Multiplexed immunoassay approach to characterize antidrug antibody like specific reactivity.

Characterization of antidrug antibody (ADA)-like reactivity has emerged as critical element of bioanalytical design and assessment of compound immunogenicity risk. Multiplex immunoassay was applied to detect and characterize ADA like reactivity using Photonic Ring Immunoassay platform (Genalyte). Specific binding to human IgE or human recombinant IL21-receptor-Fc fusion using exogenous reagents as surrogates for drug-specific reactivity was investigated. Multiplexed assay format allowed identification of spiked antihuman IgE reactivity as murine IgG1 and endogenous antihuman recombinant IL21-receptor-Fc reactivity in rheumatoid arthritis sera as antihuman Fc-specific binding.  The ability of a multiplex immunoassay platform to identify isotype and domain specificity of antidrug immunoglobulins was shown to be effective and should be considered when screening and characterizing pre- and post-dose ADA reactivity.