Extended Stability of Reconstituted and Diluted SB3 (Trastuzumab Biosimilar) Assessed by Physicochemical and Biological Properties

IntroductionStability information for the trastuzumab biosimilar SB3 is limited to 48h at 2-8 degrees C for the reconstituted solution and 24h at up to 30 degrees C for diluted solutions. Extended physicochemical stability and biological activity were assessed to evaluate the advanced preparation of reconstituted and diluted SB3.MethodsUnder controlled and aseptic conditions, the stability of reconstituted and diluted SB3 was evaluated using several assessments and according to the UK's National Health Service guidance. Reconstituted SB3 was stored at 252 degrees C with 605% relative humidity for 3days, and subsequently diluted SB3 (0.32-4mg/mL) was stored in an infusion bag in the absence of light at 252 degrees C with 60 +/- 5% relative humidity for 28days and 5 +/- 3 degrees C for 28days, respectively. Physicochemical stability (appearance, pH, protein concentration, size exclusion high-performance liquid chromatography, non-reducing capillary electrophoresis-sodium dodecyl sulfate, imaged capillary isoelectric focusing), biological activity (competitive inhibition binding assay to human epidermal growth factor receptor 2 by fluorescence resonance energy transfer, anti-proliferation assay), and properties with a potential safety impact (subvisible particulates, submicronic aggregation by dynamic light scattering) were determined.Results No physicochemical instability signs or biological activity changes were observed for either reconstituted or diluted SB3 up to 28days; all stability acceptance criteria were met. No major change was noted in the proportion of molecular weight variants (high molecular weight impurity, total purity) or relative percentages of acidic, main, and basic charge isoforms of the protein. No increases in particulates or aggregates in terms of a potential safety impact were noted.Conclusion The physicochemical stability and biological activity of reconstituted and diluted SB3 are maintained for extended time periods beyond those denoted in the product labeling, which allows for advanced SB3 preparation and may reduce drug wastage and preparation time.Funding Samsung Bioepis Co., Ltd.