The Evolution of Biosimilars in Oncology, with a Focus on Trastuzumab

Cancer therapy has evolved significantly with increased adoption of biologic agents (“biologics”). That evolution is especially true for HER2 (human epidermal growth factor receptor-2)–positive breast cancer with the introduction of trastuzumab, a monoclonal antibody against the HER2 receptor, which, in combination with chemotherapy, significantly improves survival in both metastatic and early disease. Although the efficacy of biologics is undeniable, their expense is a significant contributor to the increasing cost of cancer care. Across disease sites and indications, biosimilar agents are rapidly being developed with the goal of offering cost-effective alternatives to biologics. Biosimilars are pharmaceuticals whose molecular shape, efficacy, and safety are similar, but not identical, to those of the original product. Although these agents hold the potential to improve patient access, complexities in their production, evaluation, cost, and clinical application have raised questions among experts. Here, we review the landscape of biosimilar agents in oncology, with a focus on trastuzumab biosimilars. We discuss important considerations that must be made as these agents are introduced into routine cancer care.