pyrotinib + epirubicin + cyclophosphamide + paclitaxel

This is a combination regimen consisting of four drugs: pyrotinib, epirubicin, cyclophosphamide, and paclitaxel. Pyrotinib is an oral irreversible pan-HER tyrosine kinase inhibitor that targets HER1 (EGFR), HER2, and HER4 receptors by binding to their ATP-binding sites and blocking downstream signaling pathways involved in tumor cell proliferation. Epirubicin is an anthracycline chemotherapeutic agent that intercalates into DNA and inhibits topoisomerase II activity, leading to DNA damage and apoptosis. Cyclophosphamide is an alkylating agent that crosslinks DNA strands, preventing cell division. Paclitaxel is a taxane-class chemotherapeutic that stabilizes microtubules and inhibits their depolymerization during mitosis, resulting in cell cycle arrest. This combination has been investigated as neoadjuvant or adjuvant therapy for breast cancer—particularly for HER2-positive or high-risk early-stage disease—where it aims to maximize tumor response through multi-modal cytotoxicity[1][2][3][7].