A Competitive Ligand-Binding Assay for Simultaneous Detection of Neutralizing Antibodies to Both Arms of a Bispecific Drug.

Bispecific monoclonal antibodies gain their attractiveness as a novel class of drugs that are capable of neutralizing two or more cytokines simultaneously or activate hetero-dimeric cell receptors. Monitoring appearance of neutralizing antibodies (NAbs) to these drugs is a challenging task. Here, we report a competitive ligand- binding assay (CLBA) for detection of NAbs to a bispecific candidate drug using a multiplex Meso Scale Discovery (MSD) platform, which allows for detection of NAbs to both drug arms in the same sample. The assay has sensitivity better than 250 ng/mL, is tolerant to the presence of drug at concentration > 600 μg/mL, and to the level of soluble target(s) >400 ng/mL. Thus, multiplex approach provided by MSD platform can be successfully used for development of NAb assays in competitive ligand-binding assay format.