2018;42:48C55. Beads were washed four times with 0.9 mL PBS and eluted with 1 mL 100?mM citrate BIO-5192 of different concentrations. Released amount of mAb were determined by absorbance at 280?nm. BTPR-35-na-s002.pdf (72K) GUID:?F0FBB910-5CBB-4AD5-BE3E-ECC1F0C76D8D Abstract High capacity magnetic protein A agarose beads, LOABeads PrtA, were used in the development of a new process for affinity purification of monoclonal antibodies (mAbs) from non\clarified CHO cell broth using a pilot\scale magnetic separator. The LOABeads had a maximum binding capacity of 65?mg/mL and an adsorption capacity of 25C42?mg IgG/mL bead in suspension for an IgG concentration of 1 1 to 8?g/L. Pilot\scale separation was initially tested in a mAb capture step from 26?L clarified harvest. Small\scale experiments showed that similar mAb adsorptions were obtained in cell broth containing BIO-5192 40??106 cells/mL as in clarified supernatant. Two pilot\scale purification runs were then performed on non\clarified cell broth from fed\batch runs of 16?L, where a rapid mAb adsorption 96.6% was observed after 1?h. This process using 1 L of magnetic beads had BIO-5192 an overall mAb yield of 86% and 16 times concentration factor. After this single protein A capture step, the mAb purity was similar to the one obtained by column chromatography, while the host cell protein content was very low, 10 ppm. Our results showed that this magnetic bead mAb purification process, using a dedicated pilot\scale separation device, was a highly efficient single step, which directly connected the culture to the downstream process without cell clarification. Purification of mAb directly from non\clarified cell broth without cell separation can provide significant savings in terms of resources, operation time, and equipment, compared to legacy procedure of cell separation followed by column chromatography step. ? 2019 American Institute of Chemical Engineers this would mean 10% of the target molecule will be lost in the supernatant. In the case of IgG concentration higher than 1 g/L, if a higher adsorption is desired, a 10C20% excess of beads compared to the DBBC1\h value can be used. In the case of purification using magnetic beads in suspension (of antibodies in present case), some of the main parameters that affect the adsorption and end yield are the amount of accessible protein A\ligands per bead, the concentration of antibodies and the time allowed for the antibody adsorption to the beads. To determine the DBBC1\h of the LOABeads PrtA, IgG1 antibodies were spiked in PBS at different concentrations reflecting a range of typical final antibody titers (1 to 8 g/L) in fed\batch process. The binding load capacity at 90% was measured and represented as function of these antibody concentrations. As shown in Figure ?Figure1C,1C, the BIO-5192 90% binding load capacity for GLUR3 LOABeads PrtA increased with higher mAb input concentrations until a plateau was reached at ~7 g/L mAb concentration at a maximum of 42?mg IgG/mL bead resin. This latter value of 42?mg IgG/mL bead resin was the maximum DBBC1\h of the LOABeads PrtA. We used this DBBC1\h value as a first approximation to preliminary guide the bead usage in the first pilot scale experiment in absence of other available information. Notice however that the DBBC1\h is specific to an antibody due to the specific affinity (Kd) of an IgG for the protein A bead. It is therefore a valuable parameter to determine the practical operating conditions of bead concentration and time allowed for the adsorption. run and the high mAb adsorption in presence of cells, showed in previous sections, built the premise to perform pilot\scale purifications using non\clarified cell broth. Two experiments, run B1 and run B2, were performed essentially in the same way as run em CF /em , from a technical point of view. The amount of magnetic beads was based on the mAb titer determined the day before harvest. The input IgG concentrations, determined by HPLC the day before harvest, was expected to be between 1 and 2 g/L at harvest. Based on the guidance of the DBBC1\h chart (Figure ?(Figure1C),1C), and a bead capacity usage of 80%, 0.8 and 1 L beads were used for the 15.73 and 16.25?L of non\clarified cell broth of runs B1 and B2. For these pioneer experiments, we decided to opt for a conservative approach and used 20% more magnetic beads instead of the bead amount given by the DBBC1\h value from Figure ?Figure11C. Learning from the experience of run em CF /em , the total adsorption time was reduced from 4 h to 2 h. The adsorption curves of run B1 and run B2 (Figure ?(Figure5A),5A), showed a fast binding of the mAb to the beads with 99.5% and 95.5% mAb.