Purifying biopharmaceuticals: knowledge-based chromatographic process development

•We review process development approaches for the chromatographic purification of proteins. •We present experimental methods for the determination of protein properties and interactions. •Methods are connected to mathematical models for performance prediction and optimisation. •A modular process development concept is introduced. The purification of biopharmaceuticals is commonly considered the bottleneck of the manufacturing process. Increasing product diversity, along with growing regulatory and economic constraints raise the need to adopt new rational, systematic, and generally applicable process development strategies. Liquid chromatography is the key step in most purification processes and a well-understood unit operation, yet this understanding is still rarely effectively utilized during process development. Knowledge of the composition of the mixture, the molecular properties of the solutes and how they interact with the resins are required to rationalise the design choices. Here, we provide an overview of the advances in the determination and measurement of these properties and interactions, and outline their use throughout the different stages of downstream process development. The purification of biopharmaceuticals is commonly considered the bottleneck of the manufacturing process. Increasing product diversity, along with growing regulatory and economic constraints raise the need to adopt new rational, systematic, and generally applicable process development strategies. Liquid chromatography is the key step in most purification processes and a well-understood unit operation, yet this understanding is still rarely effectively utilized during process development. Knowledge of the composition of the mixture, the molecular properties of the solutes and how they interact with the resins are required to rationalise the design choices. Here, we provide an overview of the advances in the determination and measurement of these properties and interactions, and outline their use throughout the different stages of downstream process development. follow-on biopharmaceuticals produced by a different manufacturer after patent expiration. The higher molecular complexity of biopharmaceutical drugs requires more rigorous regulatory pathways compared to follow-on small molecular drugs. continuous loading of a chromatographic column with sample under constant conditions to determine its dynamic capacity under the specified conditions. systematic testing of identical process conditions on a small number of chromatographic columns for the purpose of performance comparison. process parameters that have been identified to have a significant impact on at least one CQA. a measureable product property that must lie within defined constraints for the product to comply to the quality requirements. parameter combinations to be tested for the optimization of multiparameter problems chosen by statistically principles in order to maximise the information gained per experiment. the combination of ranges of process parameters and material quality attributes that have been demonstrated to result in a product compliant to the quality requirements. a model for dynamic chromatography lumping dispersion effects into a single parameter. a more complex chromatography model with dedicated parameters for all mass-transfer effects. the systematic application of HTS in combination with statistical tools such as DoE and RSA in the context of process development. the systematic testing of a large number of process parameters typically with the aid of robotic liquid-handling systems. a controlled pause in mobile phase flow during a pulse elution experiment to estimate mass-transfer parameters from the resulting peak shape. the use of process understanding, monitoring of raw material quality, and CPPs throughout the process to adjust process parameters in real-time with the goal of producing products with consistent quality. a tool to describe and analyse interparameter dependencies for which no mechanistic relation is known. an estimated parameter characterising the ability of an operation to separate two proteins. a model describing the solute uptake kinetics across the radius of a spherical chromatography resin bead. common experiment to determine adsorption equilibria by mixing known amounts of resin and sample and measuring the concentration of the supernatant once equilibrium has been reached. a framework to promote the systematic use of science, process understanding, and risk management to design the production process to consistently deliver the predefined quality objectives.