BIOTECHNOLOGY 85
Mapping the immunogenicity of therapeutic protein products
Samuel Altun, Lena Heffler and Teodor Aastrup provide some examples of immunogenicity testing assays.
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t is of great importance to understand and verify desired and unwanted immunogenicity effects. Immune responses to therapeutic protein products can limit product efficacy as well as affect patient safety.
Consequently, immunogenicity- related factors should be considered early in the product development process. Guidance for immunogenicity testing is provided by the U.S. Food and Drug Administration (FDA). Factors such as aggregation, off-target interactions, target clustering and neutralising antibodies are mentioned as examples that should be evaluated1
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Fig. 2. Aggregation assays. Three assays to study aggregation properties are A) off-rate screening, B) secondary antibody interaction and C) capture assay. A) The more aggregated, the slower dissociation rate due to avidity and rebinding. B) The more aggregated, more binding to a secondary antibody due to more available epitopes. C) The more aggregated, the higher frequency response due to more mass added to the surface.
Te discussion here pertains to a proprietary quartz crystal microbalance (QCM) based biosensor that offers label-free applications to study the abovementioned factors in real time.
Te Attana Cell 200 biosensor is based on the piezoelectric effect of quartz. When applying an alternating electric potential over a quartz crystal, it will start to oscillate with a resonance
frequency related to the crystal’s mass. Hence when any molecules are bound to the crystal, the frequency changes and the interaction can be characterised, for instance as kinetic rate constants and affinity.
Aggregation Protein aggregates have been known to elicit immune responses to therapeutic protein products and are seen as an immunity-provoking factor.1
Aggregation is therefore an important factor to study during development processes and the Attana Cell 200 biosensor is an excellent tool to study it.2
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assays of studying aggregation properties are illustrated in this chapter: A) Off-rate screening, B) Secondary binding and C) Capture assay.2
Te results of the off-rate screening show the more aggregated proteins, the slower
Fig. 1. The label-free Attana Cell 200.
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