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Study Comparing DB-1303 and Chemotherapy for Patients with HER2-low, Hormone Receptor Positive, 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 focused on studying a type of breast cancer known as HER2-low, Hormone Receptor Positive, Metastatic Breast Cancer. This form of cancer is characterized by low levels of a protein called HER2 and the presence of hormone receptors. The study will compare the effectiveness of a new treatment called DB-1303 with standard chemotherapy options chosen by the doctor. DB-1303 is an experimental medication that is given through an intravenous infusion, which means it is administered directly into the bloodstream through a vein.

The purpose of the study is to evaluate how well DB-1303 works in slowing down the progression of the cancer compared to the usual chemotherapy treatments. Participants in the study will be randomly assigned to receive either DB-1303 or one of the standard chemotherapy drugs, which may include Capecitabine, Paclitaxel, or Paclitaxel Albumin-Bound. These chemotherapy drugs are commonly used to treat breast cancer and are administered either orally or through intravenous infusion, depending on the specific medication.

The study will take place over a period of time, during which participants will receive their assigned treatment and be monitored for any changes in their condition. The goal is to determine which treatment is more effective in extending the time before the cancer progresses. Participants will also be observed for any side effects or changes in their overall health. This study aims to provide valuable information that could help improve treatment options for patients with this specific 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 be randomly assigned to receive either the experimental drug DB-1303 or a chemotherapy treatment chosen by the investigator.

    The study is designed to compare the effectiveness of DB-1303 with other chemotherapy options for patients with a specific type of breast cancer.

  2. Step 2

    Treatment administration

    If assigned to the DB-1303 group, the patient will receive the medication through an intravenous infusion. The frequency and dosage will be determined by the study protocol.

    If assigned to the chemotherapy group, the patient may receive one of the following treatments: capecitabine (oral), paclitaxel (intravenous infusion), or paclitaxel albumin-bound (intravenous infusion). The specific medication, dosage, and frequency will be chosen by the investigator.

  3. Step 3

    Monitoring and assessments

    Throughout the study, the patient's health and response to treatment will be closely monitored. This includes regular physical examinations, laboratory tests, and imaging studies.

    The patient's progress will be evaluated using criteria for measuring tumor response, and any side effects will be documented.

  4. Step 4

    Completion of treatment

    The treatment phase will continue until the patient experiences disease progression, unacceptable side effects, or chooses to withdraw from the study.

    After completing the treatment, follow-up assessments will be conducted to monitor the patient's health and gather additional data on the long-term effects of the treatment.

Who can join the trial?

14 criteria

  • Must be an adult, which means being 18 years or older.
  • Must have good functioning of organs and bone marrow within 14 days before starting the study.
  • Must have a sufficient break from previous treatments before starting the study.
  • For women who can have children, they must either be post-menopausal or have a negative pregnancy test if they are sexually active with a male partner who is not sterilized.
  • Women who can have children and are sexually active with a non-sterilized male partner must use a highly effective birth control method from the time of screening and continue for 7 months after the last dose of the study treatment.
  • Men who are not sterilized and are sexually active with a woman who can have children must use a condom with spermicide from screening and throughout the study and washout period (4 months after the last dose of DB-1303, 6 months after the last dose of paclitaxel or nab-paclitaxel, and 3 months after the last dose of capecitabine).
  • Must have breast cancer that is advanced or has spread to other parts of the body, shows low levels of a protein called HER2, and is hormone receptor positive (HR+), meaning it has receptors for hormones like estrogen or progesterone.
  • Must provide a sample of tumor tissue for testing HER2 levels, preferably from the time when the cancer spread or later.
  • Must have an ECOG performance status of 0 or 1, which means being fully active or having some symptoms but still able to carry out light work.
  • Must have experienced disease progression on hormone therapy and a CDK4/6 inhibitor within 6 months of starting first-line treatment for metastatic disease and be considered suitable for chemotherapy, or have disease progression on at least two previous lines of hormone therapy with or without targeted therapy.
  • Must not have had chemotherapy for advanced or metastatic breast cancer, but can have had chemotherapy in earlier stages if there was a disease-free period of more than 12 months.
  • Must have a life expectancy of at least 12 weeks at the time of screening.
  • Must have at least one measurable lesion, which is a tumor that can be measured by imaging tests like CT or MRI. For bone-only disease, only certain types of bone lesions are eligible.
  • Must have a left ventricular ejection fraction (LVEF) of 50% or higher, which is a measure of heart function, checked by echocardiography or a MUGA scan within 28 days before starting the study.

Who cannot join the trial?

8 criteria

  • Patients who have a different type of cancer than the one being studied cannot participate.
  • Patients who have received certain treatments for their cancer recently may not be eligible.
  • Patients with serious health conditions that could interfere with the study may be excluded.
  • Patients who are pregnant or breastfeeding cannot take part in the study.
  • Patients who are unable to follow the study procedures or attend required visits may not be eligible.
  • Patients who have participated in another clinical trial recently may be excluded.
  • Patients with allergies to the study medication or similar drugs cannot participate.
  • Patients with certain infections or diseases that could affect the study results may be excluded.
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Investigated drugs

  • DB-1303

    is an experimental medication being tested for its effectiveness in treating a specific type of breast cancer. This medication is being studied in patients with metastatic breast cancer that is hormone receptor positive (HR+) and has low levels of a protein called HER2. The goal is to see if DB-1303 can help slow down the progression of the disease in patients whose cancer has worsened despite previous hormone therapy.

  • Investigator's Choice Chemotherapy

    refers to a selection of standard chemotherapy treatments chosen by the doctor overseeing the patient's care. These treatments are used to try to control the cancer and improve the patient's quality of life. The specific chemotherapy drugs used can vary, depending on what the doctor believes will be most effective for the individual patient.

What is already known about the treatment

DB-1303 – DB-1303 is administered intravenously and is currently being studied in clinical trials for its effectiveness in treating HER2-low, hormone receptor-positive metastatic breast cancer. This medication is in the investigational stage and is not yet approved for general medical use. It is designed to target and bind to the HER2 protein on cancer cells, which may help to slow or stop the growth of these cells. DB-1303 is classified as an antibody-drug conjugate, combining a monoclonal antibody with a cytotoxic agent to deliver targeted therapy to cancer cells.

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 characterized by the presence of cancer cells in distant organs, which can lead to various symptoms depending on the organs affected. The progression of metastatic breast cancer can vary, with some patients experiencing rapid spread while others may have a slower progression. The disease is often classified based on hormone receptor status, such as hormone receptor-positive, which means the cancer cells grow in response to hormones like estrogen or progesterone. Additionally, HER2-low status indicates that the cancer cells have low levels of the HER2 protein, which can influence the behavior and treatment response of the cancer.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-507333-17-00Protocol codeDB-1303-O-3002Estimated enrolment552 patientsSponsorDualitybio Inc.

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