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Monoclonal Antibody Primary Recovery Clarification: Evaluating Product Quality Impact, Process Optimization and Scale-up

Bryan C. Dravis, Bioproduct R&D - Bioprocess Operations, Eli Lilly and Company, Lilly Corporate Center, DC 3515, Indianapolis, IN 46285 and Michael D. Hilgert, Bioproducts R&D - Bioprocess Operations, Eli Lilly and Company, Lilly Corporate Center, DC 3515, Indianapolis, IN 46285.

The primary recovery clarification of monoclonal antibodies (MAbs) from a mammalian cell culture is a straightforward solid-liquid separation of insoluble cellular components from a multifaceted cell culture broth. Consisting of centrifugation followed by a series of successive normal flow filtrations, the main objective of the clarification sequence is to properly clarify the starting complex cell culture for the subsequent series of chromatographic purifications and viral removal steps. Using a tailored design of experiments (DOE), investigations were conducted to assess the impact the primary recovery operations had on the overall downstream purification process and to facilitate the design of better scale down/up models for more accurate process definition and material supply.

A modified 23 factorial DOE was employed to explore a "representative" operating window for the primary recovery unit operations at pilot and manufacturing scales. The DOE incorporated Q/Σ theory boundaries for the centrifugation such that all results could be properly scaled and constrained across equipment sets. The DOE isolated the individual operating parameters for each unit operation that directly contributed to product quality, but the study also assessed how overall effect product stream characteristics impacted subsequent downstream unit operations. Product titers, quality, stability, clarity, throughput capacity, impurity removal, cell lysis and total protein analyses were all used as quantifiable measures in this process evaluation.

These primary recovery investigations were conducted across three separate manufacturing scales and evaluated the impact to several MAbs (IgG-1, IgG-4) and "MAb-like" therapeutic proteins. The study results have been used to properly scale, model and characterize primary recovery operations from lab to commercial scale, to identify safe process hold-locations, minimize impact to product quality and optimize process robustness. This work now serves to further enable "platform" approaches that facilitate better process understanding while also reducing process development time lines and permit manufacturing flexibility.