Virus filtration is a critical process in the production of biotherapeutics and drug products derived by plasma fractionation. The processing steps upstream of virus removal filtration impact the filterability (throughput and flux) of process solutions. We processed mAb and plasma IgG spiked with aggregate by chromatography resins and examined the filterability of the output on a virus filter (Planova BioEX). The greatly reduced filterability for protein solutions with aggregate was improved by processing with specific chromatography resins. For mAb, mixed-mode AEX effectively reduced aggregate content and significantly improved filterability. Mixed-mode AEX was also effective for reducing aggregates in plasma IgG but modified CEX showed even greater improvement in filterability. The results clearly show that virus filter performance can be optimized by careful choice of column chromatography. Finally, applying the throughput and flux from the virus filter to four classical clogging models showed that mAb with aggregate was best fit to the standard blocking model and plasma IgG with aggregate was best fit to the complete blocking model, suggesting that differences in solution properties result in different clogging mechanisms.

We evaluated filtration behavior and virus removal capability for a mAb and plasma IgG under constant flow rate directly following flow-through column chromatography in an integrated process. For mAb solution with quantified host cell protein (HCP) content processed in flow-through mode on in-series mixed-mode AEX and modified CEX columns connected to the Planova BioEX filter (pool-less), HCP logarithmic reduction value (LRV) of 2.3 and 93.9% protein recovery were achieved for the process. Filtration behavior for 5 to 15 mg/mL plasma IgG run at flux of 10 to 100 LMH to 100 L/m2 throughput on Planova BioEX filters showed similar behavior across the protein concentrations tested although filtration pressure increased with throughput at 50 LMH and above, indicating the suitability of lower flux processes for continuous processing. Comparing both plasma IgG and mAb filtration behavior to four clogging models showed little difference in fit among the models, but with slightly better fit to the cake filtration model. Viral clearance tested by in-line spiking X-MuLV or MVM into purified plasma IgG showed robust removal at low flux. Integrating the Planova BioEX filter into continuous processes with column chromatography can achieve efficient downstream processing with reduced footprint and process time.

Virus filtration is a critical process in the production of biotherapeutics and drug products derived by plasma fractionation. The filterability of process solutions on virus removal filters is largely dependent on preceding downstream process steps, and column chromatography can have a particularly large impact on the throughput and flux of virus filtration. Filterability (throughput and flux) on Planova BioEX was greatly reduced for mAb and plasma IgG spiked with aggregate, and filterability improvement achieved by processing with chromatography resins (modified CEX, mixed-mode AEX and normal AEX column) was specific to protein solution. The various protein solutions spiked with aggregate showed distinct solution characteristics and by using the resulting filtration volume and flow rate, experimental and calculated filtration parameters were compared and evaluated with four clogging models: cake filtration, intermediate blocking, standard blocking and complete blocking. Effective purification of feed solutions by column chromatography has the capability to improve virus filtration processes. Further, the application of filtration parameters to the appropriate clogging model makes it possible to extrapolate filtration behavior to larger processing volumes.