An Exploration of the Ultrafiltration Behavior of Highly Concentrated Monoclonal Antibody Solutions

Open Access
Author:
Nitopi, Stephanie Anne
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Andrew Zydney, Thesis Supervisor
  • Michael John Janik, Honors Advisor
Keywords:
  • membrane; ultrafiltration; bioprocessing; bioseparations; recomb
Abstract:
Monoclonal antibodies (mAbs) are a major class of bio–therapeutic proteins with wide ranging applications in treating autoimmune diseases and cancer. Highly concentrated doses are typically needed to achieve the desired therapeutic effect given the volume limitations of subcutaneous injections. Ultrafiltration is currently used for purification and concentration of protein solutions in the pharmaceutical industry. However, there are significant challenges in applying ultrafiltration to achieve very high protein concentrations due to membrane fouling and concentration polarization effects. The objectives of this work were to explore the behavior of ultrafiltration processes at very high concentrations of a highly purified monoclonal antibody (provided by Amgen) and to determine the mechanisms controlling the filtrate flux. Ultrafiltration data were obtained in both tangential flow filtration (TFF) and stirred cell (SC) experiments. In addition, the osmotic pressure was evaluated as a function of protein concentration and buffer conditions to provide a direct measure of the effects of protein–protein interactions on the thermodynamic properties of highly concentrated antibody solutions. The filtration data clearly show that there is a maximum attainable protein concentration corresponding to the point where the filtrate flux goes to zero. The measured flux is in good qualitative agreement with predictions of the concentration polarization model, although the behavior at very high protein concentrations is more complicated due to the large variation in transmembrane pressure associated with the high viscosity of the antibody solution. These studies provide important insights into the factors that govern the performance of ultrafiltration processes for highly concentrated antibody solutions.