Cellular tools for biosimilar mAb analysis

Background For the development of biosimilar monoclonal antibodies (mAb) or related substances containing the IgG Fc part it is mandatory to fully compare immunological properties between originator and biosimilar in a “comparability exercise” [1]. The most complex Fc associated function to mediate antibody dependent cellular cytotoxicity (ADCC) needs to be characterized using the active substance of the biosimilar and the comparator. From a regulatory point of view potency assays should reflect the proposed mode of action but in vitro ADCC assays are considered difficult to validate due to the variability of the primary effector cells [2,3]. The requirement to test for ADCC with high precision and accuracy is challenging. Design of cell lines to replace primary cells for effector or target cells is a solution to provide tools for standardized and extensive biosimilar testing.