You are welcome to attend Huayu Niu's final PhD defense, in which she will discuss her research on mAb capture with cation exchange membranes.
Protein-A affinity chromatography is commonly used for monoclonal antibody (mAb) capture, however, the high cost and leaching problem of Protein-A ligands call for the development of non-affinity solutions. Cation exchange chromatography has risen as a promising alternative for mAb capture, for a few commercialized mAbs. While cation exchange capture is primarily based on cation exchange resins, single-use cation exchange membranes offer advantages, such as improved productivity and mAb quality. Nonetheless, mAb capture with cation exchange membranes has not been thoroughly investigated.
Cation exchange capture works on the basis of dynamic electrostatic interactions, thus it is critical to understand the buffer effects on binding capacity and mAb unfolding. In this work, two adsorption models, i.e. Langmuir and steric mass-action models, were employed to investigate buffer effects on the binding capacity of a weak cation exchange membrane, Natrix C membrane, with polyclonal human IgG and a humanized mAb, Bevacizumab, at the molecular level. Effect of buffer anions were extensively investigated for two commonly used buffer type in cation exchange chromatography, phoshpate citrate buffer and acetate buffer. The results facilitated buffer selection for optimal binding capacity. A high-throughput intrinsic fluorescence microplate method for the detection of mAb aggregates was developed, enabling fast in-line mAb quality control. Contrast to Protein-A ligands that mainly bind to the constant regions of mAbs, cation exchange ligands bind to the variable regions of mAbs. Therefore, process development for cation exchange capture requires more detailed mAb-specific information, which can be time-consuming to acquire.
Importantly, guidelines must be established for high-throughput design space development for cation exchange capture. With the knowledge and tools acquired in this work, a guideline for high-throughput design space development for mAb capture with cation exchange membranes was established for the first time. A chimeric mAb, Rituximab, with murine variable region was empolyed as the model material together with Natrix C membrane. Critical process parameters significantly affecting the binding capacity and Rituximab unfolding were first identified using the Failure Mode Effects Analysis. The characterization range was then investigated to define the range of design spaces, which were subsequently developed with a response surface model constructed using a high-throughput Design of Experiments approach. The optimal buffer condition was extracted from the response surface model and validated for Rixtuximab binding with Natrix C membrane under static and dynamic modes.
Supervisor: Professor Christine Moresoli, Chemical Engineering
200 University Ave West
Waterloo, ON N2L 3G1