By Taylor-Anne Gorman, Dr Sophie Moncrieff, Dr Graeme Anderson, Sartorius-Stedim BioOutsource During biosimilar drug characterization, the use of orthogonal methods is necessary in providing a complete, detailed overview of the molecule being assessed – Surface Plasmon Resonance (SPR) assays allow for the description of an interaction by both kinetics and affinity, and are able to generate a wealth of information per sample assessment. At Sartorius Stedim BioOutsource, we are developing and have developed a number of SPR assays which use Biacore instruments to assess binding of drug molecules to target molecules, FcRn, and Fcγ-Receptors, and are able to provide an overview of the performance of a biosimilar molecule.