trastuzumab + aromatase inhibitor

A combination therapy of **trastuzumab** (a monoclonal antibody targeting the HER2/neu receptor) plus **an aromatase inhibitor** (such as anastrozole or letrozole, both small molecule drugs that inhibit estrogen biosynthesis) used in the treatment of hormone receptor–positive, HER2-positive locally advanced or metastatic breast cancer. Trastuzumab blocks HER2-mediated signaling pathways and mediates immune cell cytotoxicity, while aromatase inhibitors suppress the production of estrogens by inhibiting the aromatase enzyme, thus reducing estrogen-driven tumor growth. This combination offers a non-chemotherapy option for patients, particularly in those unable or unwilling to receive cytotoxic agents. The clinical evidence supporting this combination comes from studies like PERTAIN, which demonstrated improved progression-free survival when combining trastuzumab and an aromatase inhibitor compared to aromatase inhibitor alone, especially for postmenopausal women[1][3][4].