Label-free interaction analysis as a tool to demonstrate biosimilarity of therapeutic monoclonal antibodies

In the biosimilar eon, where various analytical platforms are needed to show biosimilarity, we demonstrate the use of surface plasmon resonance biosensor as a label-free interaction analysis tool to compare two therapeutic monoclonal antibodies (mAb1-i and mAb2-i) with their biosimilars (mAb1-B and mAb2-B1, B2, B3) based on kinetics, affinity, and thermal stability studies. We calculate active analyte concentration using Biacore systems' calibration-free concentration analysis method and demonstrate its importance for kinetic evaluation. The kinetic constants ( k a and k d ) and affinity constant ( K D ) of the mAbs for binding to specific antigens were evaluated. It was found that the biosimilars were very similar to their innovator with respect to binding to its antigen demonstrating functional similarity. To further confirm biosimilarity to the originator molecules, we conducted a thermal stability analysis of both mAbs using differential scanning calorimetry. This analysis showed good structural similarity in between innovator antibodies and biosimilars, with major T m as 84.1°C (mAb1) and 72.8°C (mAb2), demonstrating structural similarity.