Immunogenicity of therapeutics: a matter of efficacy and safety.

IMPORTANCE OF THE FIELD: The unwanted immunogenicity of therapeutic proteins is a major concern regarding patient safety. Furthermore, pharmacokinetic, pharmacodynamic and clinical efficacy can be seriously affected by the immunogenicity of therapeutic proteins. Authorities have fully recognized this issue and demand appropriate and well-characterized assays to detect anti-drug antibodies (ADAs). AREAS COVERED IN THIS REVIEW: We provide an overview of the immunogenicity topic in general, the regulatory background and insight into underlying immunological mechanisms and the limited ability to predict clinical immunogenicity a priori. Furthermore, we comment on the analytical testing approach and the status-quo of appropriate method validation. WHAT THE READER WILL GAIN: The review provides insight regarding the analytical approach that is expected by regulatory authorities overseeing immunogenicity testing requirements. Additionally, the factors influencing immunogenicity are summarized and key references regarding immunogenicity testing approaches and method validation are discussed. TAKE HOME MESSAGE: The unwanted immunogenicity of protein therapeutics is of major concern because of its potential to affect patient safety and drug efficacy. Analytical testing is sophisticated and requires more than one assay. Because immunogenicity in humans is hardly predictable, assay development has to start in a timely fashion and for clinical studies immunogenicity assay validation is mandatory prior to analyzing patient serum samples. Regarding ADAs, the question remains as to when such antibodies are regarded of clinical relevance and what levels are, if at all, acceptable. In summary, the detection of ADAs should raise the awareness of the physician concerning patient safety and of the sponsor/manufacture concerning the immunogenic potential of the drug product.