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Study on the Safety and Effects of Trastuzumab Deruxtecan with Drug Combination for Patients with Metastatic HER2-low Breast Cancer

Registered drugNo placebo
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What is this trial about?

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

The study focuses on people with Metastatic Breast Cancer, a type of breast cancer that has spread beyond the breast, specifically those whose tumors are classified as HER2-low, meaning they have only small amounts of the HER2 protein on their cells. The main drug being tested is trastuzumab deruxtecan (T-DXd), an antibody‑drug conjugate that delivers chemotherapy directly to cancer cells. In different groups of patients, T‑DXd is combined with other anti‑cancer medicines such as capivasertib (a drug that blocks a growth‑promoting pathway), fulvestrant (a hormone therapy that blocks estrogen receptors), paclitaxel (a chemotherapy that stops cells from dividing), durvalumab (an immunotherapy that helps the immune system see cancer), capecitabine (an oral chemotherapy that is turned into an active drug inside the body), and anastrozole (a hormone therapy that lowers estrogen levels).

The purpose of the study is to evaluate the safety, tolerability, how the body processes the drugs, and early signs of anti‑tumor activity when T‑DXd is given together with these other treatments. The trial is divided into two parts: an initial dose‑finding phase that determines the best dose to use, followed by a dose‑expansion phase that treats more patients at that dose.

Participants receive the study medicines in cycles, usually every few weeks, and attend regular visits for physical checks, blood tests, and imaging scans to watch for side effects and see how the cancer responds. The study continues until a predefined number of treatment cycles are completed, the disease progresses, or a participant chooses to stop.

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, eligibility is confirmed based on specific criteria, including age, type of breast cancer, and previous treatments.

    A tumor sample is required for biomarker assessment to ensure the study's suitability.

  2. Step 2

    Part 1: dose-finding phase

    This phase aims to determine the appropriate dose of trastuzumab deruxtecan (T-DXd) in combination with other medications.

    Medications include paclitaxel (intravenous), fulvestrant (intramuscular), durvalumab (intravenous), and anastrozole (oral).

    The focus is on assessing safety and tolerability, with regular monitoring for any adverse effects.

  3. Step 3

    Part 2: dose-expansion phase

    This phase uses the recommended dose determined in Part 1 to further assess safety and tolerability.

    Patients may receive capecitabine (oral) and capivasertib (oral) as part of the treatment regimen.

    The goal is to evaluate the treatment's effectiveness in managing metastatic breast cancer.

  4. Step 4

    Monitoring and assessments

    Throughout the trial, regular assessments are conducted to monitor the treatment's impact on the cancer.

    These assessments include measuring the size of the tumor and checking for any side effects.

    Blood tests are performed to measure the concentration of medications in the body.

  5. Step 5

    Completion of the trial

    The trial is expected to conclude by July 2026.

    Final assessments will determine the overall effectiveness and safety of the treatment combination.

Who can join the trial?

11 criteria

  • Patients must be at least 18 years old.
  • Both male and female patients can participate.
  • Patients must have breast cancer that is confirmed by a medical test.
  • The cancer must show a history of HER2-low expression. This means the cancer has low levels of a protein called HER2, which is checked using specific tests.
  • The cancer must be either HR+ or HR-. HR+ means the cancer has hormone receptors, which are proteins that hormones can attach to. HR- means the cancer does not have these receptors.
  • Patients must provide a sufficient sample of their tumor for testing.
  • Patients must have an ECOG Performance Status of 0 or 1. This is a scale that measures how well a patient can perform daily activities, with 0 being fully active and 1 being restricted in physically strenuous activity but able to carry out light work.
  • For patients with HR+ disease:
    • In Part 1: Patients must have had at least one previous treatment with hormone therapy, with or without additional targeted therapy, and at least one previous chemotherapy treatment for metastatic breast cancer.
    • In Part 2: Patients can have had only one previous hormone therapy treatment, with or without additional targeted therapy, and no previous chemotherapy for metastatic breast cancer.
    • For patients with HR- disease:
      • In Part 1: Patients must have had at least one previous chemotherapy treatment for metastatic breast cancer.
      • In Part 2: For Module 2, no previous treatments for metastatic breast cancer are allowed. For Modules 1 and 3, only one previous chemotherapy treatment for metastatic breast cancer is allowed.

Who cannot join the trial?

6 criteria

  • Patients who do not have metastatic breast cancer. This means the cancer has spread to other parts of the body.
  • Patients who do not have HER2-low breast cancer. HER2 is a protein that can affect the growth of cancer cells. HER2-low means the cancer cells have a small amount of this protein.
  • Patients who have already received more than one prior treatment for advanced or metastatic disease. This means if you have had more than one treatment for cancer that has spread, you cannot participate.
  • Patients who are not in the age range specified for the study. The study may have specific age requirements.
  • Patients who are not part of the specified gender group. The study may be open to both males and females, or just one gender.
  • Patients who are considered part of a vulnerable population. This means people who might need special protection or care, like children or those unable to make decisions for themselves.
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Investigated drugs

Trastuzumab Deruxtecan (T-DXd) is a medication being studied for its potential to treat metastatic HER2-low breast cancer. It is designed to target and deliver chemotherapy directly to cancer cells that have low levels of the HER2 protein, which is a common characteristic in certain types of breast cancer. The study aims to explore how well this medication works when used in combination with other anti-cancer agents, focusing on its safety, how the body processes it, and its ability to reduce tumor size.

What is already known about the treatment

Trastuzumab Deruxtecan (T-DXd) – This medication is administered intravenously and is currently being studied in clinical trials for its effectiveness in treating metastatic breast cancer, specifically in patients with HER2-low expression. It is in the investigational stage, with ongoing research to determine its safety and optimal dosing when combined with other anti-cancer agents. The main therapeutic indication is for metastatic breast cancer with low HER2 expression. At the molecular level, trastuzumab deruxtecan works by targeting the HER2 protein on cancer cells, delivering a cytotoxic agent directly to the tumor, which helps to inhibit cancer cell growth. It is classified as an antibody-drug conjugate, combining targeted therapy with chemotherapy.

Investigated diseases

Metastatic Breast Cancer – This is a type of breast cancer that has spread beyond the breast to other parts of the body, such as the bones, liver, lungs, or brain. It is considered an advanced stage of breast cancer, often referred to as stage IV. The disease progresses as cancer cells travel through the bloodstream or lymphatic system to form new tumors in other organs. Symptoms can vary depending on where the cancer has spread, but may include bone pain, difficulty breathing, or neurological symptoms. The progression of metastatic breast cancer can be influenced by factors such as hormone receptor status and HER2 status. It is a chronic condition that requires ongoing management to control the spread and alleviate symptoms.
Trial detailsLast updated 14 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-505690-33-00Protocol codeD967JC00002Estimated enrolment192 patientsSponsorAstraZeneca AB

sourced from the EU Clinical Trials Register and site verification

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