On December 8, 2018 Samsung Bioepis Co., Ltd. reported the results of an additional one-year follow-up study comparing event-free survival (EFS) of SB3, a biosimilar candidate referencing HERCEPTIN 1 (trastuzumab), to reference trastuzumab (TRZ) by antibody-dependent cell-mediated cytotoxicity (ADCC) activity (Press release, Samsung Bioepis, DEC 8, 2018, View Source [SID1234531973]). ADCC is a key mechanism of action for trastuzumab. The study results are being presented at the 2018 San Antonio Breast Cancer Symposium (SABCS) which is being held December 4-8, 2018 in San Antonio, Texas.
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For the study, patients with HER2 positive early or locally advanced breast cancer were randomly assigned to receive SB3 or TRZ concurrently with chemotherapy. Patients then underwent surgery followed by treatment with SB3 or TRZ. Following completion of such therapy, 367 patients participated in a long-term follow-up study, 186 of whom were treated with SB3 and 181 of whom were treated with TRZ. Within the group of 181 patients who received TRZ, 126 patients who were exposed to at least one kit from the TRZ lots with expiry dates between August 2018 and December 2019 during neoadjuvant period were considered "Exposed," while the remaining 55 patients were considered "Unexposed." Upon monitoring the quality attributes of TRZ for the development of SB3, a marked downward shift in ADCC activity was observed in some of the TRZ lots with expiry dates between August 2018 and December 2019.
Following 30.1 months of SB3 treatment and 30.2 months of TRZ treatment, there was no statistically significant difference in EFS between SB3 (96.7%) and the Unexposed arm (98.2%) (HR 1.19, 95% CI 0.23-6.18; p-value=0.8376). However, the results did show statistically significant difference in EFS between the Unexposed (98.2%) and Exposed (92.5%) arms within the TRZ treatment group (HR 0.07, 95% CI 0.01-0.58, p-value=0.0137). In addition, while there was no statistically significant difference in events between SB3 (4.8%) and the Unexposed (3.6%) arms, there was statistically significant difference in events within the TRZ treatment group between the Unexposed (3.6%) and Exposed (10.3%) arms. An event was defined as disease recurrence or progression, or death due to any cause. The study authors are currently looking into longer-term effects of SB3 and hope to publish these results at a later date.
"This study builds on the robust evidence for SB3, and demonstrates the trastuzumab biosimilar candidate’s comparable efficacy and safety profiles to the reference biologic over a longer time period," said Chul Kim, Senior Vice President and Head of Clinical Science, Samsung Bioepis. "We remain committed to advancing our strong pipeline of biosimilar candidates, so that more patients and healthcare systems may be able to benefit from biosimilar medicines."
The poster for this study will be exhibited at SABCS, as follows:
[P6-17-09] EVENT-FREE SURVIVAL BY ADCC STATUS FROM A FOLLOW-UP STUDY COMPARING SB3 (TRASTUZUMAB BIOSIMILAR) WITH REFERENCE TRASTUZUMAB FOR HER2 POSITIVE BREAST CANCER IN NEOADJUVANT SETTING [POSTER SESSION 6, December 8, 2018, 07:00AM – 09:00AM]