The Global Need for a Trastuzumab Biosimilar for Patients With HER2-Positive Breast Cancer.

Trastuzumab improves survival outcomes for patients with HER2-positive (HER2+) breast cancer, yet not all such women receive this important therapy. Trastuzumab was approved by the US Food and Drug Administration in 1998 and the European Medicines Agency in 2000 as treatment for HER2+ metastatic breast cancer (MBC). Observational studies between 2000 and 2015 in patients with HER2+ MBC suggest that nearly 12% in the United States, 27% to 54% in Europe, and 27.1% to 49.2% in China did not receive trastuzumab or any other HER2-targeted agent as first- and/or later-line for treatment of metastatic disease. In 2006, both agencies approved trastuzumab as adjuvant therapy for patients with HER2+ early breast cancer (EBC). Observational studies on real-world treatment patterns for HER2+ EBC between 2005 and 2015 suggest that 19.1% to 59.5% of patients across regions of North America, Europe, Australia, New Zealand, and China did not receive (neo)adjuvant trastuzumab. Data suggest that some patient subgroups, including older patients, those with HER2+/hormone receptor-positive disease, and women with small and/or node-negative HER2+ tumors, were less likely to receive anti-HER2 therapy. Barriers to accessing trastuzumab are multifactorial and include issues related to drug funding and high treatment costs for patients that have been reported worldwide. Herein, we review available literature on the use of, and barriers to, treatment with trastuzumab in patients with HER2+ breast cancer. We also discuss how the availability of safe and effective biosimilars might increase access to trastuzumab and allow greater use of anti-HER2 therapy, potentially improving patient outcomes.