LYTAG‐driven purification strategies for monoclonal antibodies using quaternary amine ligands as affinity matrices

BACKGROUND Monoclonal antibodies are becoming a leading class of biopharmaceuticals but to increase their accessibility by the general population, new production processes must be developed in particular for the downstream processing. RESULTS In this work, we propose an alternative and innovative affinity chromatographic method using quaternary amine matrices. Separation is driven by the dual affinity ligand LYTAG-Z, composed of a choline binding polypeptide (LYTAG) and the synthetic antibody binding Z domain. A two-elution method was developed for the purification of mAbs and the performance of different anion exchangers containing quaternary amines that act as choline analogues – CIMmultus Q, Q Sepharose and gPore Q – was tested and compared, with both CIMmultus Q and Q Sepharose allowing a recovery of more than 94% of mAbs from a CHO cell supernatant with a purity greater than 95%. An integrated platform combining an initial affinity extraction step for the clarification and capture of mAbs and a subsequent chromatographic separation using Q-matrices for the polishing of mAbs is also proposed. LYTAG-Z triggers the extraction of 94.7 ± 1.7% mAbs to the PEG-rich phase, as opposed to 26.9 ± 0.6% in the absence of the ligand, using 7% PEG 3350 and 6% dextran 500 k. Further purification using Q Sepharose allowed a mAb recovery of 95.3 ± 1.4% with a purity level of 91.4 ± 13.0%. CONCLUSION An integrated platform based on two purification steps – affinity extraction and affinity chromatography – results in an overall process yield of 90%, allowing the processing of mAbs directly from a non-clarified CHO cell culture.