Efficient host cell protein clearance: A study of membrane adsorbers and resins in biopharmaceutical processes

In recent years, biopharmaceutical purification processes have shifted towards more productive and cost-effective methods. Membrane technology has emerged as viable alternative to conventional resins, capable of delivering similar product quality while facilitating a simpler and more flexible downstream purification process. This study compares the impurity removal efficiency of three anion-exchange media types (quaternary amine-functionalized agarose resin (Q Sepharose™ Fast Flow), cellulose membrane adsorber (Sartobind® Q), and a hybrid purifier, composed of two complementary anion-exchange media, a quaternary ammonium functional non-woven and a guanidinium functional polyamide membrane (3M™ Polisher ST)) in a flow-through mode during a monoclonal antibody product purification. The content of residual major impurities-host cell proteins (HCPs) and aggregates-were investigated using a design of experiments (DoE) approach, varying pH, ionic strength, and loading densities. Membrane-based devices exhibited high impurity removal capacity, with 3M™ Polisher ST capable of reducing HCP levels from 8000 ppm down to as low as 10 ppm at competitive loading densities in this case study. The presence of critical HCPs, such as esterases capable of hydrolysing ester bonds in polysorbates, was monitored using high-throughput enzyme assays and liquid chromatography-tandem mass spectrometry. Orthogonal HCP analytical methods were required for more informed process development, as esterase presence did not follow the same trend as the general HCP population. All chromatographic media were further tested for their robustness by conducting breakthrough experiments at an optimal pH of 6.5 and conductivity of 4 mS/cm. An additional orthogonal polishing step was required as anion-exchange chromatography alone was insufficient at clearing aggregates. Among options evaluated, 3M™ Polisher ST demonstrated the greatest potential for simplifying the purification process and enhancing productivity.