Abstract 1526
Background
Equivalence for efficacy between SB3 (a proposed trastuzumab biosimilar) and originator trastuzumab (TRZ) in terms of breast pathologic complete response (bpCR) rates has been demonstrated and previously reported.1 Here we present the one-year results on safety, immunogenicity, event-free-survival (EFS), and overall survival (OS).
Methods
Study compared neoadjuvant SB3 or TRZ for 8 cycles concurrently with chemotherapy (4 cycles of docetaxel followed by 4 cycles of 5-fluorouracil/epirubicin/cyclophosphamide). Patients then underwent surgery followed by 10 cycles of adjuvant SB3 or TRZ as randomised. The primary endpoint was bpCR rate and secondary endpoints included safety, immunogenicity, EFS, and OS up to the adjuvant period.
Results
A total of 875 patients were randomised with a median follow-up duration of 438 days, and 765 patients completed adjuvant therapy (SB3, N = 381; TRZ, N = 384). Incidences of treatment emergent adverse events (TEAEs) were comparable between arms (Table). Most frequently occurring TEAEs were alopecia, neutropenia, and nausea during the neoadjuvant period and radiation skin injury, procedural pain, and fatigue during the adjuvant period. EFS rates were 92.2% in SB3 and 91.6% in TRZ (hazard ratio 0.94; 95% CI, 0.59 to 1.51). There were a total of 6 deaths (SB3, N = 1; TRZ, N = 5). Immunogenicity was low and comparable, with anti-drug antibody positive for 3 patients (0.7%), in each arm.Table:
153PD Safety profile
| SB3 N = 437 n, (%) | TRZ N = 438 n, (%) | |
|---|---|---|
| Incidence of TEAEs | 426 (97.5) | 421 (96.1) |
| Grade ≥ 3 TEAEs | 325 (74.3) | 315 (71.9) |
| TEAEs of special interest* | 48 (11.0) | 53 (12.1) |
| Serious TEAEs | 56 (12.8) | 58 (13.2) |
| Death | 1 (0.2) | 5 (1.1) |
Includes infusion-related reaction, left ventricular systolic dysfunction, and congestive heart failure.
Conclusions
One-year safety, immunogenicity, and survival results further support the biosimilarity established between SB3 and TRZ. Reference: 1. Pivot X et al. ASCO 2017, ID50
Clinical trial identification
EudraCT Number: 2013-004172-35 ClinicalTrials.gov NCT02149524
Legal entity responsible for the study
Samsung Bioepis Co., Ltd.
Funding
Samsung Bioepis Co., Ltd.
Disclosure
X. Pivot: Consultant with honorarium for Samsung Bioepis Co., Ltd. L. Younju, J. Lim: Employee of Samsung Bioepis Co., Ltd. Stock ownership of Samsung Biologics. All other authors have declared no conflicts of interest.