Reck Jason M, Pabst Timothy M, Hunter Alan K, Carta Giorgio
Department of Chemical Engineering, University of Virginia, Charlottesville VA 22904, United States.
MedImmune, Gaithersburg, MD 20878, United States.
J Chromatogr A. 2017 Jun 2;1500:96-104. doi: 10.1016/j.chroma.2017.04.014. Epub 2017 Apr 10.
The removal of aggregates, particularly soluble dimers, from monoclonal antibodies (mAbs) remains a persistent challenge in downstream processing. In this work, we have examined the separation of an antibody monomer from its dimer on the cation exchange resin Nuvia HR-S (Bio-Rad Laboratories) using frontal analysis. In this process, a mixture of monomer and dimer is continuously fed to the column under conditions where the mixture is favorably bound, resulting in two breakthrough fronts whose monomer and dimer compositions are determined by the multi-component equilibrium and kinetics of the system. Experimentally, the selectivity for dimer was found to vary substantially with ionic strength, being lowest when conditions favor the strongest binding, and increasing to a maximum at intermediate ionic strengths where rapid exchange with the bound monomer can occur. A mechanistic model is developed to describe the competitive binding frontal analysis process, assuming pore diffusion and a significant kinetic resistance to binding as a function of ionic strength. The model was solved numerically and was able to describe both the frontal analysis processes and batch adsorption experimental data, accounting for process parameters such as feed composition and salt concentration. The resulting model can be used to optimize column operating conditions for yield and purity.
从单克隆抗体（mAb）中去除聚集体，尤其是可溶性二聚体，仍然是下游加工过程中一个长期存在的挑战。在这项工作中，我们使用前沿分析法研究了在阳离子交换树脂Nuvia HR-S（伯乐生命医学产品公司）上抗体单体与其二聚体的分离。在此过程中，单体和二聚体的混合物在混合物被有利结合的条件下连续进料到色谱柱中，产生两个突破前沿，其单体和二聚体组成由系统的多组分平衡和动力学决定。实验发现，二聚体的选择性随离子强度有很大变化，在有利于最强结合的条件下最低，在中间离子强度下达到最大值，此时与结合的单体可以快速交换。建立了一个机理模型来描述竞争性结合前沿分析过程，假设孔扩散以及作为离子强度函数的显著结合动力学阻力。该模型通过数值求解，能够描述前沿分析过程和间歇吸附实验数据，同时考虑了进料组成和盐浓度等工艺参数。所得模型可用于优化色谱柱操作条件以提高产量和纯度。
