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.

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.