Regulatory recommendations for quality by design instead of quality by testing raise increasing interest in new sensor technologies. An online monitoring system for downstream processes is developed, which is based on an array of online detectors. Besides standard detectors (UV, pH, and conductivity), our chromatographic workstation is equipped with a fluorescence and a mid‐infrared spectrometer, a light scattering, and a refractive index detector. The combination of these sensors enables the prediction of specific protein concentration and various purity attributes, such as high molecular weight impurities, DNA and host cell protein content during the elution phase of a chromatographic antibody capture process. Prediction models solely based on online signals are set up providing real‐time predictions. No mechanistic models or information about the chromatographic runs is used. These predictions allow online pooling decisions replacing time‐ and labor‐intensive laboratory measurements. Different process variations, such as changes in the column load or elution buffer, are introduced to test the predictive power of the models. Extrapolation of the models worked well when the column load is changed, whereas model adjustment is necessary when the elution conditions are changed considerably.

Process analytical technology combines understanding and control of the process with real‐time monitoring of critical quality and performance attributes. The goal is to ensure the quality of the final product. Currently, chromatographic processes in biopharmaceutical production are predominantly monitored with UV/Vis absorbance and a direct correlation with purity and quantity is limited. In this study, a chromatographic workstation was equipped with additional online sensors, such as multi‐angle light scattering, refractive index, attenuated total reflection Fourier‐transform infrared, and fluorescence spectroscopy. Models to predict quantity, host cell proteins (HCP), and double‐stranded DNA (dsDNA) content simultaneously were developed and exemplified by a cation exchange capture step for fibroblast growth factor 2 expressed in Escherichia coliOnline data and corresponding offline data for product quantity and co‐eluting impurities, such as dsDNA and HCP, were analyzed using boosted structured additive regression. Different sensor combinations were used to achieve the best prediction performance for each quality attribute. Quantity can be adequately predicted by applying a small predictor set of the typical chromatographic workstation sensor signals with a test error of 0.85 mg/ml (range in training data: 0.1–28 mg/ml). For HCP and dsDNA additional fluorescence and/or attenuated total reflection Fourier‐transform infrared spectral information was important to achieve prediction errors of 200 (2–6579 ppm) and 340 ppm (8–3773 ppm), respectively.

A two-step purification process for human basic fibroblast growth factor (FGF-2) from clarified E. coli homogenate has been developed in which the impurity level after the second step is below the limit of quantification. Endotoxin content is cleared to 0.02 EU/μg FGF-2 and the overall yield is 67%. The performance of the cation exchanger Carboxymethyl-Sepharose Fast Flow (CM-SFF) was compared to the affinity resin Heparin-SFF regarding the impurity profile and product quality in the elution peak. The CM-SFF eluate was further purified using hydrophobic interaction resin Toyopearl-Hexyl-650C. The relative amounts of target product, host cell proteins (HCPs), dsDNA, endotoxin, monomer content, and high molecular weight impurities differed along the elution peak depending on the applied method. The bioactive monomer (>99%) was obtained with a yield of 48% for CM-SFF and 68% for Heparin-SFF. A half-load reduction in CM-SFF increased the yield up to 67% without deterioration of the impurity content. Assuming a dose of 400 μg FGF-2, endotoxin was reduced to 188 EU/dose, dsDNA <10 ng/dose, and HCP <2 ppm/dose using the cation exchanger. In the pooled eluate fractions, dsDNA was removed 4-fold (291 ng/mL) and endotoxin 14-fold (0.47 EU/μg FGF-2) more efficiently by CM-SFF than by affinity chromatography. In contrast, HCP clearance was 3-fold (13 ppm) more efficient with Heparin-SFF than CM-SFF. In contrast to process monitoring by UV or SDS-PAGE, this characterization is the basis for a Process Analytical Technology attempt when correlated with online monitored signals, as it enables knowledge-based pooling according to defined quality criteria.

The aim of this study was to semi-automate process analytics for the quantification of common impurities in downstream processing such as host cell DNA, host cell proteins and endotoxins using a commercial liquid handling station. By semiautomation, the work load to fully analyze the elution peak of a purification run was reduced by at least 2.41 h. The relative standard deviation of results among different operators over a time span of up to 6 months was at the best reduced by half, e.g. from 13.7 to 7.1% in dsDNA analysis. Automation did not improve the reproducibility of results produced by one operator but released time for data evaluation and interpretation or planning of experiments. Overall, semi-automation of process analytics reduced operator-specific influence on test results. Such robust and reproducible analytics is fundamental to establish process analytical technology and get downstream processing ready for Quality by Design approaches.

Truly continuous biomanufacturing processes enable an uninterrupted feed stream throughout the whole production without the need for holding tanks. We have utilized microporous anion and cation exchangers into which only salts, but not proteins, can penetrate into the pores for desalting of protein solutions, while diafiltration or dilution is usually employed for feed adjustments. Anion exchange and cation exchange chromatography columns were connected in series to remove both anions and cations. To increase operation performance, a continuous process was developed comprised of four columns. Continuous mode was achieved by staggered cycle operation, where one set of columns, consisting of one anion exchange and one cation exchange column, was loaded during the regeneration of the second set. Refolding, desalting and subsequent ion exchange capturing with a scFv as the model protein was demonstrated. The refolding solution was successfully desalted resulting in a consistent conductivity below 0.5 mS/cm from initial values of 10 to 11 mS/cm. With continuous operation process time could be reduced by 39% while productivity was increased to 163% compared to batch operation. Desalting of the protein solution resulted in up to seven-fold higher binding capacities in the subsequent ion exchange capture step with conventional protein binding resins. www.biotechnology-journal.com Biotechnology Journalwww.advancedsciencenews.com Biotechnol. J. 2017, 12, 1700082 for IB resolubilization to unfold the protein followed by a dilution step to reduce the chaotropic conditions which initiates protein folding. However, such refolding buffers commonly require also elevated salt concentrations [5] which therefore results in feed streams being high in conductivity, making ion exchange chromatography an unsuitable option for the next unit operation. Ion exchange chromatography is attractive for industry due to the costefficient resins with high capacities. Hence, additional process steps such as dilution or diafiltration have to be introduced to reduce salt concentration in the solution and allow efficient binding of the protein to the ion exchange resins [6]. Despite the high potential of continuous downstream processing, it is still rarely applied in the manufacturing of biologics. Other industries such as the food and chemical sector, have already successfully implemented integrated processes which create highly flexible and efficient production [6,7]. In continuous operation equipment size can be down scaled, which reduces not only investment costs but also operating costs due to buffer savings [8,9]. Additionally optimized cycle times improve also productivity [10,11]. Not only FDA has addressed this topic [12,13], it also raised the interest of numerous researchers in both academia and industry [14,15]. Even it is not realized on a large production scale yet, various different strategies for continuous biomanufacturing have been developed in recent years [8,[16][17][18][19][20][21].In this work, we describe a novel alternati...

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Biosimilars are increasing in economic importance. Just how similar a biosimilar needs to be to gain market approval is currently still decided on a per case basis. The authors try to shed light on one often cited critical quality attribute of monoclonal antibodies, namely charge heterogeneity. Using high resolution electrophoretic and chromatographic methods, the authors are able to separate and quantify the charge variant content of infliximab originator and three biosimilars. Additionally the authors quantified and compared the antigen binding affinity in an SPR based binding assay and analyzed the glycosylation pattern of all four of these infliximab biosimilar products. Even though the analytical methods did not show full similarity between originator and some biosimilars, all of the biosimilars have gained approval based on their clinical comparability. The authors would therefore argue, that analytical comparison is not always a good predictor for clinical interchangeability. Any future regulatory framework for the approval of biosimilars should reflect that the parameters chosen for analytical comparability have to be chosen carefully.

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