Assessing different Protein A resins’ homodimer separation potentials through processing a two-antibody-containing artificial mixture

Homodimers represent the most difficult-to-remove byproducts associated with the production of asymmetric bispecific antibodies (bsAbs). An affinity medium can potentially separate homodimer byproducts if it binds different antibodies with distinct strengths. In the current study, we evaluated such a potential of three different Protein A resins (i.e., MabSelect SuRe LX, MabSelect PrismA and MabCaptureC) by using them to process an artificial mixture, which contained two antibodies that are different in origin of the variable region of heavy chain (VH) and molecular weight. The three resins showed distinct separation patterns of the two antibody components under identical conditions. In particular, MabSelect SuRe LX and MabCaptureC achieved complete separation of the two antibodies under optimized conditions. Consistently, MabCaptureC effectively separated the target heterodimer from two types of homodimers when used to purify an asymmetric bsAb whose two parental antibodies have distinct VH origins. This study further demonstrates that a suitable affinity medium can remove difficult-to-separate byproducts during product capture and hence alleviates the purification burden on polishing steps.