Unfortunately, if any of the following apply to you, this study is not the right fit for you:

• Have other ongoing uncontrolled illnesses
• Have a past medical history of significant cardiovascular disease
• Previous treatment with anti-HER2 therapy
• Previous treatment with chemotherapy for metastatic breast cancer
  
  

The total duration of this study is not fixed and will vary depending on the number of treatment cycles with the investigational product or control treatment. This includes:

• Tissue screening to determine eligibility.
• One clinic visit for a physical screening.
• If eligible, you will be randomised to receive either the investigational treatment (DB-1303) or a control treatment (one of three types of single-agent chemotherapy, chosen by the study doctor). You will be informed which treatment you are assigned to.
  Treatment cycles last 3-4 weeks, with no fixed number of cycles.
• End of treatment visit within 7 days after discontinuing study treatment.
• Safety follow-up visit approximately 35 days after your last dose.
• Long-term follow-up visits every 3 months.
  
  Participation in this research is voluntary, and you may withdraw from the study at any time.

This study aims to evaluate the safety and efficacy of an investigational treatment (DB-1303) compared to a control treatment (one of three types of single-agent chemotherapy, chosen by the study doctor) in treating metastatic breast cancer that has progressed despite endocrine therapy.

HER2-low (Human epidermal growth factor receptor 2 low) and HR-positive (Human receptor-positive) refer to the subtype of cancer a person has, as determined by microscopy. This type of breast cancer is driven by hormones and has spread beyond the breast to other parts of the body.

This combination of HER2-low and HR-positive breast cancer can influence treatment options, as it may respond differently to certain therapies compared to other types of breast cancer.

This study is important because it focuses on a specific type of breast cancer called HER2-low breast cancer. Until recently, patients with HER2-low breast cancer were treated the same way as those with HER2-negative breast cancer, but emerging research shows that this group may respond differently to certain treatments.

Currently, after trying hormone therapies and targeted therapies, patients whose cancer keeps progressing often turn to chemotherapy, which is associated with adverse events such as nausea, vomiting, alopecia, and skin reactions. There is a need for treatments that offer better benefits with fewer risks for this group of patients who receive chemotherapy after hormone therapy.

This study is being sponsored by DualityBio, a clinical stage company focusing on the discovery and development of the next generation ADC therapeutics to treat patients in cancer and autoimmune diseases.

Here is a list of all of the sites who are currently recruiting for this study:

• Mater Hospital Brisbane - 
  Mater Research Level 3 Aubigny Place, Raymond Terrace, South Brisbane, 4101
• GenesisCare St Andrews Hospital - 
  Level 1/337 South Tce, Adelaide SA, 5000
  
  

We are here for you! Head to our Evrima Help Centre and search for answers relating to clinical trials, study information and managing your Evrilink account. If you still have any further questions, you may contact us from the Help Centre.

You may also read more about this study at the ANZCTR (Australian New Zealand Clinical Trial Registry)