The value of affinity determination in assay development and throughout drug development
The drive to lower drug dosage, improve healthcare and reduce costs has lead to the search for therapeutic antibodies with high target affinity. As a consequence, optimizing and monitoring the specificity and affinity of drug candidates to the target molecule has become critical in the development of therapeutic antibodies – from early screening of hybridomas or recombinant antibodies from phage display libraries, to affinity maturation and antibody engineering to improve the efficacy, safety and manufacturability of the final antibody drug product. Characterizing affinity is also important when selecting reagents for quantitative assays or assessing drug product activity in manufacturing release tests. The question is, how can high affinity be measured in the best possible way?
Matrix interference can be a major challenge in the development of immunoassays to study a number of disease states. Kathi Williams and her colleagues at Genentech Inc., USA, experienced considerable problems with matrix interference when developing an ELISA for Phase III studies of a humanized monoclonal antibody when a new patient group was introduced. The solution was to transfer the assay to the Gyrolab platform that, thanks to its flow-through technology helped minimizing matrix effects by reducing the incubation times with the capture reagent antibody.
In a previous post, 
The drive to achieve regulatory approval of protein-based drugs quickly and efficiently demands methods that can deliver reliable data to support studies in pharmacokinetics, toxicokinetics, pharmacodynamics, biomarker analysis, and immunogenicity. This need has powered the development of a wide and somewhat perplexing range of ligand binding assays (LBAs) and technology platforms designed to function in a regulated environment, from non-clinical studies to post approval. Added to that, developing an assay that is ready for validation can be a real challenge. If you need guidance in this area then you would do well to read ‘Ligand Binding Assays in the Regulated Bioanalytical Laboratory’, a book chapter authored by Johanna Mora
A number of serious eye diseases, such as neovascular age-related macular degeneration (AMD) and diabetic macular edema, involve increase in the leakage of blood vessels in the eye. This is caused by vascular endothelial growth factor (VEGF) and while such diseases can be treated with protein drugs that neutralize VEGF, the drugs must be administered frequently. A research group has developed an elegant approach that significantly extends the half-life of the drugs. This exciting work involved handling a challenge that is common to much of eye research – running immunoassays on precious samples in difficult matrices.
Pharmacokinetic (PK) studies of therapeutic proteins in early preclinical development demand great flexibility in bioanalytical methods. This is a real challenge during lead candidate selection when, for example, limited amounts of specific reagents must be labeled for immunoassays. Gregor Jordan and his colleagues at the Pharma Research & Early Development (pRED) department at Roche in Munich, Germany saw the advantages of transferring their ELISAs to the Gyrolab™ platform – low reagent consumption, semi-automation and fast assay turnaround – but wanted to go one step further in conserving critical resources. They therefore developed a generic detection reagent that would allow them to use the same antibody reagents on both ELISA and Gyrolab platforms.
It is not unusual for a pharmacokinetics assay used early on in a study proves to lack the robustness needed to see the drug candidate through to more advanced clinical studies. A team at Genentech experienced just that and they solved the problem by transferring their ELISA to the Gyrolab platform.
