Advanced Process Control and Automation with Special Focus on Emerging Continuous Bioprocessing

Legacy batch processing carried out in pharmaceutical and biopharmaceutical sectors is undergoing transformation to adopt the next generation continuous processing to produce safe and effective drugs with better efficiency and consistency at a reduced cost. To facilitate innovative continuous processing, enabled by an end-to-end process with a single uninterrupted production scenario, it is essential to generate real-time or near-real-time data using process analytical technology (PAT), which has been defined by the FDA as a system for designing, analyzing, and controlling manufacturing through timely measurements to ensure final product quality. Based on quality by design (QbD) principles, PAT-enabled data monitoring is essential for the timely control of critical process parameters (CPPs) and critical quality attributes (CQAs) to keep the process in a desired state of control to achieve a predefined product quality. Based on QbD philosophy, quality cannot be tested into products; it should be built-in or should be by design. Deployment of PAT tools for real-time monitoring is integral to align with the guiding principles of QbD-enabled workflow to enhance process and product understanding to administer a control strategy to keep the process within the design space. Aim of this chapter is to highlight the recent advancements in PAT tool-development to monitor and control CPPs and CQAs

Identification of Potential Sites for Tryptophan Oxidation in Recombinant Antibodies Using tert-Butylhydroperoxide and Quantitative LC-MS

Amino acid oxidation is known to affect the structure, activity, and rate of degradation of proteins. Methionine oxidation is one of the several chemical degradation pathways for recombinant antibodies. In this study, we have identified for the first time a solvent accessible tryptophan residue (Trp-32) in the complementary-determining region (CDR) of a recombinant IgG1 antibody susceptible to oxidation under real-time storage and elevated temperature conditions. The degree of light chain Trp-32 oxidation was found to be higher than the oxidation level of the conserved heavy chain Met-429 and the heavy chain Met-107 of the recombinant IgG1 antibody HER2, which have already been identified as being solvent accessible and sensitive to chemical oxidation. In order to reduce the time for simultaneous identification and functional evaluation of potential methionine and tryptophan oxidation sites, a test system employing tert-butylhydroperoxide (TBHP) and quantitative LC-MS was developed. The optimized oxidizing conditions allowed us to specifically oxidize the solvent accessible methionine and tryptophan residues that displayed significant oxidation in the real-time stability and elevated temperature study. The achieved degree of tryptophan oxidation was adequate to identify the functional consequence of the tryptophan oxidation by binding studies. In summary, the here presented approach of employing TBHP as oxidizing reagent combined with quantitative LC-MS and binding studies greatly facilitates the efficient identification and functional evaluation of methionine and tryptophan oxidation sites in the CDR of recombinant antibodies

Detection and characterization of subvisible aggregates of monoclonal lgG in serum

To detect and characterize the aggregation of therapeutic monoclonal antibodies in undiluted biological fluids. Fluorescently labeled subvisible IgG aggregates formed by applying either heat stress or by pH-shift were investigated immediately after addition to human serum, and after 24 h. Unstressed and stressed IgG formulations were analyzed by fluorescence single particle tracking, confocal laser scanning microscopy and flow cytometry. Unstressed formulations remained free from subvisible aggregates in serum, whereas heat-stressed and pH-shift stressed formulations showed dissimilar aggregation behaviors. The aggregation profile of the heat-stressed formulation diluted in serum remained practically the same as the one diluted in buffer, even after the 24 h incubation period. The pH-shift stressed formulation had strikingly smaller and more numerous subvisible aggregates immediately after dilution in serum compared to buffer. These aggregates became noticeably larger in both diluents after 24 h, but in serum they appeared to be formed by other types of constituents than the labeled protein itself. These results show that subvisible therapeutic protein aggregates may undergo changes in number, type and size distribution upon contact with human serum. This emphasizes the importance of analytical strategies for monitoring aggregation in undiluted biological fluids

LC-MS characterization of antibody-based therapeutics: recent highlights and future prospects

Abstract Antibody-based therapeutics constitute a major growth area in medicine today. However, antibodies as drugs present significant analytical challenges as they are large, complex and heterogenous molecules produced in living cells. The key attributes that affect safety, stability and efficacy must be identified and controlled to ensure regulatory compliance. Liquid Chromatography-Mass Spectrometry (LC-MS) is a powerful analytical technology that is well suited to the task of analyzing antibody-based therapeutics. LC-MS is used to characterize antibody features ranging from the relatively simple (e.g. intact molecular weight determination and post-translational modification analysis) to the complex (e.g., higher order structure analysis and epitope identification). Few other analytical technologies are as versatile as LC-MS for monitoring a wide range of attributes or as capable of keeping pace with the innovation happening today in biotherapeutic design. In this chapter we will provide an overview of the LC-MS methods currently used for the characterization of antibody-based therapeutics, with an emphasis on the analysis of post-translational modifications. We will also highlight some recent innovations, new technologies and trends that are likely to significantly impact the manner in which antibody-based therapeutics are analyzed in the future