- Is a monoclonal antibody that binds to a different epitope on HER2 than Trastuzumab blocking the formation of HER2:HER3 heterodimers, which are believed to be an important mechanism of resistance to trastuzumab.
- Used in combination with trastuzumab and docetaxel for the treatment of metastatic HER2-positive breast cancer
- It also used in the same combination as a neoadjuvant in early HER2-positive breast cancer