Therapeutic antibody and biosimilar higher order structure (HOS) analysis should compare the primary (amino acid sequence) and higher order structures, including secondary, tertiary, and quaternary structures. The EMA stresses the importance of comparability of the biosimilar’s and the originator therapeutic antibody’s HOS. Undoubtedly, detailed structural characterization is highly relevant to the process. This is understandable, given the importance of the molecule’s overall conformation, especially the conformation of the compatibility-determining and framework regions (CDR and FR), which are essential for antigen recognition. Alterations in these structures may affect the therapeutic antibody’s ability to recognize its antigen and reduce its efficacy. Methods like UV and fluorescent spectroscopy are recommended for tertiary structure analysis, while Fourier Transform Infrared (FTIR) and CD spectroscopy are recommended for secondary structure analysis. However, as recent research has demonstrated, 2D NMR spectroscopy yields much more accurate and reliable information. The SARomics Biostructures’ team uses 2D NMR spectroscopy alone or in combination with X-ray crystallography for cost-efficient and high-precision comparability analysis of therapeutic antibody and biosimilar higher order structure.
