Automation of Dead End Filtration: An Enabler for Continuous Processing of Biotherapeutics

Abstract

Dead end filtration is a critical unit operation that is used for primary and secondary clarification during manufacturing of both microbial and mammalian cell based biotherapeutics. Dead end filtration is conventionally done in batch mode and requires filter pre-sizing using extensive scouting studies, along with filter over-sizing before deployment to handle potential variability. However, continuous manufacturing processes require consistent use of dead-end filtration over weeks or months, with potential unpredictable variations in feed stream attributes, which is a challenge currently facing the industry. In this work, a dead-end filtration skid is designed for continuous depth filtration, incorporating multiple small-sized filters along with turbidity, and pressure sensors with immediate switching to a fresh filter whenever turbidity or pressure breakthrough above a predetermined cutoff is detected in real time. The skid has been successfully tested for manufacturing of granulocyte colony stimulating factor from Escherichia coli, human serum albumin from Pichia pastoris, and a monoclonal antibody therapeutic from CHO cells. The proposed skid can be directly applied for any dead-end filtration application with minimal prior scouting studies or sizing calculations for scale-up. It is a useful solution for continuous processing trains where the nature of the feed, such as its turbidity or host cell proteins content, may change over long continuous campaigns, rendering previous sizing calculations inaccurate. The skid also allows significant cost savings by eliminating the sizing safety factor of 1.5-2x which is generally added before filter deployment at manufacturing scale.

Complete or periodic continuity in continuous manufacturing platforms for production of monoclonal antibodies?

“…A customized filtration skid was used for continuous dead‐end filtration. [ 37 ] A three‐way solenoid valve was used to connect three identical filters in parallel. The solenoid valves are shown as dark blue diamonds in Figures 1A and 1B.…”

“…A customized filtration skid was used for continuous dead-end filtration. [37] A three-way solenoid valve was used to connect three…”

Control of surge tanks for continuous manufacturing of monoclonal antibodies

“…Continuous clarification was performed on a Pall Cadence™ Acoustic Wave Separator (AWS) using four acoustic chambers in series for 90% reduction in total cell density of the harvest (Hong et al, 2020). Continuous dead‐end filtration was performed using a filtration skid developed in‐house consisting of a customized solenoid valve used to connect three filters in parallel, with an in‐line pressure sensor to direct the flow to a fresh filter whenever the pressure build‐up exceeded 1 bar (Thakur, Hebbi, Parida, et al, 2020). Two skids were placed in different locations in the continuous train, one between clarification and Protein A chromatography for depth filtration, and the other between viral inactivation and polishing chromatography for sterile filtration.…”

Process integrated biosensors for real-time monitoring of antibodies for automated affinity purification

“…The resulting optical shift of the LSPR band (Δλ) is recorded with picometer resolutions (pm) in real-time. Compared to other approaches recently developed, such as, quartz crystal microbalance (QCM) sensors functionalized with Protein A for selective in-line detection of antibodies in the effluent 26 , and near-infrared (NIR) spectroscopy combined with computer-based algorithms to measure feed titers in real-time 27 , LSPR The LSPR sensor approach was benchmarked against UV for detection of column breakthrough using cell culture supernatants and was found to drastically outperform UV-based methods regarding sensitivity and specificity. The UV detector was rapidly saturated due to sample background effects, making detection of breakthrough very challenging.…”

“…The resulting optical shi of the LSPR band (Dl) is recorded with picometer (pm) resolution in real-time. Compared to other approaches recently developed, such as, quartz crystal microbalance (QCM) sensors functionalized with Protein A for selective in-line detection of antibodies in the effluent, 26 and near-infrared (NIR) spectroscopy combined with computer-based algorithms to measure feed titers in real-time, 27 LSPR 25 is less sensitive to temperature changes, variation in sample composition, and vibrations and do not require any advanced data analysis to extract product concentrations.…”