How Similar Is Biosimilar? A Comparison of Infliximab Therapeutics in Regard to Charge Variant Profile and Antigen Binding Affinity

Biosimilars are increasing in economic importance. Just how similar a biosimilar needs to be to gain market approval is currently still decided on a per case basis. The authors try to shed light on one often cited critical quality attribute of monoclonal antibodies, namely charge heterogeneity. Using high resolution electrophoretic and chromatographic methods, the authors are able to separate and quantify the charge variant content of infliximab originator and three biosimilars. Additionally the authors quantified and compared the antigen binding affinity in an SPR based binding assay and analyzed the glycosylation pattern of all four of these infliximab biosimilar products. Even though the analytical methods did not show full similarity between originator and some biosimilars, all of the biosimilars have gained approval based on their clinical comparability. The authors would therefore argue, that analytical comparison is not always a good predictor for clinical interchangeability. Any future regulatory framework for the approval of biosimilars should reflect that the parameters chosen for analytical comparability have to be chosen carefully.