The Efficacy and Safety of Trastuzumab Rezetecan (SHR-A1811) in HER2-Low Unresectable/Metastatic Breast Cancer Patients With Visceral Crisis

This study is testing a targeted antibody drug called trastuzumab rezetecan (SHR-A1811) in people with HER2-low metastatic breast cancer who are experiencing a visceral crisis — meaning the cancer is progressing rapidly and causing serious problems in vital organs like the liver or lungs. This situation typically requires more aggressive and immediate treatment. **You may be eligible if...** - You are 18–75 years old with metastatic breast cancer classified as HER2-low - You are currently experiencing a visceral crisis (rapidly worsening organ function, such as rising bilirubin, worsening breathlessness, or other organ compromise) - Your doctors believe you need single-agent chemotherapy - You have received no more than 1 prior chemotherapy regimen for metastatic disease - Your blood counts and organ function meet required levels **You may NOT be eligible if...** - Your breast cancer is HER2-positive (not HER2-low) - You have had more than 1 line of chemotherapy for metastatic disease - You have uncontrolled brain metastases - You are pregnant or breastfeeding - You have severe heart problems or other major organ failure Talk to your doctor to see if this trial is right for you.