Efficacy and tolerability of trastuzumab emtansine in advanced human epidermal growth factor receptor 2-positive breast cancer

• Published in: Hong Kong medical journal = Xianggang yi xue za zhi Vol. 24; no. 1; p. 56
• Main Authors: Yeo, W, Luk, M Y, Soong, I S, Yuen, T Ys, Ng, T Y, Mo, F Kf, Chan, K, Wong, S Y, Tsang, J, Leung, C, Suen, J Js, Ngan, R Kc
• Format: Journal Article
• Language: English; Chinese
• Published: China Hong Kong Academy of Medicine 01.02.2018
• Subjects: Adult; Aged; Antineoplastic Agents, Immunological - administration & dosage; Antineoplastic Agents, Immunological - adverse effects; Antineoplastic Combined Chemotherapy Protocols - administration & dosage; Antineoplastic Combined Chemotherapy Protocols - adverse effects; Breast cancer; Breast Neoplasms - drug therapy; Breast Neoplasms - genetics; Breast Neoplasms - mortality; Cancer therapies; Chemotherapy; Confidence intervals; Cytotoxicity; Endocrine therapy; Epidermal growth factor; Female; Hematology; Hong Kong - epidemiology; Humans; Maytansine - administration & dosage; Maytansine - adverse effects; Maytansine - analogs & derivatives; Metastasis; Middle Aged; Patients; Receptor, ErbB-2 - genetics; Retrospective Studies; Survival Analysis; Trastuzumab - administration & dosage; Trastuzumab - adverse effects; Hong Kong China; China; Breast neoplasms; Trastuzumab
• ISSN: 1024-2708; 2226-8707
• DOI: 10.12809/hkmj176808

The management of human epidermal growth factor receptor 2 (HER2)-positive breast cancer has changed dramatically with the introduction and widespread use of HER2-targeted therapies. There is, however, relatively limited real-world information about the effectiveness and safety of trastuzumab emtansine (T-DM1) in Hong Kong Chinese patients. We assessed the efficacy and toxicity profiles among local patients with HER2-positive advanced breast cancer who had received T-DM1 therapy in the second-line setting and beyond. This retrospective study involved five local centres that provide service for over 80% of the breast cancer population in Hong Kong. The study period was from December 2013 to December 2015. Patients were included if they had recurrent or metastatic histologically confirmed HER2+ breast cancer who had progressed after at least one line of anti-HER2 therapy including trastuzumab. Patients were excluded if they received T-DM1 as first-line treatment for recurrent or metastatic HER2+ breast cancer. Patient charts including biochemical and haematological profiles were reviewed for background information, T-DM1 response, and toxicity data. Adverse events were documented during chemotherapy and 28 days after the last dose of medication. Among 37 patients being included in this study, 28 (75.7%) had two or more lines of anti-HER2 agents and 26 (70.3%) had received two or more lines of palliative chemotherapy. Response assessment revealed that three (8.1%) patients had a complete response, eight (21.6%) a partial response, 11 (29.7%) a stable disease, and 12 (32.4%) a progressive disease; three patients could not be assessed. The median duration of response was 17.3 (95% confidence interval, 8.4-24.8) months. The clinical benefit rate (complete response + partial response + stable disease, ≥12 weeks) was 37.8% (95% confidence interval, 22.2%-53.5%). The median progression-free survival was 6.0 (95% confidence interval, 3.3- 9.8) months and the median overall survival had not been reached by the data cut-off date. Grade 3 or 4 toxicities included thrombocytopaenia (13.5%), raised alanine transaminase (8.1%), anaemia (5.4%), and hypokalaemia (2.7%). No patient died as a result of toxicities. In patients with HER2-positive advanced breast cancer who have been heavily pretreated with anti-HER2 agents and cytotoxic chemotherapy, T-DM1 is well tolerated and provided a meaningful progression-free survival of 6 months and an overall survival that has not been reached. Further studies to identify appropriate patient subgroups are warranted.