David Pollard, Ph.D.
Merck & Co.
The continuous bioprocessing of mAbs provides a significant lower cost and higher throughput advantage compared to the current standard of batch processing. The transition to continuous is supported by the total cost of ownership analysis benefit from integrated unit operations. The case study will show how multiple technology improvements now make it feasible for a large scale stainless steel plant (20,000L) to be replaced with 500L single use bioreactors with continuous processing in an open ball room modular facility (Figure 1). Improvements in cell line expression enable upstream perfusion production titers to reach above the economic target of 2g/Lday. The development of novel multicolumn simulated moving bed chromatography (BioSMB) allows direct capture from the upstream process with reduced resin and buffer use while eliminating the cell removal step. The lower cost single use processing, is incorporated throughout the process including the novel flow path of the continuous chromatography using disposable columns and novel membranes. The use of automation with process analytical technology (PAT) enable a fully automated process with real time release and QC burden (Figure 1).
The case study will show how a pilot continuous mAb manufacturing has been fully automated using an overarching control strategy using Delta V control. So far multiple continuous processing batches, each over 40 day durations, have been demonstrated using the automated ‘lights out’ approach. The system includes automated filter switching triggered by pressure build up detected by the inline single use pressure sensors. If a process deviation occurs at a particular unit operation then flow is automatically diverted to the surge bag of the previous unit operation. This allows processing to continue upstream of the deviation while the issue is resolved. Further examples of deviation handling will be presented in the case study. The automation allows the user to define and control batch sizes that will be linked to raw materials based upon mass or time. A PAT toolkit has been developed to enable product attribute control and real time release. The examples go beyond traditional spectroscopy techniques to include online Ultra Performance Liquid Figure 1: Next Generation Bio therapeutic Modular Manufacturing. Capacity up to 1000kg/yr with open facility design with single use closed processing and PAT, adaptive process control with real time monitoring and release. Chromatography (UPLC) with UV and MS detection capabilities. In parallel a Multi-Attribute Method (MAM) focusing on peptide mapping MS has been implemented that covers the majority of protein critical quality attributes. A single analytical run can measure mAb identity, glycan’s, charge variants, oxidation, clipping and process impurities which eliminates the need for over 5-7 separate assays (Figure 2). Examples of combining this technology with aseptic sampling to enable attribute monitoring and control throughout the continuous processing will be demonstrated. This combination of technology enables directly control quality assurance during the continuous process. Multivariate analysis modeling is used to support the product attribute and process control. This has been incorporated to the over arching process attribute control for the complete multi-unit operation process. Bio burden control has been a challenge for extended bioprocesses. The case study will provide the strategy to minimize bio burden supported by at line rapid micro methods. The single use component strategy will be demonstrated that incorporates a standardized building block approach with sensor bundles to support surge bag process monitoring that includes novel sensors such as solid state pH. End users and equipment suppliers are collaborating together in this precompetitive space to drive technology implementation and define a regulatory pathway. Examples of this work will be provided in the case study. Further advances will be discussed as the workflow streams for drug substance and drug product become integrated as part of a minimal inventory strategy.