We employ a novel circular dichroism (CD) technology coupled with statistical analysis to assess the higher-order structure (HOS) similarity of commercially available trastuzumab and a proposed biosimilar. This technology shows good potential for enabling the comparison of similarities and differences in secondary and tertiary structures of proteins. Multiple CD spectra in far- and near-UV are obtained reproducibly from a CD spectrometer with fully integrated autosampler and flow cell to eliminate the errors typically associated with sample handling on manual CD spectrometers. The significance of similarities or differences was quantified statistically using three analytical methods (weighted spectral difference, correlation coefficient, and area of overlap). HOS comparison of the secondary structure (far-UV CD spectra) suggested similarity between the innovator drug, trastuzumab (Herceptin^®), and biosimilar products. However, the tertiary structure (near-UV CD spectra) suggested statistically significant differences. These differences may be due to changes in tertiary structure or to modifications and degradations during the process of production or storage. The results show that the automated circular dichroism technology coupled with statistical analysis is a robust tool for enabling the comparison of similarities and differences in secondary and tertiary structures of protein products.

我们采用新颖的圆二色性（CD）技术以及统计分析来评估市售曲妥珠单抗和拟议的生物仿制药的高阶结构（HOS）相似性。该技术显示出有潜力进行蛋白质二级和三级结构相似性和差异的比较。具有完全集成的自动进样器和流通池的CD光谱仪可重现远紫外光和近紫外光谱的多个CD光谱，从而消除了通常与手动CD光谱仪上的样品处理相关的误差。使用三种分析方法（加权光谱差异，相关系数和重叠面积）以统计学方式量化相似性或差异的重要性。^®）和生物仿制药产品。但是，三级结构（近紫外CD光谱）表明存在统计学差异。这些差异可能是由于在生产或储存过程中三级结构的变化或修饰和降解引起的。结果表明，自动圆二色性技术与统计分析相结合是一种强大的工具，可用于比较蛋白质产品二级和三级结构的相似性和差异。