have receptors for the hormone estrogen, which can promote the growth of the cancer. It is also negative for the human epidermal growth factor receptor 2 (HER2), meaning it does not have an excess of the HER2 protein on its surface. The disease typically progresses as the cancer cells continue to grow and spread, often to other parts of the body. Over time, the cancer may become more aggressive and resistant to hormone therapies. The progression can lead to symptoms such as lumps in the breast, changes in breast shape, and, if it spreads, symptoms related to the affected organs. The disease is monitored for changes in size and spread to assess its progression.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2022-502980-39-00Protocol codeCO44657Estimated enrolment1 050 patientsSponsorF. Hoffmann-La Roche AG

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.