Analytical approaches for the evaluation of ADCC activity of mAbs

Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) is a mechanism of action of antibodies through which virusinfected or cancer cells are targeted for destruction by components of the cell-mediated immune system, such as natural killer cells. For most monoclonal antibodies targeting cell-surface antigens, ADCC is usually the mechanism that better reflects the in vivo mode of action of the drug. For this reason, quality control assays based on ADCC activity are required. In this application note, the use of a commercial kit commercialised by Promega to determine ADCC activity of anti-CD20 antibodies is presented. Complementary methods based on binding properties by Surface Plasmon Resonance and on the determination of the N-glycosylation profile by high-resolution mass spectrometry are also discussed.

ADCC activity is one of the main mechanisms of actions of therapeutic monoclonal antibodies used for oncology indications. The activity of these antibodies can be studied in vitro using a reporter-gene cell-based assay. This test is usually part of the control strategy of the drug substance and drug product.

In some cases, surrogate tests can be used. Binding to FcγRIIIa receptor using Surface Plasmon Resonance is one of these tests. Additionally, the study of antibody core fucosylation can provide useful information, e.g. to interpret differences that may arise in terms of in vitro ADCC activity.