Samsung Bioepis Posts 3-Year Follow-up Data for Ontruzant

Samsung Bioepis released 3-year follow-up findings of Ontruzant, a biosimilar trastuzumab referencing Herceptin, in early or locally advanced HER2-positive breast cancer, and says it showed comparable overall survival and cardiac safety.

The FDA approved Ontruzant in January for marketing in the United States.

Participants enrolled in an initial phase 3 study received 8 cycles of the biosimilar trastuzumab or the reference medicine concurrently with chemotherapy in the neoadjuvant setting. After surgery, they received additional 10 cycles of the biosimilar trastuzumab or the reference medicine.

After completion of therapy, 367 of these participants (186 in the biosimilar trastuzumab group and 181 in the reference medicine group) were enrolled in the follow-up study. Median follow-up from initiation of study treatment was 40.8 months in the biosimilar trastuzumab group and 40.5 months in the reference medicine group.

Overall survival was 97% in the biosimilar trastuzumab group and 93.6% in the reference medicine group (hazard ratio [HR], 0.39; 95% CI, 0.14-1.12). Event-free survival was 92.5% in the biosimilar trastuzumab group and 86.3% in the reference medicine group (HR, 0.49; 95% CI, 0.26-0.91).

Cardiac events were rare for both treatment groups. There were 3 cases of asymptomatic significant left ventricular ejection fraction (LVEF) decrease (biosimilar trastuzumab, n = 1; reference medicine, n = 2), with all patients recovering with LVEF of 50% or greater. There were no cases of symptomatic congestive heart failure, cardiac death, or other significant cardiac conditions reported in either group.

“With the development of our biosimilar trastuzumab, we aimed to make one of the mainstays of modern cancer therapy more accessible for more people more quickly, and these long-term data underline the importance of that aim,” says Chul Kim, senior vice president and head of clinical sciences division, Samsung Bioepis, in a statement. “We are committed to increasing access to high-quality, life-changing oncology medicines through the development of biosimilars to address some of oncology’s most pressing challenges.”

The drug was first approved by the European Medicines Agency in November 2017, making it the first biosimilar trastuzumab to be approved in the European Union.

The data were presented at the 16th St. Gallen International Breast Cancer Conference 2019 in Austria.