Biotechnology Progress最新文献

For bioprocesses producing live virus, such as enterovirus Coxsackievirus A21, viral titer (infectivity basis) decay rates can exceed 30% within a day. Consequently, harvest timing is paramount. To optimize titer at harvest, a continuous viral product titer model was generated to elucidate kinetics. The model leveraged experimentally determined viable cell density, cell-specific viral productivity, and viral specific decay rates. Next, three separate online process analytical technology (PAT) harvest triggers were developed to predict maximal viral titer. Finally, the PAT harvest triggers were tested alongside traditional time-based harvests. The harvest triggers utilized common bioprocessing tools – dissolved oxygen (DO) and capacitance probes – to track DO and viable cell volume (VCV) and derived a third parameter, cell-specific oxygen uptake rate. Harvesting with PAT triggers allowed for significantly improved batch-to-batch consistency. The standard deviation of harvest yield was reduced by 41% (DO), 56% (OUR) and 71% (capacitance) as compared to the industry standard time-based harvest. Even when a process deviation in inoculated cell density occurred, causing a significant shift in viral titer kinetics, the PAT harvest triggers yielded greater than 87% of peak titer. By comparison, the time-based harvest yielded 16%.

Recombinant adeno-associated virus (rAAV) is a widely used delivery vehicle in gene therapy. A scalable production technology is essential for its wide clinical applications. We have taken a synthetic biology approach to generate HEK293-based cell lines which harbor integrated genetic elements encoding essential AAV and adenoviral helper components and can be induced to produce rAAV. Through cycles of cell line enhancement, a high rAAV productivity could be achieved. The cell lines, like their parental HEK293, grew adherently. For scalable production, cell cultivation in suspension is highly desirable. A producer cell line GX6B was adapted to suspension growth in serum-free medium (named GX6Bs). However, it had substantially reduced virus titer. Returning GX6Bs cells to adherent culture conditions using adherent medium and cultured stationarily brought the productivity back to close to the level of adherent GX6B. A survey of the transcriptome revealed that induction and rAAV production elicited a wide range of cellular changes in various functional classes, including host immune defense response and nucleosome organization. The response was more subdued in suspension-growing GX6Bs. Upon reverting to adherent growth, the cellular transcriptome change regained its vigor to be more similar to that seen in GX6B. The GX6Bs maintained in suspension serum-free conditions were then reverted to the adherent culture medium but under an agitated culture environment to keep suspension growth for rAAV production. The productivity returned to within 25%–50% of GX6B. This work demonstrated the feasibility of the suspension culture of synthetic cell lines for the expansion and production of rAAV.

In recent years, accelerating Chemistry, Manufacturing, and Controls (CMC) workflows for clinical entry has become a critical focus in biologics development. Advances in the development of cell lines, cell culture processes, and analytical technologies have enabled the generation of more homogeneous stable pool populations with increased productivity. Leveraging the experience gained from the COVID-19 product development, the strategic use of stable cell pools or a pool of clones for early-stage non-GMP material generation and process development has proven transformative in significantly reducing the CMC timeline to investigational new drug (IND). This study provides a comprehensive comparison of bioprocess performance and product quality attributes of materials produced from stable pools or a pool of clones (toxicology study materials) versus those from clonally derived cells (GMP clinical batches) across six First-in-Human (FIH) programs involving mAbs, bsAb, and Fc-fusion proteins. The results demonstrate a strong alignment and the feasibility of using protein materials from stable pools or a pool of clones in toxicology studies. In conclusion, utilizing non-clonal CHO cell-derived material for preclinical studies offers a strategic approach that can be broadly applied to complex molecules across various disease areas, even under standard regulatory filings, accelerating the path to clinical trials.

Antioxidant supplementation to serum-free culture media is a common strategy to enhance productivity through oxidative stress alleviation. In this study, it was hypothesized that certain antioxidants can improve the specific productivity of a CHO-GS cell line expressing a bi-specific antibody. A fed-batch (FB) screening study investigated several antioxidants and revealed rosmarinic acid (RoA) and retinyl acetate (RAc), to a lesser extent, improved cell productivity. Contrary to the previous literature reports, the addition of RoA and/or RAc resulted in slower cell growth and reduced peak viable cell density, counteracting the enhanced specific productivity. We hypothesized that supplementing RoA/RAc after the exponential growth phase would increase titer through enhanced specific productivity without substantially impeding cell growth. This hypothesis was tested in three different ways: (1) supplementing RoA/RAc to the feed, rather than the basal media, in the FB process; (2) implementing the intensified fed-batch (iFB) process mode which started with high seeding VCD, bypassing the exponential cell growth phase; (3) supplementing RoA/RAc to the production phase perfusion media, rather than the growth phase perfusion media, in the perfusion-based continuous manufacturing (CM) process. All three methods were proven effective in titer improvement, which supported the hypothesis. Additionally, RoA/RAc significantly impacted product quality, with variations depending on the process mode and components. Overall, their supplementation led to decreased N-glycan mannose percentage and increased product fragmentation and aggregation. These changes do not fully align with the previous reports, highlighting that the supplementation strategy needs to be evaluated carefully based on cell line and expressed molecule type.

Continuous manufacturing platforms and membrane chromatography are process technologies with the potential to reduce production costs and minimize process variability in monoclonal antibody production. This study presents a simulation and optimization framework to perform techno-economic analyses of these strategies. Multi-objective optimization was used to compare batch and continuous multicolumn operating modes and membrane and resin process alternatives, revealing performance differences in productivity and cost of goods attributed to variations in dynamic binding capacity, media geometry, and process residence time. From the set of optimal process configurations, we selected one membrane and one resin platform alternative yielding the highest net present values to undergo sensitivity analyses involving variations in batch cadence and product selling price. For the scenarios considered in this work, membrane continuous platforms showed benefits in the cost of goods and process mass intensity. Their shorter residence time compared to resins positions them as a viable alternative for single-use capture chromatography. Moreover, this low residence time makes membrane platforms more flexible to changes in throughput, an essential feature for integrating capture into fully continuous processes.

Shake flasks are one of the most widely used cultivation vessels in biotechnological process development. To improve the process understanding, new technologies have been reported for online monitoring of different parameters like oxygen, pH, or biomass in the last couple of years. However, most reports address the monitoring of a single parameter per shake flask. This work evaluates the ability to measure dissolved oxygen (DO), biomass, and fluorescence in parallel with a new Multiparameter Sensor (MPS). Therefore, abiotic tests for reproducibility, sensitivity, and accuracy were performed. In biological tests, different microbial systems were used to evaluate if a wide range of applications is feasible. This work demonstrates that three different parameters: DO, biomass, and fluorescence can be monitored online, in parallel, for various biological systems. The online data obtained provide crucial process knowledge, such as the start of intracellular product formation. Abiotic and biological tests showed good reproducibility, resolution, and sensitivity to changing environmental conditions. Compared to other existing measurement systems for DO or oxygen transfer rate, similar or in the former case, more data points can be recorded, allowing a detailed overview and a better understanding of the process.

Recombinant adeno-associated viruses (rAAV) are one of the most popular gene therapy vectors. To date, low-product yields are limiting a broader clinical application. To identify targets for improving productivity, two human embryonic kidney cell lines (HEK293) with varying productive profiles were transiently transfected for rAAV2 production and transcriptomes were compared at 18 h after transfection. As expected, high-producing cell lines exhibited elevated levels of plasmid-derived viral gene expression. Gene set enrichment analysis indicated that these cells demonstrated increased transcriptional activity and upregulation of mRNA-processing mechanisms. Furthermore, transcriptomic analysis suggested increased transcription of histone-coding genes and a modulated cell cycle under the influence of viral gene expression, with differences being more prominent in the high-producer cell line. Aiming to increase rAAV yield, cyclin-dependent kinases and histone deacetylases were targeted by treatment with the small molecule inhibitors Flavopiridol and M344, respectively. Without compromising biological activity, Flavopiridol increased rAAV titer by 2-fold, and M344 increased it up to 8-fold in a cell line-independent manner, while also enhancing the percentage of filled capsids. A DoE-based approach also revealed the potential for combining both molecules to enhance rAAV production, exhibiting an additive effect across three different HEK293 derivatives. Consequently, novel functions of M344 and Flavopiridol as enhancers of rAAV production were unraveled, which can be employed to enhance the accessibility of in vivo gene therapy applications.

Aqueous two-phase systems (ATPS) are a liquid–liquid extraction method that offers low-cost, continuous-adaptable virus purification. A two-step ATPS using polyethylene glycol (PEG) and sodium citrate that recovered 66% of infectious porcine parvovirus with 2.0 logs of protein removal and 1.0 logs of DNA removal in batch has now been run continuously. The continuous system output of <10 ng/mL DNA regardless of starting DNA titer agreed with batch studies. However, the continuous system had a five-fold higher contaminating protein titer than batch studies, likely because of incomplete mixing or settling. Turbidity was tested as a measure of mixing and settling efficiency. Monitoring in-line absorbance at 880 nm directly after mixing and before collection in the settling reservoir could track both mixing and settling during operation. Settling time was reduced by changing the settling line material from PVC to PTFE, which is more hydrophobic. A flow-through AEX filter tested to make impurity removal more robust recovered 90% of PPV and removed an additional 87% of host cell DNA. The filter did not add any additional protein removal. In the future, in-line absorbance sensors could be implemented along with conductivity sensors to measure salt concentration, refractive index sensors to track the PEG-citrate interface, and scales to track mixer and reservoir volumes to enable automated, continuous ATPS. Our vision is to integrate continuous ATPS into a fully continuous end-to-end production for viral vectors.

Recombinant adeno-associated virus (rAAV) is a promising delivery vehicle for cell and gene therapies. Upstream development faces challenges like low productivity and inconsistent performance despite advancements. This study presents a scale-up design for robust rAAV production at 250 L scale using a transfection system. Initial process development in shake flasks optimized plasmid ratio to improve rAAV production. However, genome titer decreased by up to 50% in stirred-tank bioreactors, likely due to mechanical shear forces. Stirred-tank bioreactors were modeled with computational fluid dynamics (CFD) by M-STAR (250 mL, 5 L, 50 L) and with empirical correlations by Dynochem (250 L). Hydrodynamics were characterized to provide normalized shear stress across different geometries. The power per unit volume (P/V) of 71 W/m³ was optimal for the 250 mL bioreactor, focusing on cell growth, rAAV genome titer, capsid titer, and full capsid ratio. Based on CFD modeling, a P/V of 20 W/m³ was projected to perform best at 5 and 50 L scales during development, confirmed by comparable genome titer to low shear shake flask culture. A P/V of 15 W/m³ was subsequently projected for final production at the 250 L scale. The negative impact of shear stress could be further mitigated by adding extra Poloxamer-188 as a shear protectant. Additionally, pre-transfection viable cell density (VCD) was identified as a critical attribute. The final process included a 30% fixed-volume dilution of the cell culture along with controlled DNA complexation conditions to improve process robustness. Sequential production at the 250 L scale demonstrated consistent cell growth and rAAV production.