This study is looking at a new medicine called disitamab vedotin for adults with advanced breast cancer. Advanced cancer means the cancer is hard to treat and has spread in the body. The study aims to find out if this medicine is safe and helpful for people with this type of cancer. People who join will get the medicine through an IV (a tube that goes into a vein) every two weeks at the study clinic. They will continue this until their doctor or they decide to stop. After stopping, there will be follow-up visits every 6 weeks, and phone calls every 12 weeks. HER2 is a protein that can be found on some cancer cells. This study is for people whose tumors have HER2.

• Participants will receive treatment every two weeks.
• Regular follow-up visits are required even after stopping the medicine.
• This study checks if the medicine is safe and works well.