Three-Year Data Support Efficacy of Biosimilar Ontruzant in Breast Cancer

Three-year follow-up data demonstrated comparable overall survival (OS) and cardiac safety between biosimilar trastuzumab (Ontruzant, Samsung Bioepis) and the reference product (Herceptin, Genentech), according to a recent phase 3 study.

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

Trastuzumab-dttb, Samsung Bioepis trastuzumab biosimilar product, was approved by the FDA in January 2019 for the treatment of human epidermal growth factor receptor 2- (HER2) positive breast cancer and HER2 overexpressing gastric cancer. It was first approved in the European Union in November 2017.

In an initial phase 3 study, patients with early or locally advanced HER2-positive breast cancer received 8 cycles of the biosimilar or the reference medicine concurrently with chemotherapy in the neoadjuvant setting. After surgery, they received an additional 10 cycles of the biosimilar or the reference product.

After being treated, 367 patients were enrolled in the follow-up study, in which median follow-up from initiation of the study treatment was 40.8 months in the biosimilar group versus 40.5 months in the reference product group.

According to the findings:

• In the biosimilar group, OS was 97% compared with 93.6% in the reference medicine group (HR 0.39, 95% Cl, 0.14-1.12).
• Event-free survival was 92.5% in the biosimilar group versus 86.3% in the reference medicine group (HR 0.49, 95% Cl, 0.26-0.91).
• The incidence of cardiac events was rare for both treatment groups throughout the 3-year follow-up period, with 3 cases of asymptomatic significant left ventricular ejection fraction (LVEF) decrease, with all patients recovering with LVEF ≥ 50%.

No cases of symptomatic congestive heart failure, cardiac death, or other significant cardiac conditions were reported in either treatment 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 underlie the importance of that aim,” Chul Kim, senior vice president and head of clinical sciences division at Samsung Bioepis, said in a prepared 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.”

Samsung Bioepis’ product was the third trastuzumab biosimilar to be approved in the United States.

Reference

Samsung Bioepis Announces Three-year Follow-up Data for biosimilar Ontruzant (trastuzumab) in Early or Locally Advanced HER2-positive Breast Cancer [news release]. Samsung Bioepis. http://www.samsungbioepis.com/en/newsroom/detail/Samsung-Bioepis-Announces-Three-year-Follow-up-Data.html. Accessed March 21, 2019.