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Study of Trastuzumab Deruxtecan for Patients with Unresectable or Metastatic HER2-low or HER2 IHC0 Breast Cancer

Verified siteInvestigationalNo 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 a type of breast cancer known as unresectable and/or metastatic HER2-low or HER2 IHC 0 breast cancer. This means the cancer cannot be removed by surgery and has spread to other parts of the body. The study is testing a treatment called trastuzumab deruxtecan, also known by its code name DS-8201a. This treatment is a special kind of medicine called an anti-HER2-antibody drug conjugate, which is designed to target and attack cancer cells that have low levels of a protein called HER2.

The purpose of the study is to evaluate how effective this treatment is for patients with this specific type of breast cancer. Participants in the study will receive the treatment as a solution that is given through a vein, known as an intravenous infusion. The study will follow participants over a period of time to see how long it takes before they need another cancer treatment or if the cancer progresses. Some participants may receive a placebo, which is a substance with no active medication, to compare the effects of the treatment.

Throughout the study, participants will have regular visits to monitor their health and the effects of the treatment. This will include various tests and assessments to ensure the treatment is working as intended and to check for any side effects. The study aims to provide valuable information on whether trastuzumab deruxtecan can be an effective treatment option for people with this type of breast cancer.

The research process

The trial runs in 4 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 will receive an intravenous medication called trastuzumab deruxtecan (also known as DS-8201a). This medication is a solution for infusion, which means it is administered directly into the bloodstream through a vein.

    The study is designed to evaluate the effectiveness of this medication in treating certain types of breast cancer that cannot be surgically removed or have spread to other parts of the body.

  2. Step 2

    Treatment administration

    The patient will receive the medication through an intravenous infusion. The frequency and dosage of the medication will be determined by the study protocol and the healthcare team overseeing the treatment.

    The treatment will continue as long as it is deemed beneficial and safe for the patient, or until the patient decides to discontinue participation.

  3. Step 3

    Monitoring and assessments

    Throughout the study, the patient will undergo regular monitoring and assessments to evaluate the response to the treatment. This may include imaging tests such as CT or MRI scans to measure the size of the cancer lesions.

    The healthcare team will also monitor the patient's overall health and any side effects experienced during the treatment.

  4. Step 4

    End of treatment

    The treatment will be discontinued if the patient experiences significant side effects, if the cancer progresses despite treatment, or if the patient chooses to stop participating in the study.

    After discontinuation, the patient may be offered other treatment options based on their specific medical condition and needs.

Who can join the trial?

16 criteria

  • You must sign and date the informed consent form before starting any study-specific procedures.
  • Your heart's pumping ability, known as left ventricular ejection fraction (LVEF), must be 50% or higher within 28 days before joining the study.
  • Your organs and bone marrow must be working well within 28 days before joining the study. You cannot have received blood transfusions or certain medications to boost blood cells within 2 weeks before the screening.
  • You must have a sufficient break from previous treatments before joining the study, as defined in the study protocol.
  • If you can have children, you must agree to use a highly effective form of birth control or avoid intercourse during the study and for a certain period after the study ends (7 months for females, 4 months for males).
  • Male participants must not freeze or donate sperm during the study and for at least 4 months after the last dose of the study drug. Consider preserving sperm before joining the study.
  • Female participants must not donate or retrieve eggs for their own use during the study and for at least 7 months after the last dose of the study drug. They should also not breastfeed during this time. Consider preserving eggs before joining the study.
  • You must be willing and able to attend scheduled visits, follow the drug administration plan, undergo laboratory tests, and comply with other study procedures and restrictions.
  • You must be an adult, at least 18 years old or the minimum legal adult age, whichever is greater, when signing the informed consent form.
  • You must agree to provide a new or previously collected tissue sample from your tumor for analysis. This sample must meet specific requirements for testing.
  • Your breast cancer must be unresectable (cannot be removed by surgery) and/or metastatic (has spread to other parts of the body). It must have specific characteristics related to hormone receptors and HER2 status, as defined in the study.
  • You must have had at least one and up to two prior treatments for metastatic breast cancer. Certain targeted therapies or hormone treatments count as a line of therapy.
  • You must have at least one measurable tumor lesion based on imaging tests like CT or MRI, or have bone-only disease that can be assessed by these tests.
  • If you have brain metastases, they must be small, untreated, not causing symptoms, and not requiring urgent medical intervention.
  • Your performance status, which measures your ability to carry out daily activities, must be 0 or 1 on the Eastern Cooperative Oncology Group (ECOG) scale.
  • You must have a minimum life expectancy of 12 weeks at the time of screening.

Who cannot join the trial?

4 criteria

  • Patients who have a type of breast cancer that cannot be removed by surgery or has spread to other parts of the body.
  • Patients with breast cancer that does not show certain levels of a protein called HER2, which is checked using a test called Immunohistochemistry (IHC).
  • Patients who are not within the specified age range for the study.
  • Patients who are part of a vulnerable population, meaning they might need special protection or care.
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Investigated drugs

Trastuzumab Deruxtecan (T-DXd) is a medication used in this clinical trial. It is an anti-HER2-antibody drug conjugate, which means it is designed to target and attach to the HER2 protein found on some cancer cells. Once attached, it delivers a chemotherapy drug directly to the cancer cells, helping to destroy them. This medication is being studied for its effectiveness in treating patients with breast cancer that cannot be surgically removed or has spread to other parts of the body, specifically in cases where the cancer has low levels of HER2 or none at all.

What is already known about the treatment

Trastuzumab Deruxtecan – This medication is administered intravenously and is currently being studied in clinical trials for its effectiveness in treating certain types of breast cancer that are either unresectable or have metastasized, specifically those with low HER2 expression or HER2 IHC 0. It is an antibody-drug conjugate, meaning it combines an antibody with a chemotherapy drug to target cancer cells more precisely. The main therapeutic indication is for breast cancer that cannot be surgically removed or has spread to other parts of the body. At the molecular level, it works by binding to the HER2 protein on cancer cells, delivering the chemotherapy directly to the cells, which helps to kill them while minimizing damage to normal cells. It is classified pharmacologically as an anti-HER2 antibody-drug conjugate.

Investigated diseases

Breast Cancer – Breast cancer is a disease where cells in the breast grow uncontrollably. It can begin in different parts of the breast, such as the ducts or lobules. When the cancer is described as unresectable, it means it cannot be removed completely through surgery. Metastatic breast cancer indicates that the cancer has spread to other parts of the body. HER2-low or HER2 Immunohistochemistry (IHC) 0 refers to specific characteristics of the cancer cells, which can affect how the disease progresses and responds to treatment. The progression of breast cancer can vary, with some cases growing slowly and others spreading more rapidly.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2023-505616-38-00Protocol codeDS8201-0001-CIS-MAEstimated enrolment268 patientsSponsorDaiichi Sankyo Inc.

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