Charge Variant Analysis of USP Monoclonal Antibody Reference Standards

BioPharm International sat down with Jean-François Vincent-Rocan, Director of Complex Chemistry Process Development at BIOVECTRA, to discuss antibody-drug conjugate (ADC) manufacturing. Due to their complex manufacture and supply chain management, JF emphasizes the need for a company that greatly understands the challenges and offers solutions that maintain quality and reliability. He also mentions what advancements are to come in this field and how best to stay ahead of a rapidly growing treatment option.

Application Notebook highlighting Liquid Chromatography techniques commonly used for monitoring Critical Quality Attributes (CQAs) in Bioprocessing Applications

Catalent has developed a cutting-edge bioassay using real-time quantitative reverse transcription (RT-qPCR) in a duplex format to measure transcription activity in cells treated with ligands or transgenic vectors. This reliable and reproducible assay is a valuable tool for evaluating the relative potency of various test substances. Enhance your research with Catalent’s robust cell-based potency assays.

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.