Purpose: The goal of our work has been to demonstrate that the Affimer platform is not only a viable means by which to generate anti-idiotypic binders for therapeutic antibodies, but that Affimers are an ideal method by which to develop PK and drug monitoring assays. We have established a consistent means by which to screen for and validate anti-idiotypic candidates. Taking this one step further, we have recently been exploring the ability of an Affimer to distinguish between complexes of therapeutic antibodies bound to their respective targets, and not to either the ligand or antibody independently.
Methods: A selection of therapeutic antibodies were immobilized for individual screening via phage display. Following a stringent selection process the lead clones were expressed in small scale and validated on both an iQue platform as well as classical ELISA methods in both buffer and serum. Each of the anti-idiotype lead clones was fully validated for robustness and accuracy according to EMA and FDA guidelines. For the complex work, we have followed the same methods with some modifications to account for driving specificity towards the complex and not the individual components of those complexes.
Results: Consistently the anti-idiotypic Affimer binders displayed very low matrix effects when comparing buffer to 10% serum. When compared to commercially available anti-idiotypic antibodies the Affimer displayed both tighter curves and broader dynamic ranges. Furthermore, we have explored flexibility of detection methods by utilizing either anti-Fc or anti-IgG detection. To this endpoint, we are able to demonstrate that we can consistently use a single anti-idiotypic Affimer to perform such PK assays without requiring a bridging assay to ensure specificity and low background. Affimer anti-idiotypes yield a broad dynamic range that can be catered to assay needs, furthermore we demonstrated robust and consistent production and stability to ensure manufacturability.
Conclusion: Using the Affimer® platform, we have successfully developed anti-idiotypic binders to a wide range of therapeutic antibody targets to facilitate and improve assays to better enable the drug development pipeline. The primary benefits of this approach are: a short timeline for development (14 weeks), unlimited supply, consistent detection methods only requiring a single anti-ID binder, and little to no matrix effects which often enables a broader dynamic range. In summary, the Affimer® technology is a versatile, animal-free platform that allows rapid discovery and validation of specific binders that are ideal tools for use in a multitude of applications, particularly the implementation of PK and drug monitoring assays through anti-idiotype binding.
Amanda Nicholl
– Senior Assay Development Scientist, Avacta Life Sciences, WetherbyRob Ford
– Avacta Life SciencesJames Nuttall
– Avacta Life SciencesAlex Wignall
– Avacta Life SciencesAlex Davidson
– Avacta Life SciencesHelen Curd
– Avacta Life SciencesMatt Johnson
– Avacta Life Sciences
Amanda Nicholl
– Senior Assay Development Scientist, Avacta Life Sciences, Wetherby