RESUMO
BACKGROUND: The discovery of trastuzumab as anti-HER2 therapy has markedly improved disease control and the survival rates of patients with HER2+ breast cancer. However, as trastuzumab is considered a complex molecule, the cost of production is usually elevated, which significantly affects health budgets and limits the treatment access for patients who live in underdeveloped countries. Recently, trastuzumab production has become more accessible and sustainable due to the patents' expiration, allowing biosimilar versions of trastuzumab to be developed. OBJECTIVE: Our main goal was to shed more light on the uses of biosimilars in breast cancer treatment, emphasizing trastuzumab. METHOD: An integrative search was carried out on the PubMed, Scielo, Web of Science, and SCOPUS databases using the terms "biosimilar," "breast cancer," "monoclonal antibody," and "trastuzumab." The time range included scientific articles published from 2015 to 2021. RESULTS AND DISCUSSION: The bibliographic survey showed the complexities in biological medicine manufacturing and how the monoclonal antibody's therapy with trastuzumab improved the patients' life expectancy, revolutionizing HER2+ breast cancer treatment. Nonetheless, despite its benefits, trastuzumab generates certain restrictions, especially from the economic perspective. Trastuzumab biosimilars have high selectivity and rarely cause adverse effects compared to conventional chemotherapy. CONCLUSION: This study shows that trastuzumab biosimilars improve patients' accessibility to breast cancer treatment through a safe and effective therapy compared to the drug reference.