cyclophosphamide + doxorubicin + lapatinib + paclitaxel + trastuzumab

This is a multi-drug chemotherapy and targeted therapy regimen for HER2-positive breast cancer. The combination includes cyclophosphamide and doxorubicin as anthracycline-based chemotherapy agents, paclitaxel as a taxane chemotherapy agent, trastuzumab as an anti-HER2 monoclonal antibody, and lapatinib as an oral tyrosine kinase inhibitor targeting HER2. The regimen is typically administered sequentially or concurrently in clinical trials for neoadjuvant or adjuvant treatment of early-stage or locally advanced HER2-positive breast cancer. Cyclophosphamide and doxorubicin damage DNA to prevent cancer cell division; paclitaxel stabilizes microtubules to inhibit cell division; trastuzumab binds to the extracellular domain of HER2/neu receptor to block signaling pathways; lapatinib inhibits intracellular tyrosine kinase domains of EGFR/HER1 and HER2/neu receptors.