Safety and Effectiveness of Trastuzumab Biosimilar SB3 in Korean Patients, a Post-Marketing Surveillance Study.

Introduction: SB3 is a trastuzumab biosimilar approved in Australia, Brazil, Canada, the European Union, the Republic of Korea, Switzerland, and the USA. This real-world study evaluated safety and effectiveness of SB3 as part of the Korean post approval safety management system.

Methods: This post-marketing surveillance in Korea included patients in line with approved indications, i.e., patients with early or metastatic breast cancer or metastatic gastric cancer. Safety outcomes were adverse events (AEs) and adverse drug reactions. Effectiveness outcomes were tumor response and event-free survival.

Results: 424 patients were evaluated: 366 patients (86%) with early breast cancer, 53 patients (13%) with metastatic breast cancer, and 5 patients (1%) with metastatic gastric cancer. Among patients with breast cancer, AEs (mostly mild) and adverse drug reactions were reported by 158 (37.7%) and 57 (13.6%) patients, respectively. Most patients with an AE (141, 89.2%) had no change in treatment schedule. Treatment was temporarily suspended in 14 (8.9%) patients with an AE and completely discontinued in 7 (4.4%). Among patients with early and metastatic breast cancer who were evaluated for efficacy, objective response rates were 82.7% and 38.3%, respectively. Pathological complete response was 64.6% in patients with early breast cancer.

Discussion/conclusion: Safety and efficacy of SB3 demonstrated in this real-world study were comparable with previous studies of reference trastuzumab.