Removal Of Leaked Affinity Purification Ligand

What is this patent about?

’372 is related to the field of protein purification , specifically the removal of contaminants from protein preparations. A common problem in therapeutic protein manufacturing is contamination by affinity ligands, such as Protein A or Protein G, which leach from affinity chromatography columns used in initial purification steps. These ligands bind to the target protein and are difficult to remove without also losing the desired product.

The underlying idea behind ’372 is to use a tentacle anion exchange matrix to selectively bind the target protein while allowing the contaminating affinity ligand to be washed away. The 'tentacle' structure, consisting of polymer chains extending from the resin surface, provides improved accessibility and binding capacity compared to traditional anion exchange resins, leading to better separation.

The claims of ’372 focus on a method for purifying an antibody from a sample containing the antibody and a second protein (Protein A or Protein G) that binds to the antibody. The method involves subjecting the sample to a tentacle anion exchange matrix chromatography medium under conditions where the antibody binds, followed by eluting the antibody. The key feature is achieving at least 85% antibody recovery and at least 75% removal of the contaminating protein.

In practice, the method involves loading a sample containing the antibody and leached Protein A or G onto a column packed with a tentacle anion exchange resin, such as Fractogel EMD TMAE HiCap. The column is then washed to remove unbound contaminants, including the leached affinity ligand. Finally, the antibody is eluted by changing the buffer conditions, such as increasing the salt concentration or adjusting the pH.

This approach differentiates itself from prior methods by using the unique properties of tentacle anion exchange resins. Traditional ion exchange chromatography and other methods like hydroxyapatite chromatography often struggle to achieve both high recovery and effective contaminant removal simultaneously. The tentacle structure appears to provide a more efficient binding and separation mechanism, leading to superior performance in removing leached affinity ligands while maintaining high yields of the target antibody. The use of a buffer at about pH 8 is also claimed.