With increasing time pressures to move biological therapeutics into the clinic, bioprocessing development studies have to be limited. Currently, core studies typically involve the use of shake flasks and benchtop bioreactors to select the most productive clones, optimum media, and bioprocessing conditions. The capacity for using benchtop bioreactors is especially limited as it is resource-intensive and has high capital equipment and infrastructure costs. Consequently, scientists frequently cannot perform full design-of-experiments (DoE) and are generally only able to take one or two of their most promising clones forward for partial DoE runs in benchtop bioreactors.
BioProcessing Journal Posts
The FDA’s ICH Q9 quality risk management (QRM) guidance material is the foundation for understanding and evaluating patient risks associated with developing and manufacturing pharmaceuticals. This three-part paper describes approaches a team of subject matter experts (SMEs) can use for implementing two important applications of QRM. Part I provides a method for identifying and remediating threat risks that may affect the product’s quality or other important aspects of a manufacturing enterprise’s lifecycle, from product research and development to commercial manufacturing. The second QRM application covered in Part II manages patient risks by identifying, evaluating, and managing risks associated with process parameters (PP) on the product’s critical quality attributes (CQAs). The final paper, Part III, describes an approach for accepting or further mitigating the risks evaluated by the QRM exercise…
“Closed system.” The term itself appears deceptively simple. However, the definition of a closed system, its implementation, and its impact on biomanufacturing has been anything but straightforward.
The journey toward implementing closed systems spans over 20 years. The concept of closed systems was introduced in January 2000 with the draft issue of ICH Q7. Since then, other industry guidance documents emerged, defining and supporting process/system closure as a primary means of risk mitigation to meet the baseline requirement of protecting the product, as defined in cGMP.
Presently, global regulatory agencies recognize three distinct definitions of a closed system. These definitions, found in EU Annex 1, EU Annex 2, and the PIC Annex 2A, all focus on product protection where the product is not exposed to the immediate room environment during manufacturing. This is where the journey begins.
The SARS-CoV-2 spike protein S2 subunit plays an essential role in the virus-host cell membrane fusion process. Therefore, the subject of this study was to characterize the gamma-immunoglobulin (IgG) response, in a group of COVID-19 convalescent patients, against the S2 subunit with eight linear peptides to generate a monoclonal antibody (mAb) against the immunodominant linear peptide to be used for therapeutic and diagnostic purposes. Results of antibody percentages against assessed linear peptides were 100% for A21P73, A21P74, A21P75, A21P76, M20P51, M20P65, M20P83, and 66.7% for M20P85. Plasma samples were also used for purifying IgG to corroborate specificity against the same linear peptides, where results reproduced those applying plasmas directly to ELISA-plates. Within these peptides, A21P75 was chosen as immunodominant (100% of recognition with higher absorbance). The A21P75 linear peptide showed poor immunogenicity in mice (1:4000–8000 after four doses), allowing the generation of a CB.HS2A21P75 hybridoma for mAb production that recognized the A21P75 linear peptide with middle-to-high affinity constant (Kaff) (0.8×108 M-1).
This study concludes that the A21P75 linear peptide is the assessed immunodominant linear peptide for this COVID-19 convalescent patient group. This peptide is located in the HR1 region that plays an important role in SARS-CoV-2 host cell membrane fusion process and is highly conserved between SARS-CoV-2 and SARS-CoV. Thus, due to CB.S2A21P75 mAb specificity and Kaff, it might be the proper reagent to study inhibition of virus-host cell membrane fusion, and as a diagnostic reagent for coronavirus. Finally, the combination of A21P75 linear peptide with other peptides (e.g., receptor binding domain [RBD]) could be suitable reagents for the development of vaccines and therapeutic antibodies with virus infection-blocking capacity.
Nowadays, therapeutic monoclonal antibodies (mAbs) are predominantly produced with mammalian cell culture systems such as those using Chinese hamster ovary (CHO) cells. Efforts are underway to reduce the costs of this process to meet the increasing global demand in biopharmaceuticals; meanwhile, cheaper and faster expression systems are being investigated as alternatives. The yeast, Pichia pastoris, has become a substantial workhorse for recombinant protein production. However, the N-linked glycosylation in P. pastoris, namely high mannose glycosylation, is significantly different from that in CHO or other mammalian cells, including human cells. In this study, a SuperMan5 strain of P. pastoris was constructed using Pichia GlycoSwitch® technology to successfully produce a more mammalian-like immunoglobulin G (IgG) fragment crystallizable (Fc), which showcases the potential of P. pastoris as a next-generation mAb production platform. Importantly, in this study, a strong methanol-independent promoter, PUPP, was applied, which only requires glycerol feeding for protein production. Most P. pastoris promoters used for protein expression are derived from genes in the methanol metabolism pathway, creating safety concerns due to the flammable nature of methanol, especially at large scale. Here, a fed-batch SuperMan5 P. pastoris fermentation was carried out in which methanol induction, as well as its affiliated safety risks, were eliminated. Overall, this study provides insights into the development of safe and cost-effective industrial mAb production approaches independent of mammalian cell culture.