Salt tolerant membrane adsorbers for robust impurity clearance

Area of Science:

• Biotechnology
• Bioprocessing
• Separation Science

Background:

• Effective impurity clearance, including viruses, host cell proteins (HCP), and DNA, is crucial for manufacturing monoclonal antibody therapeutics.
• Traditional anion exchange chromatography using quaternary amine (Q) ligands shows reduced impurity clearance at moderate salt concentrations (50-150 mM).

Purpose of the Study:

• To evaluate alternative salt-tolerant anion exchange ligands for impurity clearance in membrane adsorbers.
• To compare the performance of new ligands against traditional Q ligands under challenging salt conditions.

Main Methods:

• Membrane adsorbers functionalized with four novel salt-tolerant anion exchange ligands (agmatine, tris-2-aminoethyl amine, polyhexamethylene biguanide (PHMB), and polyethyleneimine) were tested.
• Viral clearance was assessed using phage phiX174 and PR772 at different pH values in the presence of salt.
• Host cell protein (HCP) clearance was evaluated under challenging conditions, specifically at pH 7.5 and 150 mM salt.

Main Results:

• All tested ligands achieved >5 log reduction value (LRV) for viral clearance, while the commercial Q membrane showed zero LRV under the same conditions.
• PHMB demonstrated the highest HCP clearance, maintaining 1.5 LRV at pH 7.5 and 150 mM salt.
• The salt tolerance of PHMB was linked to its substantial positive charge and interactions with impurities.

Conclusions:

• Membrane adsorbers with salt-tolerant anion exchange ligands provide a robust method for impurity removal in monoclonal antibody purification.
• These advanced ligands overcome limitations of traditional Q ligands, enhancing process efficiency and product safety.