liposomal doxorubicin hydrochloride + cyclophosphamide + trastuzumab

**Liposomal doxorubicin hydrochloride + cyclophosphamide + trastuzumab** is a combination chemotherapy regimen commonly studied and used for the treatment of HER2-positive breast cancer. - **Liposomal doxorubicin hydrochloride** is a pegylated or non-pegylated anthracycline encapsulated in liposomes, which improve pharmacokinetics, extend circulation time, and reduce cardiotoxicity compared to free doxorubicin by limiting distribution to the heart and non-target tissues. Its mechanism involves inhibition of topoisomerase II, leading to DNA damage and apoptosis of rapidly dividing cells[1][2]. - **Cyclophosphamide** is an alkylating agent that crosslinks DNA, preventing cell replication, and is widely used in combination regimens for its broad antineoplastic activity. - **Trastuzumab** is a monoclonal antibody targeting the human epidermal growth factor receptor 2 (HER2), blocking receptor activation and mediating antibody-dependent cellular cytotoxicity, which is critical in HER2-positive breast cancer. The combination is used in both adjuvant and metastatic settings, as numerous phase I/II and randomized studies have demonstrated its efficacy with reduced cardiotoxicity compared to conventional doxorubicin-based regimens, especially when administered concurrently with trastuzumab[1]. Its primary indications include HER2-positive early and metastatic breast cancer.