Samsung Bioepis said Thursday that SB3, a biosimilar of Herceptin (ingredient: trastuzumab), showed similar long-term survival results to its original drug after a median follow-up of 68 months from the phase 3 study.
The five-year results are the longest monitored data as of December 2021 for a trastuzumab biosimilar drug used in patients with HER2-positive early or locally advanced breast cancer. The data were presented during the 2021 San Antonio Breast Cancer Symposium (SABCS) on-site in San Antonio, Texas, and virtually, from Dec. 7-12.
The company said that the cardiac safety and efficacy results after a 68-month follow-up with 367 patients who participated in the study were also unveiled at the European Society for Medical Oncology (ESMO) Congress in September 2021.
Additional analysis results presented at the 2021 SABCS assessed five-year follow-up survival outcomes in a larger group of patients, including 171 patients with subgroup analysis based on drifted or non-drifted trastuzumab lots used in patients.
The five-year event-free survival (EFS) was comparable between SB3 and trastuzumab groups as the biosimilar SB3 showed 79.8 percent EFS while the original drug demonstrated 75.0 percent EFS.
When SB3 was compared with non-drifted trastuzumab in the post-hoc analysis, SB3 showed an EFS rate of 79.8 percent compared to the non-drifted trastuzumab group’s 82.5 percent.
The study also showed a similar outcome in OS, in which SB3 recorded 92.5 percent and the non-drifted trastuzumab group showed 91.4 percent.
“For HER2-positive breast cancer therapy, monitoring long-term outcome is important, and we hope the five-year follow-up study results in a large group of patients provide meaningful value to the oncology society by demonstrating robust comparable long-term safety and efficacy profile of a trastuzumab biosimilar,” said Shin Dong-hoon, vice president and leader of medical and lifecycle safety team at Samsung Bioepis.
Samsung Bioepis will continue to bring updated clinical and real-world evidence on biosimilars to the medical society so that health care providers and patients can feel confident in using biosimilars for oncologic conditions, Shin added.
The U.S. Food and Drug Administration approved SB3 as a single-dose vial of 150 milligrams under the brand name Ontruzant in January 2019 and as a 420-milligram multi-dose vial in March 2020. The company is marketing the biosimilar drug in the U.S. through Organon.