Abstract
Trastuzumab is a monoclonal antibody used in the treatment of breast cancer in cases where the tumor overexpresses the HER2 receptor, a cell membrane receptor activated by the epidermal growth factor. Intravenous and subcutaneous administration of trastuzumab have comparable clinical and pharmacological characteristics, but trastuzumab biosimilars are currently only available in intravenous form. Trastuzumab biosimilars are ultimately preferred by a proportion of patients, especially in cases where co-administration of other chemotherapeutic agents, such as trastuzumab and tucatinib, a small molecule of tyrosine kinase inhibitor, is required in patients with HER-positive metastatic breast cancer. Oncologists should be well-aware of the advantages of intravenously administered trastuzumab biosimilars over subcutaneous administration, certainly also taking into account the patient's preferences. Further cost-effectiveness analyses will be very important, along with expectations regarding successful concomitant subcutaneous administration of trastuzumab with other anticancer drugs, such as pertuzumab. This systematic review describes and analyzes the so-far published studies concerning the use of the available trastuzumab biosimilars in HER-positive early and metastatic breast cancer in terms of efficacy, safety, and cost-benefit ratio. An attempt was also made to draw some conclusions and to comment on future needs and perspectives.