TRASTUZUMAB EMTANSINE Tumor-Activated Prodrug (TAP) Immunoconjugate Oncolytic

Trastuzumub emtansine (T-DM1) is a novel antibody-drug conjugate. The conjugate is comprised of the antibody trastuzurnab, which is directed against the receptor tyrosine-protein kinase erbB-2 (HERZ), a derivative of the cytostatic agent maytansinoid DM1(mertansine), and a linker that covalently binds these components together Preclinically, trastuzumab emtansine has shown significant antitumor activity in HER2-positive breast cancer cell lines and xenografts, including those resistant to trastuzumab or lapatinib. The pharmacokinetic profile is predictable, with minimal systemic exposure to free DM1. Phase I and II studies have demonstrated manageable toxicity. Phase II studies of trastuzumab emtansine monotherapy have shown response rates of 25-35% in patients with metastatic breast cancer who had previously received trastuzumab. Several combination regimens are under investigation. Phase Ill studies will help to define the role of trastuzumab emtansine within current treatment strategies.