Extrapolation of indications and drug interchangeability as barriers to use trastuzumab-dkst biosimilar in Brazil.

Abstract

e13010 Background: Brazil has a complex health-care system which comprises 76% of population in the public unified health system (SUS) and only 24% in private system. Even with most of the population in the public system low resources has been allocated SUS by the government compared with that in private system. Breast cancer (BC) is the more frequent malignant neoplasm in Brazilian women, including HER2 overexpression, and the most are treated in SUS. Although, the HER2 blockage benefits in overall survival have been demonstrated since 2005, the adjuvant and neoadjuvant HER2 blockage was included in SUS protocols only 2013 while the metastatic only 2018. Brazil and development countries have limited accesses to biological drugs and target therapies due to the high cost. The biosimilar technology would improve the patient access to these drugs, health-care savings with efficacy and safety. In 2017, Brazil has approved the first biosimilar in oncology, the anti-HER2 monoclonal antibody trastuzumab-dkst. Our aim is understanding the reasons that hampered the Brazilian oncologists changing practice about biosimilars. Methods: We submitted an on-line survey with 12 questions to 144 Brazilian oncologists which are registered in Brazilian Clinical Oncology Society from North, Northeast, Center east, Center west and Southeast regions in Brazil. The questions were about the anti-HER2 biosimilars knowledge, the manufacturing process, the costs, the biosimilars-based clinical trial, the drug efficacy and safety. Results: We observed that all responders have 9 years experienced oncologist with mean of care 15 patient with HER2 BC per month. In total, 95% of oncologist knows biosimilar definition and 96% assume prescribe biosimilars without doubts. However, 81% oncologists would prescribe biosimilars to all patients, 82% would interchanges and 63% would extrapolate the indication. Conclusions: This survey was conducted to understand the Brazilian oncologist knowledge about biosimilar. We demonstrated a high knowledge of biosimilar definition, however with high percentage indicated adherence barriers. The pharmacovigilance, clinical trials that support biosimilar approval and extrapolation concepts are the main aspects to be addressed. The opportunity of patient access with biosimilars is real and it is the oncologist’s duty to engage in medical education programs. This study could highlight a crucial need for greater strategies to educate physicians, to disseminate biosimilars and provide more informed decision making.