Thought you might be interested in this recent preliminary patent filing which highlights a method purification of antibodies using displacement cation exchange chromatography skipping the protein A step. The authors point out the high cost of using protein A at scale (approximately $15,000 a liter) This is just the tip of the iceberg as limited life span, dynamic capacity, leaching, and cleaning issues all come the upfront cost of the resin. This is where the authors turned to displacement chromatography to replace the protein A step. They used Capto S from GE in a process scheme for the capture of monoclonal antibody from cultured media. They used Expellâ„¢ SP from SACHEM, a small molecular weight compound, which is easily cleared as the displacement reagent. When used in combination with an anion exchange polishing step, they were able to produce a product that meets required purity specifications. Apart from host cell proteins, the process also facilitated the clearance of DNA and aggregates common to antibody production protocols.