As therapeutic drugs have grown in complexity, so too have the bioanalysis techniques to support these products. Bioanalysis of small molecule drugs has become more routine over time with the accumulation of experience gained through decades of work. The advent of large molecule therapeutics ushered in all new challenges as protein-based immunoassays became the norm. These assays tend to be less robust than those used for small molecule work and more variable due to the nature of the methodologies required. However, regulated immunoassays to support large molecules have continued to be a major area of work in the industry and our collective experience with them has grown considerably.
The latest shift for bioanalysis is towards advanced drug modalities, such as cell and gene therapies. The novel design of these therapeutics has required equally novel bioanalytical tools to be employed for the detection and quantitation of the therapy itself along with a new selection of techniques to evaluate the impact of the therapeutics on the patient. These assessments sound remarkably similar to the definition of pharmacokinetics and pharmacodynamics but have taken a different form where some of the therapies are self-replicating and others where the drug is the genetic material that utilizes the patient’s own cells as a factory to produce proteins which then have the intended beneficial effect.
Bioanalysis for these therapeutics is equally complex and still in the early days. However, the explosion of the number of these programs (over 200 INDs submitted in 2020 (1)) is rapidly driving the field forward as we gain more experience in this space. The need for platforms that have not been typically used in regulated bioanalysis means that there is limited regulatory guidance for acceptable assay performance, but even this is catching up as advanced modalities are becoming a larger share of the drug development market. For those working on these assays, there is a unique opportunity to be on the ground floor to help set the precedent instead of being beholden to the precedent.
New Technologies Being Used for Bioanalysis
The future of advanced modality bioanalysis depends heavily on cutting-edge technologies and platforms not typically thought of for regulated work. For example, the emergence of cell and gene therapy has brought on the utility of quantitative PCR (qPCR) to bioanalysis in support of these studies. Not only has qPCR become relevant for these drug modalities but the availability of digital droplet PCR (ddPCR), a newer technology in this space, has received significant attention in the field. The PCR-based methodology is not something new to the laboratory, however, the use of these quantitative tools to effectively substitute for pharmacokinetic analysis to quantitate drugs or for a safety assessment of viral shedding are new applications of these technologies.
The emergence of technologies like ddPCR has allowed for a more robust ability to develop assays to support new drug modalities. However, this has brought about the need to understand how to best develop and validate assays using these technology platforms. The need for improvement in this space includes the need for harmonization of how to best use these technologies and develop assays that are acceptable by regulatory agencies in support of these drug products. A group of industry leaders, including Amanda Hays, Ph.D. and Dave Williams, Ph.D. from the BioAgilytix team, have authored a white paper providing guidance for the validation of assays using quantitative PCR tools (2). This is the first step to learning from the industry-wide experience on these platforms and establishing best practices going forward.
Another previously uncommon tool in bioanalysis is ELISpot which is used to assess cellular immunogenicity in response to advanced modalities. While growing in importance, these assays typically do not have what a bioanalytical scientist would think of as a “true” positive control. This is due to the fact that there is often a challenge to identify individuals with lymphocytes that will specifically and robustly respond to stimulation with therapeutic-specific peptides. As a result, process controls using non-specific stimulation of lymphocytes are employed instead. How this data can be leveraged to characterize an assay within the context of what we traditionally consider under assay validation is still to be discussed and determined.
Finally, flow cytometry is another example of a technology that is becoming more commonly used in regulated bioanalysis. As a well-established tool for whole-cell and biomarker analysis, flow cytometry has also shifted from its origins in the diagnostic clinical laboratory space to the regulated bioanalytical laboratory and is used for a wide variety of applications. Current efforts are underway to bring forth guidance on how to best validate flow cytometry assays. For example, the CLSI H62 guidance is a large collaborative effort of many bioanalytical scientists with expertise in flow cytometry. We are likely to continue to see similar efforts as this with newer technologies as they emerge.
All new technologies will need to rapidly evolve with industry trends, regulatory guidance, and the advanced computing power that make these applications possible. For now, many organizations and communities are working together to collaborate on best practices for how to employ and use these platforms to support the large wave of drug types that are continually evolving and providing room for improvement in bioanalysis.
Partner With BioAgilytix
BioAgilytix is a leading global contract research organization focused on supporting pharmaceutical and biotech partners in all phases of drug development. With laboratory locations in North Carolina’s Research Triangle Park; Cambridge, Massachusetts; San Diego, California, and Hamburg, Germany, BioAgilytix provides PK, immunogenicity, biomarkers, and cell-based assay services supporting the development and release testing of biologics across a number of industries and disease states.
BioAgilytix offers assay development, validation, and sample analysis under non-GLP, GLP, and GCP, as well as GMP quality control testing (i.e., product release testing, stability testing, etc.) BioAgilytix also offers diagnostic testing services at its CLIA-certified, CAP-accredited Boston laboratory.