Best Practices, Strategies & Utilization of Novel Biological Responses for Robust Cell-Based Potency Assays (Dec 2024)

Transcriptional activity within a cell can be used to evaluate cell response to a ligand or promoter activity within a transgene or plasmid within a cell. Catalent has developed a relative potency bioassay using real-time quantitative reverse transcription (RT-qPCR) in a duplex format to assess relative transcription activity in cells treated with ligands or transgenic vectors. The assay utilizes two fluorescent dyes with minimally overlapping emission spectra that allow real-time monitoring of the gene expression of both target and normalizer genes. The assay does not require purification of the mRNA produced by the cells once lysis has occurred. Normalizing the qPCR cycle thresholds (CT) of the target transcript to the reference transcript allows response curve to be generated and compared to a reference standard. The generation of a four-parameter fit curve analysis from raw qPCR cycle threshold data allows for comparison of relative potency and assessment of suitability based on curve parallelism. The assay platform has been used by Catalent to qualify a repeatable, accurate, linear, and specific bioassay for assessing relative potency.

The manufacture of protein-based drugs is complex and relies on using biological host systems. This can result in small changes in protein structure during production and formation of protein variants that can have a large impact on functionality. This heterogeneity — variations in the protein size, charge or structure — can significantly impact the safety and activity of the final biotherapeutic or biosimilar therapy, potentially hindering their beneficial effect. It is vital that charged variant profiles of biologics are adequately characterized, as many post-translational modifications (PTMs) may alter the charge of the molecule, in turn impacting its stability, pharmacokinetics and pharmacodynamics. In this article, Catalent explores protein variants, focusing on charged variants, by outlining their impact on protein-based drugs, and explain how specific characterization techniques can be used to determine product safety and efficacy.

Transcriptional activity within a cell can be used to evaluate cell response to a ligand or promoter activity within a transgene or plasmid within a cell. Catalent has developed a relative potency bioassay using real-time quantitative reverse transcription (RT-qPCR) in a duplex format to assess relative transcription activity in cells treated with ligands or transgenic vectors. The assay utilizes two fluorescent dyes with minimally overlapping emission spectra that allow real-time monitoring of the gene expression of both target and normalizer genes. Notably, the assay simplifies the process by eliminating the need for mRNA purification, enabling more efficient and accurate analysis. Normalizing the qPCR cycle thresholds (CT) of the target transcript to the reference transcript allows the response curve to be generated and compared to a reference standard. The generation of a four-parameter fit curve analysis from raw qPCR cycle threshold data allows for the comparison of relative potency and assessment of suitability based on curve parallelism. Catalent has successfully implemented this assay platform to develop a reliable, accurate, and specific bioassay. It stands out for its linear response and reproducibility, making it a valuable tool for evaluating the relative potency of various test substances. Join us to explore how these robust cell-based potency assays can enhance your research and provide critical data on drug product potency.

Biophysical characterization is critical to understand the make-up and behaviors of biologic therapies and vaccines, both early in development and throughout the manufacturing scale-up process. As biologics become more complex in structure, and as scientists improve their understanding of the effects of structure on stability, efficacy, safety, etc., there is a need to develop new and improved analytical methods to characterize biologic products. During this presentation, experts will discuss the latest challenges in biophysical characterization and will present solutions to overcome these challenges.

The characterization and analysis of advanced therapies, such as cell and gene therapies (CGTs) can be difficult, as these products are designed to function using complex mechanisms of action (MOA)s. There are a wide range of challenges associated with accurately assessing the potency and impurity profiles of these complex biologicals. As many CGT programs qualify for accelerated review pathways, novel approaches for analysis and characterization can help generate data that allows for real-time decision making and faster development timelines. Catalent has developed a relative potency bioassay using quantitative polymerase chain reaction (qPCR) to assess relative transcription activity in cells treated with ligands or transgenic vectors. The assay platform can be used to qualify a repeatable, accurate, linear, and specific bioassay for assessing relative potency for CGTs, mRNA- and other nucleic acid-based therapies.

Metabolic Flux Analysis (MFA) is a powerful technique used to characterize metabolic phenotype driving to improved productivity in biomanufacturing. MFA is most powerful when absolute concentrations of the metabolic intermediates are measured, but doing so in practice is often impractical due to inherent limitations of conventional absolute quantitation by mass spectral analysis. Recently, advances in artificial intelligence (AI) have been applied to solving the problem of broad, untargeted, absolute quantitation in liquid chromatography-mass spectrometry (LC-MS). These new approaches extend readily to the determination of absolute concentrations of stable isotopically-labeled metabolic intermediates, offering a new tool for MFA. Dr Sam Yenne from Metalytics Inc., a company that specializes in the science of metabolic flux, has recently assessed and adopted Pyxis, a new tool for absolute quantitation of raw LC-MS data. Dr Yenne describes MFA, its utility in biopharmaceutical development, associated challenges and how Pyxis impacts those challenges.