Trastuzumab emtansine induced hyponatremia in breast cancer - A case report.

Abstract: Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate of trastuzumab and the cytotoxic agent emtansine (DM1), approved for use as an adjuvant treatment for patients with residual disease after neoadjuvant chemotherapy and antihuman epidermal growth factor receptor 2 (HER-2) therapy and in metastatic HER-2-positive breast cancer. Previous studies have shown that T-DM1 has a favorable safety profile, with few high-grade toxicities reported so far. We describe a patient who developed profound hyponatremia-which has not been reported previously-following treatment with adjuvant T-DM1 for HER-2+ breast cancer.