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Study of Giredestrant Combined with Pertuzumab-Trastuzumab (Phesgo) for Patients with Previously Untreated HER2-Positive, Estrogen Receptor-Positive Locally Advanced or Metastatic 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 studying a treatment for HER2-positive, estrogen receptor-positive locally-advanced or metastatic breast cancer that has not been previously treated. HER2-positive means the cancer cells have higher than normal levels of a protein called human epidermal growth factor receptor 2, which promotes cancer cell growth. Estrogen receptor-positive means the cancer cells grow in response to the hormone estrogen. Locally-advanced cancer has spread to nearby tissues or lymph nodes, while metastatic cancer has spread to distant parts of the body. The study will use several medications including Phesgo, which is a combination of pertuzumab and trastuzumab given as an injection under the skin, RO7197597 (also called giredestrant) given as a capsule by mouth, and chemotherapy drugs called paclitaxel or docetaxel given through infusion into a vein. Additional medications may include hormone therapies such as letrozole, anastrozole, exemestane, or tamoxifen, and gonadotropin releasing hormone analogues.

The purpose of this study is to compare the effectiveness and safety of giredestrant combined with Phesgo versus Phesgo alone. The study will first give all participants an induction treatment phase consisting of Phesgo combined with a taxane chemotherapy. After this initial treatment phase, participants will be randomly assigned to receive either Phesgo combined with giredestrant or Phesgo alone. The study will measure how long participants live without their cancer getting worse, as well as overall survival time, how well the cancer responds to treatment, and the duration of that response.

During the study, participants will be monitored for side effects and changes in their health status. The study will also assess quality of life and how well participants are able to function in their daily activities using standardized questionnaires. Blood tests and other clinical assessments will be performed regularly to monitor safety throughout the treatment period.

The research process

The trial runs in 6 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, participants will be randomly assigned to one of two groups. This process is called randomization and ensures that each participant has an equal chance of receiving any of the treatments being tested.

  2. Step 2

    Induction therapy

    Participants will begin with an initial treatment phase known as induction therapy. During this phase, participants will receive a combination of medications called Phesgo and a type of chemotherapy known as a taxane. Phesgo is administered as an injection under the skin, while the taxane is given through an infusion into a vein. The duration and frequency of this phase will be determined by the study team.

  3. Step 3

    Treatment phase

    After completing the induction therapy, participants will enter the main treatment phase. In this phase, participants will receive either a combination of Phesgo and a new medication called giredestrant or Phesgo alone. Giredestrant is taken orally as a capsule. The specific dosage and frequency will be provided by the study team.

  4. Step 4

    Monitoring and assessments

    Throughout the trial, participants will undergo regular monitoring and assessments to evaluate the effectiveness and safety of the treatment. This includes physical examinations, blood tests, and imaging studies such as scans. Participants will also be asked to complete questionnaires about their health and quality of life.

  5. Step 5

    End of treatment

    The treatment phase will continue until the study team determines that it is appropriate to stop, based on the participant's response to the treatment and overall health. Participants will be informed about the next steps and any follow-up care that may be needed.

  6. Step 6

    Follow-up

    After the treatment phase, participants will enter a follow-up period. During this time, the study team will continue to monitor the participant's health and any long-term effects of the treatment. Follow-up visits and assessments will be scheduled as needed.

Who can join the trial?

6 criteria

  • Participants can be females or males who are 18 years or older.
  • Must have a confirmed diagnosis of breast cancer that is either metastatic (spread to other parts of the body) or locally-advanced (grown into nearby areas) and cannot be removed by surgery.
  • Must have at least one measurable tumor or disease that can be evaluated using specific criteria called RECIST version 1.1.
  • There should be a period of at least 6 months without disease after completing previous non-hormonal cancer treatment before the cancer returned.
  • Must have a performance status of 0 or 1 according to the Eastern Cooperative Oncology Group (ECOG) scale, which means being fully active or restricted in physically strenuous activity but able to carry out light work.
  • Must have a left ventricular ejection fraction (LVEF) of at least 50%, which is a measure of heart function, determined by an echocardiogram (ECHO) or a multiple-gated acquisition scan (MUGA).

Who cannot join the trial?

10 criteria

  • Patients with any other type of cancer that is not locally-advanced or metastatic breast cancer.
  • Patients who have had a heart attack or stroke in the past 6 months.
  • Patients with uncontrolled high blood pressure.
  • Patients with severe liver or kidney disease.
  • Patients who are pregnant or breastfeeding.
  • Patients who have an active infection that requires treatment.
  • Patients who have a known allergy to any of the study medications.
  • Patients who are participating in another clinical trial.
  • Patients who have a history of drug or alcohol abuse in the past year.
  • Patients who have a mental health condition that would interfere with their ability to participate in the study.
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Investigated drugs

  • Giredestrant

    is a medication being studied for its potential to treat breast cancer. It works by blocking the effects of estrogen, a hormone that can help some breast cancer cells grow. By interfering with estrogen's action, giredestrant may help slow down or stop the growth of cancer cells that rely on this hormone.

  • Phesgo

    is a combination of two medications, pertuzumab and trastuzumab, used to treat breast cancer. These medications work by targeting specific proteins on the surface of cancer cells, known as HER2 receptors. By attaching to these receptors, Phesgo can help stop the cancer cells from growing and dividing, which may slow down the progression of the disease.

  • Taxane

    is a type of chemotherapy drug used to treat various cancers, including breast cancer. It works by interfering with the ability of cancer cells to divide and grow. By disrupting the cell division process, taxane can help reduce the number of cancer cells in the body and slow the progression of the disease.

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 breast cancer. It is being evaluated for use in patients with locally-advanced or metastatic breast cancer that is both HER2-positive and estrogen receptor-positive. Giredestrant works by blocking the activity of estrogen receptors, which can slow down or stop the growth of cancer cells that rely on estrogen. It is classified as a selective estrogen receptor degrader (SERD), which means it specifically targets and degrades estrogen receptors in cancer cells.

  • Phesgo

    Phesgo is administered as an injection under the skin and is used in the treatment of HER2-positive breast cancer. It is currently approved for use in combination with other therapies to treat patients with locally-advanced or metastatic breast cancer. Phesgo combines two active ingredients, pertuzumab and trastuzumab, which work together to block the HER2 protein on cancer cells, preventing them from growing and dividing. It is classified as a monoclonal antibody therapy, which means it uses antibodies to target specific proteins on cancer cells.

Investigated diseases

Locally-Advanced or Metastatic Breast Cancer – This form of breast cancer has spread beyond the initial tumor site to nearby tissues or distant parts of the body. It often begins in the breast ducts or lobules and can invade surrounding breast tissue. As the disease progresses, cancer cells may travel through the lymphatic system or bloodstream to other organs, such as bones, liver, lungs, or brain. The progression can lead to the formation of new tumors in these areas, which can affect their function. Symptoms may vary depending on the organs involved, but can include pain, swelling, or changes in skin texture. The disease's progression is typically monitored through imaging and clinical evaluations.
Trial detailsLast updated 4 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2022-500014-26-00Protocol codeWO43571Estimated enrolment922 patientsSponsorF. Hoffmann-La Roche AG

sourced from the EU Clinical Trials Register and site verification

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