Abstract
BACKGROUND/AIM: Tolerability and safety of trastuzumab emtansine (T-DM1) was investigated in Japanese patients with HER2-positive advanced breast cancer who were previously treated with chemotherapy and trastuzumab. PATIENTS AND METHODS: Patients with inoperable or recurrent breast cancer who were previously treated with chemotherapy and trastuzumab in adjuvant and/or metastatic disease were included. T-DM1 3.6 mg/kg was administered intravenously every 21 days. The administration dosage or schedule of T-DM1 was modified based on laboratory tests on the administration day. RESULTS: Among 232 patients analyzed, adverse events were reported in 228 patients (98.3%); five patients (2.2%) discontinued due to adverse events and twenty patients (8.6%) had serious adverse events. The most commonly reported grade ≥3 adverse event of special interest was thrombocytopenia (69 patients; 29.7%), followed by hepatotoxicity (26 patients; 11.2%). CONCLUSION: T-DM1 was well tolerated in Japanese patients with HER2-positive advanced breast cancer and no new safety signals were observed.