**ARX788** is a medicine studied for people with **HER2-positive metastatic breast cancer**. This means the cancer has spread to other parts of the body and has high levels of a protein called HER2. The study is **Phase 2**, which tests how well the drug works and its safety. Patients get **ARX788** through an IV (intravenous) every three weeks. You can join if you're 18 or older, have been treated with a drug called **T-DXd**, and your cancer cannot be removed by surgery. You must have no more than five previous treatments for this cancer and at least one tumor that can be measured. You should not have serious heart, lung, or eye problems, or any severe infections. You need to be able to understand and sign a consent form.

• **Study Duration**: Every 3 weeks, ongoing treatment.
• **Visits Needed**: Regular visits for IV treatment.
• **Risks**: Possible side effects include reactions, lung issues, or heart problems.