It’s all about maintaining equilibrium
Immunoassays must be able to generate accurate and precise quantitative measurements of analytes such as drug candidates and their targets, and many studies also demand the accurate determination of levels of free or bound drug, or target. Achieving this is a challenge and success depends on many factors, including taking steps to maintain the equilibrium formed in vivo between various molecular forms of the analyte. This can be achieved with care in sample preparation, and by using an immunoassay platform that requires minimal sample dilution, and delivers results quickly before the equilibrium can shift.
With the need to increase analytical throughput in biotherapeutic R&D and cell and gene therapy, multiplexing assays can appear to be an obvious approach. There are certainly potential advantages, but also disadvantages and considerable challenges involved in multiplexing immunoassays – assays must be carefully matched to function in the same buffer and in the same analytical range. An alternative approach – to miniaturize singleplex ELISAs and run them in parallel – may be even more attractive.
Immunoassays have become invaluable in the generation of data for preclinical and clinical studies, process development/optimization and manufacture of biotherapeutics, and also for new applications such as determining viral titer in cell and gene therapy. Having confidence in the data based on the accurate and precise determination of analytes in complex matrices means overcoming many challenges. These can include interference that reduces robustness, selectivity and specificity, the poor performance of cross-reacting antibody reagents, and time-consuming methods that threaten time plans. Such challenges can be overcome by choosing the right reagents, using the right approach on the right immunoassay platform to deliver reliable data as quickly as possible.
With R&D returns for large cap biopharma companies falling to the lowest level in nine years (Deloitte, 1), the escalating cost of bringing medicines to market means that the biopharma R&D process must be examined in detail. One important factor is the development and validation of immunoassays that can deliver high quality data efficiently and in a timely manner. Speed and quality are intertwined, and while manual ELISA has been a major workhorse in biopharma R&D, automation is a key factor in speeding up the generation of high quality data with minimum hands-on time, minimum need for re-runs, and using readily validated assays that meet regulatory requirements.
Harnessing the power of cell and gene therapy involves a large range of analytical methods that can deliver robust results to support rapid data driven decision-making. One assay development team has used immunoassays to track a transgene IgG product. Their choice of immunoassay platform enabled them to generate high quality data that supported Design of Experiments to quickly optimize cell culture.
Cell and gene therapy promises to revolutionize medicine by correcting underlying genetic causes of disease or conferring new functions to cells to combat disease and has already seen spectacular successes in health care, ranging from curing rare eye diseases, to the treatment of sickle cell disease and a number of cancers. Immunoassays can be important analytical tools in cell and gene therapy and the careful choice of an immunoassay platform can improve productivity by boosting workflows, data quality and greatly reducing the consumption of precious samples, for example in detecting antibodies against lentivirus vectors that are commonly used in cell and gene therapy. 
Mammalian expression systems have driven the rise of biotherapeutics. Their ability to introduce proper protein folding, post-translational modifications, and product assembly means that they are currently used to produce almost all therapeutic antibodies to ensure correct structure and minimize the risk of immunogenicity. But the advent of smaller, simpler biotherapeutics means that prokaryote expression systems such Escherichia coli (E. coli) are playing a new role in antibody therapy. These bacteria can deliver high expression levels, with simpler bioprocessing at a lower cost together with an extensive molecular toolbox based on well-characterized genetics. This development is increasing the need for sensitive methods to monitor bioprocess development and manufacturing based on E. coli-based expression systems, including the sensitive analysis of host cell proteins. 
Obesity has become a devastating pandemic, with 108 million obese children and 604 million obese adults worldwide in 2015, and the problem is increasing (1). The result is an escalation in serious conditions such as type 2 diabetes mellitus (T2DM), cardiovascular disease, hypertension, dyslipidemia and several cancer forms, mainly gastrointestinal. Obesity is very difficult to treat through life style changes and surgery has become the most effective and long-lasting route to sustained weight loss, although it is only available to a small subset of individuals, and is both costly and risky. The search for more widely applicable treatment has driven the development of peptide-based pharmaceuticals that can meet key challenges of obesity, including control over satiety, blood sugar and LDL cholesterol levels. 
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.
