The Next Big Thing for Metastatic Breast Cancer

Even with the recent approval of pertuzumab as a component (along with trastuzumab and docetaxel) of a first-line regimen for patients with human epidermal growth factor receptor 2 (HER2)–positive, metastatic breast cancer, the anticipated approval of trastuzumab emtansine (T-DM1) is eagerly awaited by oncologists as a treatment for patients with progressive HER2-positive breast cancer following treatment with trastuzumab. Indeed, clinical experience with T-DM1 — a fusion molecule combining trastuzumab with a cytotoxic (maytansine) utilizing a stable linker (see illustration) — has shown robust clinical activity following prior anti-HER2 therapy with relatively modest toxicity (J Clin Oncol 2011 Feb; 29:398).

Now, investigators have conducte…