Effective filter screening approach with fractionation for enabling inline filtration of protein A eluate

Filtration of protein A eluates inline with a chromatography column is a common challenge for monoclonal antibody (mAb) purification due to the high system backpressure during elution, which can result in system shut down or require a decreased elution flow rate. The inability to filter inline not only poses a risk for process deviations, but can also lead to tank constraints and microbial ingress risk. Here, we evaluated and described a novel approach for identifying filters for inline filtration of protein A eluates at pilot scale. We fractionated the protein A eluates into 0.25 column volume fractions to screen filters under constant pressure or constant flow conditions. We observed that filtration properties for eluate fractions are significantly different from the offline eluate, and the conventional filter sizing study using elution pool is not able to predict inline filtration behavior. Through the submicron particle counts and size distribution in pre- and post-filtration samples, we determined that both attributes contribute to the high pressure across the filters. A successful proof-of-concept experiment on a column 10 cm in diameter inline with the filter train selected validated this fractionation method, and the approach was applied to a different mAb molecule to confirm effectiveness.