giredestrant + pertuzumab + trastuzumab + palbociclib

A combination therapy comprising **giredestrant**, an oral selective estrogen receptor degrader (**SERD**); **pertuzumab** and **trastuzumab**, both monoclonal antibodies targeting the human epidermal growth factor receptor 2 (**HER2**) but at different epitopes; and **palbociclib**, an oral cyclin-dependent kinase 4/6 (**CDK4/6**) inhibitor. This investigational regimen is designed for the treatment of **HR+ (estrogen receptor positive), HER2+ (HER2 overexpressing) breast cancer**, specifically evaluated in locally advanced or metastatic settings. The combination co-targets the estrogen and HER2 signaling pathways while also blocking cell cycle progression, aiming for enhanced anti-tumor activity by affecting multiple mechanisms of proliferation and survival in breast cancer cells[1][2][3].