Solutions for Purification of Fc-fusion Proteins

Platform processes are valuable tools in process development. Applying them to complex fusion molecules made up of different structures, however, can lead to unexpected results. EA2 is a unique engineered molecule, and it did not fit well into a platform process. It does, however, have three potential affinity and pseudo-affinity sites, each target site having a platform purification unit operation. One site is the antibody Fc region for Protein A binding, but the product was too sensitive to low pHs for typical Protein A elution conditions, so a high pH elution process was developed instead. The other two pseudo-affinity sites proved to be unusable, as did ion exchange chromatography. The final process that was developed added hydrophobic interaction and mixed mode (HIC and AEX) chromatography polishing, with a solvent and detergent (S/D) treatment instead of the typical low pH virus inactivation. This product points out the need for innovation and flexibility in cases where platforms do not work. [PUBLICATION ABSTRACT]