Real-world clinical scenarios during introduction of trastuzumab biosimilar for HER2-positive breast cancer in the European Union

Aim: Trastuzumab-anns is an intravenously administered biosimilar to trastuzumab approved by the EMA and US FDA for treatment of HER2+ early and metastatic breast cancer as well as metastatic gastric cancer. Lack of real-world characterization of biosimilar use has hindered uptake. Methods: This observational chart review characterizes 488 patients who received trastuzumab-anns in EU clinical practice settings. Results: Approximately 2/3rds of patients initiated trastuzumab-anns in adjuvant and neoadjuvant settings and most were naive new starters (70%). 30% were switchers from another trastuzumab, among whom 48% switched from trastuzumab iv. reference product. Common reasons for trastuzumab-anns discontinuation were a switch to another biosimilar product (34.8%, n = 85) or to trastuzumab reference product (15.6%, n = 38). Conclusion: Trastuzumab-anns was widely used in various treatment settings for HER2+ breast cancer. Some patients have a type of breast cancer caused by abnormal amounts of a normal growth factor receptor. This growth factor receptor, known as human epidermal growth factor receptor-2 (HER-2), plays a role in normal life changes that occur in breast tissue, including during pregnancy. HER-2 exists on the surface of breast cells and sends a signal inside cells for growth and proliferation. Sometimes an abnormal amount of HER-2 appears on breast cell surfaces, which causes HER-2 to promote excessive growth and proliferation and leads to HER2+ breast cancer. HER2+ breast cancer can be treated with trastuzumab, a medicine that specifically blocks HER-2 signals, and stops cancer cell growth. Trastuzumab has greatly improved outcomes for women worldwide with HER2+ breast cancer but trastuzumab is not always available due, in part, to its high cost. Biosimilars are medicines that are highly similar, but not identical, to the brand name (original) product and have been shown in clinical trials to result in no meaningful difference in efficacy and safety compared with the original product. Trastuzumab-anns is an intravenously administered biosimilar to trastuzumab. Biosimilars are as effective and safe as original products, although more cost-effective, such that physicians and patients can benefit from more information about their use in the real world. This study provided information about trastuzumab-anns use from clinical oncology practices in seven European countries. The study provides real world evidence that trastuzumab-anns is used widely across different patients with HER2+ breast cancer, including those with metastatic disease.