Gyrolab Spin Blog

Johan Engström, Sr Scientist at Gyros Protein Technologies

Part 2: Determining the dissociation constant (K_D) for a high-affinity Adnectin^™ imaging ligand by in-solution affinity measurement

Analyzing high-affinity ligands used to target protein-protein interactions can be a real challenge. A biotherapeutics discovery team at Bristol Myers Squibb (BMS) used Gyrolab^® in-solution affinity analysis to overcome problems in determining the picomolar-level dissociation constant of an imaging Adnectin™ ligand. Advantages also included low sample consumption, high throughput, and more accurate values for low-picomolar dissociation constants than surface plasmon resonance (SPR).

Johan Engström, Sr Scientist at Gyros Protein Technologies

Part 1: High-affinity ligands for imaging target expression in cancer immunotherapy

Cancer immunotherapy targeting protein-protein interactions saves lives. Success builds on the binding characteristics of high-affinity binding therapeutic antibodies and also ligands used to monitor target expression during clinical trials. Measuring nano- to low-picomolar affinity binding can be difficult using surface plasmon resonance (SPR), which led a biotherapeutics discovery team to choose in-solution affinity analysis in the characterization a high-affinity imaging ligand.

The COVID-19 pandemic has necessitated the need to 

generate serology data on the levels of IgM and IgG directed against the RBD of SARS-CoV-2 to help in identifying individuals with neutralizing antibodies and drive the development of therapeutics and vaccines. A number of plate-based immunoassay platforms are being employed for serology testing but there are often issues with high reagent and sample consumption, plus the limitations of laborious manual workflows and long turnaround times. Open platforms are needed that enable data to be rapidly generated using small amounts of reagent and sample, preferably over a broad analytical range to minimize the need for repeat analysis. This is now possible in an open automated platform that uses minimal amounts of precious reagent and sample. 

Serology assays that detect antibodies to

 SARS-CoV-2 in human serum are critical to delivering data that provides insight into immune responses, measures health impact, and supports vaccines and therapeutics R&D. Important factors to consider are the assay targets and the best platform to ensure reliable data can be generated efficiently and with a minimum of resources, including time and reagents.

Serology tests that detect antibodies to SARS-CoV-2 in human serum are critical to gaining insight into immune responses, measuring the impact of the virus on public health, and to support the development of effective vaccines and therapeutics. This article series takes a brief snapshot of the highly dynamic situation regarding the needs for COVID-19 serology assays, how they are constructed, how they should perform, and how data can be efficiently generated using small amounts of reagents. We start with an overview.

Vectors based on AAV (adeno-associated virus) are used widely in gene therapy for in vivo gene delivery. The success of AAV-based therapeutic production depends on the availability of laboratory tools that can efficiently deliver reliable data, including the determination of virus particle titer (physical titer). To achieve this, a team at AstraZeneca searched for an immunoassay platform that could improve on ELISA in terms of dynamic range, sample volume, and productivity. Their evaluation showed that Gyrolab® system met their needs for AAV process development, with a more reliable measurement of AAV capsid titer for in-process and purified samples.

Development of high-affinity binding interactions and utilization of the appropriate tools for affinity determination are the ultimate goals of antibody therapeutic R&D. The expansion of protein engineering methods has provided powerful techniques for affinity maturation of biotherapeutics to accomplish at least part of this goal. In particular, the recent use of phage display methods for antibody affinity evolution have produced high affinity antibodies in the picomolar dissociation constant (K_D) range, also with high specificity, such as the TNF-α inhibitor Humira^® (AbbVie Inc.)^1,2

Vaccine discovery and development

Vaccines have become key weapons in the fight against infectious disease and as immunotherapies for other conditions including certain cancers and Alzheimer’s disease. Immunoassays in vaccine development play a key role and meeting ever more pressing deadlines means that efficient and flexible platforms are at a premium, especially in times like these, with the COVID-19 pandemic pressing vaccine R&D to the limit. In this two-part series we will be looking at how immunoassays can contribute to vaccine R&D and production.

Vaccine bioprocess development and production

Only clean drinking water can match vaccination in its ability to save millions of lives every year. In the case of the ongoing COVID-19 pandemic, the availability of a vaccine is considered a prerequisite for a return to normal life worldwide. But transforming antigens into robust vaccine products is a lengthy process. In the second article of this two-part series we will look at some examples of how immunoassays can play a key role in delivering reliable vaccine bioassay data to support efficient bioprocess development and production to ensure that vaccine production lots meet targets, time and time again.

Getting a meaningful result

Many good points were raised when it comes to impurity testing at the latest Gyrolab User Seminar, held in Milan in June. This included a roundtable discussion on a subject that has been a stumbling block for many – how to measure Host Cell Protein (HCP) levels in a meaningful way.