cyclophosphamide + pegylated liposomal doxorubicin + pertuzumab + trastuzumab

This is a four-drug combination regimen consisting of cyclophosphamide, pegylated liposomal doxorubicin, pertuzumab, and trastuzumab. It is used primarily in the treatment of HER2-positive breast cancer. - **Cyclophosphamide** is an alkylating agent that interferes with DNA replication and transcription, leading to cell death. - **Pegylated liposomal doxorubicin** is an anthracycline chemotherapy encapsulated in liposomes with polyethylene glycol (PEG), which enhances drug delivery to tumors while reducing cardiac toxicity compared to conventional doxorubicin. It intercalates into DNA and inhibits topoisomerase II, causing DNA damage and apoptosis. - **Pertuzumab** and **trastuzumab** are monoclonal antibodies targeting different domains of the human epidermal growth factor receptor 2 (HER2). They block HER2 signaling pathways involved in cell proliferation and survival by binding to distinct extracellular regions on the HER2 protein. Their dual blockade provides synergistic inhibition of tumor growth in HER2-positive cancers[1][5][7]. This combination leverages cytotoxic chemotherapy with targeted anti-HER2 therapy for improved efficacy against aggressive breast cancers overexpressing HER2.