ADCC Reporter Bioassay: A Novel, Bioluminescent Cell-Based Assay for Quantifying Fc Effector Function of Antibodies

Antibody dependent cell-mediated cytotoxicity (ADCC) assays are typically performed using PBMCs or NK cells and suffer from high variability and poor reproducibility. To circumvent these issues, Promega has developed a reporter-based ADCC bioassay using an effector cell line that stably expresses an NFAT luciferase response element and human FcgIIIa high affinity (V158) receptor. When the effector cells are exposed to antibodies bound to target cells, activation of the FcgIIIa receptor signaling pathway occurs resulting in increased luciferase activity, which correlates to cytotoxic ADCC assays. By eliminating PBMCs or NK cells, the assay reproducibility is greatly increased and the variability is significantly reduced, while retaining the ability to discriminate antibodies with varying degrees of Fc effector function. The novel ADCC Reporter Bioassay contains effector cells in frozen, thaw-and-use format, which greatly reduces hands-on preparation typically required for an ADCC assay. Following DOE studies, the ADCC Reporter Bioassay was tested with FDA-approved antibodies (i.e., rituximab and trastuzumab) in qualification studies and the assay showed excellent linearity, accuracy, and precision. Studies using treated samples demonstrated the assay to be stability-indicating. Furthermore, the assay shows good linear correlation between levels of glycosylation and a fucosylation with ADCC activity. Overall, the ADCC Reporter Bioassay is able to quantify Fc effector functionality and is a suitable replacement for classic cytotoxic ADCC assays, when low variability and high reproducibility are required.