A Study of BL-M07D1, BL-M07D1+Pertuzumab and BL-M07D1+Pertuzumab+Docetaxel in Patients With Unresectable Locally Advanced or Metastatic HER2-positive Breast Cancer

This study tests BL-M07D1 — a new type of cancer treatment called an antibody-drug conjugate that targets HER2 — alone and in combination with other HER2-targeted therapies (pertuzumab and docetaxel) in patients with HER2-positive metastatic or advanced breast cancer. HER2-positive means the cancer cells have extra amounts of a protein that drives their growth. **You may be eligible if...** - You are between 18 and 75 years old - You have confirmed HER2-positive breast cancer that cannot be surgically removed or has spread - You have at least one measurable tumor on scans - You have not previously received systemic treatment for metastatic disease - Your heart, blood, liver, and kidney function are within acceptable levels **You may NOT be eligible if...** - You have received prior chemotherapy for your current stage of disease - You have active brain metastases or severe lung or heart conditions - You have HIV, active hepatitis B or C - You are pregnant or breastfeeding - You have a history of severe autoimmune disease or organ transplantation Talk to your doctor to see if this trial is right for you.