From harvest to crystalline product form: A combination of crystallization with non-chromatography pre-purification steps for monoclonal antibody capture, purification, and formulation

Abstract

In this study, we have developed a holistic non-chromatography approach for capture, purification, and formulation of monoclonal antibody (mAb). The model protein was a therapeutic mAb (Immunoglobulin IgG1). IgG1 was captured from a Chinese Hamster Ovary (CHO) cell culture medium and purified in aqueous solutions of polyethylene glycol (PEG 3.35) by a coupled process of precipitation and solid liquid extraction. The chromatographic purity of the protein in the solution obtained was 99 % with the DNA concentration reduced to 2 ppb and the host cell proteins concentration reduced to 8 ppb, at the process yield 79 %. The purified protein was subsequently subjected to forced convection crystallization (FCC), to obtain the final product in the crystalline form. In FCC, water from the protein solution was evaporated by forced convective air flow. The parameters of the air stream were altered to control the supersaturation level and temperature of the solution. FCC provided crystalline IgG1 with 99 % yield and allowed a 30 % reduction in the consumption of precipitating agent compared to standard batch crystallization. The design of FCC was aided by a mechanistic model in which mass and heat transport balances were combined with the kinetics of nucleation and crystal growth. The model was calibrated on the basis of crystallization kinetic data. It is intended to serve as a tool for the selection of operating conditions for the realization of FCC. The developed procedure for FCC design is relatively simple and easy to adopt in industry.