FTIR spectroscopy as an analytical tool to compare glycosylation in therapeutic monoclonal antibodies

Glycosylation is the most common protein post-translational modification (PTM), especially in biopharmaceuticals. It is a critical quality attribute as it impacts product solubility, stability, half-life, pharmacokinetics and pharmacodynamics (PK/PD), bioactivity and safety (e.g. immunogenicity). Yet, current glycan analysis methods involve multiple and lengthy sample preparation steps which can affect the robustness of the analyses. The development of orthogonal, direct and simple method is therefore desirable. In this study, we suggest use of FTIR spectroscopy to address this challenge. Use of this technique, combined with statistical tools, to compare samples or batches in terms of glycosylation or monosaccharide profile, has three potential applications: to compare glycosylation of a biosimilar and the original (innovator) molecule, for monitoring of batch-to-batch consistency, and for in-process control. Fourteen therapeutic monoclonal antibodies (mAbs), one Fc-fusion protein and several other common glycoproteins have been used to demonstrate that FTIR spectra of glycoproteins display spectral variations according to their glycan and monosaccharide compositions. We show that FTIR spectra of glycoproteins provide a global but accurate fingerprint of the glycosylation profile. This fingerprint is not only sensitive to large differences such as the presence or absence of several monosaccharides but also to smaller modifications of the glycan and monosaccharide content.