Antibody Cascade Design Key to Customizing Success

Last November, Abcam’s Head of Custom Services, Jamie Campbell, presented at the PEGS (Protein & Antibody Engineering Summit) Europe conference in Lisbon, Portugal.

We caught up with Jamie to get a rundown on his talk, which covered the company’s approach to discovering antibodies – key reagents in drug discovery, in vitro diagnostics and therapeutics.

Jamie gives us an outline of their RabMAb® technology, next generation sequencing platform, and phage display, and highlights current trends and opportunities in the field.

Michele Wilson (MW): Can you tell us a bit about Abcam, the company mission and goals?

Jamie Campbell (JC): Abcam provides biological reagents and tools for scientists working in research, drug discovery and diagnostics. These tools help scientists better understand biological processes and causes of disease, and aid the development of new treatments to improve health outcomes.

Where suitable reagents are currently unavailable, or not fit for purpose, we work with scientists to develop exactly what they need, whether that’s for research, drug discovery, in vitro diagnostics or therapeutics.

MW: What different approaches to antibody discovery does Abcam utilize?

JC: Success in antibody discovery is greatly improved by using the right approach. Our in-house experts select the most appropriate technology platforms to enable us to discover and engineer antibodies that bind the target with the required selectivity and sensitivity for our partners’ diagnostic and therapeutic programmes.

We have three core antibody discovery platforms: RabMAb® technology, Next Generation Sequencing (NGS) and phage display. Depending on the target of interest, any one of these platforms can be used to generate a new antibody. In some cases more than one platform is used to ensure the best chance of success.

Our RabMAb® platform is built on rabbit hybridoma technology to generate highly specific, recombinantly-produced antibodies to a range of targets. We use the rabbit immune system because it generates antibody diversity and optimizes affinity, which increases the possibility of obtaining a functional antibody that will work in a variety of applications.

Our proprietary NGS platform builds upon the diversity of the rabbit immune system and enables us to mine the breadth and depth of the immune response. Using a large pool of potential candidates naturally means a greater chance of discovering the antibody that best binds the target. Then, using a bioinformatics approach, we can select a set of binders that will be most beneficial to the application.

When antibodies to a target can’t be generated through an in vivo approach, for example the target is toxic or non-immunogenic, we can use our phage display technology. Using high-diversity libraries of antibody single chain variable fragments (scFvs) fused to the coat protein of a bacteriophage such as Gp3, the result is a recombinant antibody created using animal-free technology. 

MW: What are ‘assay cascades’ and how do they aid antibody discovery?

JC: Assay cascades are essentially how we design a custom antibody development project at Abcam. They set out the techniques and application-specific tests that will be applied at various stages of the antibody discovery process to find the best binders early. The more extensive and well-designed the cascade, the better the chance of finding and developing the best antibody.

Every project has an individualized assay cascade designed for their target of interest. An assay cascade is designed at the technical scoping stages of a project, where we discuss the customer requirements, and broadly consists of a primary screen, secondary screen, and application-specific testing.

The process is like a funnel where we narrow down the possible binders. We start with many in the primary screen, narrow this down in the secondary, and finally refine this to identify the very best application-specific antibodies. At each step we apply more precise tests, but we always ask: is this the right test, or is there something else we should do? We are constantly innovating and finding better ways to predict performance in the final application.

MW: You recently presented at the PEGS conference, which focuses on protein and antibody engineering. Could you highlight the most memorable new techniques, challenges, or themes from this conference?

JC: The trend in personalized healthcare continues – single biologic therapies are no longer the norm, and these will be replaced by double and triple combination therapies, especially in immuno-oncology (IO).

Having good quality reagents in a diagnostic is key to the effective use of biologics because these may highlight how a patient population will respond to a drug and may also monitor response to treatment. There are a lot of new, more complex, IO targets where there are not enough potentially useful reagents available or the existing reagents are not good enough quality. 

MW: What do you see as the biggest opportunities in this space for drug discovery and diagnostics?

JC: The use of other immunoglobulin antibody classes, including IgA and IgE, as therapeutics in immuno-oncology was highlighted as an emerging area. Conventional therapeutics are developed using the IgG format. However, being able to produce antibodies with different properties, through expressing them as different immunoglobulin formats that can target different cell types, opens up lots of possibilities for the development of future therapeutics.

Jamie Campbell was speaking to Michele Wilson, Science Writer for Technology Networks