Abstract OT2-01-05: A prospective real-world national study to evaluate the efficacy and safety of adjuvant biosimilar trastuzumab in the treatment of HER2-positive breast cancer

Abstract

Abstract Background: Treatment with anti-HER2 therapy significantly improved survival outcomes in patients with HER2-positive Breast Cancer (BC). In Brazil, Trastuzumab was the first biosimilar approved in the treatment of patients with breast (any disease setting) and advanced gastric cancer with overexpression of HER2. Increase access to this important treatment may be enhanced with biosimilar approval. The aim of this Real-World study is to assess the efficacy and safety of adjuvant biosimilar trastuzumab in Brazilian patients with early HER2+ BC. Methods: This is a national, multicenter, observational prospective, real-world study in a variety of Brazilian institutions. A hundred and seventy adult patients, with diagnosis of early stage HER2-positive breast cancer, who received at least one dose of biosimilar trastuzumab (Zedora) as adjuvant therapy will be included. Patients will be followed for 5 years after the use of biosimilar trastuzumab (Zedora), unless recurrence or death. Safety outcomes will be recorded. Efficacy outcomes include invasive relapse-free survival (IRFS) rate at 18, 24, 30 and 36 months treatment initiation. Given the inexistence of a specific hypothesis to be tested, sample size was based on the accuracy of the two-sided 95% confidence interval (95% CI) for the invasive disease relapse-free survival rate. Results: In development countries such as as Brazil, oncology treatments with biological drugs have high costs and represent an import ibarrier to patients access to anti HER2 therapy. The use of biosimilars may result in significant health care savings. Conclusions: Considering the HERITAGE study, in which biosimilarity was clearly demonstrated between the reference monoclonal antibody and the biosimilar, we do expect to find the same safety and efficacy profile. Citation Format: Leandro Alves, Débora Gagliato, Mayara de Paula, Ana Carolina Cardoso, Alexandre Alcantara, Maristela Precivale, Vivienne Castilho. A prospective real-world national study to evaluate the efficacy and safety of adjuvant biosimilar trastuzumab in the treatment of HER2-positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT2-01-05.