Multi-column continuous chromatography (MCC) offers significant economic advantages over traditional batch methods for purification of monoclonal antibodies (mAbs), including increased resin capacity utilization, smaller columns, reduced buffer consumption, and faster processing time. The Protein A capture step is a primary target to apply MCC due to its high cost, which is driven even higher as improvements in upstream processing have produced a steady increase in mAb titers. A humanized IgG1a was expressed in a CHO cell line using a 250 L Single-Use Bioreactor (SUB). Two separate SUB runs were harvested by filtration that resulted in titers of 5.6 and 6.2 g/L of expressed mAb. Initially, process development (PD) at gram scale was accomplished using a bench-top Octave® BIO System and 6 x 5 ml prototype SkillPak® rProtein A columns (TOYOPEARL® AF-rProtein A HC-650F). Key factors in the optimization of the MCC process included mAb titer, column size and number, residence time, mAb binding capacity, and flow properties of the resin. Use of 3 columns in the capture zone enabled 90% resin utilization even at short residence times down to 0.5 minutes, while the 6-column process relieved scheduling constraints imposed by insufficient column number. The optimized PD method file was transferred and scaled-up approximately 150-fold on the single-use ProGMP™ System. The mAb was purified using 6 SkillPak 0.79-L rProtein A prototype columns. Over 1 kilogram mAb was obtained from approximately 200 L feed in less than 4 hours using only 4.7 L of rProtein A resin in each of two separate runs. The yield of both runs averaged 92% and the overall productivity exceeded 80 g mAb/L resin/h with quality and purity attributes similar to prior batch-purified mAb.

Multi-column continuous protein A capture of a monoclonal antibody at kilogram scale

ACS Fall 2021

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