Pool‐less processing to streamline downstream purification of monoclonal antibodies

With cell culture titers and productivity increasing in the last few years, pressure has been placed on downstream purification to look at alternative strategies to meet the demand of biotech products with high dose requirements. Even when the upstream process is not continuous (perfusion based), adopting a more productive and/or continuous downstream process can be of significant advantage. Due to the recent trend in exploring continuous processing options for biomolecules, several enabling technologies have been assessed at Biogen. In this paper, we evaluate the capability of one of these technologies to streamline and improve our downstream mAb purification platform. Current conventional downstream polishing steps at Biogen are operated in flow‐through mode to achieve higher loadings while maintaining good selectivity. As titers increase, this would result in larger columns and larger intermediate product pool holding tanks. A semicontinuous downstream process linking the second and third chromatography steps in tandem can reduce/eliminate intermediate holding tanks, reduce overall processing time, and combine unit operations to reduce validation burdens. A pool‐less processing technology utilizing inline adjustment functionality was evaluated to address facility fit challenges for three high titer mAbs. Two different configurations of polishing steps were examined: (i) anion exchange and hydrophobic interaction and (ii) anion exchange and mixed mode chromatography. Initial laboratory scale proof of concept studies showed comparable performance between the batch purification process and the pool‐less process configuration.     

Stimuli-Responsive magnetic nanoparticles for monoclonal antibody purification

Monoclonal antibodies (mAbs) are important therapeutic proteins. One of the challenges facing large-scale production of monoclonal antibodies is the capacity bottleneck in downstream processing, which can be circumvented by using magnetic stimuli-responsive polymer nanoparticles. In this work, stimuli-responsive magnetic particles composed of a magnetic poly(methyl methacrylate) core with a poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) shell cross-linked with N, N'-methylenebisacrylamide were prepared by miniemulsion polymerization. The particles were shown to have an average hydrodynamic diameter of 317 nm at 18°C, which decreased to 277 nm at 41°C due to the collapse of the thermo-responsive shell. The particles were superparamagnetic in behavior and exhibited a saturation magnetization of 12.6 emu/g. Subsequently, we evaluated the potential of these negatively charged stimuli-responsive magnetic particles in the purification of a monoclonal antibody from a diafiltered CHO cell culture supernatant by cation exchange. The adsorption of antibodies onto P(NIPAM-co-AA)-coated nanoparticles was highly selective and allowed for the recovery of approximately 94% of the mAb. Different elution strategies were employed providing highly pure mAb fractions with host cell protein (HCP) removal greater than 98%. By exploring the stimuli-responsive properties of the particles, shorter magnetic separation times were possible without significant differences in product yield and purity.     

High-throughput methods for miniaturization and automation of monoclonal antibody purification processes

In the last decade, high-throughput downstream process development techniques have entered the biopharmaceutical industry. As chromatography is the standard downstream purification method, several high-throughput chromatographic methods have been developed and applied including miniaturized chromatographic columns for utilization on liquid handling stations. These columns were used to setup a complete downstream process on a liquid handling station for the first time. In this article, a monoclonal antibody process was established in lab-scale and miniaturized afterwards. The scale-down methodology is presented and discussed. Liquid handling in miniaturized single and multicolumn processes was improved and applicability was demonstrated by volume balances. The challenges of absorption measurement are discussed and strategies were shown to improve volume balances and mass balances in 96-well microtiter plates. The feasibility of miniaturizing a complete downstream process was shown. In the future, analytical bottlenecks should be addressed to gain the full benefit from miniaturized complete process development.     

Viral clearance by flow‐through mode ion exchange columns and membrane adsorbers

Anion exchange (AEX) is a common downstream purification operation for biotechnology products manufactured in cell culture such as therapeutic monoclonal antibodies (mAbs) and Fc‐fusion proteins. We present a head‐to‐head comparison of the viral clearance efficiency of AEX adsorbers and column chromatography using the same process fluids and comparable run conditions. We also present overall trends from the CDER viral clearance database. In our comparison of multiple brands of resins and adsorbers, clearance of three model viruses (PPV, X‐MuLV, and PR772) was largely comparable, with some exceptions which may reflect run conditions that had not been optimized on a resin/membrane specific basis. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:124–131, 2014     

Multistage aqueous two‐phase extraction of a monoclonal antibody from cell supernatant

This article presents results of continuous multistage aqueous two‐phase extraction of an immunoglobulin G1 from cell supernatant in a mixer‐settler unit. An aqueous two‐phase system consisting of polyethylene glycol 2000, phosphate salt, and water was applied without and with sodium chloride (NaCl). Influences of different parameters such as throughput, phase ratio, and stage number on the extraction performance were analyzed. For systems without NaCl, the extraction was carried out as a washing step. An increase of stage number from one to five stages enabled to increase the immunoglobulin G1 purity from 11.8 to 32.6% at a yield of nearly 90%. Furthermore, a reduction of product phase volume due to a higher phase ratio led to an increase of purity from 20.8 to 29.6% in a three‐stage countercurrent extraction. For experiments with NaCl moderate partitioning conditions were adjusted by adding 8 wt% NaCl. In that case, the extraction was carried out as a stripping step. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:925–936, 2015     

A fully defined,fed‐batch,recombinant NS0 culture process for monoclonal antibody production

To manufacture a glycoprotein, mammalian cells expressing the desired protein are often grown in fed‐batch mode. Feeding an undefined, nonanimal hydrolysate helps the cells receive sufficient nutrition, but makes systems difficult to optimize. Even different lots of the same hydrolysate may have significant variability; furthermore, individual components may actually be detrimental to the cells. Switching to fully defined feeds could eliminate these issues. For monoclonal antibody (mAb) production by fed‐batch NS0 cells, this article describes the replacement of a hydrolysate‐based feed with a fully defined, animal‐component‐free feed system. The defined feed initially had 67 components, but additional experiments allowed a reduction to 25 components. The mAb titer is approximately 20% higher than in the undefined system, and the feed volume is circa 20% lower. The two systems generated antibodies with similar glycosylation profiles. Other benefits of the defined feed system include lower raw material costs, the ability to optimize key nutrient concentrations, greater confidence in raw material quality, and the elimination of potential, hydrolysate‐associated endotoxin issues. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Development of downstream processing to minimize beta‐glucan impurities in GMP‐manufactured therapeutic antibodies

The presence of impurities or contaminants in biological products such as monoclonal antibodies (mAb) could affect efficacy or cause adverse reactions in patients. ICH guidelines (Q6A and Q6B) are in place to regulate the level of impurities within clinical drug products. An impurity less often reported and, therefore, lacking regulatory guideline is beta‐glucan. Beta‐glucans are polysaccharides of d ‐glucose monomers linked by (1‐3) beta‐glycosidic bonds, and are produced by prokaryotic and eukaryotic organisms, including plants. They may enter manufacturing processes via raw materials such as cellulose‐based membrane filters or sucrose. Here we report the detection of beta‐glucan contamination of a monoclonal IgE antibody (MOv18), manufactured in our facility for a first‐in‐human, first‐in‐class clinical trial in patients with cancer. Since beta‐glucans have potential immunostimulatory properties and can cause symptomatic infusion reactions, it was of paramount importance to identify the source of beta‐glucans in our product and to reduce the levels to clinically insignificant concentrations. We identified beta‐glucans in sucrose within the formulation buffer and within the housing storage buffer of the virus removal filter. We also detected low level beta‐glucan contamination in two of four commercially available antibodies used in oncology. Both formulation buffers contained sucrose. We managed to reduce levels of beta‐glucan in our product 10‐fold, by screening all sucrose raw material, filtering the sucrose by Posidyne® membrane filtration, and by incorporating extra wash steps when preparing the virus removal filter. The beta‐glucan levels now lie within a range that is unlikely to cause clinically significant immunological effects. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1494–1502, 2016     

A practical strategy for using miniature chromatography columns in a standardized high‐throughput workflow for purification development of monoclonal antibodies

The emergence of monoclonal antibody (mAb) therapies has created a need for faster and more efficient bioprocess development strategies in order to meet timeline and material demands. In this work, a high‐throughput process development (HTPD) strategy implementing several high‐throughput chromatography purification techniques is described. Namely, batch incubations are used to scout feasible operating conditions, miniature columns are then used to determine separation of impurities, and, finally, a limited number of lab scale columns are tested to confirm the conditions identified using high‐throughput techniques and to provide a path toward large scale processing. This multistep approach builds upon previous HTPD work by combining, in a unique sequential fashion, the flexibility and throughput of batch incubations with the increased separation characteristics for the packed bed format of miniature columns. Additionally, in order to assess the applicability of using miniature columns in this workflow, transport considerations were compared with traditional lab scale columns, and performances were mapped for the two techniques. The high‐throughput strategy was utilized to determine optimal operating conditions with two different types of resins for a difficult separation of a mAb monomer from aggregates. Other more detailed prediction models are cited, but the intent of this work was to use high‐throughput strategies as a general guide for scaling and assessing operating space rather than as a precise model to exactly predict performance. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:626–635, 2014     

Rapid detection and discrimination of fabaviruses by flow‐through hybridisation with genus‐ and species‐specific riboprobes

Viruses cause significant damage in agricultural crops worldwide. Disease management requires sensitive and specific tools for virus detection and identification. Also, detection techniques need to be rapid to keep pace with the continuous emergence of new viral diseases. The genus Fabavirus is composed of five viruses infecting many economically important crops worldwide. This research describes the development of a procedure based on flow‐through hybridisation (FTH), which is faster than and as sensitive as conventional hybridisation for virus detection in tissue‐prints from infected plants. Six digoxigenin‐labelled RNA probes were synthesised with two levels of specificity: (a) five specific for each viral species within this genus, and (b) a genus‐specific probe that hybridises with a nucleotide sequence signature only found in the 5′‐untranslated region of the genus Fabavirus, which is the first of this type reported for plant viruses. The new procedure developed is useful for rapid detection and discrimination of the five fabaviruses identified so far and opens the possibility of discovering new species of this genus.     

Clinical effects of monoclonal antibody 17-1A combined with granulocyte/macrophage-colony-stimulating factor and interleukin-2 for treatment of patients with advanced colorectal carcinoma

Granulocyte/macrophage-colony-stimulating factor (GM-CSF) has previously been indicated to enhance the therapeutic effect of the anti-colorectal carcinoma mAb17-1A as well as to augment in vivo immune effector functions. In vitro interleukin-2 (IL-2) augmented GM-CSF-induced antibody-dependent cellular cytotoxicity, a mechanism considered to be of significance for the therapeutic effect of mAb. A treatment regimen was elaborated that combined mAb17-1A (400 mg at day 3 of a 10-day treatment cycle) with the simultaneous administration of GM-CSF (250 μmg/m² once daily) and IL-2 (2.4 × 10⁶ U/m² twice daily) for 10 days. The treatment cycle was repeated once a month. Twenty patients with advanced colorectal carcinoma were included in the study. One patient obtained a partial remission and 2 patients stable disease for 7 and 4 months respectively. The median survival time from the start of mAb therapy was 8 months. Owing to allergic reactions, the planned mAb17-1A dose had to be reduced by repeated infusions. At the fourth treatment cycle only 25% received the planned mAb dose. In 3 patients the GM-CSF and IL-2 dose was reduced because of side-effects. The subjective tolerability of the treatment was considered good or acceptable in more than 80% of the patients. The increment in white blood cell subsets induced by the cytokines decreased by increasing number of courses. This particular regimen did not augment the therapeutic effect of mAb17-1A anticipated from in vitro data but rather hampered the clinical effect of the antibody. The reason for this is not clear but a possibility might be the induction of immune suppression in vivo resulting from an impaired human anti-(mouse Ab) and anti-idiotypic antibody response as well as antibody-dependent cellular cytotoxicity, on the basis of a comparison of mAb17-1A/GM-CSF/IL-2- and mAb17-1A/GM-CSF-treated patients. Received: 25 February 1999 / Accepted: 15 July 1999     

Development of a 3‐step straight‐through purification strategy combining membrane adsorbers and resins

The pressures to efficiently produce complex biopharmaceuticals at reduced costs are driving the development of novel techniques, such as in downstream processing with straight‐through processing (STP). This method involves directly and sequentially purifying a particular target with minimal holding steps. This work developed and compared six different 3‐step STP strategies, combining membrane adsorbers, monoliths, and resins, to purify a large, complex, and labile glycoprotein from Chinese hamster ovary cell culture supernatant. The best performing pathway was cation exchange chromatography to hydrophobic interaction chromatography to affinity chromatography with an overall product recovery of up to 88% across the process and significant clearance of DNA and protein impurities. This work establishes a platform and considerations for the development of STP of biopharmaceutical products and highlights its suitability for integration with single‐use technologies and continuous production methods. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:931–940, 2017     

Multi‐criteria manufacturability indices for ranking high‐concentration monoclonal antibody formulations

The need for high‐concentration formulations for subcutaneous delivery of therapeutic monoclonal antibodies (mAbs) can present manufacturability challenges for the final ultrafiltration/diafiltration (UF/DF) step. Viscosity levels and the propensity to aggregate are key considerations for high‐concentration formulations. This work presents novel frameworks for deriving a set of manufacturability indices related to viscosity and thermostability to rank high‐concentration mAb formulation conditions in terms of their ease of manufacture. This is illustrated by analyzing published high‐throughput biophysical screening data that explores the influence of different formulation conditions (pH, ions, and excipients) on the solution viscosity and product thermostability. A decision tree classification method, CART (Classification and Regression Tree) is used to identify the critical formulation conditions that influence the viscosity and thermostability. In this work, three different multi‐criteria data analysis frameworks were investigated to derive manufacturability indices from analysis of the stress maps and the process conditions experienced in the final UF/DF step. Polynomial regression techniques were used to transform the experimental data into a set of stress maps that show viscosity and thermostability as functions of the formulation conditions. A mathematical filtrate flux model was used to capture the time profiles of protein concentration and flux decay behavior during UF/DF. Multi‐criteria decision‐making analysis was used to identify the optimal formulation conditions that minimize the potential for both viscosity and aggregation issues during UF/DF. Biotechnol. Bioeng. 2017;114: 2043–2056. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Perodicals, Inc.     

Caprylic acid‐induced impurity precipitation from protein A capture column elution pool to enable a two‐chromatography‐step process for monoclonal antibody purification

This article presents the use of caprylic acid (CA) to precipitate impurities from the protein A capture column elution pool for the purification of monoclonal antibodies (mAbs) with the objective of developing a two chromatography step antibody purification process. A CA‐induced impurity precipitation in the protein A column elution pool was evaluated as an alternative method to polishing chromatography techniques for use in the purification of mAbs. Parameters including pH, CA concentrations, mixing time, mAb concentrations, buffer systems, and incubation temperatures were evaluated on their impacts on the impurity removal, high‐molecular weight (HMW) formation and precipitation step yield. Both pH and CA concentration, but not mAb concentrations and buffer systems, are key parameters that can affect host–cell proteins (HCPs) clearance, HMW species, and yield. CA precipitation removes HCPs and some HMW species to the acceptable levels under the optimal conditions. The CA precipitation process is robust at 15–25°C. For all five mAbs tested in this study, the optimal CA concentration range is 0.5–1.0%, while the pH range is from 5.0 to 6.0. A purification process using two chromatography steps (protein A capture column and ion exchange polishing column) in combination with CA‐based impurity precipitation step can be used as a robust downstream process for mAb molecules with a broad range of isoelectric points. Residual CA can be effectively removed by the subsequent polishing cation exchange chromatography. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1515–1525, 2015     

Impact of media and antifoam selection on monoclonal antibody production and quality using a high throughput micro‐bioreactor system

Monoclonal antibody production in commercial scale cell culture bioprocessing requires a thorough understanding of the engineering process and components used throughout manufacturing. It is important to identify high impact components early on during the lifecycle of a biotechnology‐derived product. While cell culture media selection is of obvious importance to the health and productivity of mammalian bioreactor operations, other components such as antifoam selection can also play an important role in bioreactor cell culture. Silicone polymer‐based antifoams were known to have negative impacts on cell health, production, and downstream filtration and purification operations. High throughput screening in micro‐scale bioreactors provides an efficient strategy to identify initial operating parameters. Here, we utilized a micro‐scale parallel bioreactor system to study an IgG1 producing CHO cell line, to screen Dynamis, ProCHO5, PowerCHO2, EX‐Cell Advanced, and OptiCHO media, and 204, C, EX‐Cell, SE‐15, and Y‐30 antifoams and their impacts on IgG1 production, cell growth, aggregation, and process control. This study found ProCHO5, EX‐Cell Advanced, and PowerCHO2 media supported strong cellular growth profiles, with an IVCD of 25‐35 × 10⁶ cells‐d/mL, while maintaining specific antibody production (Q_p > 2 pg/cell‐d) for our model cell line and a monomer percentage above 94%. Antifoams C, EX‐Cell, and SE‐15 were capable of providing adequate control of foaming while antifoam 204 and Y‐30 noticeably stunted cellular growth. This work highlights the utility of high throughput micro bioreactors and the importance of identifying both positive and negative impacts of media and antifoam selection on a model IgG1 producing CHO cell line. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 34:262–270, 2018