Purification of monoclonal antibodies entirely in flow-through mode

•An antibody purification process entirely in flow-through mode was achieved.•Buffer exchange improved the impurity clearance by depth filtration.•A combination of depth filters improved impurity clearance.

A depth filter is widely used in biopharmaceutical manufacturing process. In this study, we found that buffer exchange to reduce conductivity dramatically improved the removal of impurities in depth filtration. The host cell protein clearance was comparable to that of protein A affinity chromatography, which is generally used as a first capture step in monoclonal antibody purification. In addition, a combination of different depth filters showed enhanced purification. Additional flow-through purification is possible without any sample preparation, and a biopharmaceutical-quality purity level (<100 ppm for host cell protein and <5% for high molecular weight species) can be attained. These results represent the possibility of an antibody manufacturing process using an entirely flow-through mode.