Anti-drug antibodies validation

Quasi-quantitative assays traditionally include measures of enzymatic or ligandbinding activity, as in flow cytometry and anti-drug antibody assays [9]. One of the common characteristics of these assays is the lack of a true reference standard, where reference standards are poorly characterized, do not completely represent native protein, or differ from native proteins in terms of potency or immunoreactivity. As stated above, if the analytical response is continuous across the range in question, the analytical results can be expressed in terms of a characteristic of known test samples. The following is one example an ELISA qualified as a quasi-quantitative assay because it could not be validated as a relative quantitative assay. 

While the procedures and the parameters evaluated during the validation for each ADA method may be different, each of them must be able to distinguish a positive from a negative response in a complex milieu. Without appropriately validated anti-drug antibody assays, the relevance of ADA on safety and efficacy in the context of nonclinical and clinical studies cannot be determined. 

Despite all these efforts to predict protein drug immunogenicity in humans, the final proof for the presence of immunogenic epitopes are clinical trials in combination with sensitive and validated assays to reliably determine the level of anti-protein drug antibodies and their impact on drug safety and efficacy. 

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