A Phase 3, Randomized, Open-label, Multicenter, Controlled Study to Evaluate the Efficacy and Safety of Zanidatamab in Combination With Physician's Choice Chemotherapy Compared to Trastuzumab in Combination With Physician's Choice Chemotherapy for the Treatment of Participants With Metastatic HER2-positive Breast Cancer Who Have Progressed on, or Are Intolerant to, Previous Trastuzumab Deruxtecan Treatment

This study is testing a new drug called zanidatamab to see if it works better than current standard treatments for metastatic HER2-positive breast cancer. It is designed for patients whose cancer has continued to grow after receiving a previous treatment called T-DXd.

This trial is for people with HER2-positive breast cancer that has spread to other parts of the body. You may be eligible if you have already tried T-DXd and it didn't work as well as hoped, or if you were unable to tolerate its side effects.

Participants will be split into two groups: one will receive the new drug zanidatamab along with chemotherapy, while the other will receive a standard drug called trastuzumab plus chemotherapy. Doctors will closely monitor your health and how your cancer responds to the treatment throughout the study.

The study is currently recruiting volunteers at medical centers in Phoenix and Tucson, Arizona. Your doctor can help you find the exact location nearest to you.