Role of harvest depth filtration in controlling product-related impurities for a bispecific antibody

Borujeni, Ehsan Espah; Jin, Weixin; Shao, Chun; Chennamsetty, Naresh; Xu, Xuankuo; Ghose, Sanchayita

doi:10.1093/abt/tbac023

Cited by 2 publications

(3 citation statements)

References 25 publications

(42 reference statements)

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“…Polymeric binders also play important roles in the charge characteristics of depth filters, however specific information is propriety. A recent study, investigated the properties of D0HC (primary‐cellulose) and X0HC (secondary‐cellulose) for their ability to remove product‐related impurities, specifically low and high‐molecular weight species 27 . They showed that retention of impurities on the primary filter were minimal, due to the open structure and absence of DE.…”

Section: Resultsmentioning

confidence: 99%

“…A recent study, investigated the properties of D0HC (primary‐cellulose) and X0HC (secondary‐cellulose) for their ability to remove product‐related impurities, specifically low and high‐molecular weight species. 27 They showed that retention of impurities on the primary filter were minimal, due to the open structure and absence of DE. Retention on the secondary filter was due to a combination of hydrophobic, electrostatic and hydrogen bonding and also dependant on the properties of the target impurity.…”

Section: Resultsmentioning

confidence: 99%

“…A recent study, investigated the properties of D0HC (primary-cellulose) and X0HC (secondary-cellulose) for their ability to remove product-related impurities, specifically low and high-molecular weight species. 27 They showed that retention of impurities on the primary filter were minimal, due to the open Overall, HCP is not being significantly removed by primary filters;…”

Section: Filtrate Clarity (Od600) and Dna Breakthroughmentioning

confidence: 99%

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Depth filter material process interaction in the harvest of mammalian cells

Parau

Pullen

Bracewell

2023

Biotechnology Progress

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Upstream advances have led to increased mAb titers above 5 g/L in 14-day fed-batch cultures. This is accompanied by higher cell densities and process-related impurities such as DNA and Host Cell Protein (HCP), which have caused challenges for downstream operations. Depth filtration remains a popular choice for harvesting CHO cell culture, and there is interest in utilizing these to remove process-related impurities at the harvest stage. Operation of the harvest stage has also been shown to affect the performance of the Protein A chromatography step. In addition, manufacturers are looking to move away from natural materials such as cellulose and Diatomaceous Earth (DE) for better filter consistency and security of supply. Therefore, there is an increased need for further understanding and knowledge of depth filtration. This study investigates the effect of depth filter material and loading on the Protein A resin lifetime with an industrially relevant high cell density feed material (40 million cells/ml). It focuses on the retention of process-related impurities such as DNA and HCP through breakthrough studies and a novel confocal microscopy method for imaging foulant in-situ. An increase in loading of the primary-synthetic filter by a third, led to earlier DNA breakthrough in the secondary filter, with DNA concentration at a throughput of 50 L/m 2 being more than double. Confocal imaging of the depth filters showed that the foulant was pushed forward into the filter structure with higher loading. The additional two layers in the primary-synthetic filter led to better pressure profiles in both primary and secondary filters but did not help to retain HCP or DNA. Reduced filtrate clarity, as measured by OD600, was 1.6 fold lower in the final filtrate where a synthetic filter train was used. This was also associated with precipitation in the Protein A column feed. Confocal imaging of resin after 100 cycles showed that DNA build-up around the outside of the bead was associated with synthetic filter trains, leading to potential mass transfer problems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Filtrate Clarity (Od600) and Dna Breakthroughmentioning

confidence: 99%

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Depth filter material process interaction in the harvest of mammalian cells

Parau

Pullen

Bracewell

2023

Biotechnology Progress

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Combining descriptive and predictive modeling to systematically design depth filtration‐based harvest processes for biologics

Liu,

Hartmann,

Shankaran

et al. 2024

Biotech & Bioengineering

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Advances in upstream production of biologics–particularly intensified fed‐batch processes beyond 10% cell solids–have severely strained harvest operations, especially depth filtration. Bioreactors containing high amounts of cell debris (more than 40% particles <10 µm in diameter) are increasingly common and drive the need for more robust depth filtration processes, while accelerated timelines emphasize the need for predictive tools to accelerate development. Both needs are constrained by the current limited mechanistic understanding of the harvest filter‐feedstream system. Historically, process development relied on screening scale‐down depth filter devices and conditions to define throughput before fouling, indicated by increasing differential pressure and/or particle breakthrough (measured via turbidity). This approach is straightforward, but resource‐intensive, and its results are inherently limited by the variability of the feedstream. Semi‐empirical models have been developed from first principles to describe various mechanisms of filter fouling, that is, pore constriction, pore blocking, and/or surface deposit. Fitting these models to experimental data can assist in identifying the dominant fouling mechanism. Still, this approach sees limited application to guide process development, as it is descriptive, not predictive. To address this gap, we developed a hybrid modeling approach. Leveraging historical bench scale filtration process data, we built a partial least squares regression model to predict particle breakthrough from filter and feedstream attributes, and leveraged the model to demonstrate prediction of filter performance a priori. The fouling models are used to interpret and provide physical meaning to these computational models. This hybrid approach–combining the mechanistic insights of fouling models and the predictive capability of computational models–was used to establish a robust platform strategy for depth filtration of Chinese hamster ovary cell cultures. As new data continues to teach the computational models, in silico tools will become an essential part of harvest process development by enabling prospective experimental design, reducing total experimental load, and accelerating development under strict timelines.

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Role of harvest depth filtration in controlling product-related impurities for a bispecific antibody

Cited by 2 publications

References 25 publications

Depth filter material process interaction in the harvest of mammalian cells

Depth filter material process interaction in the harvest of mammalian cells

Combining descriptive and predictive modeling to systematically design depth filtration‐based harvest processes for biologics

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