Brazilian oncologists showed a solid knowledge base about biosimilars and their safety; however, concerns over extrapolation and interchangeability requirements remained, suggesting that more education on these subjects is needed.
Oncologists in Brazil demonstrated a high level of knowledge of biosimilars and are generally willing to prescribe them, but concerns about extrapolated indications and interchangeability remain, suggesting that more efforts on medical education programs on biosimilars are needed, according to a recent study.
“This [study] raises the opportunity for future educational initiatives to contribute to a broader understanding of concepts involving biosimilars and the extrapolation of indications,” the investigators wrote.
The study, published in Future Oncology, is the first study in Brazil to investigate and analyze the opinions, practices, and concerns of oncologists in regard to biosimilars referencing originator trastuzumab (Herceptin).
In Brazil, the National Health Surveillance Agency (ANVISA) has approved 4 trastuzumab biosimilars for the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer, with the first biosimilar gaining regulatory approval in 2017.
Past research has demonstrated that prescribers have some concerns and doubts surrounding the approval process for biosimilars, the definition of interchangeability and nonmedical switching, the requirements for extrapolation of indications, and the safety and efficacy of these agents.
Extrapolation allows for a biosimilar to be used for indications that have been approved for the reference product but may not have been tested for the biosimilar. Interchangeability allows for a biosimilar to be used in place of a reference product without seeking permission from a physician. Interchangeability is a regulatory designation unique to the United States and is implemented on a country-by-country basis in the European Union. It is not a regulatory requirement for biosimilar registration according to ANVISA.
The investigators distributed a 24-question survey using an online platform to 144 oncologists recruited from 5 Brazilian regions between July and September 2019. The survey asked for information on the providers’ basic knowledge of biosimilars and trastuzumab biosimilars as well as their level of comfort with extrapolation and switching treatment regimens and how the cost of HER2-positive breast cancer therapies impacts their prescribing patterns.
The median age of the respondents was 38 years and 55.6% of them were men. Regarding experience, 70% had between 3 and 10 years of clinical practice experience and 30% had more than 10 years of experience.
Overall, 95% of the respondents correctly knew what a biosimilar was. However, 4% believed that biosimilar were as effective as their reference products but not as safe and 1% equated biosimilars as being the same as generic drugs. Additionally, 95% said that they would feel comfortable prescribing a trastuzumab biosimilar, whereas 4% reported feeling uncomfortable prescribing them because they were unaware about the approval process for biosimilars.
Despite the high number of respondents who said that they would prescribe a trastuzumab biosimilar, only 63% of respondents said that they would prescribe a biosimilar in all settings where the reference product is approved, whereas 35% said that they would only do so if a patients’ case was metastatic. Also, 82% of oncologists were in favor of switching a patient from a reference product to a biosimilar but 18% said that they would avoid switching regimens.
“These results could reflect a gap in Brazilian prescribers’ knowledge of the scientific justification underlying the regulatory approval of biosimilars, as 37% of the respondents viewed extrapolation as a problem even in the same disease setting,” the authors noted.
Regarding the reasons behind whether or not to prescribe a trastuzumab biosimilar, 81% of the respondents said that they do not have any concerns and have already incorporated biosimilars into their routine practice. Alas, 8% of oncologists still expressed concerns about the clinical similarity of trastuzumab biosimilars in comparison to the reference product, and 3% said that they did not use or believe in the quality of biosimilars.
The investigators cited their small sample size as a major limitation of the study, which represented about 4% of oncologists in Brazil.
Resende HM, Lasislau L, Cardoso ACF, et al. Biosimilar use in breast cancer treatment: A national survey of Brazilian oncologists’ opinions, practices, and concerns. Futur Oncol. August 20, 2021;17(26):1316-1324. doi: 10.2217/fon-2021-0532