Samsung Bioepis Releases Positive 5-Year Follow-up Results for Trastuzumab Biosimilar

Five-year follow-up data show comparable safety and long-term efficacy profiles between Ontruzant (SB3), a trastuzumab biosimilar developed by Samsung Bioepis, and the reference product, according to a statement from the company.

The full results from its long-term safety and efficacy analysis will be presented at ESMO Congress 2021.

Trastuzumab medicines are indicated for use in patients with early or metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer, metastatic gastric cancer, and gastroesophageal junction adenocarcinoma. Currently, there are 5 trastuzumab biosimilars approved by the FDA in the United States and 6 approved in the European Union, including SB3, according to The Center for Biosimilars^® Biosimilar Approvals directory.

“The 5-year follow-up results presented at this year’s ESMO is the longest monitoring data of patients treated with a trastuzumab biosimilar for HER2-positive early or locally advanced breast cancer,” said Donghoon Shin, vice president and team leader of the Medical and Lifecycle Safety Team at Samsung Bioepis, in the company’s statement.

The investigators enrolled 875 patients in a phase 3 trial and administered 8 cycles of the trastuzumab biosimilar or the reference product Herceptin (Genentech) in combination with chemotherapy. After completing the regimen and undergoing surgery, the patients received another 10 cycles of the biosimilar or referencing product to complete 1 year of treatment.

After the phase 3 trial was completed, 367 patients were enrolled in the follow-up study, during which 186 were in the biosimilar trastuzumab group and 181 were in the reference product group. The median follow-up time was 68 months following randomization.

During the follow-up period, asymptomatic significant left ventricular ejection fraction (LVEF) decrease occurred in 1 patient from the biosimilar group and 2 patients from the reference product group. All 3 patients recovered with an LVEF of 50% or greater. No cases of symptomatic congestive heart failure or cardiac death were reported in either group.

Recurrence, progression, or death was reported in 32 (17.2%) patients in the biosimilar group and 38 (21%) patients in the reference product group (HR, 0.78; 95% CI, 0.48-1.25; P = .30). The 5-year event-free survival rate was 82.8% in the biosimilar group, which was similar to the reference product group (79.7%). The 5-year overall survival rate was also similar between the biosimilar and reference product groups (93.1% vs 86.7%; HR, 0.62; 95% CI, 0.32-1.22; P = .17).

“This valuable data signifies our continuous dedication in producing high-quality treatments with proven efficacy and safety... We look forward to sharing our data with the oncology community on the usage of biosimilars based on this long-term follow-up data,” said Shin.

The 150-mg single-dose for Ontruzant was approved by the FDA in January 2019 and launched on the US market in April 2020. Ontruzant received marketing authorization from the European Medicines Agency in November 2017.

In March 2020, the FDA approved a 420-mg multidose vial of Ontruzant. This dose was also approved in the European Union in March 2019.

Reference

Samsung Bioepis announces five-year follow-up results for Ontruzant (trastuzumab) in early or locally advanced HER2 positive breast cancer at the European Society for Medical Oncology (ESMO) Virtual Congress 2021. Press release. Samsung Bioepis. September 13, 2020. Accessed September 14, 2021. https://www.samsungbioepis.com/en/newsroom/newsroomView.do?idx=251&currentPage=1