lapatinib + trastuzumab + aromatase inhibitor

This is a **combination therapy** consisting of three agents: **lapatinib** (a small molecule tyrosine kinase inhibitor), **trastuzumab** (a monoclonal antibody targeting HER2/neu), and an **aromatase inhibitor** (letrozole, anastrozole, or exemestane, each blocking estrogen synthesis). The combination is chiefly used in **postmenopausal patients with hormone receptor-positive, HER2-positive metastatic breast cancer**. The regimen aims to achieve dual HER2 inhibition with lapatinib plus trastuzumab, while also suppressing estrogen-driven tumorigenesis via the aromatase inhibitor. Major evidence—including the phase III ALTERNATIVE trial and other studies—demonstrates that this triplet significantly improves progression-free survival and clinical benefit rate compared to single-agent HER2 blockade with endocrine therapy, offering a non-chemotherapy option for this patient group[1][4][7][8][10].