Samsung Bioepis Co., Ltd. announced findings of a three-year follow-up study comparing biosimilar ONTRUZANT® (trastuzumab) and reference medicine trastuzumab in early or locally advanced HER2-positive breast cancer.
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. 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,
said Chul Kim, Senior Vice President
and Head of Clinical Sciences Division, Samsung Bioepis.
Participants enrolled in an initial Phase III study received eight cycles of the biosimilar trastuzumab or the reference medicine concurrently with chemotherapy in the neoadjuvant setting. Following 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 (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). The incidence of cardiac events was rare for both treatment groups throughout the three-year follow-up period. There were three cases of asymptomatic significant left ventricular ejection fraction (LVEF) decrease (biosimilar trastuzumab, n=1; reference medicine, n=2), with all patients recovering with LVEF ≥ 50%. There were no cases of symptomatic congestive heart failure, cardiac death or other significant cardiac conditions reported in either group.